60 results on '"Lauber E"'
Search Results
2. Conformation of the 3'-end of beet necrotic yellow vein benevirus RNA 3 analysed by chemical and enzymatic probing and mutagenesis
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Lauber, E, primary
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- 1997
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3. Zur Werthvergleichung käuflicher Blauholzextracte
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Reinhard and Lauber, E.
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- 1882
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4. Congenital cytomegalovirus infection in newborn infants of mothers infected before pregnancy.
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SCHOPFER, KURT, LAUBER, EDGAR, KRECH, ULRICH, Schopfer, K, Lauber, E, and Krech, U
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COMMUNICABLE diseases ,CYTOMEGALOVIRUS diseases ,PREGNANCY complications ,VIRAL antibodies - Abstract
The rate of congenital cytomegalovirus (CMV) infection was studied in newborn infants in an African population in which all adults had experienced primary CMV infection during childhood. Viruria within the first 12 hours after delivery was taken as evidence of prenatal CMV infection. 28 of 2032 newborn infants examined had viruria, giving a rate of 1.4% congenital CMV infection. The presence of meternal serum antibody therefore appears not to protect the fetus from intrauterine infection. Either reactivation of latent maternal CMV infection or recurrence of infection during pregnancy despite the presence of serum antibodies may explain these findings. Whether the long-term effects of CMV infection acquired in utero differ in cases of primary maternal infection from those due to reactivated or recurrent infection in seropositive mothers, remains undecided. Thus, the value of a live CMV vaccine to prevent prenatal CMV infection may be questioned. [ABSTRACT FROM AUTHOR]
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- 1978
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5. Aufnahme und Retention von p-Aminosalicylsäure (PAS) und Benzoyl-p-aminosalicylsäure (B-PAS) durch Mycobacterium tuberculosis
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Lauber, E., Hurni, H., Schmid, U., and Aebi, H.
- Abstract
In Kulturen von Mycobacterium tuberculosis (Stamm H 37 Rv) ist die Verteilung von 14C-p-Aminosalicylsäure (PAS) und Benzoyl-p-aminosalicylsäure (B-PAS) in verschiedenen Versuchsanordnungen verglichen worden.
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- 1962
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6. Versuche mit verschieden 14C-markierter Benzoyl-p-aminosalicylsäure (B-PAS) in Kulturen von Mycobacterium tuberculosis
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Zeyer, J., Hurni, H., Fischer, R., Lauber, E., Schönholzer, G., and Aebi, H.
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Es wurde die Verteilung von verschieden 14C-markierter Benzoyl-p-aminosalicylsäure in Kulturen von Mycobacterium tuberculosis untersucht. Dabei ergab sich, daß B-PAS von Tuberkelbazillen in vitro um einen Faktor von mindestens 2—3 angereichert wird. Das Ausmaß der Anreicherung ist unter anderem von der Einwirkungsdauer der B-PAS und vom Alter der Kulturen abhängig.
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- 1960
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7. Maternal Diet, Breast Feeding and Infants' Growth
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Reinhardt, M. C. and Lauber, E.
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- 1981
8. Studies on the Purification and Characterization of 3,4-Dihydroxyphenylethylamine β-Hydroxylase
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Goldstein, M., primary, Lauber, E., additional, and McKereghan, M.R., additional
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- 1965
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9. Genomic insights into strategies used by Xanthomonas albilineans with its reduced artillery to spread within sugarcane xylem vessels
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Pieretti Isabelle, Royer Monique, Barbe Valérie, Carrere Sébastien, Koebnik Ralf, Couloux Arnaud, Darrasse Armelle, Gouzy Jérôme, Jacques Marie-Agnès, Lauber Emmanuelle, Manceau Charles, Mangenot Sophie, Poussier Stéphane, Segurens Béatrice, Szurek Boris, Verdier Valérie, Arlat Matthieu, Gabriel Dean W, Rott Philippe, and Cociancich Stéphane
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Biotechnology ,TP248.13-248.65 ,Genetics ,QH426-470 - Abstract
Abstract Background Xanthomonas albilineans causes leaf scald, a lethal disease of sugarcane. X. albilineans exhibits distinctive pathogenic mechanisms, ecology and taxonomy compared to other species of Xanthomonas. For example, this species produces a potent DNA gyrase inhibitor called albicidin that is largely responsible for inducing disease symptoms; its habitat is limited to xylem; and the species exhibits large variability. A first manuscript on the complete genome sequence of the highly pathogenic X. albilineans strain GPE PC73 focused exclusively on distinctive genomic features shared with Xylella fastidiosa—another xylem-limited Xanthomonadaceae. The present manuscript on the same genome sequence aims to describe all other pathogenicity-related genomic features of X. albilineans, and to compare, using suppression subtractive hybridization (SSH), genomic features of two strains differing in pathogenicity. Results Comparative genomic analyses showed that most of the known pathogenicity factors from other Xanthomonas species are conserved in X. albilineans, with the notable absence of two major determinants of the “artillery” of other plant pathogenic species of Xanthomonas: the xanthan gum biosynthesis gene cluster, and the type III secretion system Hrp (hypersensitive response and pathogenicity). Genomic features specific to X. albilineans that may contribute to specific adaptation of this pathogen to sugarcane xylem vessels were also revealed. SSH experiments led to the identification of 20 genes common to three highly pathogenic strains but missing in a less pathogenic strain. These 20 genes, which include four ABC transporter genes, a methyl-accepting chemotaxis protein gene and an oxidoreductase gene, could play a key role in pathogenicity. With the exception of hypothetical proteins revealed by our comparative genomic analyses and SSH experiments, no genes potentially involved in any offensive or counter-defensive mechanism specific to X. albilineans were identified, supposing that X. albilineans has a reduced artillery compared to other pathogenic Xanthomonas species. Particular attention has therefore been given to genomic features specific to X. albilineans making it more capable of evading sugarcane surveillance systems or resisting sugarcane defense systems. Conclusions This study confirms that X. albilineans is a highly distinctive species within the genus Xanthomonas, and opens new perpectives towards a greater understanding of the pathogenicity of this destructive sugarcane pathogen.
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- 2012
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10. The complete genome sequence of Xanthomonas albilineans provides new insights into the reductive genome evolution of the xylem-limited Xanthomonadaceae
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Szurek Boris, Segurens Béatrice, Poussier Stéphane, Manceau Charles, Mangenot Sophie, Lauber Emmanuelle, Jacques Marie-Agnès, Darrasse Armelle, Gouzy Jérôme, Couloux Arnaud, Cociancich Stéphane, Koebnik Ralf, Carrere Sébastien, Barbe Valérie, Royer Monique, Pieretti Isabelle, Verdier Valérie, Arlat Matthieu, and Rott Philippe
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Biotechnology ,TP248.13-248.65 ,Genetics ,QH426-470 - Abstract
Abstract Background The Xanthomonadaceae family contains two xylem-limited plant pathogenic bacterial species, Xanthomonas albilineans and Xylella fastidiosa. X. fastidiosa was the first completely sequenced plant pathogen. It is insect-vectored, has a reduced genome and does not possess hrp genes which encode a Type III secretion system found in most plant pathogenic bacteria. X. fastidiosa was excluded from the Xanthomonas group based on phylogenetic analyses with rRNA sequences. Results The complete genome of X. albilineans was sequenced and annotated. X. albilineans, which is not known to be insect-vectored, also has a reduced genome and does not possess hrp genes. Phylogenetic analysis using X. albilineans genomic sequences showed that X. fastidiosa belongs to the Xanthomonas group. Order of divergence of the Xanthomonadaceae revealed that X. albilineans and X. fastidiosa experienced a convergent reductive genome evolution during their descent from the progenitor of the Xanthomonas genus. Reductive genome evolutions of the two xylem-limited Xanthomonadaceae were compared in light of their genome characteristics and those of obligate animal symbionts and pathogens. Conclusion The two xylem-limited Xanthomonadaceae, during their descent from a common ancestral parent, experienced a convergent reductive genome evolution. Adaptation to the nutrient-poor xylem elements and to the cloistered environmental niche of xylem vessels probably favoured this convergent evolution. However, genome characteristics of X. albilineans differ from those of X. fastidiosa and obligate animal symbionts and pathogens, indicating that a distinctive process was responsible for the reductive genome evolution in this pathogen. The possible role in genome reduction of the unique toxin albicidin, produced by X. albilineans, is discussed.
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- 2009
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11. Comparative transcriptomics reveals a highly polymorphic Xanthomonas HrpG virulence regulon.
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Monnens TQ, Roux B, Cunnac S, Charbit E, Carrère S, Lauber E, Jardinaud MF, Darrasse A, Arlat M, Szurek B, Pruvost O, Jacques MA, Gagnevin L, Koebnik R, Noël LD, and Boulanger A
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- Virulence genetics, Transcriptome, Type III Secretion Systems genetics, Type III Secretion Systems metabolism, Gene Expression Profiling, Transcription Factors genetics, Transcription Factors metabolism, Xanthomonas pathogenicity, Xanthomonas genetics, Regulon, Bacterial Proteins genetics, Bacterial Proteins metabolism, Gene Expression Regulation, Bacterial
- Abstract
Background: Bacteria of the genus Xanthomonas cause economically significant diseases in various crops. Their virulence is dependent on the translocation of type III effectors (T3Es) into plant cells by the type III secretion system (T3SS), a process regulated by the master response regulator HrpG. Although HrpG has been studied for over two decades, its regulon across diverse Xanthomonas species, particularly beyond type III secretion, remains understudied., Results: In this study, we conducted transcriptome sequencing to explore the HrpG regulons of 17 Xanthomonas strains, encompassing six species and nine pathovars, each exhibiting distinct host and tissue specificities. We employed constitutive expression of plasmid-borne hrpG*, which encodes a constitutively active form of HrpG, to induce the regulon. Our findings reveal substantial inter- and intra-specific diversity in the HrpG* regulons across the strains. Besides 21 genes directly involved in the biosynthesis of the T3SS, the core HrpG* regulon is limited to only five additional genes encoding the transcriptional activator HrpX, the two T3E proteins XopR and XopL, a major facility superfamily (MFS) transporter, and the phosphatase PhoC. Interestingly, genes involved in chemotaxis and genes encoding enzymes with carbohydrate-active and proteolytic activities are variably regulated by HrpG*., Conclusions: The diversity in the HrpG* regulon suggests that HrpG-dependent virulence in Xanthomonas might be achieved through several distinct strain-specific strategies, potentially reflecting adaptation to diverse ecological niches. These findings enhance our understanding of the complex role of HrpG in regulating various virulence and adaptive pathways, extending beyond T3Es and the T3SS., (© 2024. The Author(s).)
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- 2024
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12. Bacterial host adaptation through sequence and structural variations of a single type III effector gene.
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Lauber E, González-Fuente M, Escouboué M, Vicédo C, Luneau JS, Pouzet C, Jauneau A, Gris C, Zhang ZM, Pichereaux C, Carrère S, Deslandes L, and Noël LD
- Abstract
Molecular mechanisms underlying quantitative variations of pathogenicity remain elusive. Here, we identified the Xanthomonas campestris XopJ6 effector that triggers disease resistance in cauliflower and Arabidopsis thaliana . XopJ6 is a close homolog of the Ralstonia pseudo solanacearum PopP2 YopJ family acetyltransferase. XopJ6 is recognized by the RRS1-R/RPS4 NLR pair that integrates a WRKY decoy domain mimicking effector targets. We identified a XopJ6 natural variant carrying a single residue substitution in XopJ6 WRKY-binding site that disrupts interaction with WRKY proteins. This mutation allows XopJ6 to evade immune perception while retaining some XopJ6 virulence functions. Interestingly, xopJ6 resides in a Tn 3 -family transposon likely contributing to xopJ6 copy number variation (CNV). Using synthetic biology, we demonstrate that xopJ6 CNV tunes pathogen virulence on Arabidopsis through gene dosage-mediated modulation of xopJ6 expression . Together, our findings highlight how sequence and structural genetic variations restricted at a particular effector gene contribute to bacterial host adaptation., Competing Interests: The authors declare no competing interests., (© 2024 The Authors.)
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- 2024
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13. High-risk Individuals and Naloxone Use: Implications for THN Programs in Rural Appalachian Communities.
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Garcia V, McCann L, Lauber E, Vaccaro C, Swauger M, and Heckert AD
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Introduction: Take-home naloxone (THN) is being made available across rural Appalachia to curb opioid overdose fatalities. Despite this initiative, some opioid users do not possess naloxone, and if they do, do not administer it to others., Purpose: Research findings on risk factors that contribute to opioid overdose are presented. These factors, identified in a sample of 16 overdose cases, are (1) early onset age of opioid use; (2) progressive opioid use; (3) a transition from pain medication to heroin and fentanyl; (4) fears of being arrested at a naloxone intervention if first responders are contacted, and (5) limited knowledge of Good Samaritan Laws., Methods: The findings are based on a subsample 16 overdose victims who were identified during a one-year (2018) qualitative study on the decline of overdose fatalities in four rural counties in Western Pennsylvania. They were recruited from a larger sample of 50 current and former substance users and were interviewed a second time using a semi-structured interview guide about their overdose experiences. All interview data were analyzed using thematic analysis via NVivo., Results: Findings reveal that risk factors contribute to a severe opioid dependence that interferes with naloxone use. These factors also hinder adherence to proper naloxone protocol, designed to place overdose victims in contact with treatment providers., Implications: Recommendations are made for additional research and for pursuing measures to increase efficacy of naloxone interventions. They include developing naloxone campaigns aimed at high-risk individuals, improving their knowledge of Good Samaritan Laws, increasing adherence to THN protocols that improve the possibility of treatment, and using community harm reduction specialists for community outreach., Competing Interests: Cover Page Footnote: No competing financial or editorial interests were reported by the authors of this paper., (Copyright © 2023 Victor Garcia, Lisa McCann, Erick Lauber, Christian Vaccaro, Melissa Swauger, and Alex Daniel Heckert.)
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- 2023
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14. Arabidopsis thaliana Early Foliar Proteome Response to Root Exposure to the Rhizobacterium Pseudomonas simiae WCS417.
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Marzorati F, Rossi R, Bernardo L, Mauri P, Silvestre DD, Lauber E, Noël LD, Murgia I, and Morandini P
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- Proteome metabolism, Proteomics, Plant Roots microbiology, Soil, Gene Expression Regulation, Plant, Arabidopsis metabolism, Arabidopsis Proteins genetics, Arabidopsis Proteins metabolism
- Abstract
Pseudomonas simiae WCS417 is a plant growth-promoting rhizobacterium that improves plant health and development. In this study, we investigate the early leaf responses of Arabidopsis thaliana to WCS417 exposure and the possible involvement of formate dehydrogenase (FDH) in such responses. In vitro-grown A. thaliana seedlings expressing an FDH::GUS reporter show a significant increase in FDH promoter activity in their roots and shoots after 7 days of indirect exposure (without contact) to WCS417. After root exposure to WCS417, the leaves of FDH::GUS plants grown in the soil also show an increased FDH promoter activity in hydathodes. To elucidate early foliar responses to WCS417 as well as FDH involvement, the roots of A. thaliana wild-type Col and atfdh1-5 knock-out mutant plants grown in soil were exposed to WCS417, and proteins from rosette leaves were subjected to proteomic analysis. The results reveal that chloroplasts, in particular several components of the photosystems PSI and PSII, as well as members of the glutathione S -transferase family, are among the early targets of the metabolic changes induced by WCS417. Taken together, the alterations in the foliar proteome, as observed in the atfdh1 - 5 mutant, especially after exposure to WCS417 and involving stress-responsive genes, suggest that FDH is a node in the early events triggered by the interactions between A. thaliana and the rhizobacterium WCS417. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license., Competing Interests: The author(s) declare no conflict of interest.
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- 2023
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15. Daily practices of advanced practice nurses within a multi-professional primary care practice in Switzerland: a qualitative analysis.
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Altermatt-von Arb R, Stoll H, Kindlimann A, Nicca D, Lauber E, Staudacher S, Sailer Schramm M, Vökt F, and Zúñiga F
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- Humans, Aged, Aged, 80 and over, Switzerland, Anthropology, Cultural, Primary Health Care, Professional Practice, Nurse Practitioners
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Background: The rising global population of older persons with chronic conditions demands new primary care models. Advanced practice nurses (APNs) can help meet that need. In Switzerland, APNs have only recently been introduced in primary care and little is known about their daily practice. This study aims to describe APNs' activities and general roles at four sites with multi-professional primary care practices in the Swiss cantons of Bern and Solothurn., Methods: To study the practices of APNs at the study sites, we adopted a social constructivist perspective, lending methods from ethnographic field research. We interviewed, observed and accompanied participants over five months, generating rich data on their daily practices. The analysis followed Braun and Clarke's six-step thematic analysis process., Results: The APNs' daily practices cover three main themes. Their core activities are working with expanded clinical skills and being on-site specialists for patients and their relatives. These practices are surrounded by net activities, i.e., taking care of patients in tandem with the physicians and regular visits in residential long-term care facilities. The outer activity layer consists of cohesive activities, with which APNs anchor and facilitate their role and catalyze further development of the care model. APNs tailor their expanded medical knowledge and nursing practice to maximize the value they provide in patient care., Conclusions: This study extends our knowledge of APNs' daily practice within a Swiss multi-professional primary care practice. Our results indicate competencies that need to be integrated in APN education and point out the high potential of APN integration in such primary care practices., (© 2023. The Author(s).)
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- 2023
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16. Genome-wide identification of fitness determinants in the Xanthomonas campestris bacterial pathogen during early stages of plant infection.
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Luneau JS, Baudin M, Quiroz Monnens T, Carrère S, Bouchez O, Jardinaud MF, Gris C, François J, Ray J, Torralba B, Arlat M, Lewis JD, Lauber E, Deutschbauer AM, Noël LD, and Boulanger A
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- Bacterial Proteins genetics, Bacterial Proteins metabolism, Plant Diseases microbiology, Virulence genetics, Xylem metabolism, Brassica microbiology, Xanthomonas campestris
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Plant diseases are an important threat to food production. While major pathogenicity determinants required for disease have been extensively studied, less is known on how pathogens thrive during host colonization, especially at early infection stages. Here, we used randomly barcoded-transposon insertion site sequencing (RB-TnSeq) to perform a genome-wide screen and identify key bacterial fitness determinants of the vascular pathogen Xanthomonas campestris pv campestris (Xcc) during infection of the cauliflower host plant (Brassica oleracea). This high-throughput analysis was conducted in hydathodes, the natural entry site of Xcc, in xylem sap and in synthetic media. Xcc did not face a strong bottleneck during hydathode infection. In total, 181 genes important for fitness were identified in plant-associated environments with functional enrichment in genes involved in metabolism but only few genes previously known to be involved in virulence. The biological relevance of 12 genes was independently confirmed by phenotyping single mutants. Notably, we show that XC_3388, a protein with no known function (DUF1631), plays a key role in the adaptation and virulence of Xcc possibly through c-di-GMP-mediated regulation. This study revealed yet unsuspected social behaviors adopted by Xcc individuals when confined inside hydathodes at early infection stages., (© 2022 The Authors. New Phytologist © 2022 New Phytologist Foundation.)
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- 2022
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17. Cruciferous Weed Isolates of Xanthomonas campestris Yield Insight into Pathovar Genomic Relationships and Genetic Determinants of Host and Tissue Specificity.
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Dubrow ZE, Carpenter SCD, Carter ME, Grinage A, Gris C, Lauber E, Butchachas J, Jacobs JM, Smart CD, Tancos MA, Noël LD, and Bogdanove AJ
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- Genomics, Organ Specificity, Protein Sorting Signals, Xanthomonas genetics, Xanthomonas campestris genetics
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Pathovars of Xanthomonas campestris cause distinct diseases on different brassicaceous hosts. The genomic relationships among pathovars as well as the genetic determinants of host range and tissue specificity remain poorly understood despite decades of research. Here, leveraging advances in multiplexed long-read technology, we fully sequenced the genomes of a collection of X. campestris strains isolated from cruciferous crops and weeds in New York and California as well as strains from global collections, to investigate pathovar relationships and candidate genes for host- and tissue-specificity. Pathogenicity assays and genomic comparisons across this collection and publicly available X. campestris genomes revealed a correlation between pathovar and genomic relatedness and provide support for X. campestris pv. barbareae , the validity of which had been questioned. Linking strain host range with type III effector repertoires identified AvrAC (also 'XopAC') as a candidate host-range determinant, preventing infection of Matthiola incana , and this was confirmed experimentally. Furthermore, the presence of a copy of the cellobiosidase gene cbsA with coding sequence for a signal peptide was found to correlate with the ability to infect vascular tissues, in agreement with a previous study of diverse Xanthomonas species; however, heterologous expression in strains lacking the gene gave mixed results, indicating that factors in addition to cbsA influence tissue specificity of X. campestris pathovars. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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- 2022
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18. A β-glucuronidase (GUS) Based Bacterial Competition Assay to Assess Fine Differencesin Fitness during Plant Infection.
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Luneau JS, Noël LD, Lauber E, and Boulanger A
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Competition assays are a simple phenotyping strategy that confront two bacterial strains to evaluate their relative fitness. Because they are more accurate than single-strain growth assays, competition assays can be used to highlight slight differences that would not otherwise be detectable. In the frame of host-pathogens interactions, they can be very useful to study the contribution of individual bacterial genes to bacterial fitness and lead to the identification of new adaptive traits. Here, we describe how to perform such competition assays by taking the example of the model phytopathogenic bacterium Xanthomonas campestris pv. campestris during infection of the mesophyll of its cauliflower host. This phenotypic assay is based on the use of a Competitive Index (CI) that compares the relative abundance of co-inoculated strains before and after inoculation. Since multiplication is a direct proxy for bacterial fitness, the evolution of the ratio between both strains in the mixed population is a direct way to assess differences in fitness in a given environment. In this protocol, we exploit the blue staining of GUS-expressing bacteria to count blue vs . white colonies on plates and estimate the competitiveness of the strains of interest in plant mesophyll., Competing Interests: Competing interestsThere are no competing interests., (Copyright © 2022 The Authors; exclusive licensee Bio-protocol LLC.)
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- 2022
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19. Integration of an advanced practice nurse into a primary care practice: a qualitative analysis of experiences with changes in general practitioner professional roles in a Swiss multiprofessional primary care practice.
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Lauber E, Kindlimann A, Nicca D, Altermatt-von Arb R, Sgier C, Staudacher S, Sailer Schramm M, Vökt F, and Zúñiga F
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- General Practitioners, Humans, Professional Role, Qualitative Research, Switzerland, Advanced Practice Nursing organization & administration, Primary Health Care organization & administration
- Abstract
Background: The complex care needs of people with chronic illnesses and multimorbidity pose a significant challenge to the Swiss primary care system. Ensuring efficient, high-quality care will require new care models. Internationally, the integration of advanced practice nurses (APNs) into primary care models has shown promising results. The current study investigates how general practitioners (GPs) in Switzerland experience the integration of APNs into their primary care teams with respect to their own professional roles., Methods: We used a qualitative, social-constructivist approach, focusing on six individual interviews with general practitioners within the frame of a larger study including GPs and APNs in a Swiss multiprofessional primary care practice. Data were analysed following Braun and Clarke's approach for reflexive thematic analysis., Setting and Participants: The study took place between August 2019 and February 2020 in a Swiss multiprofessional primary care practice that had been working with APNs for nine years. Participants included six general practitioners., Results: We identified three main themes characterising Swiss GPs' experiences with the integration of APNs into their primary care team: (1) trust as foundation for collaboration with APNs; (2) build-up of the APN role by delegation, teaching, and supervision, investing time particularly at the beginning of their collaboration with the APN - a time investment that declined significantly as the APNs' competencies grew - and (3) synergies of partnership-based collaboration with APNs. Physicians who were experienced teachers and supervisors, and who delegated tasks based on who would be able to fulfil them most efficiently and effectively, experienced not only a broad range of synergies, but also possibilities to further develop the range of their own activities. Comprehensive, high-quality patient care was perceived as a particular added value., Conclusion: Our analysis revealed that GPs experienced interprofessional synergies when working collaboratively with APNs. These were rooted in trust and relied on abilities in teaching, supervision and delegation to achieve maximum impact. Capitalising on the integration of APNs into primary care, this new care model can be adapted to diverse individual settings. We conclude this article by highlighting the potential of working collaboratively with APNs, who play increasingly important roles in the primary care of polymorbid patients with complex needs.
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- 2022
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20. Xanthomonas transcriptome inside cauliflower hydathodes reveals bacterial virulence strategies and physiological adaptations at early infection stages.
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Luneau JS, Cerutti A, Roux B, Carrère S, Jardinaud MF, Gaillac A, Gris C, Lauber E, Berthomé R, Arlat M, Boulanger A, and Noël LD
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- Adaptation, Physiological genetics, Bacterial Proteins metabolism, Gene Expression Regulation, Bacterial, Plant Diseases genetics, Transcriptome genetics, Virulence genetics, Brassica genetics, Xanthomonas metabolism, Xanthomonas campestris genetics
- Abstract
Xanthomonas campestris pv. campestris (Xcc) is a seed-transmitted vascular pathogen causing black rot disease on cultivated and wild Brassicaceae. Xcc enters the plant tissues preferentially via hydathodes, which are organs localized at leaf margins. To decipher both physiological and virulence strategies deployed by Xcc during early stages of infection, the transcriptomic profile of Xcc was analysed 3 days after entry into cauliflower hydathodes. Despite the absence of visible plant tissue alterations and despite a biotrophic lifestyle, 18% of Xcc genes were differentially expressed, including a striking repression of chemotaxis and motility functions. The Xcc full repertoire of virulence factors had not yet been activated but the expression of the HrpG regulon composed of 95 genes, including genes coding for the type III secretion machinery important for suppression of plant immunity, was induced. The expression of genes involved in metabolic adaptations such as catabolism of plant compounds, transport functions, sulphur and phosphate metabolism was upregulated while limited stress responses were observed 3 days postinfection. We confirmed experimentally that high-affinity phosphate transport is needed for bacterial fitness inside hydathodes. This analysis provides information about the nutritional and stress status of bacteria during the early biotrophic infection stages and helps to decipher the adaptive strategy of Xcc to the hydathode environment., (© 2021 The Authors. Molecular Plant Pathology published by British Society for Plant Pathology and John Wiley & Sons Ltd.)
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- 2022
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21. The Same against Many: AtCML8, a Ca 2+ Sensor Acting as a Positive Regulator of Defense Responses against Several Plant Pathogens.
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Zhu X, Mazard J, Robe E, Pignoly S, Aguilar M, San Clemente H, Lauber E, Berthomé R, and Galaud JP
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- Arabidopsis immunology, Arabidopsis microbiology, Arabidopsis physiology, Gene Expression Regulation, Plant, Phytophthora, Ralstonia solanacearum, Xanthomonas campestris, Arabidopsis metabolism, Calcium metabolism, Disease Resistance, Plant Diseases, Signal Transduction
- Abstract
Calcium signals are crucial for the activation and coordination of signaling cascades leading to the establishment of plant defense mechanisms. Here, we studied the contribution of CML8, an Arabidopsis calmodulin-like protein in response to Ralstonia solanacearum and to pathogens with different lifestyles, such as Xanthomonas campestris pv. campestris and Phytophtora capsici . We used pathogenic infection assays, gene expression, RNA-seq approaches, and comparative analysis of public data on CML8 knockdown and overexpressing Arabidopsis lines to demonstrate that CML8 contributes to defense mechanisms against pathogenic bacteria and oomycetes. CML8 gene expression is finely regulated at the root level and manipulated during infection with Ralstonia , and CML8 overexpression confers better plant tolerance. To understand the processes controlled by CML8, genes differentially expressed at the root level in the first hours of infection have been identified. Overexpression of CML8 also confers better tolerance against Xanthomonas and Phytophtora, and most of the genes differentially expressed in response to Ralstonia are differentially expressed in these different pathosystems. Collectively, CML8 acts as a positive regulator against Ralstonia solanaceraum and against other vascular or root pathogens, suggesting that CML8 is a multifunctional protein that regulates common downstream processes involved in the defense response of plants to several pathogens.
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- 2021
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22. From effectors to effectomes: Are functional studies of individual effectors enough to decipher plant pathogen infectious strategies?
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Arroyo-Velez N, González-Fuente M, Peeters N, Lauber E, and Noël LD
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- Host-Pathogen Interactions genetics, Host-Pathogen Interactions physiology, Plant Diseases genetics, Plant Diseases immunology, Plants immunology
- Abstract
Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2020
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23. Negative Regulation of BOK Expression by Recruitment of TRIM28 to Regulatory Elements in Its 3' Untranslated Region.
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Fernandez-Marrero Y, Bachmann D, Lauber E, and Kaufmann T
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BCL-2-related ovarian killer (BOK) is a pro-apoptotic BAX-like member of the BCL-2 family with suggested tumor suppressor activity. The molecular mechanisms regulating BOK expression are poorly understood and fail to explain a frequent lack of concordance between protein and transcript levels. Here, we describe a potent post-transcriptional mechanism that negatively regulates BOK expression mediated by conserved (AU/U)-rich elements within its 3' UTR. Using proteomics approaches we identified TRIM28 as a key component associating with U-rich elements in the human BOK 3' UTR, resulting in a dramatic reduction of BOK expression. TRIM28 is overexpressed in several cancers, correlating with poor patient outcome, whereas the BOK locus is frequently deleted or its expression downregulated in human cancers. Data mining indicated that, for certain cancers, high TRIM28 and low BOK expression are significantly correlated in the stratum of patients with the worst survival, suggesting that this mechanism might be of potential therapeutic value., (Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.)
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- 2018
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24. Dysregulation of Parvalbumin Expression in the Cntnap2-/- Mouse Model of Autism Spectrum Disorder.
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Lauber E, Filice F, and Schwaller B
- Abstract
Due to the complex and heterogeneous etiology of autism spectrum disorder (ASD), identification of convergent pathways and/or common molecular endpoints in the pathophysiological processes of ASD development are highly needed in order to facilitate treatment approaches targeted at the core symptoms. We recently reported on decreased expression of the Ca
2+ -binding protein parvalbumin (PV) in three well-characterized ASD mouse models, Shank1-/- , Shank3B-/- and in utero VPA-exposed mice. Moreover, PV-deficient mice ( PV+/- and PV-/- ) were found to show behavioral impairments and neuroanatomical changes closely resembling those frequently found in human ASD individuals. Here, we combined a stereology-based approach with molecular biology methods to assess changes in the subpopulation of PV-expressing (Pvalb) interneurons in the recently characterized contactin-associated protein-like 2 ( Cntnap2-/- ) knockout mouse model of ASD. The CNTNAP2 gene codes for a synaptic cell adhesion molecule involved in neurodevelopmental processes; mutations affecting the human CNTNAP2 locus are associated with human ASD core symptoms, in particular speech and language problems. We demonstrate that in Cntnap2-/- mice, no loss of Pvalb neurons is evident in ASD-associated brain regions including the striatum, somatosensory cortex (SSC) and medial prefrontal cortex (mPFC), shown by the unaltered number of Pvalb neurons ensheathed by VVA-positive perineuronal nets. However, the number of PV-immunoreactive (PV+ ) neurons and also PV protein levels were decreased in the striatum of Cntnap2-/- mice indicating that PV expression levels in some striatal Pvalb neurons dropped below the detection limit, yet without a loss of Pvalb neurons. No changes in PV+ neuron numbers were detected in the cortical regions investigated and also cortical PV expression levels were unaltered. Considering that Cntnap2 shows high expression levels in the striatum during human and mouse embryonic development and that the cortico-striato-thalamic circuitry is important for speech and language development, alterations in striatal PV expression and associated (homeostatic) adaptations are likely to play an important role in Cntnap2-/- mice and, assumingly, in human ASD patients with known Cntnap2 mutations.- Published
- 2018
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25. Two ancestral genes shaped the Xanthomonas campestris TAL effector gene repertoire.
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Denancé N, Szurek B, Doyle EL, Lauber E, Fontaine-Bodin L, Carrère S, Guy E, Hajri A, Cerutti A, Boureau T, Poussier S, Arlat M, Bogdanove AJ, and Noël LD
- Subjects
- Brassica microbiology, Genome, Bacterial, Phylogeny, Plant Diseases microbiology, Host-Pathogen Interactions genetics, Transcription Activator-Like Effectors genetics, Xanthomonas campestris genetics, Xanthomonas campestris pathogenicity
- Abstract
Xanthomonas transcription activator-like effectors (TALEs) are injected inside plant cells to promote host susceptibility by enhancing transcription of host susceptibility genes. TALE-encoding (tal) genes were thought to be absent from Brassicaceae-infecting Xanthomonas campestris (Xc) genomes based on four reference genomic sequences. We discovered tal genes in 26 of 49 Xc strains isolated worldwide and used a combination of single molecule real time (SMRT) and tal amplicon sequencing to yield a near-complete description of the TALEs found in Xc (Xc TALome). The 53 sequenced tal genes encode 21 distinct DNA binding domains that sort into seven major DNA binding specificities. In silico analysis of the Brassica rapa promoterome identified a repertoire of predicted TALE targets, five of which were experimentally validated using quantitative reverse transcription polymerase chain reaction. The Xc TALome shows multiple signs of DNA rearrangements that probably drove its evolution from two ancestral tal genes. We discovered that Tal12a and Tal15a of Xcc strain Xca5 contribute together in the development of disease symptoms on susceptible B. oleracea var. botrytis cv Clovis. This large and polymorphic repertoire of TALEs opens novel perspectives for elucidating TALE-mediated susceptibility of Brassicaceae to black rot disease and for understanding the molecular processes underlying TALE evolution., (© 2018 The Authors New Phytologist © 2018 New Phytologist Trust.)
- Published
- 2018
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26. 17-β estradiol increases parvalbumin levels in Pvalb heterozygous mice and attenuates behavioral phenotypes with relevance to autism core symptoms.
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Filice F, Lauber E, Vörckel KJ, Wöhr M, and Schwaller B
- Subjects
- Animals, Autistic Disorder genetics, Heterozygote, Male, Mice, Mice, Inbred C57BL, Parvalbumins metabolism, Phenotype, Up-Regulation, Autistic Disorder drug therapy, Estradiol therapeutic use, Parvalbumins genetics, Social Behavior, Stereotyped Behavior
- Abstract
Background: Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders characterized by two core symptoms: impaired social interaction and communication, and restricted, repetitive behaviors and interests. The pathophysiology of ASD is not yet fully understood, due to a plethora of genetic and environmental risk factors that might be associated with or causal for ASD. Recent findings suggest that one putative convergent pathway for some forms of ASD might be the downregulation of the calcium-binding protein parvalbumin (PV). PV-deficient mice (PV-/-, PV+/-), as well as Shank1-/-, Shank3-/-, and VPA mice, which show behavioral deficits relevant to all human ASD core symptoms, are all characterized by lower PV expression levels., Methods: Based on the hypothesis that PV expression might be increased by 17-β estradiol (E2), PV+/- mice were treated with E2 from postnatal days 5-15 and ASD-related behavior was tested between postnatal days 25 and 31., Results: PV expression levels were significantly increased after E2 treatment and, concomitantly, sociability deficits in PV+/- mice in the direct reciprocal social interaction and the 3-chamber social approach assay, as well as repetitive behaviors, were attenuated. E2 treatment of PV+/+ mice did not increase PV levels and had detrimental effects on sociability and repetitive behavior. In PV-/- mice, E2 obviously did not affect PV levels; tested behaviors were not different from the ones in vehicle-treated PV-/- mice., Conclusion: Our results suggest that the E2-linked amelioration of ASD-like behaviors is specifically occurring in PV+/- mice, indicating that PV upregulation is required for the E2-mediated rescue of ASD-relevant behavioral impairments., Competing Interests: All experiments were performed with permission of the local animal care committees (Canton of Fribourg, Switzerland) and according to the present Swiss/Germany law and the European Communities Council Directive of 24 November 1986 (86/609/EEC).Not applicable.The authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
- Published
- 2018
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27. Immunity at Cauliflower Hydathodes Controls Systemic Infection by Xanthomonas campestris pv campestris .
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Cerutti A, Jauneau A, Auriac MC, Lauber E, Martinez Y, Chiarenza S, Leonhardt N, Berthomé R, and Noël LD
- Subjects
- Abscisic Acid pharmacology, Arabidopsis anatomy & histology, Arabidopsis drug effects, Arabidopsis immunology, Arabidopsis microbiology, Brassica microbiology, Host-Pathogen Interactions, Plant Leaves microbiology, Plant Stomata anatomy & histology, Plants, Genetically Modified, Xanthomonas campestris genetics, Brassica anatomy & histology, Brassica immunology, Plant Diseases immunology, Xanthomonas campestris pathogenicity
- Abstract
Hydathodes are water pores found on leaves of a wide range of vascular plants and are the sites of guttation. We report here on the detailed anatomy of cauliflower ( Brassica oleracea ) and Arabidopsis ( Arabidopsis thaliana ) hydathodes. Hydathode surface presents pores resembling stomata giving access to large cavities. Beneath, the epithem is composed of a lacunar and highly vascularized parenchyma offering a direct connection between leaf surface and xylem vessels. Arabidopsis hydathode pores were responsive to ABA and light similar to stomata. The flg22 flagellin peptide, a well-characterized elicitor of plant basal immunity, did not induce closure of hydathode pores in contrast to stomata. Because hydathodes are natural infection routes for several pathogens, we investigated hydathode infection by the adapted vascular phytopathogenic bacterium Xanthomonas campestris pv campestris ( Xcc ), the causal agent of black rot disease of Brassicaceae. Microscopic observations of hydathodes six days postinoculation indicated a digestion of the epithem cells and a high bacterial multiplication. Postinvasive immunity was shown to limit pathogen growth in the epithem and is actively suppressed by the type III secretion system and its effector proteins. Altogether, these results give a detailed anatomic description of Brassicaceae hydathodes and highlight the efficient use of this tissue as an initial niche for subsequent vascular systemic dissemination of Xcc in distant plant tissues., (© 2017 American Society of Plant Biologists. All Rights Reserved.)
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- 2017
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28. Prenatal Valproate Exposure Differentially Affects Parvalbumin-Expressing Neurons and Related Circuits in the Cortex and Striatum of Mice.
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Lauber E, Filice F, and Schwaller B
- Abstract
Autism spectrum disorders (ASD) comprise a number of heterogeneous neurodevelopmental diseases characterized by core behavioral symptoms in the domains of social interaction, language/communication and repetitive or stereotyped patterns of behavior. In utero exposure to valproic acid (VPA) has evolved as a highly recognized rodent ASD model due to the robust behavioral phenotype observed in the offspring and the proven construct-, face- and predictive validity of the model. The number of parvalbumin-immunoreactive (PV
+ ) GABAergic interneurons has been consistently reported to be decreased in human ASD subjects and in ASD animal models. The presumed loss of this neuron subpopulation hereafter termed Pvalb neurons and/or PV deficits were proposed to result in an excitation/inhibition imbalance often observed in ASD. Importantly, loss of Pvalb neurons and decreased/absent PV protein levels have two fundamentally different consequences. Thus, Pvalb neurons were investigated in in utero VPA-exposed male ("VPA") mice in the striatum, medial prefrontal cortex (mPFC) and somatosensory cortex (SSC), three ASD-associated brain regions. Unbiased stereology of PV+ neurons and Vicia Villosa Agglutinin-positive (VVA+ ) perineuronal nets, which specifically enwrap Pvalb neurons, was carried out. Analyses of PV protein expression and mRNA levels for Pvalb, Gad67, Kcnc1, Kcnc2, Kcns3, Hcn1, Hcn2, and Hcn4 were performed. We found a ∼15% reduction in the number of PV+ cells and decreased Pvalb mRNA and PV protein levels in the striatum of VPA mice compared to controls, while the number of VVA+ cells was unchanged, indicating that Pvalb neurons were affected at the level of the transcriptome. In selected cortical regions (mPFC, SSC) of VPA mice, no quantitative loss/decrease of PV+ cells was observed. However, expression of Kcnc1 , coding for the voltage-gated potassium channel Kv 3.1 specifically expressed in Pvalb neurons, was decreased by ∼40% in forebrain lysates of VPA mice. Moreover, hyperpolarization-activated cyclic nucleotide-gated channel (HCN) 1 expression was increased by ∼40% in the same samples from VPA mice. We conclude that VPA leads to alterations that are brain region- and gene-specific including Pvalb, Kcnc1 , and Hcn1 possibly linked to homeostatic mechanisms. Striatal PV down-regulation appears as a common feature in a subset of genetic (Shank3B-/-) and environmental ASD models.- Published
- 2016
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29. Genomics and transcriptomics of Xanthomonas campestris species challenge the concept of core type III effectome.
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Roux B, Bolot S, Guy E, Denancé N, Lautier M, Jardinaud MF, Fischer-Le Saux M, Portier P, Jacques MA, Gagnevin L, Pruvost O, Lauber E, Arlat M, Carrère S, Koebnik R, and Noël LD
- Subjects
- Bacterial Proteins genetics, Bacterial Proteins metabolism, Molecular Sequence Annotation, Open Reading Frames, Regulon genetics, Xanthomonas campestris immunology, Gene Expression Profiling, Genomics, Xanthomonas campestris genetics
- Abstract
Background: The bacterial species Xanthomonas campestris infects a wide range of Brassicaceae. Specific pathovars of this species cause black rot (pv. campestris), bacterial blight of stock (pv. incanae) or bacterial leaf spot (pv. raphani)., Results: In this study, we extended the genomic coverage of the species by sequencing and annotating the genomes of strains from pathovar incanae (CFBP 1606R and CFBP 2527R), pathovar raphani (CFBP 5828R) and a pathovar formerly named barbareae (CFBP 5825R). While comparative analyses identified a large core ORFeome at the species level, the core type III effectome was limited to only three putative type III effectors (XopP, XopF1 and XopAL1). In Xanthomonas, these effector proteins are injected inside the plant cells by the type III secretion system and contribute collectively to virulence. A deep and strand-specific RNA sequencing strategy was adopted in order to experimentally refine genome annotation for strain CFBP 5828R. This approach also allowed the experimental definition of novel ORFs and non-coding RNA transcripts. Using a constitutively active allele of hrpG, a master regulator of the type III secretion system, a HrpG-dependent regulon of 141 genes co-regulated with the type III secretion system was identified. Importantly, all these genes but seven are positively regulated by HrpG and 56 of those encode components of the Hrp type III secretion system and putative effector proteins., Conclusions: This dataset is an important resource to mine for novel type III effector proteins as well as for bacterial genes which could contribute to pathogenicity of X. campestris.
- Published
- 2015
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30. The N-Glycan cluster from Xanthomonas campestris pv. campestris: a toolbox for sequential plant N-glycan processing.
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Dupoiron S, Zischek C, Ligat L, Carbonne J, Boulanger A, Dugé de Bernonville T, Lautier M, Rival P, Arlat M, Jamet E, Lauber E, and Albenne C
- Subjects
- Brassica enzymology, Glycoside Hydrolases genetics, Glycoside Hydrolases metabolism, Humans, Plant Diseases microbiology, Polysaccharides metabolism, Xanthomonas campestris genetics, Xanthomonas campestris pathogenicity, Xylosidases genetics, Xylosidases metabolism, alpha-Mannosidase genetics, alpha-Mannosidase metabolism, Brassica genetics, Plant Diseases genetics, Polysaccharides genetics, Xanthomonas campestris enzymology
- Abstract
N-Glycans are widely distributed in living organisms but represent only a small fraction of the carbohydrates found in plants. This probably explains why they have not previously been considered as substrates exploited by phytopathogenic bacteria during plant infection. Xanthomonas campestris pv. campestris, the causal agent of black rot disease of Brassica plants, possesses a specific system for GlcNAc utilization expressed during host plant infection. This system encompasses a cluster of eight genes (nixE to nixL) encoding glycoside hydrolases (GHs). In this paper, we have characterized the enzymatic activities of these GHs and demonstrated their involvement in sequential degradation of a plant N-glycan using a N-glycopeptide containing two GlcNAcs, three mannoses, one fucose, and one xylose (N2M3FX) as a substrate. The removal of the α-1,3-mannose by the α-mannosidase NixK (GH92) is a prerequisite for the subsequent action of the β-xylosidase NixI (GH3), which is involved in the cleavage of the β-1,2-xylose, followed by the α-mannosidase NixJ (GH125), which removes the α-1,6-mannose. These data, combined to the subcellular localization of the enzymes, allowed us to propose a model of N-glycopeptide processing by X. campestris pv. campestris. This study constitutes the first evidence suggesting N-glycan degradation by a plant pathogen, a feature shared with human pathogenic bacteria. Plant N-glycans should therefore be included in the repertoire of molecules putatively metabolized by phytopathogenic bacteria during their life cycle., (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2015
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31. The plant pathogen Xanthomonas campestris pv. campestris exploits N-acetylglucosamine during infection.
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Boulanger A, Zischek C, Lautier M, Jamet S, Rival P, Carrère S, Arlat M, and Lauber E
- Subjects
- Brassica microbiology, Cell Wall chemistry, Cell Wall microbiology, Computational Biology, Membrane Transport Proteins metabolism, Mutation, Peptidoglycan chemistry, Phenotype, Plasmids genetics, Promoter Regions, Genetic, Xanthomonas campestris genetics, Xylem microbiology, Acetylglucosamine metabolism, Plant Diseases microbiology, Plant Proteins metabolism, Xanthomonas campestris pathogenicity
- Abstract
Unlabelled: N-Acetylglucosamine (GlcNAc), the main component of chitin and a major constituent of bacterial peptidoglycan, is present only in trace amounts in plants, in contrast to the huge amount of various sugars that compose the polysaccharides of the plant cell wall. Thus, GlcNAc has not previously been considered a substrate exploited by phytopathogenic bacteria during plant infection. Xanthomonas campestris pv. campestris, the causal agent of black rot disease of Brassica plants, expresses a carbohydrate utilization system devoted to GlcNAc exploitation. In addition to genes involved in GlcNAc catabolism, this system codes for four TonB-dependent outer membrane transporters (TBDTs) and eight glycoside hydrolases. Expression of all these genes is under the control of GlcNAc. In vitro experiments showed that X. campestris pv. campestris exploits chitooligosaccharides, and there is indirect evidence that during the early stationary phase, X. campestris pv. campestris recycles bacterium-derived peptidoglycan/muropeptides. Results obtained also suggest that during plant infection and during growth in cabbage xylem sap, X. campestris pv. campestris encounters and metabolizes plant-derived GlcNAc-containing molecules. Specific TBDTs seem to be preferentially involved in the consumption of all these plant-, fungus- and bacterium-derived GlcNAc-containing molecules. This is the first evidence of GlcNAc consumption during infection by a phytopathogenic bacterium. Interestingly, N-glycans from plant N-glycosylated proteins are proposed to be substrates for glycoside hydrolases belonging to the X. campestris pv. campestris GlcNAc exploitation system. This observation extends the range of sources of GlcNAc metabolized by phytopathogenic bacteria during their life cycle., Importance: Despite the central role of N-acetylglucosamine (GlcNAc) in nature, there is no evidence that phytopathogenic bacteria metabolize this compound during plant infection. Results obtained here suggest that Xanthomonas campestris pv. campestris, the causal agent of black rot disease on Brassica, encounters and metabolizes GlcNAc in planta and in vitro. Active and specific outer membrane transporters belonging to the TonB-dependent transporters family are proposed to import GlcNAc-containing complex molecules from the host, from the bacterium, and/or from the environment, and bacterial glycoside hydrolases induced by GlcNAc participate in their degradation. Our results extend the range of sources of GlcNAc metabolized by this phytopathogenic bacterium during its life cycle to include chitooligosaccharides that could originate from fungi or insects present in the plant environment, muropeptides leached during peptidoglycan recycling and bacterial lysis, and N-glycans from plant N-glycosylated proteins present in the plant cell wall as well as in xylem sap., (Copyright © 2014 Boulanger et al.)
- Published
- 2014
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32. Transcriptional reprogramming and phenotypical changes associated with growth of Xanthomonas campestris pv. campestris in cabbage xylem sap.
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Dugé de Bernonville T, Noël LD, SanCristobal M, Danoun S, Becker A, Soreau P, Arlat M, and Lauber E
- Subjects
- Bacterial Proteins genetics, Bacterial Proteins metabolism, Membrane Transport Proteins genetics, Membrane Transport Proteins metabolism, Phenotype, Transcriptome, Virulence, Xanthomonas campestris growth & development, Xanthomonas campestris metabolism, Xanthomonas campestris pathogenicity, Xylem microbiology, Brassica microbiology, Gene Expression Regulation, Bacterial, Xanthomonas campestris genetics
- Abstract
Xylem sap (XS) is the first environment that xylem phytopathogens meet in planta during the early infection steps. Xanthomonas campestris pv. campestris (Xcc), the causative agent of Brassicaceae black rot, colonizes the plant xylem vessels to ensure its multiplication and dissemination. Besides suppression of plant immunity, Xcc has to adapt its metabolism to exploit plant-derived nutrients present in XS. To study Xcc behaviour in the early infection steps, we used cabbage XS to analyse bacterial growth. Mineral and organic composition of XS were determined. Significant growth of Xcc in XS was allowed by the rapid catabolism of amino acids, sugars and organic acids, and it was accompanied by the formation of biofilm-like structures. Transcriptome analysis of Xcc cultivated in XS using cDNA microarrays revealed a XS-specific transcriptional reprogramming compared to minimal or rich media. More specifically, up-regulation of genes encoding transporters such as TonB-dependent transporters (TBDTs), that could be associated with nutrient acquisition and detoxification, was observed. In agreement with the aggregation phenotype, expression of genes important for twitching motility and adhesion was up-regulated in XS. Taken together, our data show specific responses of Xcc to colonization of cabbage XS that could be important for the pathogenesis process and establish XS as a model medium to study mechanisms important for the early infection events., (© 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.)
- Published
- 2014
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33. Genomic survey of pathogenicity determinants and VNTR markers in the cassava bacterial pathogen Xanthomonas axonopodis pv. Manihotis strain CIO151.
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Arrieta-Ortiz ML, Rodríguez-R LM, Pérez-Quintero Á, Poulin L, Díaz AC, Arias Rojas N, Trujillo C, Restrepo Benavides M, Bart R, Boch J, Boureau T, Darrasse A, David P, Dugé de Bernonville T, Fontanilla P, Gagnevin L, Guérin F, Jacques MA, Lauber E, Lefeuvre P, Medina C, Medina E, Montenegro N, Muñoz Bodnar A, Noël LD, Ortiz Quiñones JF, Osorio D, Pardo C, Patil PB, Poussier S, Pruvost O, Robène-Soustrade I, Ryan RP, Tabima J, Urrego Morales OG, Vernière C, Carrere S, Verdier V, Szurek B, Restrepo S, López C, Koebnik R, and Bernal A
- Subjects
- Genome, Bacterial genetics, Minisatellite Repeats genetics, Virulence genetics, Xanthomonas axonopodis pathogenicity, Xanthomonas axonopodis genetics
- Abstract
Xanthomonas axonopodis pv. manihotis (Xam) is the causal agent of bacterial blight of cassava, which is among the main components of human diet in Africa and South America. Current information about the molecular pathogenicity factors involved in the infection process of this organism is limited. Previous studies in other bacteria in this genus suggest that advanced draft genome sequences are valuable resources for molecular studies on their interaction with plants and could provide valuable tools for diagnostics and detection. Here we have generated the first manually annotated high-quality draft genome sequence of Xam strain CIO151. Its genomic structure is similar to that of other xanthomonads, especially Xanthomonas euvesicatoria and Xanthomonas citri pv. citri species. Several putative pathogenicity factors were identified, including type III effectors, cell wall-degrading enzymes and clusters encoding protein secretion systems. Specific characteristics in this genome include changes in the xanthomonadin cluster that could explain the lack of typical yellow color in all strains of this pathovar and the presence of 50 regions in the genome with atypical nucleotide composition. The genome sequence was used to predict and evaluate 22 variable number of tandem repeat (VNTR) loci that were subsequently demonstrated as polymorphic in representative Xam strains. Our results demonstrate that Xanthomonas axonopodis pv. manihotis strain CIO151 possesses ten clusters of pathogenicity factors conserved within the genus Xanthomonas. We report 126 genes that are potentially unique to Xam, as well as potential horizontal transfer events in the history of the genome. The relation of these regions with virulence and pathogenicity could explain several aspects of the biology of this pathogen, including its ability to colonize both vascular and non-vascular tissues of cassava plants. A set of 16 robust, polymorphic VNTR loci will be useful to develop a multi-locus VNTR analysis scheme for epidemiological surveillance of this disease.
- Published
- 2013
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34. Genome sequence of Xanthomonas fuscans subsp. fuscans strain 4834-R reveals that flagellar motility is not a general feature of xanthomonads.
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Darrasse A, Carrère S, Barbe V, Boureau T, Arrieta-Ortiz ML, Bonneau S, Briand M, Brin C, Cociancich S, Durand K, Fouteau S, Gagnevin L, Guérin F, Guy E, Indiana A, Koebnik R, Lauber E, Munoz A, Noël LD, Pieretti I, Poussier S, Pruvost O, Robène-Soustrade I, Rott P, Royer M, Serres-Giardi L, Szurek B, van Sluys MA, Verdier V, Vernière C, Arlat M, Manceau C, and Jacques MA
- Subjects
- Base Sequence, Evolution, Molecular, Fabaceae genetics, Fabaceae growth & development, Fabaceae microbiology, Flagella physiology, Genome, Bacterial, Phylogeny, Plant Diseases genetics, Seeds genetics, Seeds microbiology, Sequence Analysis, DNA, Xanthomonas classification, Xanthomonas pathogenicity, Flagella genetics, Genetic Fitness, Plant Diseases microbiology, Xanthomonas genetics
- Abstract
Background: Xanthomonads are plant-associated bacteria responsible for diseases on economically important crops. Xanthomonas fuscans subsp. fuscans (Xff) is one of the causal agents of common bacterial blight of bean. In this study, the complete genome sequence of strain Xff 4834-R was determined and compared to other Xanthomonas genome sequences., Results: Comparative genomics analyses revealed core characteristics shared between Xff 4834-R and other xanthomonads including chemotaxis elements, two-component systems, TonB-dependent transporters, secretion systems (from T1SS to T6SS) and multiple effectors. For instance a repertoire of 29 Type 3 Effectors (T3Es) with two Transcription Activator-Like Effectors was predicted. Mobile elements were associated with major modifications in the genome structure and gene content in comparison to other Xanthomonas genomes. Notably, a deletion of 33 kbp affects flagellum biosynthesis in Xff 4834-R. The presence of a complete flagellar cluster was assessed in a collection of more than 300 strains representing different species and pathovars of Xanthomonas. Five percent of the tested strains presented a deletion in the flagellar cluster and were non-motile. Moreover, half of the Xff strains isolated from the same epidemic than 4834-R was non-motile and this ratio was conserved in the strains colonizing the next bean seed generations., Conclusions: This work describes the first genome of a Xanthomonas strain pathogenic on bean and reports the existence of non-motile xanthomonads belonging to different species and pathovars. Isolation of such Xff variants from a natural epidemic may suggest that flagellar motility is not a key function for in planta fitness.
- Published
- 2013
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35. xopAC-triggered immunity against Xanthomonas depends on Arabidopsis receptor-like cytoplasmic kinase genes PBL2 and RIPK.
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Guy E, Lautier M, Chabannes M, Roux B, Lauber E, Arlat M, and Noël LD
- Subjects
- Arabidopsis immunology, Arabidopsis microbiology, Arabidopsis Proteins metabolism, Bacterial Proteins genetics, Cell Membrane enzymology, Cell Membrane genetics, Cytoplasm enzymology, Cytoplasm genetics, Genes, Reporter, Host-Pathogen Interactions, Luminescent Proteins genetics, Plant Cells metabolism, Plant Cells microbiology, Plant Diseases immunology, Plant Diseases microbiology, Protein Kinases metabolism, Protein Serine-Threonine Kinases metabolism, Pseudomonas syringae physiology, Ralstonia solanacearum physiology, Arabidopsis genetics, Arabidopsis Proteins genetics, Gene Expression Regulation, Plant, Plant Diseases genetics, Plant Immunity genetics, Protein Kinases genetics, Protein Serine-Threonine Kinases genetics, Xanthomonas campestris physiology
- Abstract
Xanthomonas campestris pv. campestris (Xcc) colonizes the vascular system of Brassicaceae and ultimately causes black rot. In susceptible Arabidopsis plants, XopAC type III effector inhibits by uridylylation positive regulators of the PAMP-triggered immunity such as the receptor-like cytoplasmic kinases (RLCK) BIK1 and PBL1. In the resistant ecotype Col-0, xopAC is a major avirulence gene of Xcc. In this study, we show that both the RLCK interaction domain and the uridylyl transferase domain of XopAC are required for avirulence. Furthermore, xopAC can also confer avirulence to both the vascular pathogen Ralstonia solanacearum and the mesophyll-colonizing pathogen Pseudomonas syringae indicating that xopAC-specified effector-triggered immunity is not specific to the vascular system. In planta, XopAC-YFP fusions are localized at the plasma membrane suggesting that XopAC might interact with membrane-localized proteins. Eight RLCK of subfamily VII predicted to be localized at the plasma membrane and interacting with XopAC in yeast two-hybrid assays have been isolated. Within this subfamily, PBL2 and RIPK RLCK genes but not BIK1 are important for xopAC-specified effector-triggered immunity and Arabidopsis resistance to Xcc.
- Published
- 2013
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36. The xylan utilization system of the plant pathogen Xanthomonas campestris pv campestris controls epiphytic life and reveals common features with oligotrophic bacteria and animal gut symbionts.
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Déjean G, Blanvillain-Baufumé S, Boulanger A, Darrasse A, de Bernonville TD, Girard AL, Carrére S, Jamet S, Zischek C, Lautier M, Solé M, Büttner D, Jacques MA, Lauber E, and Arlat M
- Subjects
- Adaptation, Physiological, Animals, Bacterial Outer Membrane Proteins metabolism, Bacteroides metabolism, Brassica microbiology, Caulobacter crescentus metabolism, Membrane Transport Proteins genetics, Membrane Transport Proteins metabolism, Mutation, Oligosaccharides chemistry, Oligosaccharides metabolism, Operon, Phaseolus microbiology, Symbiosis, Xanthomonas campestris growth & development, Xanthomonas campestris pathogenicity, Xylose metabolism, Xylosidases genetics, Xylosidases metabolism, Bacterial Outer Membrane Proteins genetics, Gene Expression Regulation, Bacterial, Xanthomonas campestris genetics, Xanthomonas campestris metabolism, Xylans metabolism
- Abstract
Xylan is a major structural component of plant cell wall and the second most abundant plant polysaccharide in nature. Here, by combining genomic and functional analyses, we provide a comprehensive picture of xylan utilization by Xanthomonas campestris pv campestris (Xcc) and highlight its role in the adaptation of this epiphytic phytopathogen to the phyllosphere. The xylanolytic activity of Xcc depends on xylan-deconstruction enzymes but also on transporters, including two TonB-dependent outer membrane transporters (TBDTs) which belong to operons necessary for efficient growth in the presence of xylo-oligosaccharides and for optimal survival on plant leaves. Genes of this xylan utilization system are specifically induced by xylo-oligosaccharides and repressed by a LacI-family regulator named XylR. Part of the xylanolytic machinery of Xcc, including TBDT genes, displays a high degree of conservation with the xylose-regulon of the oligotrophic aquatic bacterium Caulobacter crescentus. Moreover, it shares common features, including the presence of TBDTs, with the xylan utilization systems of Bacteroides ovatus and Prevotella bryantii, two gut symbionts. These similarities and our results support an important role for TBDTs and xylan utilization systems for bacterial adaptation in the phyllosphere, oligotrophic environments and animal guts., (© 2013 CNRS. New Phytologist © 2013 New Phytologist Trust.)
- Published
- 2013
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37. Insights into the extracytoplasmic stress response of Xanthomonas campestris pv. campestris: role and regulation of {sigma}E-dependent activity.
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Bordes P, Lavatine L, Phok K, Barriot R, Boulanger A, Castanié-Cornet MP, Déjean G, Lauber E, Becker A, Arlat M, and Gutierrez C
- Subjects
- Base Sequence, Cadmium pharmacology, Diamide pharmacology, Gene Expression Profiling, Gene Expression Regulation, Bacterial drug effects, Hot Temperature, Multigene Family, Operon, Peptide Hydrolases metabolism, Promoter Regions, Genetic, Protein Array Analysis, Sigma Factor genetics, Stress, Physiological, Xanthomonas campestris drug effects, Xanthomonas campestris genetics, Gene Expression Regulation, Bacterial physiology, Sigma Factor metabolism, Xanthomonas campestris metabolism
- Abstract
Xanthomonas campestris pv. campestris is an epiphytic bacterium that can become a vascular pathogen responsible for black rot disease of crucifers. To adapt gene expression in response to ever-changing habitats, phytopathogenic bacteria have evolved signal transduction regulatory pathways, such as extracytoplasmic function (ECF) σ factors. The alternative sigma factor σ(E), encoded by rpoE, is crucial for envelope stress response and plays a role in the pathogenicity of many bacterial species. Here, we combine different approaches to investigate the role and mechanism of σ(E)-dependent activation in X. campestris pv. campestris. We show that the rpoE gene is organized as a single transcription unit with the anti-σ gene rseA and the protease gene mucD and that rpoE transcription is autoregulated. rseA and mucD transcription is also controlled by a highly conserved σ(E)-dependent promoter within the σ(E) gene sequence. The σ(E)-mediated stress response is required for stationary-phase survival, resistance to cadmium, and adaptation to membrane-perturbing stresses (elevated temperature and ethanol). Using microarray technology, we started to define the σ(E) regulon of X. campestris pv. campestris. These genes encode proteins belonging to different classes, including periplasmic or membrane proteins, biosynthetic enzymes, classical heat shock proteins, and the heat stress σ factor σ(H). The consensus sequence for the predicted σ(E)-regulated promoter elements is GGAACTN(15-17)GTCNNA. Determination of the rpoH transcription start site revealed that rpoH was directly regulated by σ(E) under both normal and heat stress conditions. Finally, σ(E) activity is regulated by the putative regulated intramembrane proteolysis (RIP) proteases RseP and DegS, as previously described in many other bacteria. However, our data suggest that RseP and DegS are not only dedicated to RseA cleavage and that the proteolytic cascade of RseA could involve other proteases.
- Published
- 2011
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38. Detection of Cry1Ab toxin in the leaves of MON 810 transgenic maize.
- Author
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Székács A, Lauber E, Takács E, and Darvas B
- Subjects
- Bacillus thuringiensis Toxins, Bacterial Proteins genetics, Bacterial Proteins metabolism, Endotoxins genetics, Endotoxins metabolism, Hemolysin Proteins genetics, Hemolysin Proteins metabolism, Plant Leaves chemistry, Plant Leaves genetics, Plant Leaves metabolism, Plants, Genetically Modified genetics, Plants, Genetically Modified metabolism, Zea mays genetics, Zea mays metabolism, Bacterial Proteins analysis, Endotoxins analysis, Enzyme-Linked Immunosorbent Assay methods, Hemolysin Proteins analysis, Plants, Genetically Modified chemistry, Zea mays chemistry
- Abstract
The distribution of Cry1Ab toxin was detected in the leaves of genetically modified maize of genetic event MON 810 by enzyme-linked immunosorbent assay. Cry1Ab toxin contents in the leaves at reproductive (milk, R3) phenological stage were measured to be between 3,878 and 11,148 ng Cry1Ab toxin/g fresh weight. Toxin content was significantly lesser (significant difference (SD) = 1,823 ng Cry1Ab toxin/g fresh leaf weight, p < 0.01) in leaves at the lowest leaf level, than at higher leaf levels, probably due to partial leaf necrotisation. A substantial (up to 22%) plant-to-plant variation in Cry1Ab contents in leaves was observed. When studying toxin distribution within the cross and longitudinal sections of single leaves, lesser variability was detected diagonally, with approximately 20% higher toxin concentrations at or near the leaf vein. More significant variability (SD = 2,220 ng Cry1Ab toxin/g fresh leaf weight, p < 0.01) was seen lengthwise along the leaf, starting at 1,892 ng Cry1Ab toxin/g fresh weight at the sheath and rising to maximum concentration at the middle of the lamella. Cry1Ab toxin content may suffer significant (SD = 2,230 ng Cry1Ab toxin/g fresh leaf weight, p < 0.01) decreases in the leaf due to necrotisation. The results indicate that the longitudinal dimension of the leaf has more significance for sampling purposes than the diagonal position.
- Published
- 2010
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39. Identification and regulation of the N-acetylglucosamine utilization pathway of the plant pathogenic bacterium Xanthomonas campestris pv. campestris.
- Author
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Boulanger A, Déjean G, Lautier M, Glories M, Zischek C, Arlat M, and Lauber E
- Subjects
- Bacterial Proteins metabolism, Biological Transport, Active, Carbon metabolism, Carrier Proteins metabolism, Chitin metabolism, Disaccharides metabolism, Mutation, Nitrogen metabolism, Signal Transduction, Acetylglucosamine metabolism, Gene Expression Regulation, Bacterial physiology, Xanthomonas campestris metabolism
- Abstract
Xanthomonas campestris pv. campestris, the causal agent of black rot disease of brassicas, is known for its ability to catabolize a wide range of plant compounds. This ability is correlated with the presence of specific carbohydrate utilization loci containing TonB-dependent transporters (CUT loci) devoted to scavenging specific carbohydrates. In this study, we demonstrate that there is an X. campestris pv. campestris CUT system involved in the import and catabolism of N-acetylglucosamine (GlcNAc). Expression of genes belonging to this GlcNAc CUT system is under the control of GlcNAc via the LacI family NagR and GntR family NagQ regulators. Analysis of the NagR and NagQ regulons confirmed that GlcNAc utilization involves NagA and NagB-II enzymes responsible for the conversion of GlcNAc-6-phosphate to fructose-6-phosphate. Mutants with mutations in the corresponding genes are sensitive to GlcNAc, as previously reported for Escherichia coli. This GlcNAc sensitivity and analysis of the NagQ and NagR regulons were used to dissect the X. campestris pv. campestris GlcNAc utilization pathway. This analysis revealed specific features, including the fact that uptake of GlcNAc through the inner membrane occurs via a major facilitator superfamily transporter and the fact that this amino sugar is phosphorylated by two proteins belonging to the glucokinase family, NagK-IIA and NagK-IIB. However, NagK-IIA seems to play a more important role in GlcNAc utilization than NagK-IIB under our experimental conditions. The X. campestris pv. campestris GlcNAc NagR regulon includes four genes encoding TonB-dependent active transporters (TBDTs). However, the results of transport experiments suggest that GlcNAc passively diffuses through the bacterial envelope, an observation that calls into question whether GlcNAc is a natural substrate for these TBDTs and consequently is the source of GlcNAc for this nonchitinolytic plant-associated bacterium.
- Published
- 2010
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40. The complete genome sequence of Xanthomonas albilineans provides new insights into the reductive genome evolution of the xylem-limited Xanthomonadaceae.
- Author
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Pieretti I, Royer M, Barbe V, Carrere S, Koebnik R, Cociancich S, Couloux A, Darrasse A, Gouzy J, Jacques MA, Lauber E, Manceau C, Mangenot S, Poussier S, Segurens B, Szurek B, Verdier V, Arlat M, and Rott P
- Subjects
- Models, Genetic, Molecular Sequence Data, Phylogeny, RNA, Bacterial genetics, RNA, Ribosomal genetics, Xanthomonadaceae classification, Xanthomonas classification, Evolution, Molecular, Genome, Bacterial genetics, Xanthomonadaceae genetics, Xanthomonas genetics, Xylem microbiology
- Abstract
Background: The Xanthomonadaceae family contains two xylem-limited plant pathogenic bacterial species, Xanthomonas albilineans and Xylella fastidiosa. X. fastidiosa was the first completely sequenced plant pathogen. It is insect-vectored, has a reduced genome and does not possess hrp genes which encode a Type III secretion system found in most plant pathogenic bacteria. X. fastidiosa was excluded from the Xanthomonas group based on phylogenetic analyses with rRNA sequences., Results: The complete genome of X. albilineans was sequenced and annotated. X. albilineans, which is not known to be insect-vectored, also has a reduced genome and does not possess hrp genes. Phylogenetic analysis using X. albilineans genomic sequences showed that X. fastidiosa belongs to the Xanthomonas group. Order of divergence of the Xanthomonadaceae revealed that X. albilineans and X. fastidiosa experienced a convergent reductive genome evolution during their descent from the progenitor of the Xanthomonas genus. Reductive genome evolutions of the two xylem-limited Xanthomonadaceae were compared in light of their genome characteristics and those of obligate animal symbionts and pathogens., Conclusion: The two xylem-limited Xanthomonadaceae, during their descent from a common ancestral parent, experienced a convergent reductive genome evolution. Adaptation to the nutrient-poor xylem elements and to the cloistered environmental niche of xylem vessels probably favoured this convergent evolution. However, genome characteristics of X. albilineans differ from those of X. fastidiosa and obligate animal symbionts and pathogens, indicating that a distinctive process was responsible for the reductive genome evolution in this pathogen. The possible role in genome reduction of the unique toxin albicidin, produced by X. albilineans, is discussed.
- Published
- 2009
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41. AvrAC(Xcc8004), a type III effector with a leucine-rich repeat domain from Xanthomonas campestris pathovar campestris confers avirulence in vascular tissues of Arabidopsis thaliana ecotype Col-0.
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Xu RQ, Blanvillain S, Feng JX, Jiang BL, Li XZ, Wei HY, Kroj T, Lauber E, Roby D, Chen B, He YQ, Lu GT, Tang DJ, Vasse J, Arlat M, and Tang JL
- Subjects
- Amino Acid Sequence, DNA Primers, DNA, Bacterial genetics, Immunity, Innate genetics, Leucine, Mutagenesis, Plant Diseases microbiology, Plasmids, RNA, Bacterial genetics, Sequence Deletion, Arabidopsis microbiology, Bacterial Proteins genetics, Bacterial Proteins metabolism, Genome, Bacterial, Virulence genetics, Xanthomonas campestris genetics, Xanthomonas campestris pathogenicity
- Abstract
Xanthomonas campestris pathovar campestris causes black rot, a vascular disease on cruciferous plants, including Arabidopsis thaliana. The gene XC1553 from X. campestris pv. campestris strain 8004 encodes a protein containing leucine-rich repeats (LRRs) and appears to be restricted to strains of X. campestris pv. campestris. LRRs are found in a number of type III-secreted effectors in plant and animal pathogens. These prompted us to investigate the role of the XC1553 gene in the interaction between X. campestris pv. campestris and A. thaliana. Translocation assays using the hypersensitive-reaction-inducing domain of X. campestris pv. campestris AvrBs1 as a reporter revealed that XC1553 is a type III effector. Infiltration of Arabidopsis leaf mesophyll with bacterial suspensions showed no differences between the wild-type strain and an XC1553 gene mutant; both strains induced disease symptoms on Kashmir and Col-0 ecotypes. However, a clear difference was observed when bacteria were introduced into the vascular system by piercing the central vein of leaves. In this case, the wild-type strain 8004 caused disease on the Kashmir ecotype, but not on ecotype Col-0; the XC1553 gene mutant became virulent on the Col-0 ecotype and still induced disease on the Kashmir ecotype. Altogether, these data show that the XC1553 gene, which was renamed avrAC(Xcc8004), functions as an avirulence gene whose product seems to be recognized in vascular tissues.
- Published
- 2008
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42. Plant carbohydrate scavenging through tonB-dependent receptors: a feature shared by phytopathogenic and aquatic bacteria.
- Author
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Blanvillain S, Meyer D, Boulanger A, Lautier M, Guynet C, Denancé N, Vasse J, Lauber E, and Arlat M
- Subjects
- Bacteria metabolism, Bacterial Outer Membrane Proteins chemistry, Bacterial Outer Membrane Proteins genetics, Biological Transport, Active, Carbohydrate Metabolism, Conserved Sequence, Gene Expression Regulation, Bacterial, Genes, Bacterial, Inverted Repeat Sequences, Iron metabolism, Mutagenesis, Insertional, Phylogeny, Protein Structure, Tertiary, Regulon genetics, Species Specificity, Virulence, Xanthomonas campestris genetics, Xanthomonas campestris pathogenicity, Bacterial Outer Membrane Proteins physiology, Bacterial Proteins physiology, Brassicaceae microbiology, Membrane Proteins physiology, Plant Diseases microbiology, Sucrose metabolism, Water Microbiology, Xanthomonas campestris metabolism
- Abstract
TonB-dependent receptors (TBDRs) are outer membrane proteins mainly known for the active transport of iron siderophore complexes in Gram-negative bacteria. Analysis of the genome of the phytopathogenic bacterium Xanthomonas campestris pv. campestris (Xcc), predicts 72 TBDRs. Such an overrepresentation is common in Xanthomonas species but is limited to only a small number of bacteria. Here, we show that one Xcc TBDR transports sucrose with a very high affinity, suggesting that it might be a sucrose scavenger. This TBDR acts with an inner membrane transporter, an amylosucrase and a regulator to utilize sucrose, thus defining a new type of carbohydrate utilization locus, named CUT locus, involving a TBDR for the transport of substrate across the outer membrane. This sucrose CUT locus is required for full pathogenicity on Arabidopsis, showing its importance for the adaptation to host plants. A systematic analysis of Xcc TBDR genes and a genome context survey suggested that several Xcc TBDRs belong to other CUT loci involved in the utilization of various plant carbohydrates. Interestingly, several Xcc TBDRs and CUT loci are conserved in aquatic bacteria such as Caulobacter crescentus, Colwellia psychrerythraea, Saccharophagus degradans, Shewanella spp., Sphingomonas spp. or Pseudoalteromonas spp., which share the ability to degrade a wide variety of complex carbohydrates and display TBDR overrepresentation. We therefore propose that TBDR overrepresentation and the presence of CUT loci designate the ability to scavenge carbohydrates. Thus CUT loci, which seem to participate to the adaptation of phytopathogenic bacteria to their host plants, might also play a very important role in the biogeochemical cycling of plant-derived nutrients in marine environments. Moreover, the TBDRs and CUT loci identified in this study are clearly different from those characterized in the human gut symbiont Bacteroides thetaiotaomicron, which allow glycan foraging, suggesting a convergent evolution of TBDRs in Proteobacteria and Bacteroidetes.
- Published
- 2007
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43. Early-tier tests insufficient for GMO risk assessment.
- Author
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Lang A, Lauber E, and Darvas B
- Subjects
- Internationality, Risk Factors, Environment, Environmental Monitoring methods, Environmental Pollution analysis, Environmental Pollution prevention & control, Food, Genetically Modified, Plants, Genetically Modified, Risk Assessment methods
- Published
- 2007
- Full Text
- View/download PDF
44. PopF1 and PopF2, two proteins secreted by the type III protein secretion system of Ralstonia solanacearum, are translocators belonging to the HrpF/NopX family.
- Author
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Meyer D, Cunnac S, Guéneron M, Declercq C, Van Gijsegem F, Lauber E, Boucher C, and Arlat M
- Subjects
- Amino Acid Sequence, Bacterial Proteins genetics, Base Sequence, Biological Transport, Genes, Bacterial, Solanum lycopersicum microbiology, Molecular Sequence Data, Plant Diseases microbiology, Promoter Regions, Genetic genetics, Ralstonia solanacearum pathogenicity, Sequence Alignment, Virulence, Bacterial Proteins physiology, Ralstonia solanacearum metabolism
- Abstract
Ralstonia solanacearum GMI1000 is a gram-negative plant pathogen which contains an hrp gene cluster which codes for a type III protein secretion system (TTSS). We identified two novel Hrp-secreted proteins, called PopF1 and PopF2, which display similarity to one another and to putative TTSS translocators, HrpF and NopX, from Xanthomonas spp. and rhizobia, respectively. They also show similarities with TTSS translocators of the YopB family from animal-pathogenic bacteria. Both popF1 and popF2 belong to the HrpB regulon and are required for the interaction with plants, but PopF1 seems to play a more important role in virulence and hypersensitive response (HR) elicitation than PopF2 under our experimental conditions. PopF1 and PopF2 are not necessary for the secretion of effector proteins, but they are required for the translocation of AvrA avirulence protein into tobacco cells. We conclude that PopF1 and PopF2 are type III translocators belonging to the HrpF/NopX family. The hrpF gene of Xanthomonas campestris pv. campestris partially restored HR-inducing ability to popF1 popF2 mutants of R. solanacearum, suggesting that translocators of R. solanacearum and Xanthomonas are functionally conserved. Finally, R. solanacearum strain UW551, which does not belong to the same phylotype as GMI1000, also possesses two putative translocator proteins. However, although one of these proteins is clearly related to PopF1 and PopF2, the other seems to be different and related to NopX proteins, thus showing that translocators might be variable in R. solanacearum.
- Published
- 2006
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45. Optimization of pathogenicity assays to study the Arabidopsis thaliana-Xanthomonas campestris pv. campestris pathosystem.
- Author
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Meyer D, Lauber E, Roby D, Arlat M, and Kroj T
- Abstract
SUMMARY The cruciferous weed Arabidopsis thaliana and the causal agent of black rot disease of Crucifers Xanthomonas campestris pv. campestris (Xcc) are both model organisms in plant pathology. Their interaction has been studied successfully in the past, but these investigations suffered from high variability. In the present study, we describe an improved Arabidopsis-Xcc pathosystem that is based on a wound inoculation procedure. We show that after wound inoculation, Xcc colonizes the vascular system of Arabidopsis leaves and causes typical black rot symptoms in a compatible interaction, while in an incompatible interaction bacterial multiplication is inhibited. The highly synchronous and reproducible symptom expression allowed the development of a disease scoring scheme that enabled us to analyse the effects of mutations in individual genes on plant resistance or on bacterial virulence in a simple and precise manner. This optimized Arabidopsis-Xcc pathosystem will be a robust tool for further genetic and post-genomic investigation of fundamental questions in plant pathology.
- Published
- 2005
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46. Global changes in gene expression in Sinorhizobium meliloti 1021 under microoxic and symbiotic conditions.
- Author
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Becker A, Bergès H, Krol E, Bruand C, Rüberg S, Capela D, Lauber E, Meilhoc E, Ampe F, de Bruijn FJ, Fourment J, Francez-Charlot A, Kahn D, Küster H, Liebe C, Pühler A, Weidner S, and Batut J
- Subjects
- Adaptation, Biological genetics, Adaptation, Biological physiology, Gene Expression Profiling methods, Nitrogen Fixation genetics, Nitrogen Fixation physiology, Phylogeny, Protein Array Analysis methods, Proteome genetics, Proteome metabolism, Sinorhizobium meliloti metabolism, Symbiosis drug effects, Symbiosis physiology, Transcription, Genetic genetics, Gene Expression Regulation, Bacterial drug effects, Oxygen pharmacology, Sinorhizobium meliloti genetics, Symbiosis genetics
- Abstract
Sinorhizobium meliloti is an alpha-proteobacterium that alternates between a free-living phase in bulk soil or in the rhizosphere of plants and a symbiotic phase within the host plant cells, where the bacteria ultimately differentiate into nitrogen-fixing organelle-like cells, called bacteroids. As a step toward understanding the physiology of S. meliloti in its free-living and symbiotic forms and the transition between the two, gene expression profiles were determined under two sets of biological conditions: growth under oxic versus microoxic conditions, and in free-living versus symbiotic state. Data acquisition was based on both macro- and microarrays. Transcriptome profiles highlighted a profound modification of gene expression during bacteroid differentiation, with 16% of genes being altered. The data are consistent with an overall slow down of bacteroid metabolism during adaptation to symbiotic life and acquisition of nitrogen fixation capability. A large number of genes of unknown function, including potential regulators, that may play a role in symbiosis were identified. Transcriptome profiling in response to oxygen limitation indicated that up to 5% of the genes were oxygen regulated. However, the microoxic and bacteroid transcriptomes only partially overlap, implying that oxygen contributes to a limited extent to the control of symbiotic gene expression.
- Published
- 2004
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47. A putative Ca2+ and calmodulin-dependent protein kinase required for bacterial and fungal symbioses.
- Author
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Lévy J, Bres C, Geurts R, Chalhoub B, Kulikova O, Duc G, Journet EP, Ané JM, Lauber E, Bisseling T, Dénarié J, Rosenberg C, and Debellé F
- Subjects
- Amino Acid Sequence, Calcium metabolism, Calcium Signaling, Calcium-Calmodulin-Dependent Protein Kinases chemistry, Calcium-Calmodulin-Dependent Protein Kinases genetics, Calmodulin metabolism, Chromosomes, Artificial, Bacterial, Cloning, Molecular, EF Hand Motifs, Expressed Sequence Tags, Gene Expression Regulation, Plant, Genes, Plant, Lipopolysaccharides metabolism, Medicago genetics, Medicago microbiology, Molecular Sequence Data, Mutation, Pisum sativum genetics, Pisum sativum microbiology, Plant Roots enzymology, Plant Roots microbiology, Protein Structure, Tertiary, Rhizobium genetics, Transformation, Genetic, Calcium-Calmodulin-Dependent Protein Kinases metabolism, Medicago enzymology, Mycorrhizae physiology, Pisum sativum enzymology, Sinorhizobium meliloti physiology, Symbiosis
- Abstract
Legumes can enter into symbiotic relationships with both nitrogen-fixing bacteria (rhizobia) and mycorrhizal fungi. Nodulation by rhizobia results from a signal transduction pathway induced in legume roots by rhizobial Nod factors. DMI3, a Medicago truncatula gene that acts immediately downstream of calcium spiking in this signaling pathway and is required for both nodulation and mycorrhizal infection, has high sequence similarity to genes encoding calcium and calmodulin-dependent protein kinases (CCaMKs). This indicates that calcium spiking is likely an essential component of the signaling cascade leading to nodule development and mycorrhizal infection, and sheds light on the biological role of plant CCaMKs.
- Published
- 2004
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48. Development of Sinorhizobium meliloti pilot macroarrays for transcriptome analysis.
- Author
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Bergès H, Lauber E, Liebe C, Batut J, Kahn D, de Bruijn FJ, and Ampe F
- Subjects
- Analysis of Variance, Bacterial Proteins genetics, DNA Probes, Oxygen pharmacology, Polymerase Chain Reaction, RNA, Bacterial metabolism, RNA, Messenger metabolism, Reproducibility of Results, Sensitivity and Specificity, Sinorhizobium meliloti genetics, Sinorhizobium meliloti growth & development, Transcription, Genetic, Bacterial Proteins metabolism, Gene Expression Profiling, Gene Expression Regulation, Bacterial, Genome, Bacterial, Oligonucleotide Array Sequence Analysis methods, Sinorhizobium meliloti metabolism
- Abstract
In order to prepare for whole-genome expression analysis in Sinorhizobium meliloti, pilot DNA macroarrays were designed for 34 genes of known regulation. The experimental parameters assessed were the length of the PCR products, the influence of a tag at the 5' end of the primers, and the method of RNA labeling. Variance and principal-component analysis showed that the most important nonbiological parameter was the labeling method. The sizes of PCR products were also found to be important, whereas the influence of 5' tags was minimal. The variability between replicated spots on a membrane was found to be low. These experimental procedures were validated by analyzing the effects of microaerobic conditions on gene expression.
- Published
- 2003
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49. Virtually perfect time sharing in dual-task performance: uncorking the central cognitive bottleneck.
- Author
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Schumacher EH, Seymour TL, Glass JM, Fencsik DE, Lauber EJ, Kieras DE, and Meyer DE
- Subjects
- Adult, Female, Humans, Individuality, Male, Models, Psychological, Time Factors, Choice Behavior, Cognition, Practice, Psychological, Refractory Period, Psychological, Task Performance and Analysis
- Abstract
A fundamental issue for psychological science concerns the extent to which people can simultaneously perform two perceptual-motor tasks. Some theorists have hypothesized that such dual-task performance is severely and persistently constrained by a central cognitive "bottle-neck," whereas others have hypothesized that skilled procedural decision making and response selection for two or more tasks can proceed at the same time under adaptive executive control. The three experiments reported here support this latter hypothesis. Their results show that after relatively modest amounts of practice, at least some participants achieve virtually perfect time sharing in the dual-task performance of basic choice reaction tasks. The results also show that observed interference between tasks can be modulated by instructions about differential task priorities and personal preferences for daring (concurrent) or cautious (successive) scheduling of tasks. Given this outcome, future research should investigate exactly when and how such sophisticated skills in dual-task performance are acquired.
- Published
- 2001
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50. Cell-to-cell movement of beet necrotic yellow vein virus: I. Heterologous complementation experiments provide evidence for specific interactions among the triple gene block proteins.
- Author
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Lauber E, Bleykasten-Grosshans C, Erhardt M, Bouzoubaa S, Jonard G, Richards KE, and Guilley H
- Subjects
- Movement, Plant Leaves, Plant Viruses genetics, Plants, Edible virology, Protoplasts virology, RNA Viruses genetics, RNA, Viral genetics, Replicon, Transcription, Genetic, Genes, Viral, Plant Viruses physiology, RNA Viruses physiology, RNA, Viral biosynthesis
- Abstract
Cell-to-cell movement of beet necrotic yellow vein virus (BNYVV) requires three proteins encoded by a triple gene block (TGB) on viral RNA 2. A BNYVV RNA 3-derived replicon was used to express movement proteins to functionally substitute for the BNYVV TGB proteins was tested by coinoculation of TGB-defective BNYVV with the various replicons to Chenopodium quinoa. Trans-heterocomplementation was successful with the movement protein (P30) of tobacco mosaic virus but not with the tubule-forming movement proteins of alfalfa mosaic virus and grapevine fanleaf virus. Trans-complementation of BNYVV movement was also observed when all three TGB proteins of the distantly related peanut clump virus were supplied together but not when they were substituted for their BNYVV counterparts one by one. When P30 was used to drive BNYVV movement in trans, accumulation of the first TGB protein of BNYVV was adversely affected by null mutations in the second and third TGB proteins. Taken together, these results suggest that highly specific interactions among cognate TGB proteins are important for their function and/or stability in planta.
- Published
- 1998
- Full Text
- View/download PDF
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