Search

Olive quick decline syndrome (OQDS) is a disorder associated with bacterial infections caused by Xylella fastidiosa subsp. pauca ST53 in olive trees. Metabolic profile changes occurring in infected olive trees are still poorly investigated, but have the potential to unravel reliable biomarkers to be exploited for early diagnosis of infections. In this study, an untargeted metabolomic method using high-performance liquid chromatography coupled to quadrupole-time-of-flight high-resolution mass spectrometry (HPLC-ESI-Q-TOF-MS) was used to detect differences in samples (leaves) from healthy (Ctrl) and infected (Xf) olive trees. Both unsupervised and supervised data analysis clearly differentiated the groups. Different metabolites have been identified as potential specific biomarkers, and their characterization strongly suggests that metabolism of flavonoids and long-chain fatty acids is perturbed in Xf samples. In particular, a decrease in the defence capabilities of the host after Xf infection is proposed because of a significant dysregulation of some metabolites belonging to flavonoid family. Moreover, oleic acid is confirmed as a putative diffusible signal factor (DSF). This study provides new insights into the host-pathogen interactions and confirms LC-HRMS-based metabolomics as a powerful approach for disease-associated biomarkers discovery in plants. Graphical abstract

Background: Non-occupational cases of contact dermatitis to finished wood are occasionally reported from contact with wooden jewellery, musical instruments, knife handles and wooden footwear. Two female patients, 26 and 34 years old, developed acute eczema on the wrists after they worn in the summer a kind of catholic bracelet called “memorabilia” made by single wooden chunks with over-impressed iconic religious images. Objectives: To identify the culprit photoallergen responsible for the reported adverse reactions suspected to be a compound of the wooden bracelets. Methods: Three months after the resolution of the dermatitis, patch test and photo-patch tests were performed with the S.I.D.A.P.A. (Italian Society of Allergic, Occupational and Environmental Dermatology) standard series, and with wood sawdust obtained from both bracelets and tested at 5% in pet. A thin-layer chromatogram (TLC) strip and an extract made from the bracelets were tested in both the patients as patch test and photo-patch test. The extracts of the wooden bracelets were analyzed by gas chromatography – mass spectrometry (GC-MS). Results: Patch tests and photo-patch test with standard series turned out negative. Photo-patch tests with wood sawdust in pet. 5% evidenced a positive reaction (++) in both patients. Two chemicals were detected in the wooden bracelets with GC-MS: dibutylphthalate, commonly used as plasticizer, and 8,8-dimethyl-2H,8H-benzo[1,2-b:3,4-b']dipyran-2-one, a coumarin. Patch test with TLC did not elicit positive reactions but the photo-patch test with TLC gave positive reactions in both the patients to the same invisible spot on the strips. Two coumarins (8,8-dimethyl-2H,8H-benzo[1,2-b:3,4-b']dipyran-2-one and 8,8-dimethyl-2H,8H-benzo[1,2-b:5,4-b']dipyran-2-one) were detected in the spot with GC-MS. Conclusion: Coumarins are chemicals found in many plants with a known photo-allergic potential. They are probably the main photo-allergens in religious wooden bracelets instead of quinones and psoralens hypothesized in previous reports.

Introduction Xylella fastidiosa (Xf) is a pathogenic bacterium that causes diseases in olive trees. Therefore, analytical methods for both the characterisation of the host/pathogen interaction and infection monitoring are needed. Volatile organic compounds (VOCs) are emitted by plants relate to their physiological state, therefore VOCs monitoring can assist in detecting stress or infection states before visible signs are present. Objective In this work, the headspace-solid phase microextraction-gaschromatography-mass spectrometry (HS-SPME-GC-MS) technique was used for the first time to highlight VOCs differences between healthy and Xf-infected olive trees. Methodology VOCs from olive tree twig samples were extracted and analysed by HS-SPME-GC-MS, and hence identified by comparing the experimental linear retention indexes with the reference values and by MS data obtained from NIST library. Data were processed by principal component analysis (PCA) and analysis of variance (ANOVA). Results The HS-SPME step was optimised in terms of adsorbent phase and extraction time. HS-SPME-GC-MS technique was applied to the extraction and analysis of VOCs of healthy and Xf-infected olive trees. More than 100 compounds were identified and the differences between samples were evidenced by the multivariate analysis approach. The results showed the marked presence of methyl esters in Xf-infected samples, suggesting their probable involvement in the mechanism of diffusible signal factor. Conclusion The proposed approach represents an easy and solvent-free method to evaluate the presence of Xf in olive trees, and to evidence volatiles produced by host/pathogen interactions that could be involved in the defensive mechanism of the olive tree and/or in the infective action of Xf.

The Antarctic silverfish Pleuragramma antarctica is a key species in the Southern Ocean ecosystem, and it is potentially threatened by the climate change affecting Antarctic ecosystems. Assessing the possible exposure to similar or different environmental conditions at early life stages and gathering information about connectivity or segregation between local populations of P. antarctica can be key for planning sound management strategies for this species. By using Laser Ablation Inductively Coupled Plasma Mass Spectrometry, we characterized the otolith chemical composition of 163 adult Antarctic silverfish collected from three areas located thousands of kilometers apart from each other: Cape Hallett, Adelie Land, and Joinville Island. Otoliths were analyzed for chemical composition of both the edge (reflecting the exposure of individuals to environmental conditions at the site where they were sampled) and the core (reflecting exposure to environmental conditions during early life periods after the egg fertilization). We found that the chemical composition along otolith edges was heterogeneous between samples collected at Joinville Island and those collected at the other two sampling areas. In contrast, the chemical composition of otolith cores was homogenous. Our study suggests that adult Antarctic silverfish inhabiting areas very distant from each other have been exposed to similar environmental conditions at early life stages, and could have experienced similar growth rates and physiological processes. This would imply that environmental drivers probably do not play a role in determining potential spatial variability in individual fitness at early life stages, and should not have a major impact on population replenishment.

Coccoid cyanobacteria produce a great variety of secondary metabolites, which may have useful properties, such as antibacterial, antiviral, anticoagulant or anticancer activities. These cyanobacterial metabolites have high ecological significance, and they could be considered responsible for the widespread occurrence of these microorganisms. Considering the great benefit derived from the identification of competent cyanobacteria for the extraction of bioactive compounds, two strains of picocyanobacteria (coccoid cyanobacteria &lt, 3 µm) (Cyanobium sp. ITAC108 and Synechococcus sp. ITAC107) isolated from the Mediterranean sponge Petrosia ficiformis were analyzed. The biological effects of organic and aqueous extracts from these picocyanobacteria toward the nauplii of Artemia&nbsp, salina, sea urchin embryos and human cancer lines (HeLa cells) were evaluated. Methanolic and aqueous extracts from the two strains strongly inhibited larval development, on the contrary, in ethyl acetate and hexane extracts, the percentage of anomalous embryos was low. Moreover, all the extracts of the two strains inhibited HeLa cell proliferation, but methanol extracts exerted the highest activity. Gas chromatography–mass spectrometry analysis evidenced for the first time the presence of β-N-methylamino-l-alanine and microcystin in these picocyanobacteria. The strong cytotoxic activity observed for aqueous and methanolic extracts of these two cyanobacteria laid the foundation for the production of bioactive compounds of pharmacological interest.

Extraintestinal pathogenic Escherichia coli (ExPEC) cause a wide range of clinical diseases such as bacteremia and urinary tract infections. The increase of multidrug resistant ExPEC strains is becoming a major concern for the treatment of these infections and E. coli has been identified as a critical priority pathogen by the WHO. Therefore, the development of vaccines has become increasingly important, with the surface lipopolysaccharide constituting a promising vaccine target. This study presents genetic and structural analysis of clinical urine isolates from Switzerland belonging to the serotype O25. Approximately 75% of these isolates were shown to correspond to the substructure O25B only recently described in an emerging clone of E. coli sequence type 131. To address the high occurrence of O25B in clinical isolates, an O25B glycoconjugate vaccine was prepared using an E. coli glycosylation system. The O antigen cluster was integrated into the genome of E. coli W3110, thereby generating an E. coli strain able to synthesize the O25B polysaccharide on a carrier lipid. The polysaccharide was enzymatically conjugated to specific asparagine side chains of the carrier protein exotoxin A (EPA) of Pseudomonas aeruginosa by the PglB oligosaccharyltransferase from Campylobacter jejuni. Detailed characterization of the O25B-EPA conjugate by use of physicochemical methods including NMR and GC-MS confirmed the O25B polysaccharide structure in the conjugate, opening up the possibility to develop a multivalent E. coli conjugate vaccine containing O25B-EPA., Glycoconjugate Journal, 38 (4), ISSN:0282-0080, ISSN:1573-4986

While in recent years the key role of non-coding RNAs (ncRNAs) in the regulation of gene expression has become increasingly evident, their interaction with the global regulatory circuits is still obscure. Here we analyzed the structure and organization of the transcriptome of Streptomyces ambofaciens, the producer of spiramycin. We identified ncRNAs including 45 small-RNAs (sRNAs) and 119 antisense-RNAs (asRNAs I) that appear transcribed from dedicated promoters. Some sRNAs and asRNAs are unprecedented in Streptomyces and were predicted to target mRNAs encoding proteins involved in transcription, translation, ribosomal structure and biogenesis, and regulation of morphological and biochemical differentiation. We then compared ncRNA expression in three strains: (i) the wild-type strain, (ii) an isogenic pirA-defective mutant with central carbon metabolism imbalance, “relaxed” phenotype, and repression of antibiotic production, and (iii) a pirA-derivative strain harboring a “stringent” RNA polymerase that suppresses pirA-associated phenotypes. Data indicated that the expression of most ncRNAs was correlated to the stringent/relaxed phenotype suggesting novel effector mechanisms of the stringent response.

One of the strategies adopted for the development of a bivalent conjugate vaccine against invasive nontyphoidal Salmonella consists of linking the O-antigen component of S. Typhimurium and S. Entertidis lipopolysaccharides to the carrier protein CRM197, a non-toxic variant of diphtheria toxin. The conjugation reaction uses the reducing end residue 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo) of the core to which the O-antigen chain is bound (OAg-core). OAg-core chains are cleaved from the lipid A directly in the fermentation broth by mild acid treatment. Kdo has been reported to undergo structural changes under these conditions and therefore the Kdo at the reducing end was thoroughly analysed to verify its structural integrity. For this purpose, low molecular mass OAg-core chains extracted from S. Typhimurium wild type bacteria and core oligosaccharides extracted from S. Typhimurium bacteria mutated not to produce O-antigen repeats were characterized by GLC-MS, MALDI-TOF-MS and NMR spectroscopy. Moreover, a combination of H-1-(1)Hand H-1-C-13 experiments confirmed the linkage positions, sequence and structure of the octasaccharide core with 5-linked Kdo present at the reducing end in its native structure: alpha-GlcpNAc-(1 -> 2)-alpha-Glcp-(1 -> 2)-alpha-Galp-(1 -> 3)-[alpha-Galp-(1 -> 6)]-alpha-Glcp-(1 -> 3)-[alpha-Hepp-(1 -> 7)]-alpha-Hepp- (1 -> 3)-alpha-Hepp-(1 -> 5)-Kdo.

International audience; In the marine context, information about dispersal is essential for the design of networks of marine protected areas (MPAs). Generally, most of the dispersal of demersal fishes is thought to be driven by the transport of eggs and larvae in currents, with the potential contribution of dispersal in later life stages relatively minimal.Using otolith chemistry analyses, we estimate dispersal patterns across a spatial scale of approximately 180 km at both propagule (i.e. eggs and larvae) and juvenile (i.e. between settlement and recruitment) stages of a Mediterranean coastal fishery species, the two-banded seabream Diplodus vulgaris. We detected three major natal sources of propagules replenishing local populations in the entire study area, suggesting that propagule dispersal distance extends to at least 90 km. For the juvenile stage, we detected dispersal of up to 165 km. Our work highlights the surprising and significant role of dispersal during the juvenile life stages as an important mechanism connecting populations. Such new insights are crucial for creating effective management strategies (e.g. MPAs and MPA networks) and to gain support from policymakers and stakeholders, highlighting that MPA benefits can extend well beyond MPA borders, and not only via dispersal of eggs and larvae, but also through movement by juveniles.

Histone acetylation plays essential roles in cell cycle progression, DNA repair, gene expression and silencing. Although the knowledge regarding the roles of acetylation of histone lysine residues is rapidly growing, very little is known about the biochemical pathways providing the nucleus with metabolites necessary for physiological chromatin acetylation. Here, we show that mutations in the scheggia (sea)-encoded Sea protein, the Drosophila ortholog of the human mitochondrial citrate carrier Solute carrier 25 A1 (SLC25A1), impair citrate transport from mitochondria to the cytosol. Interestingly, inhibition of sea expression results in extensive chromosome breakage in mitotic cells and induces an ATR-dependent cell cycle arrest associated with a dramatic reduction of global histone acetylation. Notably, loss of SLC25A1 in short interfering RNA (siRNA)-treated human primary fibroblasts also leads to chromosome breaks and histone acetylation defects, suggesting an evolutionary conserved role for Sea/SLC25A1 in the regulation of chromosome integrity. This study therefore provides an intriguing and unexpected link between intermediary metabolism and epigenetic control of genome stability.