Search

The sole unifying feature of the incredibly diverse Archaea is their isoprenoid‐based ether‐linked lipid membranes. Unique lipid membrane composition, including an abundance of membrane‐spanning tetraether lipids, impart resistance to extreme conditions. Many questions remain, however, regarding the synthesis and modification of tetraether lipids and how dynamic changes to archaeal lipid membrane composition support hyperthermophily. Tetraether membranes, termed glycerol dibiphytanyl glycerol tetraethers (GDGTs), are generated by tetraether synthase (Tes) by joining the tails of two bilayer lipids known as archaeol. GDGTs are often further specialized through the addition of cyclopentane rings by GDGT ring synthase (Grs). A positive correlation between relative GDGT abundance and entry into stationary phase growth has been observed, but the physiological impact of inhibiting GDGT synthesis has not previously been reported. Here, we demonstrate that the model hyperthermophile Thermococcus kodakarensis remains viable when Tes (TK2145) or Grs (TK0167) are deleted, permitting phenotypic and lipid analyses at different temperatures. The absence of cyclopentane rings in GDGTs does not impact growth in T. kodakarensis, but an overabundance of rings due to ectopic Grs expression is highly fitness negative at supra‐optimal temperatures. In contrast, deletion of Tes resulted in the loss of all GDGTs, cyclization of archaeol, and loss of viability upon transition to the stationary phase in this model archaea. These results demonstrate the critical roles of highly specialized, dynamic, isoprenoid‐based lipid membranes for archaeal survival at high temperatures. Plain Language Summary: The preponderance of tetraether membrane‐spanning lipids in many archaeal clades indicates the fitness advantage of unique membranes for archaeal survival. The inability to rationally control the synthesis of tetraether and cyclized tetraether‐lipids has limited investigations into how dynamic shifts in lipid composition support archaeal growth and phase transitions. Employing the facile genetic system of the model hyperthermophilic archaeon Thermococcus kodakarensis that naturally synthesizes abundant tetraether lipids, we identified and targeted the genes necessary for tetraether lipid synthesis and derivatization. While impairing tetraether lipid biosynthesis is possible, the lack of specialized lipids dramatically impairs long‐term survival, supporting a critical role for dynamic lipidome changes in supporting archaeal life in the extremes. [ABSTRACT FROM AUTHOR]

Objective: To assess whether migraine may be genetically and/or causally associated with inflammatory bowel disease (IBD) or celiac disease. Background: Migraine has been linked to IBD and celiac disease in observational studies, but whether this link may be explained by a shared genetic basis or could be causal has not been established. The presence of a causal association could be clinically relevant, as treating one of these medical conditions might mitigate the symptoms of a causally linked condition. Methods: Linkage disequilibrium score regression and two‐sample bidirectional Mendelian randomization analyses were performed using summary statistics from cohort‐based genome‐wide association studies of migraine (59,674 cases; 316,078 controls), IBD (25,042 cases; 34,915 controls) and celiac disease (11,812 or 4533 cases; 11,837 or 10,750 controls). Migraine with and without aura were analyzed separately, as were the two IBD subtypes Crohn's disease and ulcerative colitis. Positive control analyses and conventional Mendelian randomization sensitivity analyses were performed. Results: Migraine was not genetically correlated with IBD or celiac disease. No evidence was observed for IBD (odds ratio [OR] 1.00, 95% confidence interval [CI] 0.99–1.02, p = 0.703) or celiac disease (OR 1.00, 95% CI 0.99–1.02, p = 0.912) causing migraine or migraine causing either IBD (OR 1.08, 95% CI 0.96–1.22, p = 0.181) or celiac disease (OR 1.08, 95% CI 0.79–1.48, p = 0.614) when all participants with migraine were analyzed jointly. There was some indication of a causal association between celiac disease and migraine with aura (OR 1.04, 95% CI 1.00–1.08, p = 0.045), between celiac disease and migraine without aura (OR 0.95, 95% CI 0.92–0.99, p = 0.006), as well as between migraine without aura and ulcerative colitis (OR 1.15, 95% CI 1.02–1.29, p = 0.025). However, the results were not significant after multiple testing correction. Conclusions: We found no evidence of a shared genetic basis or of a causal association between migraine and either IBD or celiac disease, although we obtained some indications of causal associations with migraine subtypes. [ABSTRACT FROM AUTHOR]

Aim: The aim of the study was to describe different eHealth literacy domains among parents of children needing paediatric surgery in Sweden, and the correlation between these eHealth literacy domains and parents' socioeconomic factors and demographic characteristics. Design: Descriptive correlational design. Method: Thirty‐five Swedish‐speaking parents participated as a historical control group within an ongoing Swedish clinical trial developing eHealth solutions for families after hospital care; of these, 30 completed the eHealth Literacy Questionnaire and the socioeconomic and demographic questionnaire. Results: Of the seven eHealth literacy domains assessed, parents' strengths lay in those pertaining to their own digital competence, control and safety, while their weakness concerned their motivation to engage with digital services, and their ability to access eHealth platforms that work. Overall, parents presented adequate eHealth literacy. Of the five socioeconomic and demographic variables assessed (i.e. monthly wages, education levels, age, gender and residency), monthly wages correlated the strongest, and positively, with the seven eHealth literacy domains. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the effectiveness of two non‐surgical treatment protocols for periodontitis patients in general dental practice. Materials and Methods: Ninety‐five dental hygienists (59 dental clinics) were randomly assigned to one of two treatment protocols: (i) establishment of adequate self‐performed oral hygiene prior to a single session of ultrasonic instrumentation (guided periodontal infection control [GPIC]) or (ii) conventional non‐surgical therapy (CNST) including patient education and scaling and root planing integrated in multiple sessions. Residual pockets at 3 months were retreated in both groups. The primary outcome was pocket closure (probing pocket depth ≤ 4 mm) at 6 months. Multilevel models were utilized. Results: Based on data from 615 patients, no significant differences with regard to clinical outcomes were observed between treatment protocols. Treatment‐related costs (i.e., chair time, number of sessions) were significantly lower for GPIC than CNST. Smoking and age significantly affected treatment outcomes. Conclusions: No significant differences between the two approaches were observed in regard to clinical outcomes. GPIC was more time‐effective. Patient education should include information on the detrimental effects of smoking. ClinicalTrials.gov (NCT02168621). [ABSTRACT FROM AUTHOR]

Background: Prevention of child obesity is an international public health priority and believed to be effective when started in early childhood. Caregivers often ask for an early and structured response from health professionals when their child is identified with overweight, yet cost‐effective interventions for children aged 2–6 years and their caregivers in Child Health Services are lacking. Objectives: To evaluate the effects and cost‐effectiveness of a child‐centered health dialogue in the Child Health Services in Sweden on 4‐year‐old children with normal weight and overweight. Methods: Thirty‐seven Child Health Centers were randomly assigned to deliver intervention or usual care. The primary outcome was zBMI‐change. Results: A total of 4598 children with normal weight (zBMI: 0.1 [SD = 0.6] and 490 children with overweight (zBMI: 1.6 [SD = 0.3]) (mean age: 4.1 years [SD = 0.1]; 49% females) were included. At follow‐up, at a mean age of 5.1 years [SD = 0.1], there was no intervention effect on zBMI‐change for children with normal weight. Children with overweight in the control group increased zBMI by 0.01 ± 0.50, while children in the intervention group decreased zBMI by 0.08 ± 0.52. The intervention effect on zBMI‐change for children with overweight was –0.11, with a 95% confidence interval of –0.24 to 0.01 (p = 0.07). The estimated additional costs of the Child‐Centered Health Dialogue for children with overweight were 167 euros per child with overweight and the incremental cost‐effectiveness ratio was 183 euros per 0.1 zBMI unit prevented. Conclusions: This low‐intensive multicomponent child‐centered intervention for the primary prevention of child obesity did not show statistical significant effects on zBMI, but is suggested to be cost‐effective with the potential to be implemented universally in the Child Health Services. Future studies should investigate the impact of socio‐economic factors in universally implemented obesity prevention programs. [ABSTRACT FROM AUTHOR]

Introduction: Migraine is a prevalent condition causing a substantial level of disability worldwide. Despite this, the pathophysiological mechanisms are not fully understood. Migraine often co‐occurs with gastrointestinal disorders, but the direction of a potential causal link is unclear. The aim of this project was to investigate the associations between migraine and several gastrointestinal disorders in the same cohort in order to determine the relative strengths of these associations. Methods: This cross‐sectional study examined whether migraine is associated with irritable bowel syndrome (IBS), peptic ulcers, Helicobacter pylori (HP) infections, celiac disease, Crohn's disease and ulcerative colitis. Baseline data covering 489,753 UK Biobank participants (migraine group: n = 14,180) were analyzed using Pearson's chi‐square tests and adjusted binary logistic regression models. Results: Migraine was significantly associated with IBS (odds ratio [OR] 2.24, 95% confidence interval [CI] 2.08–2.40, p <.001) and peptic ulcers (OR 1.55, 95% CI 1.35–1.77, p <.001). Migraine was not associated with HP infection (OR 1.34, 95% CI 1.04–1.73, p =.024), celiac disease (OR 1.29, 95% CI 1.04–1.60, p =.023), Crohn's disease (OR 1.08, 95% CI 0.80–1.45, p =.617) or ulcerative colitis (OR 1.00, 95% CI 0.79–1.27, p =.979) after adjusting for multiple testing. Conclusions: Migraine was associated with IBS and peptic ulcers in this large population‐based cohort. The associations with HP infection, celiac disease, Crohn's disease, and ulcerative colitis did not reach significance, suggesting a weaker link between migraine and autoimmune gastrointestinal conditions or HP infection. [ABSTRACT FROM AUTHOR]

Archaeal glycerol dibiphytanyl glycerol tetraethers (GDGT) are some of the most unusual membrane lipids identified in nature. These amphiphiles are the major constituents of the membranes of numerous Archaea, some of which are extremophilic organisms. Due to their unique structures, there has been significant interest in studying both the biophysical properties and the biosynthesis of these molecules. However, these studies have thus far been hampered by limited access to chemically pure samples. Herein, we report a concise and stereoselective synthesis of the archaeal tetraether lipid parallel GDGT‐0 and the synthesis and self‐assembly of derivatives bearing different polar groups. [ABSTRACT FROM AUTHOR]

In response to contemporary forms of human mobility, there has been a continued hardening of borders seeking to deter, control and exclude certain groups of people from entering nation states in Europe, North America and Australasia. Within this context, a disconcerting evolution of new and increasingly sophisticated forms of border control measures have emerged, which often play out within bilateral arrangements of "externalised" or "offshore" border controls. Drawing on extensive first‐hand field research among displaced people in Calais, Paris and Brussels in 2016–2019, this paper argues that the externalization of the British border to France is contingent upon a harmful strategy, which can be understood as the "politics of exhaustion." This is a raft of (micro) practices and methods strategically aimed to deter, control and exclude certain groups of people on the move who have been profiled as "undesirable," with a detrimental (un)intended impact on human lives. [ABSTRACT FROM AUTHOR]

To investigate age‐related changes in oral motor strategies in response to unpredictable load demands. Sixty‐five healthy children (aged 3–17 yr) were divided into five age‐groups based on their dental eruption stages and compared with a group of healthy adults (aged 18–35 yr). Each participant was asked to perform a standardized motor control task involving 'pulling' and 'holding' a force transducer with the anterior teeth. Different loads were attached to the force transducer in an unpredictable manner. The temporal force profile was divided into two time‐segments (an initial segment and a later segment). The peak force and peak force rate during the initial time‐segment, and the holding force and intra‐trial variability (coefficient of variation) during the later time‐segment, were measured. The results showed no differences in the peak force, peak force rate, holding force, and force variability in children compared with adults. However, the trends in the data evaluated using a segmented regression analysis showed that a breakpoint (abrupt change) consistently occurred in the late‐mixed dentition group (age 9–11 yr) for most of the outcome variables. The results indicate that while the motor control strategies in children appear to be similar to those in adults, there is a shift in the oral motor developmental trend during the late‐mixed dentition stage. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: To compare the peri‐implant tissue response to subcrestal or crestal placement of implants with or without “platform‐switched” implant/abutment connections. Material and methods: On each side of the mandible in six Labrador dogs, two “platform‐switched” (PS) implants and two implants with matching implant/abutment diameters (PM) were placed in a crestal or a 1.5 mm subcrestal position. Sulcus formers/abutments were connected, baseline radiographs obtained and the distance between the abutment‐fixture junction (A/F) and the marginal bone level (B) was determined. Five months later, radiographic and clinical examinations were repeated and biopsies were obtained and processed for histological analysis. Results: The radiographic analysis showed that marginal bone level changes occurred during the first observation period (13 weeks). PS‐implants showed minor marginal bone level alterations during the full observation period (20 weeks), regardless of placement depth. For PM‐implants, placement had a significant impact on bone level changes; crestal placement resulted in a mean bone loss of 0.4 mm and subcrestal placement in a 1.5 mm bone loss. The histometric measurements resulted in a distance A/F‐B of 0.6 and 0.0 mm for PS implants, placed in a crestal or subcrestal position, respectively. The corresponding distance at PM‐implants was 1.5 mm irrespective of placement protocol. The peri‐implant mucosa was thicker at subcrestally placed implants as compared to a crestal placement. Conclusions: Bone remodeling occurred within the early healing phase. During the full 20 weeks of observation, PS‐implants demonstrated significantly less crestal bone loss compared to PM‐implants. [ABSTRACT FROM AUTHOR]

Low-quality health services are a problem across low- and middle-income countries. Information failure may contribute, as patients may have insufficient knowledge to discern the quality of health services. That decreases the likelihood that patients will sort into higher quality facilities, increasing demand for better health services. This paper presents results from a health survey in Nigeria to investigate whether patients can evaluate health service quality effectively. Specifically, this paper demonstrates that although more than 90% of patients agree with any positive statement about the quality of their local health services, satisfaction is significantly associated with the diagnostic ability of health workers at the facility. Satisfaction is not associated with more superficial characteristics such as infrastructure quality or prescriptions of medicines. This suggests that patients may have sufficient information to discern some of the most important elements of quality, but that alternative measures are crucial for gauging the overall quality of care. [ABSTRACT FROM AUTHOR]

Introduction: Pheochromocytomas are neuroendocrine tumors of the adrenal glands. Up to 40% of the cases are caused by germline mutations in one of at least 15 susceptibility genes, making them the human neoplasms with the highest degree of heritability. Recurrent somatic alterations are found in about 50% of the more common sporadic tumors with NF1 being the most common mutated gene (20-25%). In many sporadic tumors, however, a genetic explanation is still lacking. Materials and methods: We investigated the genomic landscape of sporadic pheochromocytomas with whole-exome sequencing of 16 paired tumor and normal DNA samples and extended confirmation analysis in 2 additional cohorts comprising a total of 80 sporadic pheochromocytomas. Results: We discovered on average 33 non-silent somatic variants per tumor. One of the recurrently mutated genes was FGFR1, encoding the fibroblast growth factor receptor 1, which was recently revealed as an oncogene in pediatric brain tumors. Including a subsequent analysis of a larger cohort, activating FGFR1 mutations were detected in three of 80 sporadic pheochromocytomas (3.8%). Gene expression microarray profiling showed that these tumors clustered with NF1-, RET,- and HRAS-mutated pheochromocytomas, indicating activation of the MAPK and PI3K-AKT signal transduction pathways. Conclusion: Besides RET and HRAS, FGFR1 is only the third protooncogene found to be recurrently mutated in pheochromocytomas. The results advance our biological understanding of pheochromocytoma and suggest that somatic FGFR1 activation is an important event in a subset of sporadic pheochromocytomas. [ABSTRACT FROM AUTHOR]

Little Salt Spring (Sarasota County, FL, USA) is a sinkhole with groundwater vents at ~77 m depth. The entire water column experiences sulfidic (~50 μM) conditions seasonally, resulting in a system poised between oxic and sulfidic conditions. Red pinnacle mats occupy the sediment-water interface in the sunlit upper basin of the sinkhole, and yielded 16S rRNA gene clones affiliated with Cyanobacteria, Chlorobi, and sulfate-reducing clades of Deltaproteobacteria. Nine bacteriochlorophyll e homologues and isorenieratene indicate contributions from Chlorobi, and abundant chlorophyll a and pheophytin a are consistent with the presence of Cyanobacteria. The red pinnacle mat contains hopanoids, including 2-methyl structures that have been interpreted as biomarkers for Cyanobacteria. A single sequence of hpnP, the gene required for methylation of hopanoids at the C-2 position, was recovered in both DNA and cDNA libraries from the red pinnacle mat. The hpnP sequence was most closely related to cyanobacterial hpnP sequences, implying that Cyanobacteria are a source of 2-methyl hopanoids present in the mat. The mats are capable of light-dependent primary productivity as evidenced by 13C-bicarbonate photoassimilation. We also observed 13C-bicarbonate photoassimilation in the presence of DCMU, an inhibitor of electron transfer to Photosystem II. Our results indicate that the mats carry out light-driven primary production in the absence of oxygen production-a mechanism that may have delayed the oxygenation of the Earth's oceans and atmosphere during the Proterozoic Eon. Furthermore, our observations of the production of 2-methyl hopanoids by Cyanobacteria under conditions of low oxygen and low light are consistent with the recovery of these structures from ancient black shales as well as their paucity in modern marine environments. [ABSTRACT FROM AUTHOR]

CA 125 is an antigenic determinant on a high molecular weight glycoprotein. A monoclonal antibody has been produced which recognizes this, and allows us to measure the expression of CA 125 in serum. Tissue distribution of the CA 125 determinant is most commonly seen in serous tumors of the ovary, with highest levels in borderline and frankly malignant serous cystadenocarcinomas. Occasionally cancers of the breast, gastrointestinal tract, and kidney will show elevated levels of CA 125. Normal tissues which show varying levels of CA 125 include decidual tissue and structures derived from celomic epithelium. CA 125 is clearly tumor associated, but not tumor specific. Quantitative correlation of CA 125 levels with tumor volume has not been demonstrated. This observation limits the clinical usefulness of CA 125 as a screening tool, particularly in premenopausal patients who do not have a diagnosis of ovarian cancer. An undetectable level of CA 125 antigen does not rule out the presence of an early ovarian cancer. When CA 125 is used to monitor disease state in patients with known ovarian cancers (whose tumors do express CA 125), changes in levels of CA 125 do correlate with gross changes in tumor volume. Good prognostic significance is attributed to a rapid decline in CA 125 levels following induction chemotherapy in patients with advanced ovarian cancer. However, an undetectable serum level of CA 125 does not predict clinical cure for a patient with ovarian cancer. Further clinical studies continue in the use of CA 125 as a screening tool and as a means to monitor treatment responses of known ovarian cancer. [ABSTRACT FROM AUTHOR]

Background: The aims of this study were to investigate the anti-inflammatory effect and the effect on bone regeneration of hyaluronan in surgical and non-surgical groups. Methods: In each of 15 individuals, 2 teeth with defects of similar character and magnitude in the upper or lower jaw were chosen. There were at least 2 teeth between the test and the control sites. In the surgical group, a bioabsorbable membrane was used for both test and control sites, and hyaluronan was placed in the intrabony pocket of the test site. In the non-surgical group, the periodontal pockets were scaled and hyaluronan was administered 3 times with an interval of 1 week in the test pockets. Alveolar bone height and bone healing patterns were analyzed using digital intraoral radiographs. Measurements of bone height were performed in the original digital black-and-white radiographs to obtain quantitative data on bone gain or loss. Bone healing patterns were studied with color-coded radiographs, using specially designed software in a personal computer with subsequent combinations of radiographs. Gingival crevicular fluid immunoglobulin (Ig)G, C3, and prostaglandin E2 (PGE2) responses; periodontal probing depth; bleeding on probing; and the presence of plaque were studied to evaluate the anti-inflammatory effect. Data were obtained at baseline before treatment, and at 2 weeks, and 1, 3, 6, and 12 months after treatment. Results: For the surgical treatments, bone height was increased in the test group treated with hyaluronan (mean value 2.2%, corresponding to an average increase of approximately 0.5 mm) and reduced in the control group (mean value -1.8%, corresponding to an average decrease of approximately - 0.4 mm) (P<0.05) after 12 months. For the non-surgical treatments, bone height was reduced by a mean value of -1.1% (corresponding to an average decrease of approximately -0.25 mm) in the test group treated with hyaluronan and -3.3% (corresponding to an average decrease of approximately -0.75 mm) in the control group after 12 months (N.S.). According to the digital color-coded radiographs, the test sites in the surgical and non-surgical groups showed apposition of bone minerals. Immune responses showed no differences during the 12 months studied for the surgical and non-surgical sites. Mean periodontal probing depths were reduced between 2.5 mm and 4.1 mm in the surgical and non-surgical groups. Conclusions: The observed difference in bone height between test and control sites in the surgical group after 12 months was less than 1 mm, which was only detectable on radiographs. No statistical difference was found on radiographs in the non-surgical group, where a decrease in bone height was found for both groups after scaling. Probing depth reduction after the surgical treatment, as well as after scaling and root planing, was as expected. Hyaluronan in contact with bone and soft tissues had no influence on the immune system in this study. Further studies are needed to determine the extent to which hyaluronan can lead to clinically significant healing of periodontal lesions. [ABSTRACT FROM AUTHOR]

Hopanoids are bacterial surrogates of eukaryotic membrane sterols and among earth's most abundant natural products. Their molecular fossils remain in sediments spanning more than a billion years. However, hopanoid metabolism and function are not fully understood. B urkholderia species are environmental opportunistic pathogens that produce hopanoids and also occupy diverse ecological niches. We investigated hopanoids biosynthesis in B urkholderia cenocepacia by deletion mutagenesis and structural characterization of the hopanoids produced by the mutants. The enzymes encoded by hpnH and hpnG were essential for production of all C35 extended hopanoids, including bacteriohopanetetrol ( BHT), BHT glucosamine and BHT cyclitol ether. Deletion of hpnI resulted in BHT production, while Δ hpnJ produced only BHT glucosamine. Thus, HpnI is required for BHT glucosamine production while HpnJ is responsible for its conversion to the cyclitol ether. The Δ hpnH and Δ hpnG mutants could not grow under any stress condition tested, whereas Δ hpnI, Δ hpnJ and Δ hpnK displayed wild-type growth rates when exposed to detergent, but varying levels of sensitivity to low pH and polymyxin B. This study not only elucidates the biosynthetic pathway of hopanoids in B . cenocepacia, but also uncovers a biosynthetic role for the conserved proteins HpnI, HpnJ and HpnK in other hopanoid-producing bacteria. [ABSTRACT FROM AUTHOR]

Background: Pheochromocytomas (PCCs) develop from the adrenal medulla and are often part of a hereditary syndrome such as von Hippel-Lindau (VHL) syndrome. In VHL, only about 30 % of patients with a VHL missense mutation develop PCCs. Thus, additional genetic events leading to formation of such tumors in patients with VHL syndrome are sought. SDHAF2 (previously termed SDH5) and SDHD are both located on chromosome 11q and are required for the function of mitochondrial complex II. While SDHAF2 has been shown to be mutated in patients with paragangliomas (PGLs), SDHD mutations have been found both in patients with PCCs and in patients with PGLs. Materials and methods: Because loss of 11q is a common event in VHL-associated PCCs, we aimed to investigate whether SDHAF2 and SDHD are targets. In the present study, 41 VHL-associated PCCs were screened for mutations and loss of heterozygosity (LOH) in SDHAF2 or SDHD. Promoter methylation, as well as mRNA expression of SDHAF2 and SDHD, was studied. In addition, immunohistochemistry (IHC) of SDHB, known to be a universal marker for loss of any part the SDH complex, was conducted. Results and conclusions: LOH was found in more than 50 % of the VHL-associated PCCs, and was correlated with a significant decrease ( p < 0.05) in both SDHAF2 and SDHD mRNA expression, which may be suggestive of a pathogenic role. However, while SDHB protein expression as determined by IHC in a small cohort of tumors was lower in PCCs than in the surrounding adrenal cortex, there was no obvious correlation with LOH or the level of SDHAF2/SDHD mRNA expression. In addition, the lack of mutations and promoter methylation in the investigated samples indicates that other events on chromosome 11 might be involved in the development of PCCs in association with VHL syndrome. [ABSTRACT FROM AUTHOR]

* Premise of the study: Adventitious root (AR) formation is indispensable for vegetative propagation, but difficult to achieve in many crops. Understanding its molecular mechanisms is thus important for such species. Here we aimed at developing a rooting protocol for direct AR formation in stems, locating cellular AR origins in stems and exploring molecular differences underlying adventitious rooting in hypocotyls and stems. * Methods." In-vitro-grown hypocotyls or stems of wild-type and transgenic ecotype Columbia (Col-0) of Arabidopsis thaliana were rooted on rooting media. Anatomy of AR formation, qRT-PCR of some rooting-related genes and in situ GUS expression were carried out during rooting from hypocotyls and stems. * Key results: We developed a rooting protocol for AR formation in stems and traced back root origins in stems by anatomical and in situ expression studies. Unlike rooting in hypocotyls, rooting in sterns was slower, and AR origins were mainly from lateral parenchyma of vascular bundles and neighboring starch sheath cells as well as, to a lesser extent, from phloem cap and xylem parenchyma. Transcript levels of GH3-3, LBD16, LBD29, and LRP1 in hypocotyls and stems were similar, but transcript accumulation was delayed in stems. In situ expression signals of DRS::GUS, LBD16::GUS, LBD29::GUS, and rolB::GUS reporters in stems mainly occurred at the root initiation sites, suggesting their involvement in AR formation. * Conclusions: We have developed an efficient rooting protocol using half-strength Lepoivre medium for studying AR formation in stems, traced back the cellular AR origins in stems, and correlated expression of roofing-related genes with root initiation sites. [ABSTRACT FROM AUTHOR]

Inclusions of intraneuronal alpha-synuclein (α-synuclein) can be detected in brains of patients with Parkinson's disease and dementia with Lewy bodies. The aggregation of α-synuclein is a central feature of the disease pathogenesis. Among the different α-synuclein species, large oligomers/protofibrils have particular neurotoxic properties and should therefore be suitable as both therapeutic and diagnostic targets. Two monoclonal antibodies, mAb38F and mAb38E2, with high affinity and strong selectivity for large α-synuclein oligomers were generated. These antibodies, which do not bind amyloid-beta or tau, recognize Lewy body pathology in brains from patients with Parkinson's disease and dementia with Lewy bodies and detect pathology earlier in α-synuclein transgenic mice than linear epitope antibodies. An oligomer-selective sandwich ELISA, based on mAb38F, was set up to analyze brain extracts of the transgenic mice. The overall levels of α-synuclein oligomers/protofibrils were found to increase with age in these mice, although the levels displayed a large interindividual variation. Upon subcellular fractionation, higher levels of α-synuclein oligomers/protofibrils could be detected in the endoplasmic reticulum around the age when behavioral disturbances develop. In summary, our novel oligomer-selective α-synuclein antibodies recognize relevant pathology and should be important tools to further explore the pathogenic mechanisms in Lewy body disorders. Moreover, they could be potential candidates both for immunotherapy and as reagents in an assay to assess a potential disease biomarker. [ABSTRACT FROM AUTHOR]

Microbialites (stromatolites and thrombolites) are mineralized mat structures formed via the complex interactions of diverse microbial-mat communities. At Highborne Cay, in the Bahamas, the carbonate component of these features is mostly comprised of ooids. These are small, spherical to ellipsoidal grains characterized by concentric layers of calcium carbonate and organic matter and these sand-sized particles are incorporated with the aid of extra-cellular polymeric substances ( EPS), into the matrix of laminated stromatolites and clotted thrombolite mats. Here, we present a comparison of the bacterial diversity within oolitic sand samples and bacterial diversity previously reported in thrombolitic and stromatolitic mats of Highborne Cay based on analysis of clone libraries of small subunit ribosomal RNA gene fragments and lipid biomarkers. The 16 S-r RNA data indicate that the overall bacterial diversity within ooids is comparable to that found within thrombolites and stromatolites of Highborne Cay, and this significant overlap in taxonomic groups suggests that ooid sands may be a source for much of the bacterial diversity found in the local microbialites. Cyanobacteria were the most diverse taxonomic group detected, followed by Alphaproteobacteria, Gammaproteobacteria, Planctomyces, Deltaproteobacteria, and several other groups also found in mat structures. The distributions of intact polar lipids, the fatty acids derived from them, and bacteriohopanepolyols provide broad general support for the bacterial diversity identified through analysis of nucleic acid clone libraries. [ABSTRACT FROM AUTHOR]

Hopanes preserved in both modern and ancient sediments are recognized as the molecular fossils of bacteriohopanepolyols, pentacyclic hopanoid lipids. Based on the phylogenetic distribution of hopanoid production by extant bacteria, hopanes have been used as indicators of specific bacterial groups and/or their metabolisms. However, our ability to interpret them ultimately depends on understanding the physiological roles of hopanoids in modern bacteria. Toward this end, we set out to identify genes required for hopanoid biosynthesis in the anoxygenic phototroph Rhodopseudomonas palustris TIE-1 to enable selective control of hopanoid production. We attempted to delete 17 genes within a putative hopanoid biosynthetic gene cluster to determine their role, if any, in hopanoid biosynthesis. Two genes, hpnH and hpnG, are required to produce both bacteriohopanetetrol and aminobacteriohopanetriol, whereas a third gene, hpnO, is required only for aminobacteriohopanetriol production. None of the genes in this cluster are required to exclusively synthesize bacteriohopanetetrol, indicating that at least one other hopanoid biosynthesis gene is located elsewhere on the chromosome. Physiological studies with the different deletion mutants demonstrated that unmethylated and C30 hopanoids are sufficient to maintain cytoplasmic but not outer membrane integrity. These results imply that hopanoid modifications, including methylation of the A-ring and the addition of a polar head group, may have biologic functions beyond playing a role in membrane permeability. [ABSTRACT FROM AUTHOR]

Markers for caspase activation and apoptosis have been shown in brains of Alzheimer's disease (AD) patients and AD-mouse models. In neurons, caspase activation is associated with elevated amyloid β-peptide (Aβ) production. Caspases cleave numerous substrates including presenilin-1 (PS1). The cleavage takes place in the large cytosolic loop of PS1-C-terminal fragment (PS1CTF), generating a truncated PS1CTF lacking half of the loop domain (caspCTF). The loop has been shown to possess important regulatory functions with regard to Aβ40 and Aβ42 production. Previously, we have demonstrated that γ-secretase complexes are active during apoptosis regardless of caspase cleavage in the PS1CTF-loop. Here, a PS1/PS2-knockout mouse blastocyst-derived cell line was used to establish stable or transient cell lines expressing either caspCTF or full-length CTF (wtCTF). We show that caspCTF restores γ-secretase activity and forms active γ-secretase complexes together with Nicastrin, Pen-2, Aph-1 and PS1-N-terminal fragment. Further, caspCTF containing γ-secretase complexes have a sustained capacity to cleave amyloid precursor protein (APP) and Notch, generating APP and Notch intracellular domain, respectively. However, when compared to wtCTF cells, caspCTF cells exhibit increased intracellular production of Aβ42 accompanied by increased intracellular Aβ42/Aβ40 ratio without changing the Aβ secretion pattern. Similarly, induction of apoptosis in wtCTF cells generate a similar shift in intracellular Aβ pattern with increased Aβ42/Aβ40 ratio. In summary, we show that caspase cleavage of PS1 generates a γ-secretase complex that increases the intracellular Aβ42/Aβ40 ratio. This can have implications for AD pathogenesis and suggests caspase inhibitors as potential therapeutic agents. [ABSTRACT FROM AUTHOR]

γ-Secretase is a transmembrane protease complex responsible for the processing of a multitude of type 1 transmembrane proteins, including amyloid precursor protein (APP) and Notch. A functional complex is dependent on the assembly of four proteins: presenilin (PS), nicastrin, Aph-1 and Pen-2. Little is known about how the substrates are selected by γ-secretase, but it has been suggested that γ-secretase associated proteins (GSAPs) could be of importance. For instance, it was recently reported from studies in cell lines that TMP21, a transmembrane protein involved in trafficking, binds to γ-secretase and regulates the processing of APP-derived substrates without affecting Notch cleavage. Here, we present an efficient and selective method for purification and analysis of γ-secretase and GSAPs. Microsomal membranes were prepared from rat or human brain and incubated with a γ-secretase inhibitor coupled to biotin via a long linker and a S-S bridge. After pulldown using streptavidin beads, bound proteins were eluted under reducing conditions and digested by trypsin. The tryptic peptides were subjected to LC-MS/MS analysis, and proteins were identified by sequence data from MS/MS spectra. All of the known γ-secretase components were identified. Interestingly, TMP21 and the PS associated protein syntaxin1 were associated to γ-secretase in rat brain. We suggest that the present method can be used for further studies on the composition of the γ-secretase complex. [ABSTRACT FROM AUTHOR]

The article describes a study which investigated the use of a perlite biofilter to treat air contaminated with α-pinene. To make the particle surface more hydrophobic, the perlite was coated partially with silicone oil. In comparison to the filter with uncoated perlite, the silicone oil-coated perlite biofilter performed better in removing the air contaminant at 2.5 L/min airflow rate. However, the removal efficiency was almost the same at 1.5 L/min airflow rate. It has been shown that the mass transport of the α-pinene contaminant from gas to liquid is improved by the silicone oil.

One hallmark of Alzheimer disease (AD) is the extracellular deposition of the amyloid β-peptide (Aβ) in senile plaques. Two major forms of Aβ are produced, 40 (Aβ40) and 42 (Aβ42) residues long. The most abundant form of Aβ is Aβ40, while Aβ42 is more hydrophobic and more prone to form toxic oligomers and the species of particular importance in early plaque formation. Thus, the length of the hydrophobic C-terminal seems to be very important for the oligomerization and neurotoxicity of the Aβ peptide. Here we investigated which Aβ species are deposited in AD brain. We analyzed plaque cores, prepared from occipital and frontal cortex, from sporadic and familial AD cases and performed a quantitative study using Aβ standard peptides. Cyanogen bromide was used to generate C-terminal Aβ fragments, which were analyzed by HPLC coupled to an electrospray ionisation ion trap mass spectrometer. We found a longer peptide, Aβ43, to be more frequent than Aβ40. No variants longer than Aβ43 could be observed in any of the brains. Immunohistochemistry was performed and was found to be in line with our findings. Aβ1-43 polymerizes rapidly and we suggest that this variant may be of importance for AD. [ABSTRACT FROM AUTHOR]

Objectives: It has been reported that one of the core features in patients with bipolar disorder II (BD II) is increased impulsivity. The aim of this study was to investigate whether patients with BD II showed decreased activation in the dorsal anterior cingulate cortex (dACC) as compared to healthy controls when performing a task sensitive to impulsivity. Methods: Twenty-seven BD II patients and 28 healthy controls performed a Go/No-go task during a functional magnetic resonance imaging (fMRI) session. Eleven of the patients were unmedicated, and possible group differences between medicated and unmedicated patients were also assessed. Results: The groups did not differ in behavioral performance on the Go/No-go task. Both BD II subjects and healthy controls demonstrated dACC activity during the task, and analyses revealed no statistically significant group differences. Medicated and unmedicated patients also did not differ in the degree of fMRI activation. Conclusions: These findings do not support the hypothesis of abnormal dACC activity during a Go/No-go task in BD II patients. [ABSTRACT FROM AUTHOR]

Objective: The aim of the present experiment was to study the healing around two-part implants that were placed in a subcrestal position. Material and methods: Five mongrel dogs, about 2 years old, were included. The mandibular premolars and the first, second and third maxillary premolars were extracted. Three months later two test and two control implants (OsseoSpeed™, 3.5 mm × 8 mm) were placed in one side of the mandible. The implants were placed in such a way that the implant margin was located 2 mm apical to the bone crest. In the test implants, the surface modification extended to the implant margin and, thus, included the shoulder part of the implant. Regular abutments with a turned surface (Zebra™) were connected to the control implants, while experimental abutments with a modified surface (TiOblast™) were connected to the test implants. A plaque control program that included cleaning of implants and teeth every second day was initiated. Four months later the dogs were euthanized and biopsies were obtained and prepared for histological analysis. Results: The marginal bone level at the test implants was identified in a more coronal position than that at the control implants. In 40% of the test implants, the bone-to-implant contact extended coronal of the abutment/fixture (A/F) border, i.e. in contact with the abutment part of the implant. The connective tissue portion of the peri-implant mucosa that was facing the test abutments contained a higher density of collagen and a smaller proportion of fibroblasts than that at the control sites. Conclusion: It is suggested that osseointegration may occur coronal to the A/F interface of two-part implants. Such a result, however, appears to depend on the surface characteristics of the implant components. [ABSTRACT FROM AUTHOR]

1 Short-snouted weevils, including Strophosoma spp. and related species, may damage tree seedlings. We investigated the damage caused by these weevils feeding on seedlings of seven tree species planted in clear-cuts and under shelterwoods with three densities (control, dense, and sparse). 2 There were no pronounced differences in damage caused by short-snouted weevils in the various shelterwood densities. Most feeding occurred in the clear-cuts during the first year, whereas more seedlings were damaged in the shelterwoods of all densities in the second year. In the third year, virtually no feeding occurred in either the clear-cuts or shelterwoods. We cannot explain this pattern of damage, but a fallow period of 2 years seems to prevent short-snouted weevil damage. 3 We determined the general feeding preferences for short-snouted weevils to be cherry, lime > beech, oak, spruce > maple, ash. However, although Strophosoma mellanogrammum [Correction added after online publication 8 December 2008: Strophosoma melanogrammum corrected to Strophosoma mellanogrammum] was observed feeding on seedlings, no full short-snouted weevil inventory was conducted, so caution must be exercised when drawing conclusions from this study regarding weevil damage patterns and feeding preferences. 4 Short-snouted weevils can sometimes occur in large numbers and may destroy entire reforestation projects, but in our study their influence on seedling growth and survival was minor. [ABSTRACT FROM AUTHOR]

Background: Recipient sites for implants often exhibit a vertical discrepancy between the buccal and lingual bone crest. The potential to preserve the lingual bone when placing the implant within the dimension determined by the buccal bone in such sites remains to be evaluated. Methods: Five dogs were included in this study. The premolars were extracted on one side of the mandible, and a buccal defect was prepared by the resection of a 2-mm-high portion of the buccal bone wall. Three months later, two test (surface modification on the shoulder part of the implant) and two control implants were placed within the area of the buccal bone defect. Following placement, the implant margin at the buccal side coincided with the buccal bone crest, whereas the implant margin at the lingual side was in a subcrestal position. Regular abutments with a turned surface were connected to the control implants, whereas experimental abutments with a modified surface were connected to the test implants. A plague-control program was initiated. Four months later, biopsies were obtained and prepared for histologic analysis. Results: The marginal bone level was located at a more coronal position at the lingual aspect than at the buccal aspect of the test implants, whereas the buccal and lingual bone levels were similar at control implants. Conclusion: It is suggested that different marginal bone levels are obtainable at the lingual and buccal aspects when two-part implants with suitable surface characteristics are placed in sites with different buccal and lingual bone heights. [ABSTRACT FROM AUTHOR]

Objective: The aim of the present study was to analyze the soft tissue barrier formed to implant abutments made of different materials. Material and methods: Six Labrador dogs, about 1 year old, were used. All mandibular premolars and the first, second and third maxillary premolars were extracted. Three months later four implants (OsseoSpeed™, 4.5 × 9 mm, Astra Tech Dental, Mölndal, Sweden) were placed in the edentulous premolar region on one side of the mandible and healing abutments were connected. One month later, the healing abutments were disconnected and four new abutments were placed in a randomized order. Two of the abutments were made of titanium (Ti), while the remaining abutments were made of ZrO2 or AuPt-alloy. A 5-months plaque control program was initiated. Three months after implant surgery, the implant installation procedure and the subsequent abutment shift were repeated in the contra-lateral mandibular region. Two months later, the dogs were euthanized and biopsies containing the implant and the surrounding soft and hard peri-implant tissues were collected and prepared for histological analysis. Results: It was demonstrated that the soft tissue dimensions at Ti- and ZrO2 abutments remained stable between 2 and 5 months of healing. At Au/Pt-alloy abutment sites, however, an apical shift of the barrier epithelium and the marginal bone occurred between 2 and 5 months of healing. In addition, the 80-μm-wide connective tissue zone lateral to the Au/Pt-alloy abutments contained lower amounts of collagen and fibroblasts and larger fractions of leukocytes than the corresponding connective tissue zone of abutments made of Ti and ZrO2. Conclusion: It is suggested that the soft tissue healing to abutments made of titanium and ZrO2 is different to that at abutments made of AuPt-alloy. [ABSTRACT FROM AUTHOR]

Several lines of evidence suggest that polymerization of the amyloid β-peptide (Aβ) into amyloid plaques is a pathogenic event in Alzheimer’s disease (AD). Aβ is produced from the amyloid precursor protein as the result of sequential proteolytic cleavages by β-secretase and γ-secretase, and it has been suggested that these enzymes could be targets for treatment of AD. γ-Secretase is an aspartyl protease complex, containing at least four transmembrane proteins. Studies in cell lines have shown that γ-secretase is partially localized to lipid rafts, which are detergent-resistant membrane microdomains enriched in cholesterol and sphingolipids. Here, we studied γ-secretase in detergent-resistant membranes (DRMs) prepared from human brain. DRMs prepared in the mild detergent CHAPSO and isolated by sucrose gradient centrifugation were enriched in γ-secretase components and activity. The DRM fraction was subjected to size-exclusion chromatography in CHAPSO, and all of the γ-secretase components and a lipid raft marker were found in the void volume (> 2000 kDa). Co-immunoprecipitation studies further supported the notion that the γ-secretase components are associated even at high concentrations of CHAPSO. Preparations from rat brain gave similar results and showed a postmortem time-dependent decline in γ-secretase activity, suggesting that DRMs from fresh rat brain may be useful for γ-secretase activity studies. Finally, confocal microscopy showed co-localization of γ-secretase components and a lipid raft marker in thin sections of human brain. We conclude that the active γ-secretase complex is localized to lipid rafts in human brain. [ABSTRACT FROM AUTHOR]

The risk of venous thromboembolism (VTE) was examined in individuals with coeliac disease (CD). The Swedish national inpatient register was used to identify 14 207 individuals with a diagnosis of CD (1964–2003). These individuals were matched for age, sex, calendar year and county with 69 048 reference individuals. Cox regression was used to estimate hazard ratios (HRs) for subsequent thromboembolism in individuals with more than 1 year of follow-up and no prior VTE. CD was associated with an increased risk of subsequent VTE (HR = 1·86; 95% confidence interval (CI) 1·54–2·24). The risk increase was restricted to individuals with CD diagnosed in adulthood. Risk estimates were not affected by the presence of diabetes mellitus or concomitant surgery. Compared with inpatients as reference individuals, CD individuals remained at increased risk of subsequent VTE (adjusted HR = 1·27; 95% CI = 1·06–1·52). In conclusion, this study found a statistically significantly positive association between CD and VTE. This modest association might be explained by a combination of surveillance bias and chronic inflammation. [ABSTRACT FROM AUTHOR]

Objective: To analyse the soft tissue healing at titanium implants coated with type 1 collagen. Material and methods: Six dogs were used. The mandibular pre-molars and the three anterior maxillary pre-molars were extracted. Three months later mucoperiosteal flaps were raised and two test and two control implants were installed (3i® TG Osseotite®3.75 × 10 and 2.8 mm transmucosal collar). The test implants were coated with a purified porcine type I collagen. Cover screws were placed and flaps were sutured. The sutures were removed 2 weeks later and a plaque-control programme was initiated. Another 2 weeks later, the procedure was repeated in the contra-lateral mandibular region. Four weeks after the second implant surgery, biopsies were obtained and prepared for histological examination. Results/Conclusion: The vertical dimensions of the epithelial and connective tissue components as well as the composition of the connective tissue portion facing the implant were similar at collagen-coated and uncoated implants after 4 and 8 weeks of healing. It is suggested that soft tissue healing to implants coated with type I collagen was similar to that at non-coated titanium implants and that no adverse reactions to the collagen-coated implants occurred. [ABSTRACT FROM AUTHOR]

Purpose: The objective of the present experiment was to study the morphogenesis of the mucosal attachment to implants made of c.p. titanium. Material and methods: All mandibular premolars were extracted in 20 Labrador dogs. After a healing period of 3 months, four implants (ITI® Dental Implant System) were placed in the right and left sides of the mandible. A non-submerged implant installation technique was used and the mucosal tissues were secured to the conical marginal portion of the implants with interrupted sutures. The sutures were removed after 2 weeks and a plaque control program including daily cleaning of the remaining teeth and the implants was initiated. The animals were sacrificed and biopsies were obtained at various intervals to provide healing periods extending from Day 0 (2 h) to 12 weeks. The mandibles were removed and placed in the fixative. The implant sites were dissected using a diamond saw and processed for histological analysis. Results: Large numbers of neutrophils infiltrated and degraded the coagulum that occupied the compartment between the mucosa and the implant during the initial phase of healing. At 2 weeks after surgery, fibroblasts were the dominating cell population in the connective tissue interface but at 4 weeks the density of fibroblasts had decreased. Furthermore, the first signs of epithelial proliferation were observed in specimens representing 1–2 weeks of healing and a mature barrier epithelium occurred after 6–8 weeks of healing. The collagen fibers of the mucosa were organized after 4–6 weeks of healing. Conclusion: It is suggested that the soft-tissue attachment to implants placed using a non-submerged installation procedure is properly established after several weeks following surgery. [ABSTRACT FROM AUTHOR]

When ferrochromium is produced at Vargön Alloys AB (Vargön, Sweden), an offgas dust is generated as a byproduct. A leachate that contains hexavalent chromium (Cr6+) is formed when rainwater percolates through the dust deposit. In this study, Cr6+ in the leachate was reduced to trivalent chromium (Cr3+) by biological treatment in a biofilm process operated under anaerobic conditions. The reactor volume was 26 m³ and it was filled with 16 m³ plastic packing. Acetic acid was added as an electron donor. The Cr6+ was reduced from 10 to 20 mg/L to below 0.03 mg/L when the reactor was operated at a hydraulic retention time of 11 hours. The reduction activity in the process gradually decreased as the water temperature dropped below 10°C. [ABSTRACT FROM AUTHOR]

The aims of this study were to examine whether viewers agreed on details seen in direct (real time) digital and conventional film radiographs of implants, and whether there were differences in agreement between the systems. Intra-oral radiographs of implants were exposed both as direct digital and conventional film radiographs. Fifty pairs of radiographs with similar projection and exposure were selected, showing 59 implants . Ten viewers assessed the radiographs separately and noted eight different details. The viewers showed very high agreement in their assessments of radiographs of each technique separately, and there were no statistically significant differences. However, there was a tendency to stronger agreement in the direct digital radiographs in four assessed points out of eight. The patients' experience of having radiographs exposed with the two methods was also studied by questionnaire. The patients' opinions on the two techniques did not differ statistically. This study shows that digital radiography has at least equal diagnostic yield compared to film radiography. [ABSTRACT FROM AUTHOR]

Abstract. The effect of radiation on TK is more complicated than would be expected from earlier results on bone marrow cells (Feinendegen et al. 1984, Int. J. Radiat. Biol. 45, 205). TK activity increased at 0.01 Gy and then decreased up to 1 Gy in mouse spleen. In contrast to the results for the spleen, an increase in activity at 0.1 Gy was seen in mouse thymus. The activity of dephosphorylated TK1 (TK1a) in both spleen and thymus was reduced to 50% after irradiation at 0.5–1 Gy. The degree of phosphorylation (TK1b/TK1a ratio) changed in spleen, but not in thymus. The activity of TK2 in mouse liver increased at 3 h after 5 Gy by about 60%. In mouse ascites tumour, a dose-independent (1–5 Gy) oscillating TK1 activity was found up to 24 h, especially for TK1a and TK1b. The amount of TK1 was unchanged up to 12 h, but decreased at 24 h. This suggests that the differences in the changes in the degree of phosphorylation of TK1 after irradiation among spleen, thymus and ascites tumour further underline the complexity of the response of TK1 activity to irradiation. The dramatic change in the activities of TK1a and TK1b may illustrate that both of them are more radiosensitive than TK-h, a variant with mixed TK1 and TK2 properties. [ABSTRACT FROM AUTHOR]

Abstract. The purpose of this study was to investigate the mechanism behind the high sensitivity of thymidine kinase 1 (TK1) to X-irradiation. The deoxythymidine triphosphate (dTTP) pool was studied in mouse ascites tumour cells 1–24 h after X-irradiation with 5 Gy. Irradiation changed the Michaelis-Menten kinetics of TK1 from linear to biphasic, showing a negative co-operativity. These changes were closely related to changes in the dTTP pool. Addition of dTTP to the cell extract of non-irradiated cells, or thymidine (dTdR) to the culture medium, resulted in changes very similar to the kinetics found in the irradiated cells. Addition of 5¢-amino-5¢-deoxythymidine (5¢-AdTdR), a thymidine analogue that eliminated the inhibitory effect of dTTP on TK1 activity, completely abolished the irradiation-induced inhibition of TK1 activity. We suggest that the reduced TK1 activity is mainly due to an elevated intracellular concentration of dTTP. [ABSTRACT FROM AUTHOR]

In order to obtain optimum conditions for in vitro propagation of the apple rootstock M 26 (Malus pumila Mill.) in adult and juvenile growth phases, several rooting experiments were performed. Supraoptimal concentrations of indole‐3‐butyric acid (IBA) added to the rooting media resulted in profuse callus formation. Since extensive callus production is detrimental to the survival of the plantlets, modified culture conditions were established to reduce callus formation. A reduction of the time of exposure to IBA to 5 days and, thereafter, transfer to a hormone‐free medium did not eliminate callus production. Exposure to darkness during the root initiation phase increased rooting. When the rooting medium was based on the Lepoivre formula instead of the Murashige and Skoog formula, callus formation was reduced. Optimum conditions for rooting were obtained at much lower concentration than earlier reported, being 1.25 μM for the juvenile and 0.5 μM for the adult growth phase in the range of IBA concentrations tested. Anatomical studies revealed that root initials are formed after 5 days of IBA‐treatment. Therefore, we transferred shoots directly to non‐sterile conditions after the root‐inducing phase. This resulted in a 90% survival of the plantlets. Subculture on hormone‐free medium can thus be eliminated when the optimum auxin concentration is known. [ABSTRACT FROM AUTHOR]

The apple rootstock A2 can be readily propagated in vitro both in the juvenile and in. the adult growth phase. Shoots were produced by meristem tip culture from the apple rootstock A2 in different growth phases. The influence of growth phases and different concentrations of PG and IBA was investigated as to rooting percentage, survival percentage, number of roots per tooted shoot, root length, shoot length and formation of callus. IBA at 15 μM without PG gave a significantly lower rooting percentage than 5 and 10 μM IBA. PG together with IBA stimulated rooting, the optimum concentrations of PG being, however, not the same for the different growth phases. For the adult growth phase, 10-4M PG promoted rooting, whereas 10-3M PG markedly inhibited rooting. In the juvenile growth phases, both 10-4 and 10-4M PG stimulated rooting. PG at 10-4M also increased the number of roots. The longest roots were obtained at 10-4M PG and 5 μM IBA. PG at 10-3M reduced callus formation at all IBA concentrations used. Neither shoot length nor root length influenced the survival percentage.

The effect of mercaptoethanol at different concentrations on enzyme activity was investigated in leaves from Urtica dioica and Spinacia oleracea. The interference of mercaptoethanol with enzyme activity is dependent on the type of plant. the configuration of the enzyme and the concentration of mercaptoethanol. A stimulation of GDH (glutamate-dehydrogenase) was obtained in both species, while inhibition of GOT (glutamate-oxaloacetate transaminase) and GPT (glutamate-pyruvate transaminase) was demonstrated in Spinacia. The stimulation of GOT and GPT activity in Urtica was probably due to inhibition of phenol oxidase. Conclusions concerning the effect of mercaptoethanol on NR (nitrate reductase) activity were difficult to draw, since mercaptoethanol itself reduced nitrite and interfered with NR determination in tests in vitro. In Urtica, no activity could be obtained at all with the in vitro method, probably because an inhibitor of NR was liberated during the extraction procedure. Activity of NR could however be obtained in both species when using the in vivo method. Addition of protective agents to the extraction medium has been supposed to influence the protein extractability. In conformity with this increasing amount of fresh matter to the same volume of extraction medium resulted in decreased protein extractability. This led to differences in enzyme activity when expressed on a fresh weight basis but the specific activity remained constant. [ABSTRACT FROM AUTHOR]

In vitro root formation was studied in petiole explants from Pelargonium × hortorum Bailey cv. Radio exposed to different irradiance (2.5. 11.6 or 23.0 W/m²). Optimal root formation was found when stock plants were subjected to 2.5 W/mm² and explants were grown on a medium with 20 g/1 of sucrose and 5.0 mM of nitrogen. The number of roots per explant decreased with increasing nitrogen or sucrose concentrations in the growth medium and with increasing irradiance applied to the stock plants. Variation in temperature (17, 21 or 25°C) did not affect root formation. The number of roots per explant was higher in explants from young petioles than in explants from older petioles. The initial nitrogen content of the explants was highest at the lowest irradiance. The content of reducing sugars and sucrose increased with increasing irradiance. The endogenous levels of lysine. arginine and ornithine were highest at 2.5 W/mm² and the levels of proline. alanine, γ-aminobutyric acid, glutamic acid, glutamine. aspartic acid and asparagine were highest at 23.0 W/mm². With rising nitrogen concentration in the medium, the final endogenous content of nitrogen in the explants increased, whereas the content of reducing sugars decreased. When the sucrose concentration in the medium increased, the endogenous content of reducing sugars rose, and the nitrogen level was lowered. Variations in the nitrogen concentration in the growth medium influenced the final level of free amino acids in the explants. [ABSTRACT FROM AUTHOR]

Petiole explants from 17 cultivars of Begonia × hiemalis were grown on a basal agar medium with different combinations of NAA and BA as well as on media lacking microelements or vitamins. The stock plants were kept either under short days (7-8 h of light per day) at 15°C or under long days (15-16 h of light) at 18-21°C. The day length during the in vitro culture was 20 h of light and the temperature 2 1°C. Explants from short-day treated stock plants did not show any differentiation. In explants from long-day treated stock plants, the percentage of explants with shoot, root and with both shoot and root initiation were recorded after 55 days. Explants forming both shoots and roots were transferred to soil, and plantlet formation was observed after another 55 days. The percentage of explants with organ and plantlet formation differed between cultivars. With increasing NAA and decreasing BA concentrations, the percentage of explants forming only roots increased, whereas the percentage of explants with only shoots decreased. Plantlet formation was most frequent in explants from NAA : BA ratios of 2: 1 and 10: 1, and a variation was found between different cultivars. When the vitamin fraction was not added to the medium, this did not influence formation of shoots, roots and plantlets. When the microelements were omitted, shoots, roots and callus were formed, but no plantlets. [ABSTRACT FROM AUTHOR]

Hypocotyl explants of Beta rulgaris L. were grown on defined agar media with different combinations of IAA and kinetin at varying concentrations of nitrogen or sucrose. The cultures were kept in light (18 h a day) at 27°C for 5 weeks. Root initiation and callus growth were recorded and the callus tissue was analysed for N and K. Root formation was found to increase with increasing nitrogen concentration (from 5 mM to 23.3 mM) in the medium at 10.0 mg/I of IAA, whereas no stimulation was found at 0.1 mg/l of IAA. When raising the sucrose level from 20 g/l to 100 g/l at 10.0mg/I of IAA and 1.0mg/I of kinetin. root initiation was also stimulated. At a lower kinetin and auxin level, however, no increase was recorded. Callus growth was affected by changes in the nitrogen or sucrose concentration of the culture media. The nitrogen content of the callus tissue increased with rising nitrogen concentration of the media. When raising the sucrose level instead of the nitrogen level, the nitrogen content of the tissue decreased. [ABSTRACT FROM AUTHOR]