bluuebunny/crossref_metadata_2025_split huggingface dataset:
Response of green alder (Alnus viridis subsp. fruticosa) patch dynamics and plant community composition to fire and regional temperature in north‐western Canada
Authors: Lantz Trevor C. , Gergel Sarah E. , Henry Greg H. R. 
Published: May 2010

AbstractAim  Feedbacks between climate warming and fire have the potential to alter Arctic and sub‐Arctic vegetation. In this paper we assess the effects and interactions of temperature and wildfire on plant communities across the transition between the Arctic and sub‐Arctic.Location  Mackenzie Delta region, Northwest Territories, Canada.Methods  We sampled air temperatures, green alder (Alnus viridis ssp. fruticosa) cover, growth, reproduction and age distributions, and overall plant community composition on burned and unburned sites across a latitudinal gradient.Results  Mean summer temperature across the study area decreased by 3 °C per degree of increasing latitude (6 °C across the study area). In the northern part of the study area, where seed viability was low, alder was less dominant than at southern sites where seed viability was high. The age structure of alder populations across the temperature gradient was highly variable, except in the northern part of the forest–tundra transition, where populations were dominated by young individuals. Alder growth and reproduction were significantly greater on burned sites (38–51 years following fire) than on unburned sites. North to south across the temperature gradient, vegetation changed from a community dominated by dwarf shrubs and fruticose lichens to one characterized by black spruce (Picea mariana), alder and willows (Salix spp.). Regardless of the position along the temperature gradient, burned sites were dominated by tall shrubs.Main conclusions  Temperature limitation of alder abundance and repro‐duction, combined with evidence of recent recruitment on unburned sites, indicates that alder is likely to respond to increased temperature. Elevated alder growth and reproduction on burned sites shows that wildfire also has an important influence on alder population dynamics. The magnitude of alder’s response to fire, combined with observations that burns at the southern margin of the low Arctic are shrub dominated, suggest that increases in the frequency of wildfire have the potential to alter northern vegetation on decadal scales. By creating new seedbeds, fire provides opportunities for colonization that may facilitate the northward movement of tall shrubs. Feedbacks between the global climate system and low Arctic vegetation make understanding the long‐term impact of increasing fire frequency critical to predicting the response of northern ecosystems to global change.
Evidence for climatic niche and biome shifts between native and novel ranges in plant species introduced to Australia
Authors: Gallagher Rachael V. , Beaumont Linda J. , Hughes Lesley , Leishman Michelle R. 
Published: May 2010

Summary 1. The potential invasive success of exotic plant species is thought to be associated with similarity in climate and biome between the original and novel range. We tested this assumption by quantifying the match between the realized climatic niches and biomes occupied in the exotic and native range of 26 plant species introduced to Australia. We then explored correlations between the propensity to shift climatic niche with residence time, invasion status, geographic range size, and species traits. 2. Occurrence data from the native and exotic range of 26 species introduced to Australia were obtained, and the overlap between native and exotic climate niches was calculated using between‐class analysis. Shifts into novel biomes were assessed using a Geographic Information System (GIS). Correlations between introduction, distribution and species traits and the degree of climate matching were examined using nonparametric statistical tests. 3. Exotic species frequently occurred in climatic conditions outside those occupied in their native range (20 of 26 species). Nineteen species inhabited biomes in Australia not occupied in the native range and in some instances this shift represented the establishment of populations in novel biomes not present in the native range. No single‐species trait, introduction or distributional characteristic was significantly associated with the degree of climatic niche shift. 4. Synthesis. Exotic species are able to occupy climate niches in the new range that differ substantially from those of the native range, and generally do not show biome conservatism between their native and introduced ranges. This implies that novel climatic conditions are not a major obstacle for exotic species establishing populations outside their native range. These results have important implications for the use and interpretation of ecological niche models used to predict the distribution of species in novel climates in time or space. The results also highlight the importance of alternate mechanisms, such as enemy release, phenotypic plasticity or rapid evolution, in the establishment of naturalized and invasive populations.
Effects of a leisure programme on quality of life and stress of individuals with ASD
Authors: García‐Villamisar D. A. , Dattilo J. 
Published: May 2010

AbstractBackground  Even though there is research demonstrating a positive relationship between leisure participation and the two constructs of quality of life and stress reduction, current conceptualisation of leisure as a contributor to quality of life is limited. In addition, in spite of improvements in accurate diagnosis of autism spectrum disorder (ASD) at increasingly earlier ages and proliferation of interventions, research associated with leisure and quality of life for people with ASD is lacking.Methods  Therefore, a study using a repeated measures design was used to measure effects of a 1‐year group leisure programme intended to facilitate interaction with media, engagement in exercise, playing games and doing crafts, attending events, and participating in other recreation activities on quality of life and stress of 37 participants (22 male, 15 female), ages 17–39 (M = 31.49) years at the beginning of the programme) diagnosed with an ASD and a group of 34 adults with ASD as control group (waiting list) (19 male, 15 female), ages 24–38 (M = 30 at programme initiation) years.Results  There was a significant decrease in overall scores of stress levels for participants over the course of the study and there was a significant increase in the four factors of quality of life that were measured (satisfaction, independence, competence and social interaction) as well as the total score for quality of life from baseline to the end of the intervention 12 months later. In contrast, the control group demonstrated no significant improvements related to stress or quality of life. Implications of these findings to leisure services and the quality of life of individuals with ASD are discussed.Conclusion  Findings support the contention that participation in recreation activities positively influenced the stress and quality of life of adults with ASD.
Effect of gallium focused ion beam milling on preparation of aluminium thin foils
Authors: UNOCIC K.A. , MILLS M.J. , DAEHN G.S. 
Published: May 2010

SummaryFocussed ion beam milling has greatly extended the utility of the atom probe and transmission electron microscope because it enables sample preparation with a level of dimensional control never before possible. Using focussed ion beam it is possible to extract the samples from desired and very specific locations. The artefacts associated with this sample preparation method must also be fully understood. In this work, issues specifically relevant to the focussed ion beam milling of aluminium alloys are presented. After using the focussed ion beam as a sample preparation technique it is evident that gallium will concentrate in three areas of the sample: on the surface, on grain boundaries and at interphase boundaries. This work also shows that low‐energy Ar ion nanomilling is potentially quite effective for removing gallium implantation layers and gallium from the internal surfaces of aluminium thin foils.
The changing faces of Streptococcus antigen I/II polypeptide family adhesins
Authors: Brady L. Jeannine , Maddocks Sarah E. , Larson Matthew R. , Forsgren Nina , Persson Karina , Deivanayagam Champion C. , Jenkinson Howard F. 
Published: May 2010

Summary Streptococcus mutans antigen I/II (AgI/II) protein was one of the first cell wall‐anchored adhesins identified in Gram‐positive bacteria. It mediates attachment of S. mutans to tooth surfaces and has been a focus for immunization studies against dental caries. The AgI/II family polypeptides recognize salivary glycoproteins, and are also involved in biofilm formation, platelet aggregation, tissue invasion and immune modulation. The genes encoding AgI/II family polypeptides are found among Streptococcus species indigenous to the human mouth, as well as in Streptococcus pyogenes, S. agalactiae and S. suis. Evidence of functionalities for different regions of the AgI/II proteins has emerged. A sequence motif within the C‐terminal portion of Streptococcus gordonii SspB (AgI/II) is bound by Porphyromonas gingivalis, thus promoting oral colonization by this anaerobic pathogen. The significance of other epitopes is now clearer following resolution of regional crystal structures. A new picture emerges of the central V (variable) region, predicted to contain a carbohydrate‐binding trench, being projected from the cell surface by a stalk formed by an unusual association between an N‐terminal α‐helix and a C‐terminal polyproline helix. This presentation mode might be important in determining functional conformations of other Gram‐positive surface proteins that have adhesin domains flanked by α‐helical and proline‐rich regions.
A novel nucleotide kinase encoded by gene 1.7 of bacteriophage T7
Authors: Tran Ngoc Q. , Lee Seung‐Joo , Richardson Charles C. , Tabor Stanley 
Published: May 2010

SummaryGene 1.7 of bacteriophage T7 confers sensitivity of both phage T7 and its host Escherichia coli to dideoxythymidine (ddT). We have purified the product of gene 1.7, gp1.7. It exists in two forms of molecular weight 22 181 and 17 782. Only the C‐terminal half of the protein is required to confer ddT sensitivity. We show that gp1.7 catalyses the phosphorylation of dGMP and dTMP to dGDP and dTDP, respectively, by using either GTP, dGTP or dTTP as the phosphate donor. Either form of gp1.7 exhibit identical kinase activity as compared with wild‐type gp1.7 that contains a mixture of both forms. The Km of 70 µM and Kcat of 4.3 s−1 for dTMP are similar to those found for E. coli thymidylate kinase. However, unlike the host enzyme, gp1.7 efficiently catalyses the conversion of the chain‐terminating dideoxythymidylate (ddTMP) to ddTDP. This finding explains the sensitivity of phage T7 but not E. coli to exogenous ddT. Gp1.7 is unusual in that it has no sequence homology to any known nucleotide kinase, it has no identifiable nucleotide‐binding motif and its activity is independent of added metal ions. When coupled with nucleoside diphosphate kinase, gp1.7 exponentially converts dTMP to dTTP.
DipM links peptidoglycan remodelling to outer membrane organization in Caulobacter
Authors: Goley Erin D. , Comolli Luis R. , Fero Katherine E. , Downing Kenneth H. , Shapiro Lucy 
Published: May 2010

SummaryCell division in Gram‐negative organisms requires coordinated invagination of the multilayered cell envelope such that each daughter receives an intact inner membrane, peptidoglycan (PG) layer and outer membrane (OM). Here, we identify DipM, a putative LytM endopeptidase in Caulobacter crescentus, and show that it plays a critical role in maintaining cell envelope architecture during growth and division. DipM localized to the division site in an FtsZ‐dependent manner via its PG‐binding LysM domains. Although not essential for viability, ΔdipM cells exhibited gross morphological defects, including cell widening and filamentation, indicating a role in cell shape maintenance and division that we show requires its LytM domain. Strikingly, cells lacking DipM also showed OM blebbing at the division site, at cell poles and along the cell body. Cryo electron tomography of sacculi isolated from cells depleted of DipM revealed marked thickening of the PG as compared to wild type, which we hypothesize leads to loss of trans‐envelope contacts between components of the Tol–Pal complex. We conclude that DipM is required for normal envelope invagination during division and to maintain a sacculus of constant thickness that allows for maintenance of OM connections throughout the cell envelope.
A protein critical for cell constriction in the Gram‐negative bacterium Caulobacter crescentus localizes at the division site through its peptidoglycan‐binding LysM domains
Authors: Poggio Sebastian , Takacs Constantin N. , Vollmer Waldemar , Jacobs‐Wagner Christine 
Published: May 2010

SummaryDuring division of Gram‐negative bacteria, invagination of the cytoplasmic membrane and inward growth of the peptidoglycan (PG) are followed by the cleavage of connective septal PG to allow cell separation. This PG splitting process requires temporal and spatial regulation of cell wall hydrolases. In Escherichia coli, LytM factors play an important role in PG splitting. Here we identify and characterize a member of this family (DipM) in Caulobacter crescentus. Unlike its E. coli counterparts, DipM is essential for viability under fast‐growth conditions. Under slow‐growth conditions, the ΔdipM mutant displays severe defects in cell division and FtsZ constriction. Consistent with its function in division, DipM colocalizes with the FtsZ ring during the cell cycle. Mutagenesis suggests that the LytM domain of DipM is essential for protein function, despite being non‐canonical. DipM also carries two tandems of the PG‐binding LysM domain that are sufficient for FtsZ ring localization. Localization and fluorescence recovery after photobleaching microscopy experiments suggest that DipM localization is mediated, at least in part, by the ability of the LysM tandems to distinguish septal, multilayered PG from non‐septal, monolayered PG.
DipM, a new factor required for peptidoglycan remodelling during cell division in Caulobacter crescentus
Authors: Möll Andrea , Schlimpert Susan , Briegel Ariane , Jensen Grant J. , Thanbichler Martin 
Published: May 2010

SummaryIn bacteria, cytokinesis is dependent on lytic enzymes that facilitate remodelling of the cell wall during constriction. In this work, we identify a thus far uncharacterized periplasmic protein, DipM, that is required for cell division and polarity in Caulobacter crescentus. DipM is composed of four peptidoglycan binding (LysM) domains and a C‐terminal lysostaphin‐like (LytM) peptidase domain. It binds to isolated murein sacculi in vitro, and is recruited to the site of constriction through interaction with the cell division protein FtsN. Mutational analyses showed that the LysM domains are necessary and sufficient for localization of DipM, while its peptidase domain is essential for function. Consistent with a role in cell wall hydrolysis, DipM was found to interact with purified murein sacculi in vitro and to induce cell lysis upon overproduction. Its inactivation causes severe defects in outer membrane invagination, resulting in a significant delay between cytoplasmic compartmentalization and final separation of the daughter cells. Overall, these findings indicate that DipM is a periplasmic component of the C. crescentus divisome that facilitates remodelling of the peptidoglycan layer and, thus, coordinated constriction of the cell envelope during the division process.
Bacillus subtilis BY‐kinase PtkA controls enzyme activity and localization of its protein substrates
Authors: Jers Carsten , Pedersen Malene Mejer , Paspaliari Dafni Katerina , Schütz Wolfgang , Johnsson Christina , Soufi Boumediene , Macek Boris , Jensen Peter Ruhdal , Mijakovic Ivan 
Published: May 2010

Summary Bacillus subtilis BY‐kinase PtkA was previously shown to phosphorylate, and thereby regulate the activity of two classes of protein substrates: UDP‐glucose dehydrogenases and single‐stranded DNA‐binding proteins. Our recent phosphoproteome study identified nine new tyrosine‐phosphorylated proteins in B. subtilis. We found that the majority of these proteins could be phosphorylated by PtkA in vitro. Among these new substrates, single‐stranded DNA exonuclease YorK, and aspartate semialdehyde dehydrogenase Asd were activated by PtkA‐dependent phosphorylation. Because enzyme activity was not affected in other cases, we used fluorescent protein tags to study the impact of PtkA on localization of these proteins in vivo. For several substrates colocalization with PtkA was observed, and more importantly, the localization pattern of the proteins enolase, YjoA, YnfE, YvyG, Ugd and SsbA was dramatically altered in ΔptkA background. Our results confirm that PtkA can control enzyme activity of its substrates in some cases, but also reveal a new mode of action for PtkA, namely ensuring correct cellular localization of its targets.
More than just activity control: phosphorylation may control all aspects of a protein's properties
Authors: Stülke Jörg 
Published: May 2010

SummaryProtein phosphorylation is a major post‐translational modification of proteins. Due to the introduction of a very large, strongly charged group, phosphorylation often has a dramatic effect on the characteristics of the protein, including alterations in activity or interaction properties. In this issue of Molecular Microbiology, Jers et al. have addressed the effect of protein tyrosine phosphorylation in Bacillus subtilis. They demonstrate that tyrosine phosphorylation stimulates the activity of several but not all targets. In addition, the subcellular localization of several proteins was shown to depend on tyrosine phosphorylation that is catalysed by the BY kinase PtkA. This is the first report showing that phosphorylation controls protein localization in bacteria and adds another important function to this post‐translational modification.
Gastroesophageal reflux and altered motility in lung transplant rejection
Authors: Castor J. M. , Wood R. K. , Muir A. J. , Palmer S. M. , Shimpi R. A. 
Published: May 2010

AbstractBackground Lung transplantation has become an effective therapeutic option for selected patients with end stage lung disease. Long‐term survival is limited by chronic rejection manifest as bronchiolitis obliterans syndrome (BOS). The aspiration of gastric contents has been implicated as a causative or additive factor leading to BOS. Gastroesophageal reflux (GER) and altered foregut motility are common both before and after lung transplantation. Further, the normal defense mechanisms against reflux are impaired in the allograft. Recent studies using biomarkers of aspiration have added to previous association studies to provide a growing body of evidence supporting the link between rejection and GER. Further, the addition of high‐resolution manometry (HRM) and impedance technology to characterize bolus transit and the presence and extent of reflux regardless of pH might better identify at‐risk patients. Although additional prospective studies are needed, fundoplication appears useful in the prevention or treatment of post‐transplant BOS.Purpose This review will highlight the existing literature on the relationship of gastroesophageal reflux and altered motility to lung transplant rejection, particularly BOS. The article will conclude with a discussion of the evaluation and management of patients undergoing lung transplantation at our center.
Substance P and vasoactive intestinal peptide are reduced in right transverse colon in pediatric slow‐transit constipation
Authors: King S. K. , Sutcliffe J. R. , Ong S.‐y. , Lee M. , Koh T. L. , Wong S. Q. , Farmer P. J. , Peck C. J. , Stanton M. P. , Keck J. , Cook D. J. , Chow C. W. , Hutson J. M. , Southwell B. R. 
Published: May 2010

AbstractBackground Slow‐transit constipation (STC) is recognized in children but the etiology is unknown. Abnormalities in substance P (SP), vasoactive intestinal peptide (VIP) and nitric oxide (NO) have been implicated. The density of nerve fibers in circular muscle containing these transmitters was examined in colon from children with STC and compared to other pediatric and adult samples.Methods Fluorescence immunohistochemistry using antibodies to NO synthase (NOS), VIP and SP was performed on colonic biopsies (transverse and sigmoid colon) from 33 adults with colorectal cancer, 11 children with normal colonic transit and anorectal retention (NAR) and 51 with chronic constipation and slow motility in the proximal colon (STC). The percentage area of nerve fibers in circular muscle containing each transmitter was quantified in confocal images.Key Results In colon circular muscle, the percentage area of nerve fibers containing NOS > VIP > SP (6 : 2 : 1). Pediatric groups had a higher density of nerve fibers than adults. In pediatric samples, there were no regional differences in NOS and VIP, while SP nerve fiber density was higher in sigmoid than proximal colon. STC children had lower SP and VIP nerve fiber density in the proximal colon than NAR children. Twenty‐three percent of STC children had low SP nerve fiber density.Conclusions & Inferences There are age‐related reductions in nerve fiber density in human colon circular muscle. NOS and VIP do not show regional variations, while SP nerve fiber density is higher in distal colon. 1/3 of pediatric STC patients have low SP or VIP nerve fiber density in proximal colon.
Ameliorating effects of mirtazapine on visceral hypersensitivity in rats with neonatal colon sensitivity
Authors: Yin J. , Wang W. , Winston J. H. , Zhang R. , Chen J. D. Z. 
Published: May 2010

AbstractBackground The aim was to investigate the effects of mirtazapine on visceral hypersensitivity and gastric emptying in an established rodent model of colonic sensitization.Methods Twenty colonic sensitized rats and 20 matched controls were used. Visceral sensitivity during colorectal distension (CRD) was assessed by the measurement of abdominal electromyogram (EMG) with the pressures of 20, 40, and 60 mmHg. Mirtazapine with doses of 1, 5, and 10 mg kg−1were administered orally. Gastric emptying and small intestinal transit were performed in a separated experiment after gavage of 1.5 mL of phenol red solution.Key Results (i) Visceral hypersensitivity after neonatal colonic sensitization was confirmed. (ii) Mirtazapine dose‐dependently reduced visceral hypersensitivity in the colonic sensitized rats. The increases in EMG during CRD at 40, 60 mmHg were, 17.59 ± 6.49 and 26.04 ± 8.30, respectively, with saline session, and substantially reduced to 10.0 ± 5.95 (P = 0.02vscorresponding saline) and 12.58 ± 7.43 (P < 0.001vssaline) with mirtazapine at 10 mg kg−1. Similar findings were noted at doses of 5 and 1 mg kg−1at a lesser degree. In the control rats, mirtazapine‐reduced visceral sensitivity only during CRD at 60 mmHg. (iii) Mirtazapine 10 mg kg−1significantly accelerated gastric emptying (P = 0.045) but slightly and marginally delayed intestinal transit (P = 0.058) the colonic sensitized rats.Conclusions & Inferences Mirtazapine dose‐dependently ameliorates visceral hypersensitivity in colonic sensitized rats. Mirtazapine at a high dose improves delayed gastric emptying in colonic sensitized rats but slightly and marginally delays small intestinal transit. Its roles in altering gastrointestinal motility need further investigation.