bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tree transpiration varies spatially in response to atmospheric but not edaphic conditions
Authors: Traver Elizabeth , Ewers Brent E. , Mackay David S. , Loranty Michael M. 
Published: November 2009

Summary1. Measuring transpiration simultaneously in time and space can establish a better understanding of how to mechanistically scale spatiotemporal values.2. This study tested the following predictions to falsify a tree hydraulic hypothesis of spatial variation in transpiration: (i) stands with larger trees will a have longer range and greater sill and nugget at a given vapour pressure deficit (D); (ii) the range, sill and nugget will decline faster with increasingDwith larger trees; and (iii) soil moisture, texture and/or N levels will be correlated with transpiration.3. We used cyclic sampling to efficiently collect spatial sap flux data from 144 trees in two forested stands in northern Wisconsin: an Aspen‐dominated stand with small trees and a Maple–Pine‐dominated stand with larger trees.4. In the Maple stand, the range of spatial autocorrelation in half‐hourly transpiration dropped from 80 to 20 m with increasedD, whereas in the Aspen stand the range dropped from 55 to 35 m with a similar increase inD.5. Differences in the range of spatial autocorrelation at a givenDwere driven by sapwood area, which is a function of tree size.6. These results show that species and tree size as well as individual tree hydraulics drive spatial variability in transpiration with little additional variation explained by the measured edaphic conditions.7. Scaling from individual tree transpiration to the landscape in time and space should incorporate atmospheric drivers in time and investigate other potential drivers of tree size in space such as light competition.
Male moths provide pollination benefits in the Silene latifolia–Hadena bicruris nursery pollination system
Authors: Labouche Anne‐Marie , Bernasconi Giorgina 
Published: November 2009

Summary 1. Evolutionary conflicts of interest underlie mutualisms, including plant/pollinator interactions. This is particularly evident in ‘nursery pollination’, in which the pollinators lay eggs inside the flowers and the offspring of the pollinator consume the developing seeds. Low benefit (pollination service) to cost (seed predation) ratios could destabilize such associations towards parasitism. 2. Although in most of the well‐known cases pollen transfer is associated with oviposition, in some systems the males of the seed predator may contribute to pollination, affecting the strength and outcome of the interaction between the plant and their ovipositing pollinators. In addition, in dioecious species male and female plants differ in the direct costs of seed predation and benefits of attracting pollinators, which may lead to sex‐specific strategies. 3. We investigated whether pollinator and plant sex affect pollination in the interaction between dioecious plant Silene latifolia and its nursery pollinator, Hadena bicruris (Noctuidae). 4. Data on visitation behaviour and pollination efficiency in experimental plant patches demonstrate that (i) male moths are equally efficient pollinators as female moths, leading to fruit initiation in around 80% of visits and to fertilization of around 45% of the ovules in one visit; (ii) female and male moths do not preferentially visit flowers of one sex; and (iii) feeding behaviour is sufficient to ensure pollen transfer. However, female moths visited significantly more flowers than male moths. 5. Altogether this suggests that both moth sexes provide a pollination benefit to the plant with no differences in pollination efficiency but that female moths, before seed predation costs are accounted for, seem to provide greater benefits owing to their increased activity. That male moths contribute to seed production likely decreases the plant’s dependency on ovipositing moths for pollination.
Staff attributions about challenging behaviours of people with intellectual disabilities and transactional stress process: a qualitative study
Authors: Cudré‐Mauroux A. 
Published: November 2009

AbstractBackground  Staff explanations about challenging behaviours of people with intellectual disabilities are purported to play a significant role in the way they respond to them. Despite attempts made in research to understand the mechanisms of causality, a lack of association between attributions, emotions and behaviours is reported. This study investigates these relationships within a broader framework including attributions in the transactional stress model of Lazarus and Folkman.Method  A qualitative design has been selected; semi‐structured interview format was used in order to investigate implication of attributions in stress regarding Weiner's model of helping behaviour. A case study method has been adopted to allow consideration of ecological data, a case study representing a special encounter with a challenging behaviour. Categorical analysis was conducted.Results  The results suggest three main issues. First, it appears that Weiner's model is too restrictive in order to explain the complexity of contextualised encounters. Second, a need to differentiate types of attributions within a temporal perspective is highlighted. Finally, consideration of the coping role of attributions is suggested.Conclusions  A need to extent the research concerning attribution is suggested. The insertion of research into ecological contexts and the introduction of coping concept regarding staff attributions of challenging behaviours would allow a broader view of the role of attributions.
Home literacy environment of pre‐school children with intellectual disabilities
Authors: Van Der Schuit M. , Peeters M. , Segers E. , Van Balkom H. , Verhoeven L. 
Published: November 2009

AbstractBackground  For pre‐school children, the home literacy environment (HLE) plays an important role in the development of language and literacy skills. As there is little known about the HLE of children with intellectual disabilities (ID), the aim of the present study was to investigate the HLE of children with ID in comparison with children without disabilities.Method  Parent questionnaires concerning aspects of the HLE were used to investigate differences between 48 children with ID, 107 children without disabilities of the same chronological age and 36 children without disabilities of the same mental age (MA). Furthermore, for the children with ID, correlations were computed between aspects of the HLE and children's non‐verbal intelligence, speech intelligibility, language and early literacy skills.Results and conclusions  From the results of the multivariate analyses of variance it could be concluded that the HLE of children with ID differed from that of children in the chronological age group on almost all aspects. When compared with children in the MA group, differences in the HLE remained. However, differences mainly concerned child‐initiated activities and not parent‐initiated activities. Correlation analyses showed that children's activities with literacy materials were positively related with MA, productive syntax and vocabulary age, and book orientation skills. Also, children's involvement during storybook reading was related with their MA, receptive language age, productive syntax and vocabulary age, book orientation and rapid naming of pictures. The amount of literacy materials parents provided was related to a higher productive syntax age and level of book orientation of the children. Parent play activities were also positively related to children's speech intelligibility. The cognitive disabilities of the children were the main cause of the differences found in the HLE between children with ID and children without disabilities. Parents also adapt their level to the developmental level of their child, which may not always be the most stimulating for the children.
Melatonin decreases daytime challenging behaviour in persons with intellectual disability and chronic insomnia
Authors: Braam W. , Didden R. , Maas A. P. H. M. , Korzilius H. , Smits M. G. , Curfs L. M. G. 
Published: November 2009

AbstractBackground Persons with intellectual disability (ID) and sleep problems exhibit more daytime challenging behaviours than persons with ID without sleep problems. Several anecdotal reports suggest that melatonin is not only effective in the treatment of insomnia, but also decreases daytime challenging behaviour. However, the effect of melatonin treatment on daytime challenging behaviour in persons with ID has not been investigated in a randomised controlled trial.Method We investigated the effects of melatonin on challenging behaviour using data from two randomised controlled trials on the efficacy of melatonin on sleep problems in 49 persons (25 men, 24 women; mean age 18.2 years, SD = 17.1) with ID and chronic insomnia. Participants received either melatonin 5 mg (<6 years 2.5 mg) or placebo during 4 weeks. Daytime challenging behaviour was measured by the Storend Gedragsschaal voor Zwakzinnigen – Maladaptive Behaviour Scale for the Mentally Retarded (SGZ;Kraijer & Kema, 1994) at baseline week and the end of the fourth treatment week. Salivary dim light melatonin onset (DLMO) was measured at baseline and the last day of the fourth treatment week. Sleep logs were used to gather information on sleep parameters.Results Melatonin treatment significantly reduced SGZ scores, sleep latency, and number and duration of night wakes, and treatment increased total sleep time and advanced DLMO. However, after 4 weeks of treatment, change in SGZ scores did not significantly correlate with change in sleep parameters, nor with change in DLMO. Relatively strong correlations were found between change in SGZ scores, change in DLMO and number of night wakes.Conclusions Melatonin treatment in persons with ID and chronic insomnia decreases daytime challenging behaviour, probably by improving sleep maintenance or by improving circadian melatonin rhythmicity.
Turtle groups or turtle soup: dispersal patterns of hawksbill turtles in the Caribbean
Authors: BLUMENTHAL J. M. , ABREU‐GROBOIS F. A. , AUSTIN T. J. , BRODERICK A. C. , BRUFORD M. W. , COYNE M. S. , EBANKS‐PETRIE G. , FORMIA A. , MEYLAN P. A. , MEYLAN A. B. , GODLEY B. J. 
Published: November 2009

AbstractDespite intense interest in conservation of marine turtles, spatial ecology during the oceanic juvenile phase remains relatively unknown. Here, we used mixed stock analysis and examination of oceanic drift to elucidate movements of hawksbill turtles (Eretmochelys imbricata) and address management implications within the Caribbean. Among samples collected from 92 neritic juvenile hawksbills in the Cayman Islands we detected 11 mtDNA control region haplotypes. To estimate contributions to the aggregation, we performed ‘many‐to‐many’ mixed stock analysis, incorporating published hawksbill genetic and population data. The Cayman Islands aggregation represents a diverse mixed stock: potentially contributing source rookeries spanned the Caribbean basin, delineating a scale of recruitment of 200–2500 km. As hawksbills undergo an extended phase of oceanic dispersal, ocean currents may drive patterns of genetic diversity observed on foraging aggregations. Therefore, using high‐resolution Aviso ocean current data, we modelled movement of particles representing passively drifting oceanic juvenile hawksbills. Putative distribution patterns varied markedly by origin: particles from many rookeries were broadly distributed across the region, while others would appear to become entrained in local gyres. Overall, we detected a significant correlation between genetic profiles of foraging aggregations and patterns of particle distribution produced by a hatchling drift model (Mantel test,r = 0.77,P < 0.001; linear regression,r = 0.83,P < 0.001). Our results indicate that although there is a high degree of mixing across the Caribbean (a ‘turtle soup’), current patterns play a substantial role in determining genetic structure of foraging aggregations (forming turtle groups). Thus, for marine turtles and other widely distributed marine species, integration of genetic and oceanographic data may enhance understanding of population connectivity and management requirements.
Genetic analysis across different spatial scales reveals multiple dispersal mechanisms for the invasive hydrozoan Cordylophora in the Great Lakes
Authors: DARLING JOHN A. , FOLINO‐ROREM NADINE C. 
Published: November 2009

AbstractDiscerning patterns of post‐establishment spread by invasive species is critically important for the design of effective management strategies and the development of appropriate theoretical models predicting spatial expansion of introduced populations. The globally invasive colonial hydrozoan Cordylophora produces propagules both sexually and vegetatively and is associated with multiple potential dispersal mechanisms, making it a promising system to investigate complex patterns of population structure generated throughout the course of rapid range expansion. Here, we explore genetic patterns associated with the spread of this taxon within the North American Great Lakes basin. We collected intensively from eight harbours in the Chicago area in order to conduct detailed investigation of local population expansion. In addition, we collected from Lakes Michigan, Erie, and Ontario, as well as Lake Cayuga in the Finger Lakes of upstate New York in order to assess genetic structure on a regional scale. Based on data from eight highly polymorphic microsatellite loci we examined the spatial extent of clonal genotypes, assessed levels of neutral genetic diversity, and explored patterns of migration and dispersal at multiple spatial scales through assessment of population level genetic differentiation (pairwise FST and factorial correspondence analysis), Bayesian inference of population structure, and assignment tests on individual genotypes. Results of these analyses indicate that Cordylophora populations in this region spread predominantly through sexually produced propagules, and that while limited natural larval dispersal can drive expansion locally, regional expansion likely relies on anthropogenic dispersal vectors.
The cobinamide amidohydrolase (cobyric acid‐forming) CbiZ enzyme: a critical activity of the cobamide remodelling system of Rhodobacter sphaeroides
Authors: Gray Michael J. , Escalante‐Semerena Jorge C. 
Published: November 2009

SummaryThe chemical structures of cobamides [cobalamin (Cbl)‐like compounds] are the same, except for the lower ligand, which in adenosylcobalamin (AdoCbl) is 5,6‐dimethylbenzimidazole, and in adenosylpseudocobalamin (AdopseudoCbl) is adenine. Why the lower ligand of cobamides varies and what the mechanism of lower ligand replacement is are long‐standing questions in the field of B12 biosynthesis. Work reported here uncovers the strategy used by the photosynthetic α‐proteobacterium Rhodobacter sphaeroides to procure the cobamide it needs to grow on acetate as a carbon and energy source. On the basis of genetic and biochemical evidence we conclude that, in R. sphaeroides, the activity of the cobyric acid‐producing amidohydrolase CbiZ enzyme is essential for the conversion of AdopseudoCbl into AdoCbl, the cobamide needed for the catabolism of acetate. The CbiZ enzyme uses AdopseudoCbl as a substrate, but not AdoCbl. Implications of these findings for cobamide remodelling in R. sphaeroides and in other CbiZ‐containing microorganisms are discussed.
Different roles for anti‐sigma factors in siderophore signalling pathways of Pseudomonas aeruginosa
Authors: Mettrick Karla A. , Lamont Iain L. 
Published: November 2009

SummaryGroup IV (extracytoplasmic function) sigma factors direct the expression of a large number of regulons in bacteria. The activities of many Group IV sigma factors are inhibited by members of a family of anti‐sigma factor proteins, with appropriate environmental signals causing the sigma factor to be released for interaction with core RNA polymerase and consequent transcription of target genes. One subgroup of Group IV sigmas directs expression of genes for uptake of siderophores (iron‐chelating compounds) by Gram‐negative bacteria. The activities of these sigma factors are controlled by anti‐sigma factors that span the cytoplasmic membrane. Binding of siderophore by a receptor protein in the outer membrane results in signal transduction from the periplasmic portion to the cytoplasmic portion of the appropriate anti‐sigma factor, with consequent activity of the cognate sigma factor and upregulation of the gene encoding the receptor protein. We have investigated receptor/anti‐sigma/sigma factor signalling pathways for uptake of the siderophores ferrichrome and desferrioxamine by Pseudomonas aeruginosa. In these pathways the ‘anti‐sigma’ proteins are normally required for sigma factor activity and the cytoplasmic parts of the ‘anti‐sigmas’ have ‘pro‐sigma’ activity. We suggest that the family of anti‐sigma factor proteins may be better considered as ‘sigma regulators’.
Expression of the yeast aquaporin Aqy2 affects cell surface properties under the control of osmoregulatory and morphogenic signalling pathways
Authors: Furukawa Kentaro , Sidoux‐Walter Frédéric , Hohmann Stefan 
Published: November 2009

SummaryAquaporins mediate rapid and selective water transport across biological membranes. The yeast Saccharomyces cerevisiae possesses two aquaporins, Aqy1 and Aqy2. Here, we show that Aqy2 is involved in controlling cell surface properties and that its expression is controlled by osmoregulatory and morphogenic signalling pathways. Deletion of AQY2 results in diminished fluffy colony morphology while overexpression of AQY2 causes strong agar invasion and adherence to plastic surfaces. Hyper‐osmotic stress inhibits morphological developments including the above characteristics as well as AQY2 expression through the osmoregulatory Hog1 mitogen‐activated protein kinase. Moreover, two pathways known to control morphological developments are involved in regulation of AQY2 expression: the protein kinase A pathway derepresses AQY2 expression through the Sfl1 repressor, and the filamentous growth Kss1 mitogen‐activated protein kinase pathway represses AQY2 expression in a Kss1 activity‐independent manner. The AQY2 expression pattern resembles in many ways that of MUC1/FLO11, which encodes a cell surface glycoprotein required for morphological developments. Our observations suggest a potential link between aquaporins and cell surface properties, and relate to the proposed role of mammalian aquaporins in tumour cell migration and invasion.
The antifungal protein PAF interferes with PKC/MPK and cAMP/PKA signalling of Aspergillus nidulans
Authors: Binder Ulrike , Oberparleiter Christoph , Meyer Vera , Marx Florentine 
Published: November 2009

SummaryThe Penicillium chrysogenum antifungal protein PAF inhibits polar growth and induces apoptosis in Aspergillus nidulans. We report here that two signalling cascades are implicated in its antifungal activity. PAF activates the cAMP/protein kinase A (Pka) signalling cascade. A pkaA deletion mutant exhibited reduced sensitivity towards PAF. This was substantiated by the use of pharmacological modulators: PAF aggravated the effect of the activator 8‐Br‐cAMP and partially relieved the repressive activity of caffeine. Furthermore, the Pkc/mitogen‐activated protein kinase (Mpk) signalling cascade mediated basal resistance to PAF, which was independent of the small GTPase RhoA. Non‐functional mutations of both genes resulted in hypersensitivity towards PAF. PAF did not increase MpkA phosphorylation or induce enzymes involved in the remodelling of the cell wall, which normally occurs in response to activators of the cell wall integrity pathway. Notably, PAF exposure resulted in actin gene repression and a deregulation of the chitin deposition at hyphal tips of A. nidulans, which offers an explanation for the morphological effects evoked by PAF and which could be attributed to the interconnection of the two signalling pathways. Thus, PAF represents an excellent tool to study signalling pathways in this model organism and to define potential fungal targets to develop new antifungals.
LrhA positively controls the expression of the locus of enterocyte effacement genes in enterohemorrhagic Escherichia coli by differential regulation of their master regulators PchA and PchB
Authors: Honda Naoko , Iyoda Sunao , Yamamoto Shouji , Terajima Jun , Watanabe Haruo 
Published: November 2009

SummaryGenes essential for eliciting pathogenicity of enterohemorrhagic Escherichia coli are located within the locus of enterocyte effacement (LEE). Expression of LEE genes is positively regulated by paralogues PchA, PchB and PchC, which are encoded by separate loci of the chromosome. To elucidate the underlying regulatory mechanism, we screened transposon mutants exhibiting reduced expression of pchA, transcription level of which is highest among the pch genes. Here, we report that the LysR‐homologue A (LrhA) positively regulated the transcription of pchA and pchB. A deletion in lrhA reduced the transcription levels of pchA and pchB to different degrees, and also reduced the expression of LEE‐coded type 3‐secreted protein, EspB. Expression of LrhA from a plasmid restored and markedly increased the transcription levels of pchA and pchB respectively, and highly induced EspB expression. Deletion analysis of the regulatory region showed that both promoter‐proximal (−195 to +88) and promoter‐distal (−418 to −392 for pchA and −391 to −375 for pchB) sequences were required for the LrhA‐mediated upregulation of pchA and pchB genes. Purified His6‐LrhA protein differentially bound to the regulatory regions of pchA/B, suggesting that direct regulation of pchA and pchB genes by LrhA in turn controls the expression of LEE genes.
Dissecting the role of the Tir:Nck and Tir:IRTKS/IRSp53 signalling pathways in vivo
Authors: Crepin Valérie F. , Girard Francis , Schüller Stephanie , Phillips Alan D. , Mousnier Aurelie , Frankel Gad 
Published: November 2009

SummaryAttaching and effacing (A/E) lesions and actin polymerization, the hallmark of enteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. coli (EHEC) and Citrobacter rodentium (CR) infections, are dependent on the effector Tir. Phosphorylation of TirEPEC/CR Y474/1 leads to recruitment of Nck and neural Wiskott–Aldrich syndrome protein (N‐WASP) and strong actin polymerization in cultured cells. TirEPEC/CR also contains an Asn‐Pro‐Tyr (NPY454/1) motif, which triggers weak actin polymerization. In EHEC the NPY458 actin polymerization pathway is amplified by TccP/EspFU, which is recruited to Tir via IRSp53 and/or insulin receptor tyrosine kinase substrate (IRTKS). Here we used C. rodentium to investigate the different Tir signalling pathways in vivo. Following infection with wild‐type C. rodentium IRTKS, but not IRSp53, was recruited to the bacterial attachment sites. Similar results were seen after infection of human ileal explants with EHEC. Mutating Y471 or Y451 in TirCR abolished recruitment of Nck and IRTKS respectively, but did not affect recruitment of N‐WASP or A/E lesion formation. This suggests that despite their crucial role in actin polymerization in cultured cells the Tir:Nck and Tir:IRTKS pathways are not essential for N‐WASP recruitment or A/E lesion formation in vivo. Importantly, wild‐type C. rodentium out‐competed the tir tyrosine mutants during mixed infections. These results uncouple the Tir:Nck and Tir:IRTKS pathways from A/E lesion formation in vivo but assign them an important in vivo role.