bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phenological changes in six Australian subalpine plants in response to experimental warming and year‐to‐year variation
Authors: Hoffmann Ary A. , Camac James S. , Williams Richard J. , Papst Warwick , Jarrad Frith C. , Wahren Carl‐Henrik 
Published: April 2010

Summary1. The likely phenological responses of plants to climate warming can be measured through experimental manipulation of field sites, but results are rarely validated against year‐to‐year changes in climate. Here, we describe the response of 1–5 years of experimental warming on phenology (budding, flowering and seed maturation) of six common subalpine plant species in the Australian Alps using the International Tundra Experiment (ITEX) protocol.2. Phenological changes in some species (particularly the forbCraspedia jamesii) were detected in experimental plots within a year of warming, whereas changes in most other species (the forbErigeron bellidioides, the shrubAsterolasia trymalioidesand the graminoidsCarex breviculmisandPoa hiemata) did not develop until after 2–4 years; thus, there appears to be a cumulative effect of warming for some species across multiple years.3. There was evidence of changes in the length of the period between flowering and seed maturity in one species (P. hiemata) that led to a similar timing of seed maturation, suggesting compensation.4. Year‐to‐year variation in phenology was greater than variation between warmed and control plots and could be related to differences in thawing degree days (particularly, forE. bellidioides) due to earlier timing of budding and other events under warmer conditions. However, inCarex breviculmis, there was no association between phenology and temperature changes across years.5. These findings indicate that, although phenological changes occurred earlier in response to warming in all six species, some species showed buffered rather than immediate responses.6. Synthesis. Warming in ITEX open‐top chambers in the Australian Alps produced earlier budding, flowering and seed set in several alpine species. Species also altered the timing of these events, particularly budding, in response to year‐to‐year temperature variation. Some species responded immediately, whereas in others the cumulative effects of warming across several years were required before a response was detected.
Effects of clonal integration and light availability on the growth and physiology of two invasive herbs
Authors: Xu Cheng‐Yuan , Schooler Shon S. , Van Klinken Rieks D. 
Published: April 2010

Summary 1. Clonal plants benefit from the ability to translocate resources among interconnected ramets to colonize heterogeneous habitats. Clonal integration affects the resource level and morphological traits of ramets, and thus may influence their physiology and general performance. Although leaf gas exchange and its associated physiological adjustments are key traits to assess plant fitness, the effect of clonal integration on these functional traits is insufficiently understood. 2. In a glasshouse experiment, we addressed how clonal integration affects gas exchange properties, leaf characters and growth of ramets in two invasive plants, Alternanthera philoxeroides and Phyla canescens, under full sun and 85% shade. We also used stable‐isotope labelling to assess the maternal subsidy to daughter ramets. 3. Similar effects of connection were observed in both species for most gas exchange parameters and leaf characters. Clonal integration did not affect photosynthetic capacity and respiratory rates of ramets. When grown in shade, ramets connected with an unshaded mother plant displayed higher area‐based leaf nitrogen and chlorophyll content than severed ramets, but the additional nitrogen and chlorophyll was not translated to increased photosynthetic capability. Overall, severed ramets displayed significant light response for leaf nitrogen (area‐based), photosynthetic nitrogen use efficiency, chlorophyll to nitrogen ratio, and nitrogen stable‐isotope signature, but the light response was eliminated by clonal integration in connected ramets. 4. Both species displayed substantial maternal carbohydrate subsidy that benefited the growth of daughter ramets, but species‐specific patterns were observed in the growth of daughter ramets and the amount of subsidy. The amount of subsidy was independent of ramet growth light levels for P. canescens, but shaded, connected ramets of A. philoxeroides received more subsidy than unshaded controls, facilitating a larger growth improvement relative to severed counterparts than P. canescens. 5. Synthesis. We observed increased leaf nitrogen and chlorophyll in shaded, connected ramets of two clonal invasive plants. Clonal integration may facilitate nitrogen assimilation and allow pre‐acclimation to high‐light conditions for shaded, connected ramets, thus promoting the opportunistic expansion of these invaders on site scale. The species‐specific maternal subsidy pattern demonstrated that clonal plants possess different strategies to subsidize ramets under light‐limited conditions.
AFLP genome scan in the black rat (Rattus rattus) from Madagascar: detecting genetic markers undergoing plague‐mediated selection
Authors: TOLLENAERE C. , DUPLANTIER J.‐M. , RAHALISON L. , RANJALAHY M. , BROUAT C. 
Published: April 2010

AbstractThe black rat (Rattus rattus) is the main reservoir of plague (Yersinia pestis infection) in Madagascar’s rural zones. Black rats are highly resistant to plague within the plague focus (central highland), whereas they are susceptible where the disease is absent (low altitude zone). To better understand plague wildlife circulation and host evolution in response to a highly virulent pathogen, we attempted to determine genetic markers associated with plague resistance in this species. To this purpose, we combined a population genomics approach and an association study, both performed on 249 AFLP markers, in Malagasy R. rattus. Simulated distributions of genetic differentiation were compared to observed data in four independent pairs, each consisting of one population from the plague focus and one from the plague‐free zone. We found 22 loci (9% of 249) with higher differentiation in at least two independent population pairs or with combining P‐values over the four pairs significant. Among the 22 outlier loci, 16 presented significant association with plague zone (plague focus vs. plague‐free zone). Population genetic structure inferred from outlier loci was structured by plague zone, whereas the neutral loci dataset revealed structure by geography (eastern vs. western populations). A phenotype association study revealed that two of the 22 loci were significantly associated with differentiation between dying and surviving rats following experimental plague challenge. The 22 outlier loci identified in this study may undergo plague selective pressure either directly or more probably indirectly due to hitchhiking with selected loci.
Control of Bacillus subtilis mtl operon expression by complex phosphorylation‐dependent regulation of the transcriptional activator MtlR
Authors: Joyet Philippe , Derkaoui Meriem , Poncet Sandrine , Deutscher Josef 
Published: April 2010

SummaryMany bacteria transport mannitol via the mtlAF‐encoded phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system (PTS). In most firmicutes the transcriptional activator MtlR controls expression of the mtl operon. MtlR possesses an N‐terminal DNA binding domain, two PTS regulation domains (PRDs), an EIIBGat‐ and EIIAMtl‐like domain. These four regulatory domains contain one or two potential PTS phosphorylation sites. Replacement of His‐342 or His‐399 in PRD2 with Ala prevented the phosphorylation of Bacillus subtilis MtlR by PEP, EI and HPr. These mutations as well as EI inactivation caused a loss of MtlR function in vivo. In contrast, phosphomimetic replacement of His‐342 with Asp rendered MtlR constitutively active. The absence of phosphorylation in PRD2 serves as catabolite repression mechanism. When EIIAMtl and the soluble EIIBMtl domain of the EIICBMtl permease were included in the phosphorylation mixture, His‐599 in the EIIA‐like domain of MtlR also became phosphorylated. Replacement of His‐599 with Asp rendered MtlR inactive, while His599Ala replacement caused slightly constitutive, glucose‐repressible MtlR activity. Doubly mutated His342Ala/His599Ala MtlR was still phosphorylated by EI, HPr and EIIAMtl at Cys‐419 in the EIIBGat‐like domain. Cys419Ala replacement and deletion of EIIAMtl caused strong constitutive glucose‐repressible MtlR activity. This is the first report that Cys phosphorylation controls PRD‐containing transcriptional activators.
SecA: a tale of two protomers
Authors: Sardis Marios Frantzeskos , Economou Anastassios 
Published: April 2010

SummaryBacteria, Archaea and Eukaryotes have evolved a plethora of mechanisms to translocate proteins across their various membranes. The bacterial Sec pathway is ubiquitous and essential for cell viability and is used by most proteins destined for the inner membrane, the periplasm or beyond. In bacteria, Sec system components include the heterotrimers SecY/SecE/SecG and SecD/SecF/YajC and the peripherally associated ATPase motor SecA. SecA in solution is mainly dimeric. Unexpectedly, structures of SecA dimers from different or even the same bacterium do not have a consistent dimerization interface. Analysis of the functional assembled translocase complexes blurs the picture even further as the functional quaternary state of the SecYEG channel is also disputed. Several experimental approaches tried to define the oligomeric state of SecA during preprotein ‘pushing’ through SecYEG. One high‐resolution SecA–SecYEG complex has been visualized. This snapshot might be a step closer to the actual translocating machinery. Nevertheless, because of the use of detergent, the true quartenary state of the translocase might have been disturbed. Hence, even after this and other studies, several issues remain puzzling. New approaches must be combined with current tools to gain insight into the functionally relevant quartenary states of SecA and SecYEG during preprotein translocation.
Genetic diversity of weedy red rice (Oryza sativa) in Arkansas, USA
Authors: SHIVRAIN V K , BURGOS N R , AGRAMA H A , LAWTON‐RAUH A , LU B , SALES M A , BOYETT V , GEALY D R , MOLDENHAUER K A K 
Published: April 2010

Shivrain VK, Burgos NR, Agrama HA, Lawton‐Rauh A, Lu B, Sales MA, Boyett V, Gealy DR & Moldenhauer KAK (2010). Genetic diversity of weedy red rice (Oryza sativa) in Arkansas, USA. Weed Research50, 289–302.SummaryWeedy red rice (Oryza sativa) is a problematic weed in cultivated rice. About 50% of US rice is produced in Arkansas and 60% of these fields have some red rice infestation. Red rice populations are morphologically and phenologically diverse. We hypothesise that red rice in Arkansas has high genetic diversity, which underlies its wide phenotypic diversity, and that some alleles from cultivated rice have been introgressed into red rice during more than a century of coexistence. We tested 137 red rice accessions from four ecological zones in Arkansas and 36 cultivars that have been grown in Arkansas in the past century. Twenty‐seven rice microsatellite primers, distributed across 12 chromosomes, were used to generate molecular markers. The overall Nei’s genetic distance (GD) of red rice accessions was 0.70. Rice grown in the last century had an overall GD of 0.26. The awnless strawhull red rice was genetically distant from blackhull (GD = 0.55) and brownhull (GD = 0.60) red rice types. Nei’s GD between blackhull and brownhull red rice was 0.42. Brownhull and blackhull formed one genotypic cluster, whereas the majority of strawhull red rice formed another cluster. Within blackhull red rice, the GD was 0.76, whereas for awnless strawhull it was 0.68, 0.75 for awned strawhull and 0.80 for brownhull types. The gene diversity of blackhull and strawhull correlated with zone of origin. A quarter of the red rice accessions share common alleles with cultivated rice. A diverse complex of weedy populations has evolved in a region devoid of other weedy and wild Oryza species.
Definitions of hypotension after spinal anaesthesia for caesarean section: literature search and application to parturients
Authors: KlÖHR S. , ROTH R. , HOFMANN T. , ROSSAINT R. , HEESEN M. 
Published: April 2010

Background: Spinal anaesthesia for caesarean section may cause hypotension, jeopardizing the foetus and its mother. We aimed to identify the spectrum of definitions of hypotension used in the scientific literature. In a second part, we applied these definitions to a prospective cohort in order to evaluate the effect of different definitions on the incidence of hypotension.Methods: A systematic literature search in PubMed was performed from 1999 to 2009 with the search terms ‘hypotension’ and ‘caesarean section’. Consecutive parturients undergoing caesarean section under spinal anaesthesia were included in a prospective study.Results: Sixty‐three eligible publications (7120 patients) were retrieved, revealing 15 different definitions of hypotension. A decrease below 80% baseline and the combined definition of a blood pressure below 100 mmHg or a decrease below 80% baseline were the two most frequent definitions, found in 25.4% and 20.6% of the papers, respectively. When applying the spectrum of definitions to a prospective cohort, the incidences of hypotension varied between 7.4% and 74.1%. The incidence increased from 26.7% to 38.5% when using a value below 75% of baseline instead of below 70% of baseline.Conclusion: There is not one accepted definition of hypotension in the scientific literature. The incidence of hypotension varies depending on the chosen definition. Even minor changes of the definition cause major differences in the frequency of hypotension. This makes it difficult to compare studies on interventions to treat/prevent hypotension and probably hampers progress in this area of research.
Sex‐specific heritability of cell‐mediated immune response in the blue tit nestlings (Cyanistes caeruleus)
Authors: DROBNIAK S. M. , WIEJACZKA D. , ARCT A. , DUBIEC A. , GUSTAFSSON L. , CICHOŃ M. 
Published: April 2010

AbstractHere, we aimed at estimating sex‐specific heritabilities of cell‐mediated immune response (CMI) in the blue tit nestlings (Cyanistes caeruleus). To separate genetic and environmental components of the phenotypic variance in CMI (measured using phytohaemagglutinin assay), we performed a cross‐fostering experiment. Additionally, controlled environmental variation was introduced by enlarging some broods. Our analyses revealed a significant genetic component (as approximated by the nest‐of‐origin term) of the phenotypic variance in immune response. More importantly, these genetic effects differed between sexes and experimentally manipulated brood sizes, as indicated by significant genotype‐by‐sex and genotype‐by‐environment interactions. We discuss possible causes of such sexual dimorphism in gene expression and suggest that sex‐ and environment‐specific genetic interactions may contribute to the maintenance of genetic variability in traits related to immune functions.
Interaction between female mating preferences and predation may explain the maintenance of rare males in the pentamorphic fish Poecilia parae
Authors: HURTADO‐GONZALES J. L. , BALDASSARRE D. T. , UY J. A. C. 
Published: April 2010

AbstractVariation in mating preferences coupled with selective predation may allow for the maintenance of alternative mating strategies. Males of the South American live‐bearing fish Poecilia parae fall in one of five discrete morphs: red, yellow, blue, stripe‐coloured tail (parae) and female mimic (immaculata). Field surveys indicate that the red and yellow morphs are the rarest and that their rarity is consistent across years. We explored the role of variable female mating preference and selective predation by visual predators in explaining the rarity of red and yellow males, and more generally, the maintenance of this extreme colour polymorphism. We presented wild‐caught P. parae females and Aequidens tetramerus, the most common cichlid predator, with the five male colour morphs in separate trials to determine mating and prey preferences, respectively. We found that a large proportion of females shared a strong preference for the rare carotenoid‐based red and yellow males, but a distinct group also preferred the blue and parae morphs. The cichlid predator strongly preferred red and yellow males as prey. Together, these results suggest that the interaction between premating sexual selection favouring and predation acting against the red and yellow morphs may explain their rarity in the wild. The trade‐off between sexual and natural selection, accompanied by variation in female mating preferences, may therefore facilitate the maintenance of the striking colour polymorphism in P. parae.
Environmental and not maternal effects determine variation in offspring phenotypes in a passerine bird
Authors: MAINWARING M. C. , DICKENS M. , HARTLEY I. R. 
Published: April 2010

AbstractMaternal and environmental effects can profoundly influence offspring phenotypes, independent of genetic effects. Within avian broods, both the asymmetric post‐hatching environment created by hatching asynchrony and the differential maternal investment through the laying sequence have important consequences for individual nestlings in terms of the allocation of resources to body structures with different contributions to fitness. The purpose of this study was to evaluate the relative importance of post‐hatching environmental and maternal effects in generating variation in offspring phenotypes. First, an observational study showed that within blue tit,Cyanistes caeruleus, broods, late‐hatched nestlings allocated resources to tarsus development, maintained mass gain and head‐bill growth and directed resources away from the development of fourth primary feathers. Second, a hatching order manipulation experiment resulted in nestlings from first‐laid eggs hatching last, thereby allowing comparison with both late and early‐hatched nestlings. Experimental nestlings had growth patterns which were closer to late‐hatched nestlings, suggesting that within‐brood growth patterns are determined by post‐hatching environmental effects. Therefore, we conclude that post‐hatching environmental effects play an important role in generating variation in offspring phenotypes.
Ancestral polymorphism in exon 2 of bluethroat (Luscinia svecica) MHC class II B genes
Authors: ANMARKRUD J. A. , JOHNSEN A. , BACHMANN L. , LIFJELD J. T. 
Published: April 2010

AbstractThe genes of the major histocompatibility complex (MHC) are important model genes for understanding selective forces in evolution. Here, we document, using a cloning and sequencing approach, high polymorphism at the exon 2 of the MHC class II B (MHCIIB) genes in the bluethroat (Luscinia svecica); a minimum of 61 unique alleles were detected in 20 individuals, and at least 11 functional loci. In addition, several pseudogenes were revealed. The specimens originated from three different bluethroat subspecies (azuricollis, cyanecula and svecica), and we also analysed four specimens of the closely related thrush nightingale (L. luscinia) for comparison. Phylogenetic analyses of the functional alleles revealed 258 equally parsimonious trees with poor statistical support for the majority of nodes. The distribution of the sequences in the trees point to an ancestral origin of the polymorphism in MHC class II B genes, a portion of which predated the phylogenetic split between the bluethroat and the thrush nightingale. Strong signatures of balancing selection were uncovered for the codons coding for the peptide‐binding residues of the functional MHCIIB exon 2 alleles. Our results highlight the importance of duplication and recombination events for shaping passerine MHC and give insights in the evolutionary dynamics of MHC variation among closely related taxa.
Geological and mineralogical study of eclogite and glaucophane schists in the Naga Hills Ophiolite, Northeast India
Authors: Ghose Naresh C. , Agrawal Om Prakash , Chatterjee Nilanjan 
Published: April 2010

AbstractA variety of low‐ to high‐pressure metamorphic assemblages occur in the metabasic rocks and metachert in the Upper Cretaceous–Eocene ophiolite belt of the central part of the Naga Hills, an area in the northern sector of the Indo–Myanmar Ranges in the Indo–Eurasian collision zone. The ophiolite suite includes peridotite tectonite containing garnet lherzolite xenoliths, layered ultramafic–mafic cumulates, metabasic rocks, basaltic lava, volcaniclastics, plagiogranite, and pelagic sediments emplaced as dismembered and imbricated bodies at thrust contacts between moderately metamorphosed accretionary rocks/basement (Nimi Formation/Naga Metamorphics) and marine sediments (Disang Flysch). It is overlain by coarse clastic Paleogene sediments of ophiolite‐derived rocks (Jopi/Phokphur Formation). The metabasic rocks, including high‐grade barroisite/glaucophane‐bearing epidote eclogite and glaucophane schist, and low‐grade greenschist and prehnite–clinochlore schist, are associated with lava flows and ultramafic cumulates at the western thrust contact. Chemically, the metabasites show a low‐K tholeiitic affinity that favors derivation from a depleted mantle source as in the case of mid‐ocean ridge basalt. Thermobarometry indicates peakP–Tconditions of about 20 kb and 525°C. Retrogression related to uplift is marked by replacement of barroisite and omphacite by glaucophane followed by secondary actinolite, albite, and chlorite formation. A metabasic lens with an eclogite core surrounded by successive layers of glaucophane schist and greenschist provides field evidence of retrogression and uplift. Presence of S‐C mylonite in garnet lherzolite and ‘mica fish’ in glaucophane schist indicates ductile deformation in the shear zone along which the ophiolite was emplaced.
Restriction–modification systems may be associated with Helicobacter pylori virulence
Authors: Ando Takafumi , Ishiguro Kazuhiro , Watanabe Osamu , Miyake Nobuyuki , Kato Tsuyoshi , Hibi Satoshi , Mimura Shunya , Nakamura Masanao , Miyahara Ryoji , Ohmiya Naoki , Niwa Yasumasa , Goto Hidemi 
Published: April 2010

AbstractRestriction–modification (R‐M) systems are exclusive to unicellular organisms and ubiquitous in the bacterial world. Bacteria use R‐M systems as a defense against invasion by foreign DNA. Analysis of the genome sequences of Helicobacter pylori strains 26 695 and J99 identified an extraordinary number of genes with homology to R‐M genes in other bacterial species. All H. pylori strains possess their own unique complement of active R‐M systems. All of the methylases that have been studied so far were present in all major human population groupings, suggesting that their horizontal acquisition pre‐dated the separation of these populations. The two most strongly conserved methylase genes of H. pylori, hpy IM and hpy IIIM, are both preceded by alternative genes that compete for presence at their loci, and furthermore these genes may be associated with H. pylori pathogenicity. Further study should investigate the roles of H. pylori R‐M systems.