bluuebunny/crossref_metadata_2025_split huggingface dataset:
Historical biogeography of European leuciscins (Cyprinidae): evaluating the Lago Mare dispersal hypothesis
Authors: Levy André , Doadrio Ignacio , Almada Vítor C. 
Published: September 2008

AbstractAim  To test the importance of the Lago Mare stage of the Messinian Salinity Crisis for the dispersal and diversification of European leuciscins (Cyprinidae: Leuciscinae).Location  Europe.Methods  Cytochrome b sequences of European leuciscins were employed to investigate phylogenetic relationships among species, using Bayesian inference, and to estimate times of diversification, using a relaxed molecular clock. The distributions of 190 European leuciscins were compiled, and regional species compositions were compared using a taxonomic similarity index and an area cladogram.Results  Leuciscins restricted to the Iberian and Italian peninsulas and the West and South Balkan regions are phylogenetically more closely related to northern European species than to species from another southern European area. Application of a relaxed molecular clock to a Bayesian phylogeny indicates that most southern clades originated and diversified prior to the Messinian. Southern European regions are taxonomically distinct from one another, and from a more taxonomically homogeneous group of areas that includes Anatolia, East Balkans, Middle East, North Europe and West Russia.Main conclusions  The scenario of a Messinian period of dispersal of Paratethyan fauna into Mediterranean regions, via the Lago Mare, predicts a rapid period of diversification and a pattern of close association among southern European faunas. Phylogenetic relationships among leuciscins, the timing of cladogenic events, and the taxonomic similarity among geographical regions do not conform to this expectation. The depth of clades endemic to southern Europe, together with the high levels of endemism in these regions, suggests that the faunas in these regions diverged prior to the Messinian and have evolved largely in isolation from one another. Our results support a model of gradual colonization of Mediterranean regions since the Oligocene. Subsequent connections between adjacent areas may have occurred in the Messinian or Pleistocene.
A Quaternary perspective on the conservation prospects of the Tertiary relict tree Prunus lusitanica L.
Authors: Calleja J. A. , Benito Garzón M. , Sainz Ollero H. 
Published: September 2008

AbstractAim  To assess the importance of climate and human pressure as factors limiting the past, present and future distribution of Prunus lusitanica L. (the Portuguese laurel), a relict of Europe’s ancient subtropical laurel‐forest flora.Location  The Iberian Peninsula.Methods  A census was taken of the current populations of P. lusitanica in the Iberian Peninsula and the threats they face. The potential distribution of the species was modelled under current climatic conditions and under simulations of the climate for the Last Glacial Maximum (LGM), the mid‐Holocene and the year 2080.Results  The present total population of 31,000 individuals is largely distributed as small, fragmented subpopulations, often threatened by agriculture or forestry. The species’ current range is much smaller than its potentially suitable range. During the LGM, P. lusitanica would have been constrained to a limited number of sites along the Atlantic coast. In the mid‐Holocene, its potential range was much wider than during the LGM and similar to that of the present day. Under the 2080 climate scenario its potential range is reduced by almost 40% compared to that of the present. This reduction includes the loss of territories currently home to three‐quarters of its Iberian population.Main conclusions  Drastic climatic changes and the existence of refugia are usually invoked to explain the rarity and fragmented distribution – yet persistence – of a subtropical flora in southern Europe. The availability of climatically suitable habitats is, however, not necessarily the main factor limiting its distribution. Human impact would appear to have been – and continues to be – of fundamental importance in the current population sizes and potential range of P. lusitanica in the Iberian Peninsula.
Towards a generalized biogeography of the Southern Ocean benthos
Authors: Griffiths Huw J. , Barnes David K. A. , Linse Katrin 
Published: September 2008

AbstractAim  To investigate whether the biogeographical regions proposed by J. W. Hedgpeth and widely adopted by other authors hold true, are an oversimplification or with further data might show a unified Antarctic province.Location  Southern Hemisphere.Methods  The distributions of 1318 species of bivalves, 4656 species of gastropods, 1465 species of cheilostome and 167 species of cyclostome bryozoans were analysed for 29 regions in the Southern Hemisphere, including South American, South African, Tasmanian, New Zealand, sub‐Antarctic and Antarctic regions. We present data on species richness, rates of endemism, patterns of radiation, faunal similarities and multivariate biogeographical analyses.Results  The most striking pattern to emerge from our data set of species counts per region was a strong east–west hemispheric asymmetry, with high species numbers in New Zealand, Tasmania and South Africa and low numbers in South America. In contrast, no difference was found in richness between the east and west parts of the Southern Ocean. We compared findings in our model taxa with published data on ascidians, cephalopods and pycnogonids. Further evidence of strong faunal links between the Antarctic and South America is reported in this study, although we found little evidence for a biogeographical relationship between the Antarctic or South America and New Zealand/Tasmania. Strong evidence exists for a long‐term influence of the Antarctic Circumpolar Current upon the distribution of Southern Ocean benthos. This is demonstrated by the reduced prevalence of South American species in the Antarctic and sub‐Antarctic with increasing distance from South America in the direction of the current. Three of our four study taxa (bivalves, cheilostomes and cyclostomes) show the Southern Ocean as a ‘single functional unit’ with no evidence for a biogeographical split between east and west.Main conclusions  Unlike the biogeographical schemes previously proposed, we show that biogeographical regions in the Southern Ocean differ depending upon the class of animals being considered. Despite this we suggest that some general rules are viable, including species endemism rates of around 50%, a single Antarctic province and a definite distinction between the sub‐Antarctic islands influenced by South America and those of New Zealand.
When groups decide to use asynchronous online discussions: collaborative learning and social presence under a voluntary participation structure
Authors: So H.‐J. 
Published: September 2008

AbstractThe purpose of this study is to explore how groups decide to use asynchronous online discussion forums in a non‐mandatory setting, and, after the group decision is made, how group members use online discussion forums to complete a collaborative learning project requiring complex data gathering and research processes. While a large body of research on computer‐mediated communication (CMC) has documented successful intervention strategies to promote and sustain online discussion forums, little of the research has examined the use of online discussion forums in voluntarily contexts, wherein the decision to use online discussion forums is a personal decision and participation is not a graded component. This study approaches the research questions using a naturalistic case study of one graduate‐level blended learning course with 55 students. Employing both student interviews and content analysis methods, this study revealed that the factors affecting the group decision to use online discussion forums are (1) successful or unsuccessful experiences during the first trial, (2) perceived affordances of CMC tools, and (3) the interplay between the nature of collaborative tasks and perceived efficiency. The content analysis of online postings in two voluntary groups revealed that when groups decided to use online discussion forums, participation levels were almost equal among individual group members, and discussion threads were sustained until the final completion of the collaborative project.
Examining student satisfaction with wholly online learning
Authors: Palmer S.R. , Holt D.M. 
Published: September 2008

AbstractLearner satisfaction has been shown to be positively correlated with quality of learning outcomes. An understanding of the factors that influence student satisfaction with online learning in a particular context can be used as an input to the appropriate design of learning environments, and for the provision of targeted support to students, with an aim to positively influence the student online learning experience. Following the mandatory inclusion of at least one wholly online unit of study in all undergraduate programs at Deakin University, a large ‘experiences of learning online’ (ELO) survey was undertaken to gauge students’ perceptions of studying in the wholly online mode. A multivariate linear regression of all the questionnaire items was performed against an overall satisfaction item. Five items were found to significantly contribute to a model that explained approximately 70% of reported student satisfaction. Factors that were found to positively influence student satisfaction with studying a wholly online unit primarily related to how confident they felt about their ability to communicate and learn online, having a clear understanding of what was required to succeed in the unit and how well they thought they were performing in the unit. Other results are also reported.
Antiflagellin antibodies recognize the autoantigens Toll‐Like Receptor 5 and Pals 1‐associated tight junction protein and induce monocytes activation and increased intestinal permeability in Crohn’s disease
Authors: Lunardi C. , Bason C. , Dolcino M. , Navone R. , Simone R. , Saverino D. , Frulloni L. , Tinazzi E. , Peterlana D. , Corrocher R. , Puccetti A. 
Published: September 2008

Abstract.Background and objectives.  Bacterial flagellin is considered an important antigen in Crohn’s disease (CD) as it activates innate immunity through Toll‐Like Receptor 5 (TLR5) engagement and induces an elevated adaptive immune response. Little is known about the presence of an autoimmune process in CD. We aimed to identify pathogenically relevant autoantigen targets in CD.Methods.  We screened a random peptide library with pooled sera of patients with active CD. Transepithelial flux of [3H] mannitol in T84 human intestinal epithelial cell line was used to study the epithelial barrier function. Monocyte activation was evaluated by surface expression of activation markers and by production of pro‐inflammatory cytokines. Gene modulation of T84 cells exposed to antipeptide antibodies was analysed by gene array.Results.  We identified a peptide that shares homology with Salmonella typhimurium flagellin and with self‐antigens such as TLR5 and cell junction protein, Pals 1‐associated tight junction protein. The affinity‐purified antipeptide antibodies recognized the self‐antigens and induced increased intestinal epithelial cell permeability. Moreover, the antibodies induced monocyte activation upon binding TLR5. Finally, in cultured intestinal cells (T84) the purified antibodies induced the modulation of clusters of proinflammatory genes similar to the one induced by the engagment of TLR5 by its natural ligand flagellin.Conclusions.  Antibodies directed against an immunodominant peptide of flagellin recognize self‐antigens and are functionally active suggesting the presence of an autoimmune process that can both facilitate loss of tolerance to intestinal microflora by increasing cell permeability and amplify the innate immunity involvement through a novel mechanism of TLR5 activation.
ruvA and ruvB mutants specifically impaired for replication fork reversal
Authors: Le Masson Marie , Baharoglu Zeynep , Michel Bénédicte 
Published: September 2008

SummaryReplication fork reversal (RFR) is a reaction that takes place in Escherichia coli at replication forks arrested by the inactivation of a replication protein. Fork reversal involves the annealing of the leading and lagging strand ends; it results in the formation of a Holliday junction adjacent to DNA double‐strand end, both of which are processed by recombination enzymes. In several replication mutants, replication fork reversal is catalysed by the RuvAB complex, originally characterized for its role in the last steps of homologous recombination, branch migration and resolution of Holliday junctions. We present here the isolation and characterization of ruvA and ruvB single mutants that are impaired for RFR at forks arrested by the inactivation of polymerase III, while they remain capable of homologous recombination. The positions of the mutations in the proteins and the genetic properties of the mutants suggest that the mutations affect DNA binding, RuvA–RuvB interaction and/or RuvB‐helicase activity. These results show that a partial RuvA or RuvB defect affects primarily RFR, implying that RFR is a more demanding reaction than Holliday junction resolution.
Effect of pea plant architecture on spatiotemporal epidemic development of ascochyta blight (Mycosphaerella pinodes) in the field
Authors: Le May C. , Ney B. , Lemarchand E. , Schoeny A. , Tivoli B. 
Published: September 2008

The effect of pea canopy structure on epidemics of Mycosphaerella pinodes was investigated in four spring pea cultivars (Bridge, Obelisque, Solara and Athos) in two field experiments. These cultivars had similar levels of susceptibility to ascochyta blight and presented different architectural features (branching, standing ability and stem height). Stem height ranged from 77 to 95 cm in 1999 and from 72 to 92 cm in 2000, while leaf area index (LAI) ranged from 3·8 to 5·1 in 1999 and from 3·8 to 4·7 in 2000. Internode lengths varied from 4·6 to 6·0 in 1999 and from 3·8 to 4·7 in 2000. Mean distance between nodes in the canopy (MDN) ranged from 12·2 to 15·3 cm in 1999 and from 11·2 to 13·9 cm in 2000. Canopies with different architecture differed in disease progression on stipules and mainly on pods. The levels of disease on stipules and pods were strongly correlated. Moreover, if disease was considered as a function of stipule height up the stem, large differences in vertical disease distribution were observed between cultivars. Three architectural features acted on disease development: cumulative LAI above the node on which disease was assessed (LAIcum) and large MDN favouring disease development, and large internode length reducing disease severity. Modifying LAI distribution and plant organization could be one way to reduce the impact of ascochyta blight, by direct or indirect effects on environmental and dispersal conditions.
Orbital calibration of the Early Kimmeridgian (southeastern France): implications for geochronology and sequence stratigraphy
Authors: Boulila S. , Galbrun B. , Hinnov L. A. , Collin P.‐Y. 
Published: September 2008

AbstractClassic stratigraphic methods rarely provide high‐resolution correlations between intrabasinal sedimentary sequences, which are important to understand the origin of sedimentation process and its environmental change. In this study, we investigate high‐resolution cyclostratigraphic correlation from magnetic susceptibility in two Early Kimmeridgian pelagic marl‐limestone successions, at La Méouge and Châteauneuf‐d'Oze, southeastern France. Spectral analysis reveals the complete suite of orbital frequencies (precession, obliquity, and eccentricity) with the marl‐limestone couplets being primarily precession‐driven. Frequencies detected by the spectral analysis are similar between the sections, but their relative amplitudes are somewhat different, linked to the palaeoenvironmental position and the completeness of the sections. High‐resolution correlation reveals two significant hiatuses at Châteauneuf‐d’Oze. Early Kimmeridgian Platynota, Hypselocyclum, and Divisum ammonite zones were orbitally calibrated for an ultra‐high resolution assessment of geological time. Finally, strong 405‐kyr eccentricity cycles are recorded as third‐order depositional sequences.
Could Iceland be a modern analogue for the Earth's early continental crust?
Authors: Martin E. , Martin H. , Sigmarsson O. 
Published: September 2008

AbstractFor the last two decades, Iceland and other oceanic plateaux have been considered as potential analogues for the formation of the early Earth's continental crust. This study examines the compositions of silicic rocks from modern oceanic plateaux, revealing their differences to Archaean continental rock types (trondhjemite–tonalite–granodiorite or TTG) and thereby emphasising the contrasted mechanisms and/or sources for their respective origins. In most oceanic plateaux, felsic magmas are thought to be formed by fractional crystallization of basalts. In Iceland, the interaction between mantle plume and the Mid‐Atlantic ridge results in an abnormally high geothermal gradient and melting of the hydrated metabasaltic crust. However, despite the current `Archaean‐like' high geothermal gradients, melting takes place at a shallow depth and is unable to reproduce the TTG trace element signature. Consequently, oceanic plateaux are not suitable environments for the genesis of the Archaean continental crust. However, their subduction could account for the episodic crustal growth which has occurred throughout the Earth's history.
Selection of High Nitrogen‐Fixing Rhizobia Nodulating Chickpea (Cicer arietinum) for Semi‐Arid Tunisia
Authors: Ben Romdhane S. , Aouani M. E. , Trabelsi M. , De Lajudie P. , Mhamdi R. 
Published: September 2008

AbstractInoculation of grain legumes with rhizobia may improve biological N2 fixation and crop yield. However, drought, high temperature and soil salinity constrain legume root‐nodule formation and function. Here, two rhizobial strains nodulating Tunisian chickpea, Mesorhizobium ciceri strain CMG 6 and Mesorhizobium mediterraneum strain CTM 226 originating from semi‐arid regions, were selected for their symbiotic performance and their salt stress tolerance (3 % NaCl). Both strains were then examined as inoculants in different soils and field conditions. Field experiments were conducted in four sites using four chickpea cultivars. Rhizobia occupying nodules in non‐inoculated plots were isolated and characterized using 16S rDNA typing; to examine nodule occupancy by the inoculant strains we used polymerase chain reaction (PCR)‐restriction fragment length polymorphism of 16S rDNA gene and repetitive extragenic palindromic PCR. The inoculant strains gave a significant increase in nodule number, shoot dry weight and grain yield in all the experimented fields for the four cultivars used, even in the non‐irrigated soils. The improvement in plant production was equal to or better than nitrogen fertilization. Moreover, the monitoring of the nodule occupancy showed that inoculant strains competed well in the native populations of rhizobia. These results suggest that nodulation and yield of chickpea can be improved by inoculation with competitive and salt‐tolerant rhizobia and is economically promising to increase chickpea production in water‐limited regions.
Physiological Responses of Krishum (Iris lactea Pall. var. chinensis Koidz) to Neutral and Alkaline Salts
Authors: Wang Y. , Guo J. X. , Meng Q. L. , Cui X. Y. 
Published: September 2008

AbstractThe aims of this study were to compare the physiological responses of krishum (Iris lactea Pall. var. chinensis Koidz) to neutral and alkaline salt stress and identify and examine the mechanisms involved in plant response to salt treatments. In this study, biomass, ion accumulation (Na+, K+, Ca2+, Mg2+), organic solute (proline) concentration, rate of membrane electrolyte leakage (REL) and antioxidase activities including those of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6) and peroxidase (POD, EC 1.11.1.7) were investigated in krishum under different concentrations of NaCl, Na2CO3 and the mixture of the two salts in the same volume. All three treatments caused increases in Na+ concentration, proline content and REL and decreases in root Mg2+ and K+ content. Increased Ca2+ and antioxidase activities were observed at lower external Na+ concentrations. However, at higher external Na+ levels, decreased Ca2+ and antioxidase activities were detected. Alkaline salt resulted in more damage to krishum than neutral salt including lower SOD, POD and CAT activities and decreased proline content, relative to neutral salt. High Na+ and low K+ in krishum intensified ion toxicity under alkaline condition. Alkaline salt caused greater harm to plants than neutral salt, the primary reason of which might be the lower Ca2+ content in the plant under alkaline salt stress.
Fish assemblages and rapid colonization after enlargement of an artificial reef off the Algarve coast (Southern Portugal)
Authors: Leitão Francisco , Santos Miguel N. , Erzini Karim , Monteiro Carlos C. 
Published: September 2008

AbstractArtificial reefs (ARs) have been deployed in Algarve (Southern Portugal) coastal waters to contribute to the sustainability of local nearshore fisheries. Herein, we describe the colonization process of the recently deployed Faro/Ancão AR, and assess the time until the fish assemblage reaches stability and their seasonal patterns. In addition, we compare the results from the present study with those previously reported for an older AR. The fish assemblages were monitored monthly over a 2‐year period by means of visual census. A rapid increase in fish colonization occurred within the first 4 months. After this initial period the assemblage structure showed high similarity (> 73%). The high rate of colonization of the AR was related to the maturity already achieved by the nearby 14‐year‐old AR and to the fish migration from the Ria Formosa lagoon, a nearby nursery habitat. The reef fish assemblage structure showed a seasonal pattern, mainly associated with recruitment episodes of occasional demersal species (Boops boops, Trachurus trachurus and Pagellus spp.) in spring and summer. A total of 66% of the species found in AR are of commercial and recreational importance. The overall mean density and biomass were 2.8 ind·m−3 and 207 g·m−3. The occasional demersal species accounted for 42% of the fish density. The most important species in terms of biomass belong to the Sparidae family along with Dicentrarchus labrax. The fish assemblage of the new ARs showed higher mean number of species, diversity, density and biomass values than those reported for the older AR. This result was associated with enlargement of the AR area and with the fishing exploitation of the isolated, small and patchy old AR. Moreover, the high biomass values recorded in the new ARs were mainly due to the increased density of D. labrax after AR enlargement. The results of the present study are used to define guidelines for suitable management strategies for the AR areas that are exploited by the local commercial and recreational fisheries.