bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapoport's bathymetric rule and the latitudinal species diversity gradient for Northeast Pacific fishes and Northwest Atlantic gastropods: evidence against a causal link
Authors: Smith Katherine F. , Gaines Steven D. 
Published: July 2003

AbstractAim  Few studies have explicitly considered the recurrent pattern of declining species diversity and increasing geographical range size that exists for numerous taxa across a variety of physical gradients. We extend Stevens’ [Stevens, G.C. (1996)Journal of Biogeography, 23, 149] work on Rapoport's bathymetric rule, using a more complete latitudinal assemblage of Northeast Pacific fishes and new data from Northwest Atlantic gastropods, to show that bathymetrical range size and species diversity are not causally linked.Location  Fishes from the Northeast Pacific (0°–60° N) and gastropods from the Northwest Atlantic (0°–74° N) distributed from the surface to depths greater than 200 m.Methods  Species pools were divided into three bathymetrical subgroups: (1) species restricted to shallow waters, between the surface and 200 m, (2) species that occurred in waters, both shallow and deep of 200 m, and (3) species restricted to waters deeper than 200 m. Median bathymetrical range size and total number of species were plotted against latitude (2° bins) using Stevens’ method, for the entire species pool and individual bathymetrical groups.Results  For both fishes and gastropods, the apparent link between extratropical diversity and bathymetrical range size is an artefact resulting from the disproportionately high number of shallow restricted species in tropical latitudes, and the loss of these species in temperate latitudes. Furthermore, the extratropical gradient in gastropod diversity and bathymetrical range size are decoupled by approximately 15°, and while the latitudinal pattern for diversity is consistent across bathymetrical groups, median bathymetrical range size is highly irregular.Main conclusions  These results suggests that functional groups can contribute disproportionately to patterns apparent at larger scales and that analysis of ecographical patterns by subregion is a novel approach that can help resolve debates over causality when patterns are seemingly coincident.
Patterns of distribution and processes of speciation in Brazilian reef fishes
Authors: Rocha Luiz A. 
Published: July 2003

AbstractAim  To evaluate the state of knowledge about the biogeography of Brazilian reef fishes and propose processes that lead to the observed distribution patterns.Location  The tropical western Atlantic.Methods  The geological history of the Amazon barrier was obtained from the literature, and its potential influence on speciation of reef fishes was analysed. Species distributions were analysed based on literature records and material deposited at Brazilian and American collections.Results  Recent estimates indicate that about 12% of the Brazilian reef fish species are endemic, and most ichthyologists agree that this endemism is generated by the barrier formed by the freshwater and sediment discharge of large rivers in north‐eastern South America, mainly the Amazon, Orinoco and their tributaries. However, little is known about the dynamics of this barrier, and recent studies have demonstrated that it can be crossed through deep sponge bottoms on the outer continental shelf off north‐eastern South America. Moreover, the recent discovery of species regarded as Brazilian endemics in the extreme southern Caribbean is showing that the Amazon barrier is weaker than previously thought.Main conclusions  The Amazon freshwater and sediment outflow is a strong barrier to shallow water reef fish and other organisms, and it is probably responsible for most of the endemism found in Brazilian coastal habitats. However, sea‐level fluctuations influence the effectiveness of such barrier and may play a large role in the generation of diversity in the western tropical Atlantic. Alternatively, larval exchange between Brazil and the Caribbean is small but constant, and contrasting selection pressures in divergent environments (continental Brazil vs. insular Caribbean) may be the central force driving speciation.
Simulating tick distributions over sub‐Saharan Africa: the use of observed and simulated climate surfaces
Authors: Olwoch J. M. , Rautenbach C. J. de W. , Erasmus B. F. N. , Engelbrecht F. A. , Van Jaarsveld A. S. 
Published: July 2003

AbstractAim A broad suit of climate data sets is becoming available for use in predictive species modelling. We compare the efficacy of using interpolated climate surfaces [Center for Resource and Environmental Studies (CRES) and Climate Research Unit (CRU)] or high‐resolution model‐derived climate data [Division of Atmospheric Research limited‐area model (DARLAM)] for predictive species modelling, using tick distributions from sub‐Saharan Africa.Location The analysis is restricted to sub‐Saharan Africa. The study area was subdivided into 3000 grids cells with a resolution of 60 × 60 km.Methods Species distributions were predicted using an established multivariate climate envelope modelling approach and three very different climate data sets. The recorded variance in the climate data sets was quantified by employing omnidirectional variograms. To further compare the interpolated tick distributions that flowed from using three climate data sets, we calculated true positive (TP) predictions, false negative (FN) predictions as well as the proportional overlaps between observed and modelled tick distributions. In addition, the effect of tick data set size on the performance of the climate data sets was evaluated by performing random draws of known tick distribution records without replacement.Results The predicted distributions were consistently wider ranging than the known records when using any of the three climate data sets. However, the proportional overlap between predicted and known distributions varied as follows: for Rhipicephalus appendiculatus Neumann (Acari: Ixodidae), these were 60%, 60% and 70%; for Rhipicephalus longus Neumann (Acari: Ixodidae) 60%, 57% and 75%; for Rhipicephalus zambeziensis Walker, Norval & Corwin (Acari: Ixodidae) 57%, 51% and 62%, and for Rhipicephalus capensis Koch (Acari: Ixodidae) 70%, 60% and 60% using the CRES, CRU and DARLAM climate data sets, respectively. All data sets were sensitive to data size but DARLAM performed better when using smaller species data sets. At a 20% data subsample level, DARLAM was able to capture more than 50% of the known records and captured more than 60% of known records at higher subsample levels.Main conclusions The use of data derived from high‐resolution nested climate models (e.g. DARLAM) provided equal or even better species distribution modelling performance. As the model is dynamic and process based, the output data are available at the modelled resolution, and are not hamstrung by the sampling intensity of observed climate data sets (c. one sample per 30,000 km2 for Africa). In addition, when exploring the biodiversity consequences of climate change, these modelled outputs form a more useful basis for comparison with modelled future climate scenarios.
Predicting reptile distributions at the mesoscale: relation to climate and topography
Authors: Guisan Antoine , Hofer Ulrich 
Published: July 2003

AbstractAim To explore the respective power of climate and topography to predict the distribution of reptiles in Switzerland, hence at a mesoscale level. A more detailed knowledge of these relationships, in combination with maps of the potential distribution derived from the models, is a valuable contribution to the design of conservation strategies.Location All of Switzerland.Methods Generalized linear models are used to derive predictive habitat distribution models from eco‐geographical predictors in a geographical information system, using species data from a field survey conducted between 1980 and 1999.Results The maximum amount of deviance explained by climatic models is 65%, and 50% by topographical models. Low values were obtained with both sets of predictors for three species that are widely distributed in all parts of the country (Anguis fragilis, Coronella austriaca, and Natrix natrix), a result that suggests that including other important predictors, such as resources, should improve the models in further studies. With respect to topographical predictors, low values were also obtained for two species where we anticipated a strong response to aspect and slope, Podarcis muralis and Vipera aspis.Main conclusions Overall, both models and maps derived from climatic predictors more closely match the actual reptile distributions than those based on topography. These results suggest that the distributional limits of reptile species with a restricted range in Switzerland are largely set by climatic, predominantly temperature‐related, factors.
Distribution patterns in butterflies and birds of the Czech Republic: separating effects of habitat and geographical position
Authors: Storch David , Konvicka Martin , Benes Jiri , Martinková Jana , Gaston Kevin J. 
Published: July 2003

AbstractAimTo evaluate the relative role of environmental factors and geographical position (latitude and longitude) in determining species distribution and composition of local assemblages of butterflies and birds.LocationCzech Republic, central Europe.MethodsCanonical correspondence analysis that ordinates species and samples (grid cells in distribution atlases) such that interspecific and intersample differences attributable to environmental factors are maximized. The technique allowed us to test the significance of individual factors, including the geographical ones, by controlling the other factors and accounting for spatial autocorrelation.ResultsAltitude and climate (temperature and precipitation) accounted for most variance in the interspecific differences in distribution of both butterflies and birds. The distribution of birds was also strongly affected by the area of water bodies, and less strongly, but still significantly, by the area of meadows and mountain open habitats. Habitat types important for the differences in butterfly distribution were deciduous forests, meadows, swamps and mountain open habitats. Some less common habitat types were important only because of the presence of rare species. Latitude and longitude invariably accounted for a large proportion of total variance, and their effect was highly significant even after controlling for the effect of all other environmental factors.Main conclusionsAlthough environmental factors, especially those related to elevation and climate, represent the main determinants of species distribution and composition of local assemblages, the geographical position is very important on this scale of resolution. Understanding distribution patterns, thus, must include not only an understanding of species ecological requirements, but also an understanding of geographical context, which affects structure and dynamics of species’ geographical ranges.
Spatial patterns of disparity and diversity of the Recent cuttlefishes (Cephalopoda) across the Old World
Authors: Neige Pascal 
Published: July 2003

AbstractAim Diversity and disparity metrics of all Recent cuttlefishes are studied at the macroevolutionary scale (1) to establish the geographical biodiversity patterns of these cephalopods at the species level and (2) to explore the relationships between these two metrics.Location Sampling uses what is known about these tropical, subtropical and warm temperate cephalopods of the Old World based on a literature review and on measurements of museum specimens. Some 111 species spread across seventeen biogeographical areas serve as basic units for exploring diversity and disparity metrics in space.Methods Landmarks describe the shape of the cuttlebone (the inner shell of the sepiids) and differences between shapes are quantified using relative warp analyses. Relative warps are thus used as the morphological axis for constructing morphospaces whose characteristics are described by disparity indices: total variance, range, and minimum and maximum of relative warps. These are analysed and then compared with the diversity (species richness) metric.Results Results show no significant latitudinal or longitudinal gradients either for diversity or for disparity. Around the coast of southern Africa, disparity is high regardless of whether diversity (species richness) is high or low. In the ‘East Indies’ area disparity is low despite the high diversity.Main conclusions The relationship between diversity and disparity is clearly not linear and no simple adjustment models seem to fit. The number of species in a given area does not predict its disparity level. The particular pattern of southern Africa may be the result of paleogeographical changes since the Eocene, whereas that of the ‘East Indies’ may indicate that this area could act as a centre of origin. However, the lack of any clear phylogenetical hypothesis precludes the study from providing any explanation of the observed patterns.
Plio‐Pleistocene climatic oscilations, Holarctic biogeography and speciation in an avian subfamily
Authors: Drovetski Sergei V. 
Published: July 2003

AbstractAim In this paper, I discuss the temporal and spatial aspects of historical biogeography and speciation in a widely distributed Holarctic subfamily of birds (Tetraoninae).Location Northern Holarctic.Results Using dated fossils, I calibrated the molecular clock for the mitochondrial control region at 7.23 ± 1.58% nucleotide divergence (maximum likelihood corrected) per million years. The data suggest that grouse (Tetraoninae) originated in the Middle Pliocene, 6.3 Ma. Grouse apparently originated in the northern part of western Nearctic, and Palearctic was colonized independently three times, first by the ancestor of all grouse in the Middle Pliocene, then by the ancestor of forest (Falcipennis, Tetrao and Lyrurus) and prairie (Centrocercus, Dendragapus and Tympanuchus) grouse in the Late Pliocene, and finally by the ancestral Lagopus in the Early Pleistocene. Only once Nearctic was colonized from Palearctic by a common ancestor of forest grouse. Sympatry and range symmetry were positively correlated with molecular divergence. These correlations suggest that peripatric isolation was the predominant mode of speciation throughout grouse history.Main conclusions Speciation events in grouse were driven by climatic oscillations of the Pliocene and Pleistocene. Isolation of small peripheral populations from widely distributed ancestors was the dominant mode of speciation in grouse. Isolations during interglacials both across Beringia, and in southern mountain areas when boreal habitats were restricted to high elevations, suggest an important role for vicariance in grouse speciation.
Comparative effects of fluoroquinolones on subsets of T lymphocytes in normothermic and hyperthermic mice
Authors: Szczypka M. , Obmińska‐Mrukowicz B. 
Published: July 2003

The subsets of T lymphocytes in thymus, spleen and mesenteric lymph nodes were investigated in normothermic and hyperthermic mice treated with fluoroquinolones administered orally six times at 24 h intervals at doses of 15 or 75 mg/kg (flumequine, norfloxacin and ciprofloxacin) and 5 or 25 mg/kg (enrofloxacin). It has been found that fluoroquinolones can modulate CD3+, CD4+ and CD8+ marker expression on thymocytes, splenocytes and lymphocytes of mesenteric lymph nodes. Flumequine (15 mg/kg) decreased the percentage of immature CD4+CD8+ thymic cells and increased the percentage of mature CD4+ and CD8+. When the dose of flumequine was increased to 75 mg/kg a reduction in the maturation of thymocytes was observed. Administration of flumequine, norfloxacin and ciprofloxacin, irrespective of doses applied, increased the percentages of CD3+ splenocytes of CD4+ spleen cells. Exposure to enrofloxacin decreased the percentage of T helper‐inducer cells. Flumequine and ciprofloxacin augmented the percentage of CD3+ mesenteric lymph node cells and increased the percentage of CD8+ cells. In contrast, norfloxacin and enrofloxacin decreased the percentage of CD3+ mesenteric lymph node cells and the percentage of CD4+ cells.Lipopolysaccharide (LPS) from E. coli (25 μg/mouse) increased the percentage of single‐positive CD4+ thymocytes, but did not affect the percentage of CD3+, CD4+ and CD8+ splenocytes and mesenteric lymph node cells. Flumequine and ciprofloxacin administered to mice pior to LPS potentiated its stimulant effect on the maturation of thymic cells ( increased percentage of mature CD4+ and CD8+ thymocytes). Pre‐treatment with norfloxacin or enrofloxacin either reduced or did not modify the stimulant effect of LPS on maturation of thymic cells. Flumequine, norfloxacin, enrofloxacin and ciprofloxacin administered prior to LPS decreased the percentage of CD8+ splenocytes and increased the percentage of CD4+ spleen cells. Norfloxacin and ciprofloxacin at a dose of 75 mg/kg reduced the percentage of CD8+ mesenteric lymph node cells in hyperthermic mice. Pretreatment with norfloxacin at a dose of 15 mg/kg augmented the percentage of mesenteric lymph node cells.It was concluded that the modulating effects of fluoroquinolones depends on the chemial structure of drugs, dose administered as well as immunologic status.
Pharmacokinetics and sedative effects of intramuscular medetomidine in domestic sheep
Authors: Kästner S. B. R. , Wapf P. , Feige K. , Demuth D. , Bettschart‐ Wolfensberger R. , Akens M. K. , Huhtinen M. 
Published: July 2003

Intramuscular (i.m.) administration of medetomidine (MED) may avoid the severe pressor effects caused by peripheral actions of MED associated with intravenous (i.v.) dosing. The purpose of this study was to determine the pharmacokinetics, the time course of sedation and occurence of hypoxaemia after i.m. administration of MED in domestic sheep. The MED was injected i.m. at a dose of 30 μg/kg in nine domestic sheep. Blood was sampled at 0, 5, 10, 20, 30, 40, 60, 120, 180, 240, 360 and 600 min after MED. Sedation was assessed and arterial blood samples were taken before and 35 min after MED application. Mean (SD) pharmacokinetic parameters of i.m. MED were: absorption half‐life: 13.2 (7.5) min; terminal half‐life: 32.7 (14.9) min; time to peak concentration: 29.2 (8.9) min; peak concentration: 4.98 (1.89) ng/mL; volume of distribution: 3.9 (2.4) l/kg; total body clearance: 81.0 (21.5) mL/(min kg). Peak sedation occurred between 30 and 40 min after injection of MED. The degree of sedation correlated with individual plasma concentrations (rS: 0.926). One animal became hypoxaemic (PaO2 = 54.1 mmHg).
Apoptotic mitochondrial pathway in neurones and astrocytes after neonatal hypoxia‐ischaemia in the rat brain
Authors: Benjelloun N. , Joly L.‐M. , Palmier B. , Plotkine M. , Charriaut‐Marlangue C. 
Published: July 2003

Neuronal apoptosis plays an essential role in early brain development and contributes to secondary neuronal loss after acute ischaemia. Recent studies have provided evidence that caspase‐3 is an important downstream event after hypoxia‐ischaemia in the immature brain, but a minor event in the adult brain. Our investigations have focused on cell populations that expressed apoptotic effectors in the enzymatic death pathway including cytochrome c, caspase‐9 and caspase‐3. Expression, activation and cellular localization of these proteins were studied using cleavage of fluorogenic substrate and immunohistochemistry in neonatal rat brain after unilateral focal ischaemia. Caspase‐3 enzyme activity was elevated in brain homogenate between 6 and 48 h after reperfusion. This activation was preceded by that of caspase‐9, between 3 and 24 h. Apoptotic cell death was finally accomplished by poly‐ADP‐ribose polymerase cleavage, an endogenous caspase‐3 substrate. In addition, immunodetection demonstrated that cytochrome c and activated caspase‐9 and caspase‐3 were expressed not only in the neurones, the primarily affected cells, but also within the astrocytes, which constituted a dense network delineating the infarct. These results suggested that glial injury may promote the formation of cystic lesions such as those observed clinically in the newborn brain.
Antigen Presentation by Murine Dendritic Cells is Nuclear Factor‐kappa B Dependent Both In Vitro and In Vivo
Authors: Yoshimura S. , Bondeson J. , Brennan F. M. , Foxwell B. M. J. , Feldmann M. 
Published: July 2003

AbstractAntigen presentation is a key rate‐limiting step in the immune response. Dendritic cells (DCs) have been reported to be the most potent antigen‐presenting cells for naïve T cells, but little is known about the biochemical pathways that regulate this function. We here demonstrate that mature murine DC can be infected with adenovirus at high efficiency (>95%) and that an adenovirus transferring the endogenous inhibitor IκBα blocks nuclear factor‐kappa B (NF‐κB) function in murine DC. This result indicates that antigen presentation in the mixed leucocyte reaction is NF‐κB dependent, confirming data with human DC in vitro. However, the importance of this finding depends on verifying that this is true also in vivo. Using delayed type hypersensitivity with allogeneic cells, we show that NF‐κB inhibition had a marked immunosuppressive effect in vivo. These results thus establish NF‐κB as an effective target for blocking DC antigen presentation and hence inhibiting T‐cell‐dependent immune responses. This finding has potential implications for the development of therapeutic agents for use in various pathological conditions of the immune system, including allergy and autoimmunity, and also in transplantation.
Inclusion Body Myositis: Clonal Expansions of Muscle‐Infiltrating T Cells Persist Over Time
Authors: Müntzing K. , Lindberg C. , Moslemi A.‐R. , Oldfors A. 
Published: July 2003

AbstractInclusion body myositis (IBM) is a chronic inflammatory myopathy. The muscle histology is characterized by infiltration of T cells, which invade and apparently destroy muscle fibres. This study was performed to investigate whether predominant clones of muscle‐infiltrating T cells are identical in different muscles and whether they persist over time in IBM. By reverse transcriptase‐polymerase chain reaction, 25 T‐cell receptor (TCR) variable β (Vβ) chain families and the complementarity‐determining region 3 (CDR3) of the TCR were analysed in two different muscle biopsies of four patients with IBM. In two of the patients, the muscle biopsies were obtained from different muscles at one time point, whereas in two patients, the second biopsy was obtained 9 years after the first biopsy. T cells expressing predominant Vβ families were analysed for clonality by fragment length analysis of the CDR3. Predominant Vβ families were analysed by DNA sequencing to identify identical clones. Immunohistochemical staining of Vβ families was performed to study the distribution of T cells expressing identified predominant Vβ families. The muscle‐infiltrating lymphocytes showed restricted expression of TCR Vβ families. DNA sequencing proved that clonally expanded T cells were identical in different muscles and persisted 9 years after the first biopsy. Immunohistochemical analysis with Vβ family‐specific antibodies demonstrated the endomysial localization of these T cells in inflammatory cell infiltrates. Our results show that in IBM there is clonal restriction of TCR expression in muscle‐infiltrating lymphocytes. Identical T‐cell clones predominate in different muscles, and these clones persist for many years. These results indicate an important, continuous, antigen‐driven inflammatory reaction in IBM.