bluuebunny/crossref_metadata_2025_split huggingface dataset:
Proinflammatory cytokine synthesis by mucosal fibroblasts from mouse colitis is enhanced by interferon-γ-mediated up-regulation of CD40 signalling
Authors: De L Karlson T , Whiting C V , Bland P W 
Published: November 2006

Summary
Gut mesenchymal fibroblasts form complex phenotypical and functional populations. They participate actively in homeostatic maintenance of the extracellular matrix, epithelial barrier function, repair mechanisms and leucocyte migration. In inflammation, they become activated, change matrix expression and synthesize proinflammatory mediators. Subpopulations of mucosal fibroblasts express CD40 and the aim of this study was to define its role in their proinflammatory function. Stable primary fibroblast lines derived from normal mouse colon and inflamed colon from CD4+ CD45RBhigh-transplanted SCID mice were used as models to explore the role of mucosal fibroblast CD40 in the inflammatory process. Phenotype correlated with in situ fibroblast phenotype in the tissues of origin. Lines from both sources co-expressed CD40 and Thy1·2 independently of α-smooth muscle actin. A subpopulation of CD40+ fibroblasts from normal colon expressed CD40 at high levels and expression was enhanced by interferon (IFN)-γ treatment, whereas all CD40+ fibroblasts from colitis expressed at low levels and expression was unaffected by IFN-γ treatment. Despite lower-level expression of CD40 by cells from colitis, they secreted constitutively interleukin (IL)-6 and C-C chemokine (CCL)2. Ligation of CD40 enhanced secretion of these mediators and induced secretion of CCL3. CD40 in cells from colitis was more responsive to ligation than CD40 on cells from normal tissue and this sensitivity was amplified selectively by the action of IFN-γ. We conclude that the inflammatory milieu in colitis induces long-lasting changes in phenotype and proinflammatory function in colonic fibroblasts. In particular, proinflammatory signalling from fibroblast CD40 is amplified synergistically by the Th1 effector T cell cytokine, IFN-γ.
The impact of interleukin-6 promoter −597/−572/−174genotype on interleukin-6 production after lipopolysaccharide stimulation
Authors: Müller-Steinhardt M , Ebel B , Härtel C 
Published: November 2006

Summary
Interleukin (IL)-6 is a pleiotropic cytokine, produced by different cells. There is accumulating evidence that IL-6 promoter polymorphisms impact substantially on various diseases and we identified kidney transplant recipients carrying the IL-6 GGG/GGG −597/−572/−174genotype to have superior graft survival. To prove a functional impact on gene expression, we analysed systematically IL-6 production in healthy individuals with respect to the IL-6 −597/−572/−174genotype. IL-6 was determined in 100 healthy blood donors at protein and mRNA levels upon specific stimulation in monocytes and T lymphocytes under whole blood conditions. GGG/GGG individuals showed a lower IL-6 secretion upon lipopolysaccharide (LPS)-stimulation versus all others (P = 0·039). This link was even stronger when −597 and −174GG genotypes were reanalysed separately (P = 0·008, P = 0·017). However, we found neither a difference at the mRNA level or percentage of CD14+ cells nor after T cell stimulation. We found evidence for the IL-6 −597/−572/−174genotype to affect IL-6 synthesis, i.e. lower levels of IL-6 protein upon LPS-stimulation in GGG/GGG individuals. Further studies are needed in kidney transplant recipients to investigate the potential link between the GGG/GGG genotype and graft survival. In line with this, determination of the genetic risk profiles might be promising to improve the transplant outcome in the individual patient.
Rheumatoid factor induction in murine models of liver injury
Authors: Nowak U , Gill K , Skamene E , Newkirk M M 
Published: November 2006

SummaryAlcoholic liver disease and hepatitis C are associated with the production of autoantibodies such as rheumatoid factors (RF), which bind to IgG and can aid in host defence, but are also associated with pathological conditions such as rheumatoid arthritis. Because little is known about the role of RF in liver disease, we characterized the RF production that either occurred spontaneously in response to alcohol consumption or was induced by injection of an Escherichia coli glycolipoprotein in C57Bl/6 mice. Whereas severe liver damage was induced by carbon tetrachloride (CCl4), minimal damage was caused by chronic alcohol consumption. Liver damage was monitored by measurements of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Circulating RF was induced in response to chronic alcohol consumption; the latter probably involved Toll-like receptor ligation. In contrast, CCl4-induced damage was not associated with RF induction. However, concurrent treatment with an E. coli glycolipoprotein macromolecule that induced RF, protected against CCL4-induced liver damage as measured by a highly significant decrease (P = 0·008) at 4 weeks in AST and ALT. RF induced by E. coli glycolipoprotein correlated with ‘protection’ from liver damage, indicating that the RF autoimmune response does not necessarily exacerbate liver disease.
Critical evaluation of three indirect assays for quantifying phytosiderophores released by the roots of Poaceae
Authors: Reichman S. M. , Parker D. R. 
Published: November 2006

SummaryIndirect assays are commonly used to measure phytosiderophore (PS) concentrations in the root exudates of grasses. The Cu‐mobilizing, Cu‐CAS and Fe‐binding assays are three commonly used assays but there have been few published attempts to validate or calibrate them rigorously. Thus, we undertook to compare, validate and, where appropriate, to improve and/or optimize each assay. Ethylenediamine‐N,N′‐diacetic acid (EDDA) and N‐2‐hydroxyethylethylenediamine‐N,N′,N′‐triacetic acid (HEDTA) bracket deoxymugineic acid for binding strength with both Fe and Cu and were thus used as model ligands. For the Cu‐mobilizing assay, reasonable regressions (as R2) were obtained between measured and known ligand concentrations for all resin combinations tested. However, the relationship was non‐stoichiometric; less than 5% of the ligand present was recovered as a Cu‐complex. Testing of the Cu‐CAS assay yielded good 1:1 stoichiometric relationships (slopes of 0.97 and 1.08 for EDDA and HEDTA, respectively) with little scatter (R2= 0.97). However, the limits of quantification were approximately 30 μm, which is greater than concentrations generally found in root‐exudate collections. Thus, the Cu‐CAS assay is best suited to situations where large concentrations of PSs are expected. Results from the original Fe‐binding assay indicated a lack of linearity and considerable scatter (R2= 0.57 for EDDA; R2= 0.28 for HEDTA). Thus, as published, use of the original Fe‐binding assay is not recommended. The effects of filter paper, FeCl3 reagent concentration and increase in the reduction time were tested and a revised Fe‐binding assay developed with both good stoichiometry and great precision (R2≥ 0.99). We suggest the use of the revised Fe‐binding assay in most situations where PS concentration would be expected to be < 30 μm.
Lead sorption to selected Portuguese soils
Authors: Trancoso M. A. , Correiados Santos M. M. , Gonçalves M. L. S 
Published: November 2006

SummaryWe studied the interaction of lead with seven Portuguese soils with different physical and chemical properties in order to elucidate more fully the behaviour of Pb in soil. We studied these adsorption phenomena by voltammetric titrations with differential pulse polarography (DPP) at different pH (6.0–7.2) and ionic strengths, I (0.010–0.50 m) in order to clarify some of the factors that might control soil sorption capacity for Pb. From the voltammetric data, average formation constants, , and binding capacity, Cc, have been estimated according to a surface complexation model based on Scatchard and van den Berg–R?zic methods. Linear Scatchard and van den Berg–R?zic plots (r≥ 0.99) indicated that the results can be interpreted according to the existence of just one predominant active site for Pb(II) adsorption. The values from both procedures () agreed in all cases (r= 0.938, n= 66, P < 0.001). The same happened with Cc values that were statistically equivalent (r= 0.9998; n= 66; P < 0.001). The Cc values were found to depend on the pH and I, as well as on the soil properties. Either Langmuir or Freundlich isotherms fitted the experimental data well (r > 0.90, P < 0.05). The lead binding capacities were strongly and significantly correlated (P < 0.05) with pH, cation exchange capacity, organic carbon, loss‐on‐ignition, total Al2O3 content, extractable forms of Al and pyrophosphate extractable Fe, [Fep]. From a forward, stepwise regression model we concluded that [Al2O3], [Pb′] (concentration of labile lead in solution), [Fep], pH and I are able to explain more than 99.7% of the variation in lead sorption in our soils. The soils’ surface groups with special affinity to Pb(II) are in the inorganic fraction associated with aluminium.
From Plinthic Acrisols to Plinthosols and Gleysols: iron and groundwater dynamics in the tertiary sediments of the upper Amazon basin
Authors: Fritsch E. , Herbillon A. J. , Do Nascimento N. R. , Grimaldi M , Melfi A. J. 
Published: November 2006

SummaryTopography has been reported to be the major factor ruling the spatial distribution of Acrisols, Plinthosols and Gleysols on the seasonally flooded, low elevation plateaux of the upper Amazon basin occupied by Tertiary (Iça & Solimões) sediments. In this study, detailed morphological and mineralogical investigations conducted in a representative 25‐ha site were combined with hydro‐geochemical data to relate the vertical and lateral soil differentiations observed to the hydro‐geological history of that part of the basin. As a result of the uplift of the Andes, several cuts in the extensive Tertiary marshlands have formed, at first, slightly incised plateaux of low elevation. There, weathering under hot and humid climates would have generated a reddish, freely drained and bioturbated topsoil layer and the vertical differentiation in subsoil sediments of a plinthite over an iron‐depleted mottled clay. The second episode of soil differentiation is linked to the replacement of the forest by a savannah under the drier climates of the late Pleistocene, which favours surface runoff and the infill of the incisions by fine particles. This infill, combined with the return to the present humid climate, has then enabled the local groundwater to rise on the plateaux and to generate episaturation at the topsoil/subsoil transition close to the depressions. Nowadays, ferrous iron is released from the partly iron‐depleted topsoil weathering front at high water levels during the rainy seasons. It moves from footslope to low‐lying positions and from top to bottom in the soil profile according to the groundwater dynamics. The present general trend is thus to the lateral export of iron at high water levels due to subsurface and overland flows, its vertical transfer during the recession of the groundwater and accumulation in a nodular plinthite. In the latter, ferrous iron is adsorbed onto its softest iron masses where it feeds the neoformation of ferrihydrite that rapidly dehydrates into haematite.
Bacteria can control stoichiometry and nutrient limitation of phytoplankton
Authors: DANGER M. , OUMAROU C. , BENEST D. , LACROIX G. 
Published: November 2006

Summary

The chemical composition of primary producers, which occupy the base of food webs, is highly variable over space and time. Determining the causes of these variations is crucial to the understanding of ecosystem functioning.
By differentially stocking and recycling nutrients, heterotrophic organisms such as bacteria may change the nature of the factor that limits algal growth, thus influencing algal chemical composition.
We tested this hypothesis by growing a green alga, Scenedesmus obliquus (Turpin) Kützing, along a phosphorus gradient in the presence or absence of a bacterial community.
We first confirmed that the limiting factor affects the chemical composition of phytoplankton. We then observed that the bacteria switched the nutrient that limited algal growth, from nitrogen to phosphorus in high N : P media. This generated considerable variation in algal stoichiometry.
We propose that the bacterial compartment may have a greater influence on the structure and functioning of aquatic ecosystems than previously believed.
Clinical correlates of the biological variation of sperm DNA fragmentation in infertile men attending an andrology outpatient clinic
Authors: Smit M. , Dohle G. R. , Hop W. C. J. , Wildhagen M. F. , Weber R. F. A. , Romijn J. C. 
Published: November 2006

SummaryDetermination of sperm DNA fragmentation, as assessed by the sperm chromatin structure assay (SCSA), has become an important tool for the evaluation of semen quality. The aim of the present study was to describe the biological variation of sperm DNA fragmentation in men attending an andrology clinic and to identify clinical correlates of the biological variation of sperm DNA fragmentation. For this study, two consecutive semen samples from 100 patients attending our andrology outpatient clinic were subjected to semen analysis, performed in parallel according to WHO guidelines and by SCSA. A good agreement between pairs of samples was found for SCSA‐derived variables, as indicated by a significantly lower median coefficient of variation (CV) of the DNA Fragmentation Index (DFI) and the high DNA stainability (HDS) compared with WHO semen parameters. In half of the men attending our andrology clinic, however, the individual biological variation of DFI and HDS, expressed as CV of two samples, exceeded 10%. Dysregulation of spermatogenesis, as seen as testicular insufficiency or varicocele, was not associated with increased variability of DFI or HDS. A backward multiple linear regression analysis, however, indicated that the biological variation of DFI may be more profound in men with characteristics of normal spermatogenesis. In conclusion, we confirm previous reports that sperm DNA fragmentation has a lower biological variability than classical semen parameters. We hypothesize that the sperm chromatin structure may be more influenced in patients with normal spermatogenesis, whereas in men with disturbed spermatogenesis, the chromatin structure may be already so impaired that the effect of unidentified factors leading to variability of sperm DNA fragmentation in time may not be as profound.
Vigilance and fitness in grey partridges Perdix perdix: the effects of group size and foraging‐vigilance trade‐offs on predation mortality
Authors: WATSON MARK , AEBISCHER NICHOLAS J. , CRESSWELL WILL 
Published: November 2006

Summary

Vigilance increases fitness by improving predator detection but at the expense of increasing starvation risk. We related variation in vigilance among 122 radio‐tagged overwintering grey partridges Perdix perdix (L.) across 20 independent farmland sites in England to predation risk (sparrowhawk Accipiter nisus L., kill rate), use of alternative antipredation behaviours (grouping and use of cover) and survival.
Vigilance was significantly higher when individuals fed in smaller groups and in taller vegetation. In the covey period (in early winter when partridges are in flocks), vigilance and use of taller vegetation was significantly higher at sites with higher sparrowhawk predation risk, but tall vegetation was used less by larger groups. Individuals were constrained in reducing individual vigilance by group size and habitat choice because maximum group size was determined by overall density in the area during the covey period and by the formation of pairs at the end of the winter (pair period), when there was also a significant twofold increase in the use of tall cover.
Over the whole winter individual survival was higher in larger groups and was lower in the pair period. However, when controlling for group size, mean survival decreased as vigilance increased in the covey period. This result, along with vigilance being higher at sites with increasing with raptor risk, suggests individual vigilance increases arose to reduce short‐term predation risk from raptors but led to long‐term fitness decreases probably because high individual vigilance increased starvation risk or indicated longer exposure to predation. The effect of raptors on survival was less when there were large groups in open habitats, where individual partridges can probably both detect predators and feed efficiently.
Our study suggests that increasing partridge density and modifying habitat to remove the need for high individual vigilance may decrease partridge mortality. It demonstrates the general principle that antipredation behaviours may reduce fitness long‐term via their effects on the starvation–predation risk trade‐off, even though they decrease predation risk short‐term, and that it may be ecological constraints, such as poor habitat (that lead to an antipredation behaviour compromising foraging), that cause mortality, rather than the proximate effect of an antipredation behaviour such as vigilance.
Long‐term enhancement of agricultural production by restoration of biodiversity
Authors: BULLOCK JAMES M. , PYWELL RICHARD F. , WALKER KEVIN J. 
Published: November 2006

Summary

Experimental manipulations have shown positive impacts of increased species richness on ecosystem productivity, but there remain some questions about this relationship. First, most studies last < 4 years, which raises issues about whether diversity–productivity relationships are maintained in mature communities. Secondly, the conservation relevance of many studies is debatable. We addressed both issues using long‐term experimental studies of the agriculturally relevant hay yield of recreated species‐rich grasslands.
Grasslands were recreated within replicated experiments in ex‐arable fields at two sites in southern England by using either species‐poor or species‐rich seed mixtures. The species‐poor mixture comprised seven grasses as recommended for grassland creation in English agri‐environment schemes. The species‐rich mixture comprised 11 grasses and 28 forbs and was designed to recreate a typical southern English hay meadow.
After 8 years the plots sown with species‐rich mixtures resembled target diverse community types. The plots sown with species‐poor mixtures had been colonized by a number of forbs but had lower numbers of grasses, legumes and other forbs than the species‐rich plots. Increased hay yield of the species‐rich plots in the first years of the experiments have been described in an earlier paper, and these differences were maintained after 8 years.
In the eighth year the species‐rich plots had an average 43% higher hay yield than the species‐poor plots. Regression analysis showed that the variation in hay yield was related to differences in the number of non‐leguminous forbs and showed no relation to grass or legume numbers. This suggests increased hay yield is an effect of the greater range of life forms exhibited by forbs rather than a simple fertilizing effect of legumes.
The nitrogen content and phosphorus content of the hay showed complex treatment effects over time. However, the nutritional value of the hay was above the minimum requirements for livestock.
Synthesis and applications. The aims of conservationists and farmers can often be in conflict. This study has shown that the recreation of diverse grasslands of conservation value can have a positive impact on hay yield, which benefits the farm business, and this is repeated across differing sites. Because the effect is maintained over time, farm income will be increased in the long term.
Amassing diversity in an ancient lake: evolution of a morphologically diverse parthenogenetic gastropod assemblage in Lake Malawi
Authors: GENNER MARTIN J. , TODD JONATHAN A. , MICHEL ELLINOR , ERPENBECK DIRK , JIMOH ABAYOMI , JOYCE DOMINO A. , PIECHOCKI ANDRZEJ , POINTIER JEAN‐PIERRE 
Published: November 2006

AbstractExceptional ecological niche diversity, clear waters and unique divergent selection pressures have often been invoked to explain high morphological and genetic diversity of taxa within ancient lakes. However, it is possible that in some ancient lake taxa high diversity has arisen because these historically stable environments have allowed accumulation of lineages over evolutionary timescales, a process impossible in neighbouring aquatic habitats undergoing desiccation and reflooding. Here we examined the evolution of a unique morphologically diverse assemblage of thiarid gastropods belonging to the Melanoides polymorpha‘complex’ in Lake Malawi. Using mitochondrial DNA sequences, we found this Lake Malawi complex was not monophyletic, instead sharing common ancestry with Melanoides anomala and Melanoides mweruensis from the Congo Basin. Fossil calibrations of molecular divergence placed the origins of this complex to within the last 4 million years. Nuclear amplified fragment length polymorphism markers revealed sympatric M. polymorpha morphs to be strongly genetically differentiated lineages, and males were absent from our samples indicating that reproduction is predominantly parthenogenetic. These results imply the presence of Lake Malawi as a standing water body over the last million years or more has facilitated accumulation of clonal morphological diversity, a process that has not taken place in more transient freshwater habitats. As such, the historical stability of aquatic environments may have been critical in determining present spatial distributions of biodiversity.
Reproductive isolation among deep‐water cichlid fishes of Lake Malawi differing in monochromatic male breeding dress
Authors: GENNER MARTIN J. , NICHOLS PAUL , CARVALHO GARY R. , ROBINSON ROSANNA L. , SHAW PAUL W. , TURNER GEORGE F. 
Published: November 2006

AbstractMale nuptial colour hues are important for the maintenance of reproductive isolation among cichlid fish species, and environmental changes that lead to narrower light spectra can lead to hybridization. However, cichlid species can naturally co‐occur in narrow light spectrum habitats, such as turbid shallow lakes and the deep benthic zones of African rift lakes. Closely related species from narrow light spectrum habitats tend to differ little in the palette of male nuptial colours, thus for these taxa differences in colour patterns may be more important than differences in colour hue for species recognition. To investigate this hypothesis we examined morphometric and genetic differentiation among males of four sympatric putative species within the deep‐water genus Diplotaxodon. These taxa live in a narrow‐light spectrum environment where only blue light is present, and males differ primarily in ‘monochromatic’ black, white and silver patterning of the body and fins. Significant genetic differentiation was present among taxa in both microsatellite DNA and mitochondrial DNA, including one pair with no significant morphometric differentiation. Thus, these taxa represent reproductively isolated biological species, a result consistent with male nuptial patterning being important for species recognition and assortative mating. As such, we suggest that narrow‐light spectra need not always represent barriers to effective visually mediated mate recognition.