bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular evidence for deep phylogenetic divergence in Mandrillus sphinx
Authors: Telfer P. T. , Souquière S. , Clifford S. L. , Abernethy K. A. , Bruford M. W. , Disotell T. R. , Sterner K. N. , Roques P. , Marx P. A. , Wickings E. J. 
Published: June 2003

AbstractMandrills (Mandrillus sphinx) are forest primates indigenous to western central Africa. Phylogenetic analysis of 267 base pairs (bp) of the cytochrome b gene from 53 mandrills of known and 17 of unknown provenance revealed two phylogeographical groups, with haplotypes differentiated by 2.6% comprising seven synonymous transitions. The distribution of the haplotypes suggests that the Ogooué River, Gabon, which bisects their range, separates mandrill populations in Cameroon and northern Gabon from those in southern Gabon. The haplotype distribution is also concordant with that of two known mandrill simian immunodeficiency viruses, suggesting that these two mandrill phylogroups have followed different evolutionary trajectories since separation.
The demographic history of the New Zealand short‐tailed bat Mystacina tuberculata inferred from modified control region sequences
Authors: Lloyd Brian D. 
Published: June 2003

AbstractShort‐tailed bats Mystacina tuberculata were widespread throughout the forest that dominated prehuman New Zealand, but extensive deforestation has restricted them to scattered populations in forest fragments. In a previous study, the species’ intraspecific phylogeny was investigated using multiple mitochondrial gene sequences. Six phylogroups were identified with estimated divergences of 0.93–0.68 Ma. In the current study, the phylogeographical structure and demographic history of the phylogroups were investigated using control region sequences modified by removing homoplasic sites. Phylogeographical structure in the North Island was generally consistent with an isolation‐by‐distance dispersal model. Coalescent‐based analyses (i.e. mismatch distributions, skyline plots, lineage dispersal analysis and nested clade analysis) indicated that the three phylogroups found in central and southern North Island expanded before the last glacial maximum, presumably during interstadials when Nothofagus forest was most extensive. Genetic structure within a central North Island hybrid zone was consistent with range expansion from separate refugia following reforestation after catastrophic volcanic eruptions. Phylogeographical structure in the South Island was consistent with southern populations originating during rapid southward range expansion from refugia in northern South Island following postglacial reforestation of the South Island 10–9 kya.
Nuclear markers, mitochondrial DNA and male secondary sexual traits variation in a newt hybrid zone (Triturus vulgaris × T. montandoni)
Authors: Babik W. , Szymura J. M. , Rafiński J. 
Published: June 2003

AbstractThe smooth and the Montandon's newts (Triturus vulgarisandT. montandoni) are genetically similar sister species with highly divergent male secondary sexual traits involved in complex courtship behaviour. Their parapatric ranges overlap at moderate elevations in the Carpathian Mountains where they hybridize readily. Here we present a detailed study of genetic and morphological variation in populations from the area of sympatry. Analysis of variation at seven nuclear markers, mtDNA and male sexual secondary traits was complemented with an ecological survey of breeding sites characteristics. Extensive hybridization was revealed with back‐cross individuals similar to either parental species predominating among hybrids. The hybrid zone exhibited a mosaic pattern: the genetic composition of the populations was correlated only weakly with their geographical position. No association with habitat type was found. Departures from Hardy–Weinberg proportions, significant linkage disequilibria and bimodal distribution of genotypes suggest strongly that assortative mating is an important factor shaping the genetic composition of hybrid populations. The pattern of cytonuclear disequilibria did not indicate much asymmetry in interspecific matings. Changes in the frequency of nuclear markers were highly concordant, whereas mtDNA showed much wider bidirectional introgression with 14% excess ofT. montandonihaplotype. We argue that the mosaic structure of the newt hybrid zone results mainly from stochastic processes related to extinction and recolonization. Microgeographical differences in mtDNA introgression are explained by historical range shifts. Since morphologically intermediate males were underrepresented when compared to hybrid males identified by genetic markers, sexual selection acting against the morphological intermediates is implied. We discuss the implications of these findings in the context of reinforcement of prezygotic isolation in newts.
The role of plant species in biomass production and response to elevated CO2and N
Authors: Craine Joseph M. , Reich Peter B. , David Tilman G. , Ellsworth David , Fargione Joseph , Knops Johannes , Naeem Shahid 
Published: June 2003

AbstractIn an experiment that factorially manipulated plant diversity, CO2, and N, we quantified the effects of the presence of species on assemblage biomass over 10 time points distributed over 5 years. Thirteen of the 16 species planted had statistically significant effects on aboveground and/or belowground biomass. Species differed dramatically in their effects on biomass without any relationship between aboveground and below‐ground effects. Temporal complementarity among species in their effects seasonally, successionally, and in response to a dry summer maintained the diversity–biomass relationships over time and may be the cause behind higher diversity plots having less variation in biomass over time. The response of plant biomass to elevated N, but not CO2, was at times entirely dependent on the presence of a single species.
The population consequences of natural enemy enhancement, and implications for conservation biological control
Authors: Kean John , Wratten Steve , Tylianakis Jason , Barlow Nigel 
Published: June 2003

AbstractWe explore models for the management of invertebrate pests by enhancing the efficacy or local abundance of existing natural enemies. Different aspects of natural enemy biology had different effects on prey density. Enhancement of enemy search rate or prey conversion efficiency showed the greatest potential for reducing prey density, while maximum consumption rate by predators, and parasitoid fecundity, had less effect. The effect on prey density of increased natural enemy longevity depended on its interaction with other parameters. The degree of manipulation needed to achieve a given reduction in prey populations was largely determined by the enemy's potential reproductive rate. Spatial ‘‘attraction’’ of enemies to a target site had an almost linear effect on local prey density. We conclude that successful conservation biological control benefits from a directed approach, targeting the most important aspects of natural enemy ecology, and that there is considerable potential for further research in this area.
Food web complexity and higher‐level ecosystem services
Authors: Montoya José M. , Rodríguez Miguel A. , Hawkins Bradford A. 
Published: June 2003

AbstractStudies mostly focused on communities of primary producers have shown that species richness provides and promotes fundamental ecosystem services. However, we know very little about the factors influencing ecosystem services provided by higher trophic levels in natural food webs. Here we present evidence that differences in food web structure and the richness of herbivores in 19 plant‐herbivore‐parasitoid food webs influence the service supplied by natural enemies, namely, the parasitism rates on hosts. Specifically, we find that parasitoids function better in simple food webs than in complex ones, a result relevant to biological control practice. More generally, we show that species richnessper seonly contributes partially to the understanding of higher‐level ecosystem services in multitrophic communities, and that changes in food web complexity should also be taken into account when predicting the effects of human‐driven disturbances in natural communities.
Bacterial diversity patterns along a gradient of primary productivity
Authors: Claire Horner‐Devine M. , Leibold Mathew A. , Smith Val H. , Bohannan Brendan J. M. 
Published: June 2003

AbstractPrimary productivity is a key determinant of biodiversity patterns in plants and animals but has not previously been shown to affect bacterial diversity. We examined the relationship between productivity and bacterial richness in aquatic mesocosms designed to mimic small ponds. We observed that productivity could influence the composition and richness of bacterial communities. We showed that, even within the same system, different bacterial taxonomic groups could exhibit different responses to changes in productivity. The richness of members of the Cytophaga‐Flavobacteria‐Bacteroides group exhibited a significant hump‐shaped relationship with productivity, as is often observed for plant and animal richness in aquatic systems. In contrast, we observed a significant U‐shaped relationship between richness and productivity for α‐proteobacteria and no discernable relationship for β‐proteobacteria. We show, for the first time, that bacterial diversity varies along a gradient of primary productivity and thus make an important step towards understanding processes responsible for the maintenance of bacterial biodiversity.
Size‐dependent species richness: trends within plant communities and across latitude
Authors: Niklas Karl J. , Midgley Jeremy J. , Rand Richard H. 
Published: June 2003

AbstractWe examine how species richness and species‐specific plant density (number of species and number of individuals per species, respectively) vary within community size frequency distributions and across latitude. Communities from Asia, Africa, Europe, and North, Central and South America were studied (60°4′N–41°4′S latitude) using the Gentry data base. Log–log linear stem size (diameter) frequency distributions were constructed for each community and the species richness and species‐specific plant density within each size class were determined for each frequency distribution. Species richness in the smallest stem size class correlated with the Y‐intercepts (β‐values) of the regression curves describing each log–log linear size distributions. Two extreme community types were identified (designated as type A and type B). Type A communities had steep size distributions (i.e. large β‐values), log–log linear species‐richness size distributions, low species‐specific plant density distributions, and a small size class (2–4 cm) containing the majority of all species but rarely conspecifics of the dominant tree species. Type B communities had shallow size distributions (i.e. small β‐values), more or less uniform (and low) size class species‐ richness and species‐specific density distributions and size‐dominant species resident in the smallest size class. Type A communities were absent in the higher latitudes but increased in number towards the equator, i.e. in the smallest size class, species richness increased (and species‐specific density decreased) towards the tropics. Based on our survey of type A and type B communities (and their intermediates), species richness evinces size‐dependent and latitudinal trends, i.e. species richness increased with decreasing body size and most species increasingly reside in the smallest plant size class towards the tropics. Across all latitudes, a trade‐off exists between the number of species and the number of individuals per species residing in the smaller size classes.
Grazer diversity effects on ecosystem functioning in seagrass beds
Authors: Emmett Duffy J. , Paul Richardson J. , Canuel Elizabeth A. 
Published: June 2003

AbstractHigh plant species richness can enhance primary production, animal diversity, and invasion resistance. Yet theory predicts that plant and herbivore diversity, which often covary in nature, should have countervailing effects on ecosystem properties. Supporting this, we show in a seagrass system that increasing grazer diversity reduced both algal biomass and total community diversity, and facilitated dominance of a grazer‐resistant invertebrate. In parallel with previous plant results, however, grazer diversity enhanced secondary production, a critical determinant of fish yield. Although sampling explained some diversity effects, only the most diverse grazer assemblage maximized multiple ecosystem properties simultaneously, producing a distinct ecosystem state. Importantly, ecosystem responses at high grazer diversity often differed in magnitude and sign from those predicted from summed impacts of individual species. Thus, complex interactions, often opposing plant diversity effects, arose as emergent consequences of changing consumer diversity, advising caution in extrapolating conclusions from plant diversity experiments to food webs.
Habitat loss and connectivity of reserve networks in probability approaches to reserve design
Authors: Cabeza Mar 
Published: June 2003

AbstractQuantitative methods for the design of reserve networks often select over‐dispersed reserves, and consequently a number of species extinctions can be expected in such reserves, especially if unprotected surrounding habitat is lost. A novel approach that deals with this problem is presented by considering factors such as habitat quality and spatial configuration of reserves during the selection process. Species‐specific effects of habitat loss and fragmentation, together with habitat composition, are taken into account when computing species probabilities of local occurrence. Sites are then chosen to represent all species with a given target probability. The method is applied to a dataset of butterflies and moths from the Creuddyn Peninsula, North Wales, UK, which includes species with various responses to habitat quality and configuration. The results show that the resulting level of reserve clustering will depend on the number of species for which the spatial configuration plays an important role (at the scale under consideration), and on the pattern and amount of habitat loss that is expected to follow around the reserves. The method represents a step towards taking better into account species persistence when selecting reserve networks in a changing world.
The adaptive response of a natural microbial population to carbon‐ and nitrogen‐limitation
Authors: Goddard Matthew R. , Bradford Mark A. 
Published: June 2003

AbstractThe majority of experiments investigating the population and community level consequences of altered carbon and nitrogen availability implicitly assume a fixed range of ability to obtain and process these nutrients. This may be fair when considering long‐lived organisms, however, short‐lived organisms (e.g. microbes) will pass through many more generations in the same time period providing scope for evolutionary adaptation. Using isolates of a natural fungal population we demonstrate significant adaptation to carbon‐limitation, but not to nitrogen‐limitation, over a modest number of generations. However, adaptation comes at a cost: those adapted to carbon‐limitation are significantly worse competitors for limited nitrogen when compared with their ancestors. The potential for adaptation (and correlated cost) we demonstrate with our model system highlights the need to consider evolutionary adaptation when interpreting responses of populations, communities and ecosystems to treatments that manipulate, either directly or indirectly, resource availability.
Male age, germline mutations and the benefits of polyandry
Authors: Radwan Jacek 
Published: June 2003

AbstractThe number of de novo mutations in the germline can be expected to increase with age in males, therefore females might decrease mutation load in their progeny by avoiding mating with older males. Here, I propose that female polyandry can be more effective in decreasing the risk of genetic disorders in progeny than pre‐copulatory mate choice, particularly if sperm competitiveness declines more steeply with age than other traits affecting chances of males to mate. If faster ageing of spermatogenic tissue causes older males to transfer inadequate numbers of functional sperm, polyandry would also benefit females directly.
Valproic acid inhibits substance P‐induced activation of protein kinase C epsilon and expression of the substance P receptor
Authors: Lieb Klaus , Treffurth Yvonne , Hamke Maike , Akundi Ravi Shankar , Von Kleinsorgen Matthias , Fiebich Bernd L. 
Published: June 2003

AbstractThe neuropeptide substance P (SP) has been hypothesized to be involved in the etiopathology of affective disorders. This hypothesis is based on the findings that neurokinin‐1‐receptor antagonists have antidepressant effects in depressed patients and that SP may worsen mood. In this study, we investigated the effect of the mood‐stabilizing agents valproic acid (VPA), carbamazepine, and lithium on SP‐induced gene expression. As a model system, we used primary rat astrocytes and human astrocytoma cells, which both express functional SP‐receptors and, upon stimulation with SP, synthesize interleukin‐6 (IL‐6), a cytokine which has been shown to be elevated during the acute depressive state. We found that VPA dose‐dependently inhibited SP‐induced IL‐6 synthesis which was seen with pre‐incubation periods of 30 min, 3, 7 and 14 days, whereas carbamazepine and lithium showed no inhibitory effect. The inhibitory effect of VPA was not mediated by inhibition of the stress‐regulated kinases p38 and p42/44 (Erk1/2) but by inhibition of protein kinase C epsilon activation. Furthermore, VPA down‐regulated the expression of the substance P receptor (neurokinin(NK)‐1‐receptor) as assessed by real‐time PCR. Whether both mechanisms contribute to the mood‐stabilizing properties of VPA has to be evaluated in further studies.
Tumour necrosis factor‐related apoptosis‐inducing ligand sequentially activates pro‐survival and pro‐apoptotic pathways in SK‐N‐MC neuronal cells
Authors: Milani Daniela , Zauli Giorgio , Rimondi Erika , Celeghini Claudio , Marmiroli Sandra , Narducci Paola , Capitani Silvano , Secchiero Paola 
Published: June 2003

AbstractThe SK‐N‐MC neuroblastoma cell line, which expresses surface tumour necrosis factor‐related apoptosis‐inducing ligand (TRAIL) receptors TRAIL‐R2 and TRAIL‐R4, was used as a model system to examine the effect of TRAIL on key intracellular pathways involved in the control of neuronal cell survival and apoptosis. TRAIL induced distinct short‐term (1–60 min) and long‐term (3–24 h) effects on the protein kinase B (PKB)/Akt (Akt), extracellular signal‐regulated kinase (ERK), cAMP response element‐binding protein (CREB), nuclear factor kappa B (NF‐κB) and caspase pathways. TRAIL rapidly (from 20 min) induced the phosphorylation of Akt and ERK, but not of c‐Jun NH2‐terminal kinase (JNK). Moreover, TRAIL increased CREB phosphorylation and phospho‐CREB DNA binding activity in a phosphatidylinositol 3‐kinase (PI 3K)/Akt‐dependent manner. At later time points (from 3 to 6 h onwards) TRAIL induced a progressive degradation of inhibitor of κB (IκB)β and IκBε, but not IκBα, coupled to the nuclear translocation of NF‐κB and an increase in its DNA binding activity. In the same time frame, TRAIL started to activate caspase‐8 and caspase‐3, and to induce apoptosis. Remarkably, caspase‐dependent cleavage of NF‐κB family members as well as of Akt and CREB proteins, but not of ERK, became prominent at 24 h, a time point coincident with the peak of caspase‐dependent apoptosis.
The heterogeneous growth cone glycoprotein gp93 is identical to the signal regulatory protein SIRPα/SHPS‐1/BIT
Authors: Wang Xiaoxin X. , Dangott Lawrence J. , Pfenninger Karl H. 
Published: June 2003

AbstractGrowth cone gp93 is a highly heterogeneous membrane glycoprotein with an Mr of about 93 kDa. It was purified from adult rat brain and microsequenced. The sequences of four different peptide fragments of gp93 matched those of the ‘signal regulatory protein’ SIRPα (also known as SHPS‐1, BIT or P84), an Ig superfamily member. SIRPα contains a cytoplasmic tail that is a tyrosine kinase substrate and binds the protein tyrosine phosphatase SHP‐2. SIRPα and gp93 also were immunochemically cross‐reactive. A PCR strategy was used to determine whether gp93/SIRPα heterogeneity in the brain depended upon the presence of different transcripts and, thus, sequence heterogeneity. However, we observed only a single full‐length transcript. A short splice variant also was detected. These data identify gp93 as the Ig superfamily member SIRPα. Together with our previous results, the data also demonstrate that, in rat brain, gp93/SIRPα heterogeneity is the result of differential glycosylation (plus phosphorylation), rather than sequence heterogeneity.
Inhibition of NMDA‐induced striatal dopamine release and behavioral activation by the neuroactive steroid 3α‐hydroxy‐5β‐pregnan‐20‐one hemisuccinate
Authors: Sadri‐Vakili G. , Johnson D. W. , Janis G. C. , Gibbs T. T. , Pierce R. C. , Farb D. H. 
Published: June 2003

AbstractOur laboratory has previously shown that the synthetic neuroactive steroid 3α‐hydroxy‐5β‐pregnan‐20‐one hemisuccinate (3α5βHS) is a negative modulator of NMDA receptors in vitro. Similarly, 3α5βHS exhibits rapid sedative, analgesic, anticonvulsive, and neuroprotective effects in vivo. Here we report a study designed to investigate whether a negatively charged neuroactive steroid, 3α5βHS, modulates the action of NMDA receptors in vivo. Our results indicate that peripherally administered 3α5βHS enters the CNS and inhibits NMDA‐mediated motor activity and dopamine release in the rat striatum. The increase in motor activity induced by intrastriatal microinjection of NMDA was blocked by the systemic administration of 3α5βHS and the NMDA‐induced increase in extracellular dopamine in the striatum was also attenuated by both systemically administered and intrastriatally administered (by in vivo microdialysis) 3α5βHS. These data indicate that 3α5βHS acts through striatal NMDA receptors in vivo. When taken together, these results suggest that neuroactive steroids may prove to be effective in the treatment of neurological and psychiatric disorders involving over‐stimulation of NMDA receptors in the mesotelencephalic dopamine system.