bluuebunny/crossref_metadata_2025_split huggingface dataset:
Swimming in the deep end of the gene pool: global population structure of an oceanic giant
Authors: BRADSHAW COREY J. A. 
Published: October 2007

AbstractDespite the impression held by some that few biological mysteries remain, even evocative species such as humpback whales (Megaptera novaeangliae), white sharks (Carcharodon carcharias) and green turtles (Chelonia mydas) have poorly documented movement patterns, reproductive strategies and population dynamics despite years of dedicated research. This is largely due to the difficulty of observing wide‐ranging marine species over the majority of their life cycle. The advent of powerful tracking devices has certainly improved our understanding, but it is usually only with molecular tools that the nature of population structure becomes apparent. In this issue of Molecular Ecology, Castro and colleagues have provided the first global‐scale assessment of population structure for the largest fish — whale sharks (Rhincodon typus). Whale sharks can reach lengths > 12 m and are a popular tourist attraction at places where they aggregate, yet for most of their life cycle, we know little indeed of where they go and how they interact with other populations. Previous tracking studies imply a high dispersal capacity, but only now have Castro and colleagues demonstrated high gene flow and haplotype diversity among the major ocean basins where they are found.
Genetic structure and evolved malaria resistance in Hawaiian honeycreepers
Authors: FOSTER JEFFREY T. , WOODWORTH BETHANY L. , EGGERT LORI E. , HART PATRICK J. , PALMER DANIELLE , DUFFY DAVID C. , FLEISCHER ROBERT C. 
Published: October 2007

AbstractInfectious diseases now threaten wildlife populations worldwide but population recovery following local extinction has rarely been observed. In such a case, do resistant individuals recolonize from a central remnant population, or do they spread from small, perhaps overlooked, populations of resistant individuals? Introduced avian malaria (Plasmodium relictum) has devastated low‐elevation populations of native birds in Hawaii, but at least one species (Hawaii amakihi,Hemignathus virens) that was greatly reduced at elevations below about 1000 m tolerates malaria and has initiated a remarkable and rapid recovery. We assessed mitochondrial and nuclear DNA markers from amakihi and two other Hawaiian honeycreepers, apapane (Himatione sanguinea) and iiwi (Vestiaria coccinea), at nine primary study sites from 2001 to 2003 to determine the source of re‐establishing birds. In addition, we obtained sequences from tissue from amakihi museum study skins (1898 and 1948–49) to assess temporal changes in allele distributions. We found that amakihi in lowland areas are, and have historically been, differentiated from birds at high elevations and had unique alleles retained through time; that is, their genetic signature was not a subset of the genetic variation at higher elevations. We suggest that high disease pressure rapidly selected for resistance to malaria at low elevation, leaving small pockets of resistant birds, and this resistance spread outward from the scattered remnant populations. Low‐elevation amakihi are currently isolated from higher elevations (> 1000 m) where disease emergence and transmission rates appear to vary seasonally and annually. In contrast to results from amakihi, no genetic differentiation between elevations was found in apapane and iiwi, indicating that slight variation in genetic or life‐history attributes can determine disease resistance and population recovery. Determining the conditions that allow for the development of resistance to disease is essential to understanding how species evolve resistance across a landscape of varying disease pressures.
Phylogeny, divergence times and species limits of spiny lizards (Sceloporus magisterspecies group) in western North American deserts and Baja California
Authors: LEACHÉ ADAM D. , MULCAHY DANIEL G. 
Published: October 2007

AbstractThe broad distribution of theSceloporus magisterspecies group (squamata: phrynosomatidae) throughout western North America provides an appropriate model for testing biogeographical hypotheses explaining the timing and origins of diversity across mainland deserts and the Baja California Peninsula. We inferred concordant phylogenetic trees describing the higher‐level relationships within themagistergroup using 1.6 kb of mitochondrial DNA (mtDNA) and 1.7 kb of nuclear DNA data. These data provide strong support for the parallel divergence of lineages endemic to the Baja California Peninsula (S. zosteromusand theorcutticomplex) in the form of two sequential divergence events at the base of themagistergroup phylogeny. A relaxed phylogenetic analysis of the mtDNA data using one fossil and one biogeographical constraint provides a chronology of these divergence events and evidence that further diversification within the Baja California clades occurred simultaneously, although patterns of geographical variation and speciation between clades differ. We resolved four major phylogeographical clades withinS. magisterthat (i) provide a novel phylogenetic placement of the Chihuahuan Desert populations sister to the Mojave Desert; (ii) illustrate a mixed history for the Colorado Plateau that includes Mojave and Sonoran Desert components; and (iii) identify an area of overlap between the Mojave and Sonoran Desert clades near Yuma, Arizona. Estimates of bidirectional migration rates among populations ofS. magisterusing four nuclear loci support strong asymmetries in gene flow among the major mtDNA clades. Based on the nonexclusivity of mtDNA haplotypes, nuclear gene flow among populations and wide zones of phenotypic intergradation,S. magisterappears to represent a single geographically variable and widespread species.
Fundamental links between genes and elements: evolutionary implications of ecological stoichiometry
Authors: JEYASINGH PUNIDAN D. , WEIDER LAWRENCE J. 
Published: October 2007

AbstractOrganisms require elements to live and reproduce. We already know that availability of certain elements [e.g. phosphorus (P)] is highly variable spatiotemporally. In addition, there is variability in demand for various elements ontogenetically, as well as phylogenetically. Nonetheless, we know little about the underlying causes for such variation. In this study, we surveyed the literature to identify genes involved in the homeostasis of one biogenic element, P. Evidence from the literature suggests that variation in the environmental supply of P affects expression of highly conserved genes (e.g. the phosphate transporter system). In addition, we found evidence for genetic variation in the acquisition, assimilation, and allocation of P. Such effects of P supply should impinge on fitness, and drive evolutionary change. Further understanding of the inter‐ and intraspecific fitness consequences to imbalances in the availability of P in relation to other biogenic elements may be useful to disentangle primary mechanisms driving diversifications. We argue that studying the interactions between stoichiometric constraints and underlying genes is relevant to the majority of organisms, and conclude by furnishing information on designing and interpreting experiments using this approach.
Phenotype matching and inbreeding avoidance in African elephants
Authors: MOORE JIM 
Published: October 2007

AbstractPerhaps the most important ‘decision’ made by any animal (or plant) is whether to disperse — leave kith and kin, or remain with the familiar and related. The benefits of staying at home are obvious, so dispersal requires an explanation — and the most popular is that dispersal functions to avoid inbreeding depression. Strong support comes from the observation that dispersal is so often sex biased. Simply put, all else being equal members of both sexes should prefer to remain philopatric, but this would lead to inbreeding depression so members of one sex have to disperse. In principle, this link between inbreeding depression and sex‐biased dispersal could be broken if individuals recognize close kin and avoid mating with them. Archie et al. (2007) provide one of the most compelling analyses to date of the interaction among inbreeding avoidance, kin recognition and mating strategies in any mammal, clearly showing that elephants recognize even close paternal kin and avoid mating with them. Their important results illuminate the subtleties of elephant inbreeding avoidance as well as illustrate the difficulty of arriving at definitive answers to questions about the evolution of dispersal behaviour.
Microsatellite variation points to local landscape plantings as sources of invasive pampas grass (Cortaderia selloana) in California
Authors: OKADA MIKI , AHMAD RIAZ , JASIENIUK MARIE 
Published: October 2007

AbstractInternational trade in horticultural plants is a major pathway of introduction of invasive species. Pampas grass (Cortaderia selloana) is an invasive species of horticultural origin that is native to South America but cultivated as an ornamental in regions with Mediterranean climates worldwide. To gain insight into the introduction history of invasive populations in California, we analysed microsatellite marker variation in cultivated and invasive C. selloana. We sampled 275 cultivated plants from diverse sources and 698 invasive plants from 33 populations in four geographical regions of California. A model‐based Bayesian clustering analysis identified seven distinct gene pools in cultivated C. selloana. Probabilities of assignment of invasive individuals to cultivated gene pools indicated that two gene pools accounted for the genomic origin of 78% of the invasive C. selloana sampled. Extensive admixture between cultivated source gene pools was detected within invasive individuals. Sources of admixed invasive individuals are probably landscape plantings. Consistent with the Bayesian assignment results indicating that multiple cultivated gene pools and landscape plantings are probable sources of invasive populations, FST and neighbour‐joining clustering analyses indicated multiple escapes from shared sources in each geographical region. No isolation by distance or geographical trend in reduction of genetic diversity was evident. Furthermore, a generally random and discontinuous distribution of proportional assignments of invasive populations to cultivated gene pools suggests that introductions occurred recurrently within each geographical region. Our results strongly suggest that dispersal through local landscape plantings has contributed to the range expansion of invasive C. selloana in California.
Role of the Trypanosoma brucei natural cysteine peptidase inhibitor ICP in differentiation and virulence
Authors: Santos Camila C. , Coombs Graham H. , Lima Ana Paula C. A. , Mottram Jeremy C. 
Published: October 2007

SummaryICP is a chagasin‐family natural tight binding inhibitor of Clan CA, family C1 cysteine peptidases (CPs). We investigated the role of ICP in Trypanosoma brucei by generating bloodstream form ICP‐deficient mutants (Δicp). A threefold increase in CP activity was detected in lysates of Δicp, which was restored to the levels in wild type parasites by re‐expression of the gene in the null mutant. Δicp displayed slower growth in culture and increased resistance to a trypanocidal synthetic CP inhibitor. More efficient exchange of the variant surface glycoprotein (VSG) to procyclin during differentiation from bloodstream to procyclic form was observed in Δicp, a phenotype that was reversed in the presence of synthetic CP inhibitors. Furthermore, we showed that degradation of anti‐VSG IgG is abolished when parasites are pretreated with synthetic CP inhibitors, and that parasites lacking ICP degrade IgG more efficiently than wild type. In addition, Δicp reached higher parasitemia than wild type parasites in infected mice, suggesting that ICP modulates parasite infectivity. Taken together, these data suggest that CPs of T. brucei bloodstream form play a role in surface coat exchange during differentiation, in the degradation of internalized IgG and in parasite infectivity, and that their function is regulated by ICP.
Selective chromosome amplification in Vibrio cholerae
Authors: Srivastava Preeti , Chattoraj Dhruba K. 
Published: October 2007

SummaryMost bacteria have one chromosome but some have more than one, as is common in eukaryotes. How multiple chromosomes are maintained in bacteria remains largely obscure. Here we have examined the behaviour of the two Vibrio cholerae chromosomes as a function of growth rate. At slow growth rates, both chromosomes were maintained at copy numbers of one to two per cell. Increasing the growth rate by nutritional shift‐up amplified the origin‐proximal DNA of the larger chromosome (chrI) to four copies per cell, but not that of the smaller chrII. The latter was amplified when its specific initiator was supplied in excess or a specific negative regulator was deleted. The growth rate‐insensitive behaviour of chrII, whose origin is similar to origins of members of a major class of plasmids, was shared by some but not all of several representative plasmids tested in V. cholerae. Also, unlike plasmid replication, chrII replication is known to be initiated at a specific stage of the cell cycle. Raising chrII copy number decreased growth rate, suggesting that this chromosome might serve as a repository for necessary but potentially deleterious genes.
Cross‐protection between attenuated Plasmodium berghei and P. yoelii sporozoites
Authors: SEDEGAH M. , WEISS W. W. , HOFFMAN S. L. 
Published: October 2007

SUMMARY An attenuated Plasmodium falciparum sporozoite (PfSPZ) vaccine is under development, in part, based on studies in mice with P. berghei. We used P. berghei and P. yoelii to study vaccine‐induced protection against challenge with a species of parasite different from the immunizing parasite in BALB/c mice. One‐hundred percent of mice were protected against homologous challenge. Seventy‐nine percent immunized with attenuated P. berghei sporozoite (PbSPZ) (six experiments) were protected against challenge with P. yoelii sporozoite (PySPZ), and 63% immunized with attenuated PySPZ (three experiments) were protected against challenge with PbSPZ. Antibodies in sera of immunized mice only recognized homologous sporozoites and could not have mediated protection against heterologous challenge. Immunization with attenuated PySPZ or PbSPZ induced CD8+ T cell‐dependent protection against heterologous challenge. Immunization with attenuated PySPZ induced CD8+ T cell‐dependent protection against homologous challenge. However, homologous protection induced by attenuated PbSPZ was not dependent on CD8+ or CD4+ T cells, and depletion of both populations only reduced protection by 36%. Immunization of C57BL/10 mice with PbSPZ induced CD8+ T cell‐dependent protection against P. berghei, but no protection against P. yoelii. The cross‐protection data in BALB/c mice support testing a human vaccine based on attenuated PfSPZ for its efficacy against P. vivax.
The role of TNF‐α in Trichuris muris infection II: global enhancement of ongoing Th1 or Th2 responses
Authors: HAYES K. S. , BANCROFT A. J. , GRENCIS R. K. 
Published: October 2007

SUMMARY Host resistance to Trichuris muris is driven by Th2 responses. However, TNF‐α has also been shown to play a role in protection. As TNF‐α has a variety of actions, the exact role of TNF‐α in immunity to T. muris is yet to be established. Here we demonstrate that although blocking TNF‐α has been shown to abrogate resistance, rTNF‐α treatment does not promote resistance. Further, we show that TNF‐α functions to enhance the ongoing immune response. AKR animals that typically respond to infection with a polarized Th1 response produce greater levels of Th1 cytokines when treated with TNF‐α and BALB/c animals that normally respond with a polarized Th2 response produce higher levels of Th2 cytokines. Crucially, blocking TNF‐α in the strong Th2 responder strain BALB/c does not prevent expulsion of T. muris, thus supporting its role as a biological enhancer. TNF‐α does increase transcription of both IFN‐γ and IL‐13 in vitro but can also act synergistically with IL‐13 in vitro to promote production of RELMβ, which has also been shown to play a role in resistance to T. muris. Thus, this data demonstrates that TNF‐α acts to enhance an ongoing immune response but is not necessary for a strong protective Th2 response.
The overexpression of an alternative oxidase gene triggers ozone sensitivity in tobacco plants
Authors: PASQUALINI STEFANIA , PAOLOCCI FRANCESCO , BORGOGNI ANDREA , MORETTINI ROBERTA , EDERLI LUISA 
Published: October 2007

ABSTRACTThe alternative oxidase (AOX) of plant mitochondria transfers electrons from the ubiquinione pool to oxygen without energy conservation and prevents the formation of reactive oxygen species (ROS) when the ubiquinone pool is over‐reduced. Thus, AOX may be involved in plant acclimation to a number of oxidative stresses. To test this hypothesis, we exposed wild‐type (WT) Xanthi tobacco plants as well as Xanthi plants transformed with the Bright Yellow tobacco AOX1a cDNA with enhanced (SN21 and SN29), and decreased (SN10) AOX capacity to an acute ozone (O3) fumigation. As a result of 5 h of O3 exposition (250 nL L−1), SN21 and SN29 plants surprisingly showed localized leaf damage, whereas SN10, similarly to WT plants, was undamaged. In keeping with this observation, WT and SN21 plants differed in their response to O3 for the expression profiles of catalase 1 (CAT1), catalase 2 (CAT2), glutathione peroxidase (GPX) and ascorbate peroxidase (APX) genes, and for the activity of these antioxidant enzymes, which were induced in WT. Concomitantly, although ozone induced H2O2 accumulation in WT and in all transgenic lines, only in transgenics with high AOX capacity the H2O2 level in the post‐fumigation period was high. The alternative pathway of WT plants was strongly stimulated by O3, whereas in SN21 plants, the respiratory capacity was always high across the treatment. The present results show that, far from exerting a protective role, the overexpression of AOX triggers an increased O3 sensitivity in tobacco plants. We hypothesize that the AOX overexpression results in a decrease of mitochondrial ROS level that in turn alters the defensive mitochondrial to nucleus signalling pathway that activates ROS scavenging systems.
Cord Blood Cytokine Profile Detection in Neonates with T1D Parents – Monitoring of Cellular Auto‐reactivity Using Protein Microarray
Authors: Bohmova K. , Hladikova Z. , Cerny M. , Flajsmanova K. , Vrabelova Z. , Skramlikova T. , Spalova I. , Cerna M. , Chudoba D. , Pithova P. , Stadlerova G. , Bartaskova D. , Faresjo M. , Stechova K. 
Published: October 2007

AbstractType 1 diabetes (T1D) is a great medical challenge and its incidence rises rapidly. T lymphocytes and their cytokine production are supposed to play a major role in T1D development. So far, there is no potent tool to recognize the early signs of cellular auto‐reactivity which leads to β‐cell damage. The naïve immune system of the newborn (not yet influenced by external factors) can be used as an important model for T1D pathogenesis studies. Cord blood samples of 22 healthy neonates born at term to a diabetic parent (T1DR) and 15 newborns with no family history of any autoimmune disease (controls) were collected. Determination of 23 cytokines was performed before and after the stimulation with diabetogenic autoantigens using protein microarray. We observed lower basal production of all detected cytokines in the T1DR group – granulocyte/macrophage colony‐stimulating factor (GM‐CSF) (P = 0.025), growth regulated protein (GRO) (P = 0.002), GRO‐α (P = 0.027), interleukin (IL)‐1‐α (P = 0.051), IL‐3 (P = 0.008), IL‐7 (P = 0.027), IL‐8 (P = 0.042), monocyte chemoattractant proteins (MCP)‐3 (P = 0.022), monokine‐induced by IFN‐γ (MIG) (P = 0.034) and regulated upon activation normal T‐cell express sequence (RANTES) (P = 0.004). Exclusively lower post‐stimulative levels of G‐CSF (P = 0.030) and GRO‐α (P = 0.04) were observed in controls in comparison with the basal levels. A significant post‐stimulative decrease in G‐CSF (P = 0.030) and MCP‐2 (P = 0.009) levels was observed in controls in comparison with T1DR neonates. We also observed the interesting impact of the risky genotype on the protein microarray results. Protein microarray seems to be a useful tool to characterize a risk pattern of the immune response for T1D also in newborns.
Human Soluble CD80 is Generated by Alternative Splicing, and Recombinant Soluble CD80 Binds to CD28 and CD152 Influencing T‐cell Activation
Authors: Kakoulidou M. , Giscombe R. , Zhao X. , Lefvert A. K. , Wang X. 
Published: October 2007

AbstractCD80 is a costimulatory factor mainly expressed on the surface of activated monocytes, B cells and dendritic cells. In this study, we demonstrate that 24% of healthy individuals have soluble forms of CD80, sCD80, in their serum. The concentration of sCD80 ranged from 0 to 1 mg/l. At the mRNA level, we detected a spliced form s1CD80 (771 bp), in unstimulated monocytes and B cells, while another form named s2CD80 (489 bp) was expressed in activated T cells as well as in freshly isolated and activated monocytes. s1CD80 lacks the transmembrane domain, and the IgC‐like domain plus the transmembrane domain are spliced out of s2CD80. We also present data demonstrating that recombinant s1CD80 binds to recombinant CD152‐Ig and CD28‐Ig. It can also bind to T cells, preferentially to activated T cells. Recombinant sCD80 had immunomodulatory effects shown by its inhibition of the mixed lymphocyte reaction and inhibition of T‐cell proliferation. sCD80 in human serum adds a new member to the family of soluble receptors, implying a network of soluble costimulatory factors with functional relevance. The inhibitory effect of the recombinant protein on T‐cell activation makes it a possible candidate for treatment of diseases associated with hyperactivated T cells.
The Effect of the Cholinergic Anti‐Inflammatory Pathway on Experimental Colitis
Authors: Bai A. , Guo Y. , Lu N. 
Published: October 2007

AbstractInflammatory bowel diseases (IBD) are characterized by proinflammatory cytokines, tissue damage and loss of neuron in inflamed mucosa, which implies the cholinergic anti‐inflammatory pathway may be destroyed during the process of inflammatory response. In the study, we identified the effect of cholinergic agonist as anabaseine (AN) and nicotinic receptor antagonist as chlorisondamine diiodide (CHD) on trinitrobenzene sulfonic acid (TNBS)‐induced colitis, to investigate the potential therapeutic effect of the cholinergic anti‐inflammatory pathway on IBD. Experimental colitis was induced by TNBS at day 1, 10 μg AN or 1.5 μg CHD was injected i.p. to mouse right after the induction of colitis, and repeated on interval day till the mice were sacrificed at day 8. Colonic inflammation was examined by histological analysis, myeloperoxidase (MPO) activity, and the production of tumour necrosis factor (TNF)‐α in tissue. Lamina propria mononuclear cells (LPMC) were isolated, and NF‐κB activation was detected by western blot. The mice with colitis treated by AN showed less tissue damage, less MPO activity, less TNF‐α production in colon, and inhibited NF‐κB activation in LPMC, compared with those mice with colitis untreated, whereas the mice with colitis treated by CHD showed the worst tissue damage, the highest MPO activity, the highest TNF‐α level, and enlarged NF‐κB activation in LPMC. Agonist of the cholinergic anti‐inflammatory pathway inhibits colonic inflammatory response by downregulating the production of TNF‐α, and inhibiting NF‐κB activation, which suggests that modulating the cholinergic anti‐inflammatory pathway may be a new potential management for IBD.