Systematics within Gyps vultures: a clade at risk

Background  

Populations of the Oriental White-backed Vulture (Gyps bengalensis) have declined by over 95% within the past decade. This decline is largely due to incidental consumption of the non-steroidal anti-inflammatory veterinary pharmaceutical diclofenac, commonly used to treat domestic livestock. The conservation status of other Gyps vultures in southern Asia is also of immediate concern, given the lack of knowledge regarding status of their populations and the continuing existence of taxonomic uncertainties. In this study, we assess phylogenetic relationships for all recognized species and the majority of subspecies within the genus Gyps. The continuing veterinary use of diclofenac is an unknown but potential risk to related species with similar feeding habits to Gyps bengalensis. Therefore, an accurate assessment of the phylogenetic relationships among Gyps vultures should aid in their conservation by clarifying taxonomic uncertainties, and enabling inference of their respective relatedness to susceptible G. bengalensis.     

The structure of V alpha and J alpha segments in the mouse.

Antigen receptors on most T-cells are heterodimeric glycoproteins, comprised of an alpha chain and a beta chain. These chains are encoded by discontiguous variable (V), diversity (D) and joining (J) gene segments that rearrange to produce a contiguous and functional alpha or beta chain gene. To investigate the size and diversity of the germline repertoire of alpha-chain gene segments, we have characterized and sequenced 20 alpha chain cDNAs. Among these cDNA clones, we have found 4 J alpha and 4 V alpha sequences that have not yet been described. The relationship of these "new" gene segments to those already characterized is discussed.     

Maturation proteins associated with desiccation tolerance in soybean

A set of proteins that accumulates late in embryogenesis (Lea proteins) has been hypothesized to have a role in protecting the mature seed against desiccation damage. A possible correlation between their presence and the desiccation tolerant state in soybean seeds (Glycine max L. Chippewa) was tested. Proteins that showed the same temporal pattern of expression as that reported for Lea proteins were identified in the axes of soybean. They were distinct from the known storage proteins and were resistant to heat coagulation. The level of these “maturation” proteins was closely correlated with desiccation tolerance both in the naturally developing and in the germinating seed: increasing at 44 days after flowering, when desiccation tolerance was achieved, and decreasing after 18 hours of imbibition, when desiccation tolerance was lost. During imbibition, 100 micromolar abscisic acid or Polyethylene glycol-6000 (−0.6 megapascals) delayed disappearance of the maturation proteins, loss of desiccation tolerance, and germination. During maturation, desiccation tolerance was prematurely induced when excised seeds were dried slowly but not when seeds were held for an equivalent time at high relative humidity. In contrast, maturation proteins were induced under both conditions. We conclude that maturation proteins may contribute to desiccation tolerance of soybean seeds, though they may not be sufficient to induce tolerance by themselves.     

Two better cell lines for making hybridomas expressing specific T cell receptors

Two variants of the AKR thymoma BW5147 have been isolated which can no longer express functional TCR alpha- and beta-chains. By generating hybridomas with these variant fusion lines, TCR of any normal T lymphocyte, including TCR-gamma/delta, can be studied at a clonal level, without interference of the BW5147-derived receptor chains. In this study one of the variants has been useful in identifying the reactivity to allogeneic MHC Ag of BW5147 itself.     

Patterns of divergence during evolution of alpha 1-proteinase inhibitors in mammals

alpha 1-Proteinase inhibitor (alpha 1-PI), a member of the serine proteinase inhibitor superfamily, has a primary role in controlling neutrophil elastase activity within the mammalian circulation. Several studies have indicated that the reactive center region of alpha 1-PI, the amino acid sequence of which is critical to recognition of and binding to target proteinases, is highly divergent within and among species. This appears to be a consequence of accelerated rates of evolution that may have been driven by positive Darwinian selection. In order to examine this and other features of alpha 1-PI evolution in more detail, we have isolated and sequenced cDNAs representing alpha 1- PI mRNAs of the mouse species Mus saxicola and Mus minutoides and have compared these with a number of other mammalian alpha 1-PI mRNAs. Relative to other mammalian mRNAs, the extent of nonsynonymous substitution is generally high throughout the alpha 1-PI mRNA molecule, indicating greater overall rates of amino acid substitution. Within and among mouse species, the 5'-half of the mRNA, but not the 3'-half, has been homogenized by concerted evolution. Finally, the reactive center is under diversifying or positive Darwinian selection in murid rodents (rats, mice) and guinea pigs yet is under purifying selection in primates and artiodactyls. The significance of these findings to alpha 1-PI function and the possible selective forces driving evolution of serpins in general are discussed.      

Mitochondrial DNA polymorphisms in subterranean mole-rats of the Spalax ehrenbergi superspecies in Israel, and its peripheral isolates

Patterns of mitochondrial DNA (mtDNA) variation were examined in 133 mole-rats constituting all four chromosomal species (2n = 52, 2n = 54, 2n = 58, and 2n = 60) of the Spalax ehrenbergi superspecies in Israel, as well as the peripheral isolates of 2n = 60. In the main range of the complex, a total of 28 mtDNA haplotypes were found in 64 mole-rats, with most haplotypes being unique to either a single chromosomal species or population. mtDNA divergence increased from low to high diploid number in a north-to-south direction in Israel. Overall levels of mtDNA diversity were unexpectedly the highest in the 2n = 60, the youngest species of the complex. The mtDNA haplotypes can be separated into two major groups, 2n = 52-54 and 2n = 58-60, and a phylogenetic analysis for each group revealed evidence of a few haplotypes not sorted by diploid number. The overall patterns of mtDNA divergence seen within and among the four chromosomal species are consistent with the parapatric mode of speciation as suggested from previous studies of allozyme and DNA hybridization. In a separate data set the patterns of mtDNA variation were examined across the main geographic range and across peripheral semi-isolates and isolates of the 2n = 60 chromosomal species. Fifteen haplotypes were found in 69 mole-rats. High levels of mtDNA diversity characterized the main range, semi-isolated, and even some desert isolated populations. The peripheral isolates contain much mtDNA diversity, including novel haplotypes.      

Use of a recombinant baculovirus product to measure naturally-acquired human antibodies to disulphide-constrained epitopes on the P. falciparum merozoite surface protein-1 (MSP1)

Abstract An enzyme-linked immunosorbent assay (ELISA) has been developed to measure antibody levels in human sera to a candidate vaccine antigen, merozoite surface protein-1 (MSP1), of the malaria parasite Plasmodium falciparum . To ensure the detection of antibodies reactive with important conformational epitopes, antigens used in the ELISA were obtained from either in vitro parasite cultures, or from a baculovirus expression system in which correct folding of recombinant MSP1-derived polypeptides has been previously demonstrated. The specificity of the ELISA was confirmed using a novel antibody affinity select method. The assay was used to investigate the pattern of acquisition of anti-MSP1 antibodies in a cross-sectional survey of 387 3–8 year old residents of a malaria endemic area of the Gambia. A significant positive correlation between anti-MSP1 antibody levels and age was evident, though individual responses to two antigens corresponding to two distinct domains of the MSP1 varied widely.