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排序方式: 共有125条查询结果,搜索用时 15 毫秒
1.
Jeff A Johnson Heather RL Lerner Pamela C Rasmussen David P Mindell 《BMC evolutionary biology》2006,6(1):65-12
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. 相似文献2.
3.
Polyamines and basic proteins stimulate activation by cAMP and catalytic activity of Mucor rouxii cAMP-dependent protein kinase 总被引:1,自引:0,他引:1
Partial activation of Mucor rouxii cAMP-dependent protein kinase by cAMP was obtained when kemptide was used as substrate, but complete activation was attained with cAMP plus protamine or histone. Full activation could not be achieved by increasing kemptide or cAMP concentration. Complete activation by cAMP could be obtained by addition of 10 microM polylysine, 10 microM lysine-rich histone or 0.5 mM spermine plus spermidine. The degree of stimulation could be up to 5-fold, depending on the amount of enzyme in the assay. The same concentrations of polycations increased 1.5-2.3-fold the Vmax of kemptide phosphorylation by the free catalytic subunits of both Mucor and bovine heart protein kinases; 10 microM polyarginine inhibited completely the activity of both enzymes. 相似文献
4.
5.
Protein kinase from Mucor rouxii 总被引:1,自引:0,他引:1
Summary Cyclic AMP binding to Mucor rouxii protein kinase holoenzyme and free regulatory subunit was measured by the classical membrane filtration technique and by equilibrium dialysis. The results obtained demonstrate that the filtration method can be used without loss of any cyclic AMP binding site. Both methods unambiguously demonstrate that the number of molecules of cyclic AMP bound to the holoenzyme are half of those bound to the regulatory subunit. This result suggests that unshielding of new cyclic AMP binding sites occurs upon dissociation of the ternary complex holoenzyme-cyclic AMP. 相似文献
6.
7.
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.
相似文献
8.
The nucleotide data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession number L22178. 相似文献
9.
Mitochondrial DNA polymorphisms in subterranean mole-rats of the Spalax ehrenbergi superspecies in Israel, and its peripheral isolates 总被引:1,自引:0,他引:1
Nevo E; Honeycutt RL; Yonekawa H; Nelson K; Hanzawa N 《Molecular biology and evolution》1993,10(3):590-604
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.
相似文献
10.
Coordinate estrogen-regulated instability of serum protein-coding messenger RNAs in Xenopus laevis 总被引:3,自引:0,他引:3
R L Pastori J E Moskaitis S W Buzek D R Schoenberg 《Molecular endocrinology (Baltimore, Md.)》1991,5(4):461-468
Estrogen causes the cytoplasmic destabilization of albumin and gamma-fibrinogen mRNA in Xenopus laevis liver. The purpose of the present study was to determine whether mRNA destabilization is a generalized phenomenon in response to estrogen, or whether this process is restricted to a particular class of mRNAs. To address this, we have expanded our bank of serum protein-coding cDNA clones to include transferrin, the second protein of inter-alpha-trypsin inhibitor and clone 12B, for which there is no mammalian homolog. Together with albumin and gamma-fibrinogen, these represent more than 85% of the mRNAs encoding liver secreted proteins. Estrogen administration to male Xenopus or to liver explant cultures causes the generalized disappearance of all of these mRNAs. In contrast, estrogen has no effect on actin, ferritin, or poly(A)-binding protein mRNA, all of which encode intracellular proteins. We have previously demonstrated that albumin mRNA is degraded in both messenger ribonucleoprotein and polysome fractions. Sucrose gradient analysis demonstrates the same pattern for degradation of all other serum protein-coding mRNAs. Estrogen has no effect on the amounts or gradient distribution of actin, ferritin, or poly(A)-binding protein mRNA. We conclude that regulated destabilization of mRNAs encoding secreted proteins is a generalized phenomenon in response to estrogen stimulation of Xenopus liver. 相似文献