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排序方式: 共有126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.
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
4.
William R. Gower Jr. Robert M. Risch Constantine V. Godellas Peter J. Fabri 《In vitro cellular & developmental biology. Animal》1994,30(3):151-161
Summary A new human pancreatic cancer (HPAC) cell line was established from a nude mouse xenograft (CAP) of a primary human pancreatic
ductal adenocarcinoma. In culture, HPAC cells form monolayers of morphologically heterogenous, polar epithelial cells, which
synthesize carcinoembryonic antigen, CA 19-9, CA-125, cytokeratins, antigens for DU-PAN-2, HMFG1, and AUA1, but do not express
chromogranin A or vimentin indicative of their pancreatic ductal epithelial cell character. In the presence of serum, HPAC
cell DNA synthesis was stimulated by insulin, insulin growth factor-I, epidermal growth factor, and TGF-α but inhibited
by physiologic concentrations of hydrocortisone and dexamethasone. Dose-dependent inhibition of DNA synthesis was limited
to steroids with glucocorticoid activity. The inhibitory effect of dexamethasone was abolished by the glucocorticoid antagonist
RU 38486. Binding of [3H]dexamethasone to cytosolic proteins was specific and saturable at 4° C. Scatchard analysis of binding data demonstrated
a single class of high-affinity binding sites (Kd=3.8±0.9 nM; Bmax=523±128 fmol/mg protein). Western blot analysis revealed a major protein band that migrated at a Mr of 96 kDa. Northern blot analysis identified an mRNA of approximately 7 kilobases which hybridized with a specific glucocorticoid
receptor complementary DNA probe (OB7). These findings support a role for glucocorticoids in the regulation of human malignant
pancreatic cell function. 相似文献
5.
Z I Fabri E Iu Len'o A E Pashchenko 《Nauchnye doklady vysshe? shkoly. Biologicheskie nauki》1983,(2):55-60
By the spectrophotometric method the age changes of total iodine content, its hormonal and non-hormonal compounds in rats and men tissues (muscles, liver, kidney, heart, lungs, brain, spleen and blood) have been studied. It was established that the total iodine content decreased at the expense of the protein-bound iodine concentration and also of the butyl-alcohol extractable iodine. The exchange of thyroid hormones intensity lowered. 相似文献
6.
Resistance to receptor-mediated degradation of a murine epidermal growth factor analogue (EGF-Val-47) potentiates its mitogenic activity 总被引:2,自引:0,他引:2
F Walker E Nice L Fabri F J Moy J F Liu R Wu H A Scheraga A W Burgess 《Biochemistry》1990,29(47):10635-10640
In most cell types two classes of epidermal growth factor (EGF) receptors can be found: a major class that binds EGF with relatively low affinity and a minor class that binds with very high affinity. Structure-function studies have shown that mutations at amino acid 47 in the EGF molecule severely reduce its affinity for the EGF receptor but do not cause preferential binding to one or the other subclass of receptors. Using three EGF derivatives with a mutation at amino acid 47 (Ser-47, Leu-37-Tyr-47, and Val-47), we have investigated the relative contribution of the two receptor subclasses to the EGF-dependent mitogenic response. We show that mitogenicity correlates exclusively with occupancy of the high-affinity receptor and that full occupancy of this subclass is required for maximal stimulation. In addition we demonstrate that for the EGF-Val-47 analogue this requirement can be abrogated and half-maximal biological activity reached with a high-affinity receptor occupancy of only 8%. While the rate of internalization did not significantly differ between EGF-Val-47 and native mEGF, the analogue was much more resistant to degradation by cellular proteases and, after binding and receptor-mediated internalization, was released into the medium predominantly in an intact form. We propose that the increased mitogenicity of EGF-Val-47 is due to its prolonged half-life, resulting in continued occupancy of the high-affinity EGF receptor. 相似文献
7.
Salom Fabri‐Ruiz Bruno Danis Nicolas Navarro Philippe Koubbi Rmi Laffont Thomas Saucde 《Global Change Biology》2020,26(4):2161-2180
The Southern Ocean (SO) is among the regions on Earth that are undergoing regionally the fastest environmental changes. The unique ecological features of its marine life make it particularly vulnerable to the multiple effects of climate change. A network of Marine Protected Areas (MPAs) has started to be implemented in the SO to protect marine ecosystems. However, considering future predictions of the Intergovernmental Panel on Climate Change (IPCC), the relevance of current, static, MPAs may be questioned under future scenarios. In this context, the ecoregionalization approach can prove promising in identifying well‐delimited regions of common species composition and environmental settings. These so‐called ecoregions are expected to show similar biotic responses to environmental changes and can be used to define priority areas for the designation of new MPAs and the update of their current delimitation. In the present work, a benthic ecoregionalization of the entire SO is proposed for the first time based on abiotic environmental parameters and the distribution of echinoid fauna, a diversified and common member of Antarctic benthic ecosystems. A novel two‐step approach was developed combining species distribution modeling with Random Forest and Gaussian Mixture modeling from species probabilities to define current ecoregions and predict future ecoregions under IPCC scenarios RCP 4.5 and 8.5. The ecological representativity of current and proposed MPAs of the SO is discussed with regard to the modeled benthic ecoregions. In all, 12 benthic ecoregions were determined under present conditions, they are representative of major biogeographic patterns already described. Our results show that the most dramatic changes can be expected along the Antarctic Peninsula, in East Antarctica and the sub‐Antarctic islands under both IPCC scenarios. Our results advocate for a dynamic definition of MPAs, they also argue for improving the representativity of Antarctic ecoregions in proposed MPAs and support current proposals of Conservation of Antarctic Marine Living Resources for the creation of Antarctic MPAs. 相似文献
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