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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.
A stereotaxic apparatus and technique for its implantation in diencephalic nuclei of Atlantic salmon parr of 20 to 30 g body weight is described. An atlas of nuclei in the diencephalon is also presented. 相似文献
3.
IL-4 (B cell-stimulatory factor 1) regulates multiple aspects of influenza virus-specific cell-mediated immunity 总被引:3,自引:0,他引:3
D W Horohov J A Crim P L Smith J P Siegel 《Journal of immunology (Baltimore, Md. : 1950)》1988,141(12):4217-4223
The effect of endogenous and exogenous IL-4 on the generation of influenza virus-specific cell-mediated immunity was examined. When added at the onset of the culture, IL-4 augmented both cluster of differentiation (CD)8+ lymphoproliferation and MHC-restricted, influenza virus-specific cytotoxicity. When added 5 or 6 days after initiation of cultures, IL-4 was highly effective at augmenting cytotoxicity, whereas no augmentation of proliferation was observed. This disassociation of the effect of IL-4 on lymphoproliferation and cytotoxicity indicated that IL-4 was providing a late signal in CTL generation. Studied at the level of CTL precursor maturation in microcultures, IL-4 was found not to increase cytotoxicity but to be required, in some cases, for the generation of cytotoxicity. Endogenous IL-4 production was observed and demonstrated to be important because neutralizing antiserum to IL-4 suppressed CTL development. In contrast to the effects of IL-4 when added later to the cultures, pulsing the lymphocytes with IL-4 before, or shortly after, exposure to antigen resulted in suppression of the CTL response. These results indicate that IL-4 has differentiative, proliferative, and suppressive effects on cell-mediated immune responses. 相似文献
4.
5.
FMRFamide- and pancreatic polypeptide-like immunoreactivity of endocrine cells in the midgut of a mosquito 总被引:1,自引:0,他引:1
Immunocytochemical surveys of midguts from female mosquitoes, Aedes aegypti, reveal that half of the estimated 500 endocrine cells in a midgut contain a substance recognized by antisera to bovine pancreatic polypeptide and a molluscan peptide, FMRFamide (phenylalanine-methionine-arginine-phenylalanine-amide). With light microscopy the cells resemble an endocrine type because of their basal position in the epithelium, conical shape, and, in some instances, apical extensions to the lumen. At the ultrastructural level, the immunoreactive substance is contained specifically within the secretory granules of such cells. Immunoreactive cells are distributed exclusively in the midgut region where blood is stored, and ingestion of vertebrate blood reduces the number of such cells and the intensity of reaction in others. These two facts suggest that a blood meal stimulates release of the immunoreactive substance from the cells. Since the immunocytochemical localization is supplemented by a demonstrated secretory response, the cells are considered to be peptidergic endocrine cells. 相似文献
6.
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
7.
Phylogenetic utility of the nuclear gene arginine decarboxylase: an example from Brassicaceae 总被引:8,自引:2,他引:8
Arginine decarboxylase (ADC) is an important enzyme in the production of
putrescine and polyamines in plants. It is encoded by a single or low-copy
nuclear gene that lacks introns in sequences studied to date. The rate of
Adc amino acid sequence evolution is similar to that of ndhF for the
angiosperm family studied. Highly conserved regions provide several target
sites for PCR priming and sequencing and aid in nucleotide and amino acid
sequence alignment across a range of taxonomic levels, while a variable
region provides an increased number of potentially informative characters
relative to ndhF for the taxa surveyed. The utility of the Adc gene in
plant molecular systematic studies is demonstrated by analysis of its
partial nucleotide sequences obtained from 13 representatives of
Brassicaceae and 3 outgroup taxa, 2 from the mustard oil clade (order
Capparales) and 1 from the related order Malvales. Two copies of the Adc
gene, Adc1 and Adc2, are found in all members of the Brassicaceae studied
to data except the basal genus Aethionema. The resulting Adc gene tree
provides robust phylogenetic data regarding relationships within the
complex mustard family, as well as independent support for proposed tribal
realignments based on other molecular data sets such as those from
chloroplast DNA.
相似文献
8.
9.
10.
Among insects, short neuropeptide Fs (sNPF) have been implicated in regulation of reproduction and feeding behavior. For Drosophila melanogaster, the nucleotide sequence for the sNPF precursor protein encodes four distinctive candidate sNPFs. In the present study, all four peptides were identified by mass spectrometry in body extracts of D. melanogaster; some also were identified in hemolymph, suggesting potential neuroendocrine roles. Actions of sNPFs in D. melanogaster are mediated by the G protein-coupled receptor Drm-NPFR76F. Mammalian CHO-K1 cells were stably transfected with the Drm-NPFR76F receptor for membrane-based radioreceptor studies. Binding assays revealed that longer sNPF peptides comprised of nine or more amino acids were clearly more potent than shorter ones of eight or fewer amino acids. These findings extend understanding of the relationship between structure and function of sNPFs. 相似文献