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1.
2.
The effects of subacute treatment with cocaine on activities of cocaine N-demethylase, UDP-glucuronyltransferase (GT) toward 4-nitrophenol and phenolphthalein and sulfotransferase (ST) toward androsterone and 4-nitrophenol in livers from Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were investigated. Hepatic metabolism of cocaine was different between the sexes (with males having higher N-demethylase activity) and the strains (with WKY rats having higher activity). The effects of subacute cocaine administration on the activity of cocaine N-demethylase were also sex- and strain-related. Whereas cocaine administration increased activity of hepatic N-demethylase in both female strains, it decreased activity in male WKY and had no effect on activity in male SHR. Sex and strain-related as well as cocaine-induced differences were also found in activities of hepatic GT toward 4-nitrophenol and phenolphthalein as well as in activity of hepatic ST towards andersterone and 4-nitrophenol. These results suggest that some of the individual variation in the effects of cocaine may be due to sex and genetic differences in the hepatic metabolism of cocaine and/or in sexually and/or/genetically-determined differences in how cocaine affects hepatic metabolism of other xenobiotics. 相似文献
3.
We have isolated the delta-globin gene of the New-World spider monkey,
Ateles geoffroyi, and compared its nucleotide sequence with those of other
primate delta- and beta-globin genes. Among primate delta-globin genes, the
rate of nonsynonymous substitutions is much less than the rate of
synonymous substitutions. This suggests that primate delta- globin genes
may remain under evolutionary conservation, perhaps because hemoglobin A2
has an as yet unknown physiological importance.
相似文献
4.
Srinivasan Vijayaraghavan Dale D. Hoskins 《Molecular reproduction and development》1988,20(3):343-352
Secretions from the mammalian epididymis contain proteins that bind to developing sperm and are presumed to play a role in sperm maturation. The biochemical functions in sperm of most of these proteins are not known. In this report we describe the presence of a low molecular weight compound in bovine caudal epididymal luminal fluid (CF) that has a potent stimulatory effect on calcium (45Ca2+) uptake in immature caput epididymal spermatozoa. The studies were initially undertaken to characterize the effect of the protein caltrin, present in bovine seminal plasma (BSP), on calcium uptake into caput spermatozoa. Caltrin is known to block calcium influx into mature bovine sperm. Unexpectedly, the kinetics of calcium uptake into caput sperm showed a biphasic response when treated with BSP, namely, a stimulation of uptake at 1 to 5 min and inhibition of uptake after this time. Since caudal sperm do not show this biphasic response, we reasoned that BSP contained a factor derived from CF that must interact with developing sperm before the binding of caltrin to sperm can prevent further calcium uptake. We first demonstrated that preincubation of caput sperm with CF eliminated the biphasic calcium uptake effect induced in caput sperm by BSP and that caudal fluid alone had a potent stimulatory effect on calcium uptake in caput sperm. Half-maximal stimulation (fivefold over control) occurred at a caudal fluid protein concentration of 0.27 mg/ml. Partial purification of the factor indicates that it is of low molecular weight (MW ~ 1,000), but further chemical characterization has not been carried out and its epididymal site of origin is not known. The results indicate that the regulation of intracellular calcium levels in sperm differs in immature and mature bovine sperm in that an epididymal factor promotes calcium uptake during epididymal maturation, and the seminal fluid protein caltrin prevents it at ejaculation. 相似文献
5.
The ERG2 gene encoding the Saccharomyces cerevisiae C-8 sterol isomerase, an enzyme involved in plant, animal, and fungal sterol biosynthesis was sequenced. A large open reading frame comprising 222 amino acids was observed. 相似文献
6.
The role of dopamine in behavioral supersensitivity to muscarinic antagonists following cholinesterase inhibition 总被引:1,自引:0,他引:1
The role of brain dopamine (DA) in the enhancement of muscarinic antagonist-induced hyperactivity was investigated. The effects of atropine and scopolamine on the concentrations of DA and its metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), following DFP administration were determined. In control animals, atropine and scopolamine decreased the concentration of DA and increased the ratios of DOPAC/DA and HVA/DA in the striatum, but not in the N. accumbens - T. olfactorium (mesolimbic) area. Following a single dose of DFP, the two antimuscarinic drugs caused decreases of DA and further increases of the above ratios in both brain regions. However, following repeated DFP treatment for 2 weeks, these antimuscarinic drug-induced changes were observed only in the mesolimbic area, but not in the striatum. It is suggested that an increased DA turnover, indicated by elevated DOPAC/DA and HVA/DA ratios, underlies the muscarinic antagonist-induced hyperactivity. The well-known occurrence of muscarinic receptor down-regulation after DFP administration, could be responsible for the enhancement of the actions of muscarinic antagonists in DFP-treated animals. The observed differential effect on DA turnover in the two broad areas may involve both muscarinic and DA receptors. 相似文献
7.
Biochemical pathways in prokaryotes can be traced backward through evolutionary time 总被引:10,自引:0,他引:10
For the first time, a credible prokaryotic phylogenetic tree is being
assembled by Woese and others using quantitative sequence analysis of
oligonucleotides in the highly conservative rRNA. This provides an
evolutionary scale against which the evolutionary steps that led to the
arrangement and regulation of contemporary biochemical pathways can be
measured. This paper presents an emerging evolutionary picture of aromatic
amino acid biosynthesis within a large superfamily assemblage of
prokaryotes that is sufficiently developed to illustrate a new perspective
that will be applicable to many other biochemical pathways.
相似文献
8.
Summary Sub-type selective ligands revealed a differential distribution of endothelin (ET) receptors within human adrenal glands.
High densities of ETA receptors were localized, using [125I]-PD151242, to the smooth muscle layer of the arteries, smaller vessels within the capsular plexus and to the secretory cells
of zona glomerulosa (K
D=139.8±39.7,B
max=69.7±9.1 fmol mg−1 protein, mean of 3 individuals±sem). ETB receptors were present in the medulla (K
D=145.2±16.4,B
max=75.5±12.3), zona glomerulosa (KD=100.6±35.1,B
max=63.1±10.0), fasiculata (K
D 145.1±162.,B
max=67.9±6.9) and reticularis (KD=118.2±18.6,B
max=71.9±6.5). ETB receptors were not detected within the smooth muscle of the vasculature. Messenger RNA encoding both sub-types was present
in adrenals. ET-like immunoreactivity was localized to the cytoplasm of the endothelial cells from arteries supplying the
gland and resistance vessels within the capsular plexus. Staining was also detected in these cells using anti-big ET-1 and
less intensely with anti-big ET-2 antisera but not within cells within the cortex or medulla. Big ET-3-like immunoreactivity
was localized to secretory cells of the medulla. Staining was not found using antiserum that could detect ET-3, suggesting
further processing of big ET-3 may occur within the plasma, and that the cdrenals could be a source of ET-3. The presence
of ET-1 was confirmed by high performance liquid chromatography and radioimmunoassay although ET-3 was not detected. The results
suggest that ET-1 is the predominant mature isoform, which is localized mainly to adrenal vasculature, particularly the capsular
plexus, and may contribute to blood flow regulation in the gland. 相似文献
9.
In Drosophila pseudoobscura, the amylase (Amy) multigene family is
contained within a series of inversions, or gene arrangements, on the third
chromosome. The Standard (ST), Santa Cruz (SC), and Tree Line (TL)
inversions are central to the phylogeny of arrangements, and have clusters
of other arrangements derived from them. The gene arrangements belonging to
each of these three clusters have a characteristic number of Amy genes,
ranging from three in ST to two in SC to one in TL. This distribution
pattern can reflect a history of either duplications or deletions, although
the data available in the past did not permit a decision between these
alternatives. We provide unambiguous evidence that three Amy genes were
present before the divergence of the ST, SC, and TL arrangements. Thus, the
current status of the Amy multigene family is the result of deletions in
the TL and SC arrangements, which created three new pseudogenes: TL
Amy2-psi, TL Amy3-psi, and SC Amy3- psi. Analysis of pseudogene sequences
revealed that, in the SC and ST arrangements, pseudogene evolution has been
retarded, most likely due to the homogenization effect of gene conversion.
Finally, by determining the original copy number, we have reconstructed the
evolutionary history of the Amy multigene family and linked it with the
evolution of the central gene arrangements.
相似文献
10.
Cloning and characterisation of the Schizosaccharomyces pombe rad8 gene, a member of the SNF2 helicase family. 总被引:5,自引:3,他引:2 下载免费PDF全文
C L Doe J M Murray M Shayeghi M Hoskins A R Lehmann A M Carr F Z Watts 《Nucleic acids research》1993,21(25):5964-5971
The Schizosaccharomyces pombe rad8 mutant is sensitive to both UV and gamma irradiation. We have cloned the rad8 gene by complementation of the UV sensitivity of a rad8.190 mutant strain. The gene comprises an open reading frame of 3.4 kb which does not contain any introns and is capable of encoding a 1133 amino acid protein of 129 kDa. Deletion of the gene indicates that it is not essential for cell viability. Recognisable motifs are present for a nuclear localisation signal, a RING finger and helicase domains. The predicted protein is a member of the SNF2 subfamily of proteins and shows particular homology to the Saccharomyces cerevisiae RAD5 protein. Double mutant analysis demonstrated that the rad8 mutant is not epistatic to mutants in the excision repair pathway (rad13) or checkpoint pathway (rad9). Analysis of radiation sensitivity though the cell cycle indicates that, unlike most other rad mutants, rad8 is most sensitive to irradiation during the G1/S period. 相似文献