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排序方式: 共有479条查询结果,搜索用时 785 毫秒
1.
TRH analog MK-771 reverses neurochemical and learning deficits in medial septal-lesioned rats 总被引:1,自引:0,他引:1
Microinjection of ibotenic acid into medial septum of rats decreased choline acetyltransferase (CAT) and high-affinity choline uptake (HACU) activities in hippocampus and retarded the learning of a spatial memory task in the radial-arm maze. Administration of MK-771, a stable TRH analog, to such animals restored HACU activity in hippocampus to normal levels. Daily treatment of rats with MK-771 prior to maze running also restored the animals' learning ability. MK-771 did not enhance hippocampal HACU activity or maze performance in sham-lesioned rats. These results suggest that MK-771 reversed the ibotenic acid-induced memory deficit by restoring septohippocampal cholinergic function. MK-771 and other TRH analogs may represent novel agents for improving memory deficits produced by cholinergic insufficiency in Alzheimer's disease. 相似文献
2.
Payant V; Abukashawa S; Sasseville M; Benkel BF; Hickey DA; David J 《Molecular biology and evolution》1988,5(5):560-567
Nuclear DNA was extracted from each of the eight species comprising the
Drosophila melanogaster species subgroup. Southern hybridization of this
DNA by using a molecular probe specific for the alpha-amylase coding region
showed that the duplicated structure of the amylase locus, first found in
D. melanogaster, is conserved among all species of the melanogaster
subgroup. Evidence is also presented for the concerted evolution of the
duplicated genes within each species. In addition, it is shown that the
glucose repression of amylase gene expression, which has been extensively
studied in D. melanogaster, is not confined to this species but occurs in
all eight members of the species subgroup. Thus, both the duplicated gene
structure and the glucose repression of Drosophila amylase gene activity
are stable over extended periods of evolutionary time.
相似文献
3.
SKF 38393 (5 mg/kg), but not quinpirole, shortened the duration of loss of righting reflex produced in pentobarbital-narcotized rats. This effect was blocked by atropine (2 mg/kg), but not by atropine methylbromide, suggesting involvement of central cholinergic mechanisms. The analeptic effect was also blocked by SCH 23390 (0.2 mg/kg) or raclopride (2 mg/kg). SKF 38393 also increased sodium dependent high affinity choline uptake (HACU) in cortical and hippocampal synaptosomes that had been depressed by pentobarbital. SCH 23390 or raclopride prevented the SKF 38393 reversal of the depressed HACU, indicating that both D1 and D2 mechanisms were involved mediating the analeptic effect. These results provide neurochemical evidence that cortical and hippocampal D1-mediated cholinergic activation results in a behavioral arousal (analeptic) response. They also suggest that DA mechanisms may be involved in regulation of cortical and hippocampal cholinergic neurons. 相似文献
4.
JOÃO BATISTA TAVARES DA SILVA ISAAC ROITMAN 《The Journal of eukaryotic microbiology》1990,37(6):521-523
ABSTRACT. Three strains of Phytomonas serpens two from tomatoes, Lycopersicon esculentum one from the insect Phtia picta (Hemiptera, Coreidae), were cultivated in a chemically defined medium developed from a defined medium for cultivating insect flagellates. Besides organic growth factors required by other insect trypanosomatids this flagellate requires, serine and inositol. Glutamine stimulates growth, and, surprisingly, does not require heme. 相似文献
5.
MARC J. FAZIO ALBA C. DA SILVA THOM K. ROSIERE G. BENJAMIN BOUCK 《The Journal of eukaryotic microbiology》1995,42(5):570-580
ABSTRACT. Proteins of the membrane skeleton of Euglena gracilis were extensively phosphorylated in vivo and in vitro after incubation with [32 P]-orthophosphate or γ-[32 P] ATP. Endogenous protein threonine/serine activity phosphorylated the major membrane skeletal proteins (articulins) and the putative integral membrane protein (IP39) anchor for articulins. The latter was also the major target for endogenous protein tyrosine kinase activity. A cytoplasmic domain of IP39 was specifically phosphorylated, and removal of this domain with papain eliminated the radiolabeled phosphoamino acids and eliminated or radically shifted the PI of the multiple isoforms of IP39. In gel kinase assays IP39 autophosphorylated and a 25 kDa protein which does not autophosphorylate was identified as a threonine/serine (casein) kinase. Plasma membranes from the membrane skeletal protein complex contained threonine/serine (casein) kinase activity, and cross-linking experiments suggested that IP39 was the likely source for this membrane activity. pH optima, cation requirements and heparin sensitivity of the detergent solubilized membrane activity were determined. Together these results suggest that protein kinases may be important modulators of protein assembly and function of the membrane skeleton of these protistan cells. 相似文献
6.
Borrelia burgdorferi is a spirochete pathogen transmitted among warm-
blooded hosts by ixodid ticks. Frequency-dependent selection for variant
outer-surface proteins might be expected to arise in this species, since
rare variants are more likely to avoid immune surveillance in previously
infected hosts. We sequenced the OspA and OspB genes of nine North American
strains and compared them with nine strains previously described. For each
gene, the mean number of synonymous substitutions per synonymous site and
the mean number of nonsynonymous substitutions per nonsynonymous site show
only a twofold excess of silent mutations. Synonymous rates vary widely
along the OspB protein. Some regions show a significant excess of silent
substitutions, while divergence in other regions is constrained by biased
base composition or selection. The presence, in antigenically important
regions of the protein, of significant variation among strains, as well as
evidence for recombination among strains, should be considered in attempts
to develop vaccines against this disease.
相似文献
7.
M P ROBINSON G BUTCHER R H CURTIS K G DA VIES K EVANS 《The Annals of applied biology》1993,123(2):337-347
Two monoclonal antibodies, which differentially recognise the two species of potato cyst nematodes (PCN), Globodera pallida and G. rostochiensis, are described. They have been shown to have potential for quantification of these two species, recognising proteins of the same molecular weight (34 kD) in both species. Further investigation showed these proteins to have isoelectric points at pH values of 5.7 in G. pallida and 5.9 in G. rostochiensis, in common with the proteins used by Fleming & Marks (1983) to differentiate the species of PCN. They are likely to be structurally very similar, with the same physiological function (and therefore similar concentrations) in the two species. In cross-reactivity tests with a wide range of soil nematode species, the antibodies reacted strongly only with species of the genus Globodera, and thereby confirmed their potential as the basis of a quantitative immunoassay likely to be useful in management of PCN populations. 相似文献
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