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41.
In rat brain slices the synthesis of [3H]phosphoinositides and the production of [3H]inositol monophosphate (IP1) induced by norepinephrine (NE) were inhibited by glutamate. Calcium concentrations were varied to test if these inhibitory effects of glutamate were mediated by a calcium-dependent process. Although reducing calcium or addition of the calcium antagonist verpamil reduced the inhibitory effects of glutamate, these results were equivocal because reduced calcium directly decreased agonist-induced [3H]phosphoinositide synthesis. The inhibitory effects of glutamate were mimicked by quisqualate in a dose-dependent manner, but none of a variety of excitatory amino acid receptor antagonists modified the inhibition caused by quisqualate. It is suggested that glutamate activates a quisqualate-sensitive receptor (for which an antagonist is not available) and causes inhibition of phosphoinositide hydrolysis mediated in part by a direct or indirect inhibitory effect of calcium on phosphoinositide synthesis. Modulatory effects of arachidonic acid were examined because glutamate and calcium can activate phospholipase A2. Arachidonic acid caused a rapid and dose-dependent inhibition of [3H]phosphoinositide synthesis and of NE-stimulated [3H]IP1 production. A similar inhibition of the response to carbachol also occurred. The inhibition caused by arachidonic acid was unchanged by addition of inhibitors of cyclooxygenase or lipoxygenase. Activation of phospholipase A2 with melittin caused inhibitory effects similar to those of arachidonic acid. Inhibitors of phospholipase A2 were found to impair phosphoinositide metabolism, likely due to their lack of specificity for phospholipase A2. Further studies were carried out in slices that were prelabelled with [3H]inositol in an attempt to separate modulatory effects on [3H]phosphoinositide synthesis and agonist-stimulated [3H]IP1 production. Several excitatory amino acid agonists inhibited NE-stimulated [3H]IP1 production. This inhibitory inter-action could be due to impaired synthesis of [3H]phosphoinositides because, even though the slices were prelabeled, addition of unlabelled inositol reduced NE-stimulated [3H]IP1 production, indicating that continuous regeneration of [3H]phosphoinositides is required. In contrast to the inhibitory effects of the excitatory amino acids, gamma-aminobutyric acid (GABA) enhanced the response to NE in cortical and hippocampal slices. GABA also enhanced the response to carbachol in hippocampal and striatal slices and to ibotenic acid in hippocampal slices. Baclofen potentiated the response to NE similarly to the effect of GABA and baclofen partially blocked the inhibitory effect of arachidonic acid but did not alter that of quisqualate.Abbreviations AMPA
-amino-3-hydroxy-5-methyl-4-isoxazolepropionic
- acid AP4
dl-2-amino-4-phosphonobutyric acid
- BPB
bromphenacyl bromide
- BSA
bovine serum albumin
- CNQX
6-cyano-7-nitroquinoxaline-2,3-dione
- DFMO
-difluoromethylornithine
- DIDS
diisothiocyanotostilbene-2,2-disulfonic acid
- EGTA
ethyleneglycol-bis-N
- N, N
N-tetraacetic acid
- GABA
-aminobutyric acid
- GDEE
glutamate diethyl ether
- -GG
-glutamylglycine
- IP1
inositol monophosphate
- IP2
inositol bisphosphate
- IP3
inositol trisphosphate
- NDGA
nordihydroguaiaretic acid
- NE
norepinephrine
- NMDA
N-methyl-d-aspartate 相似文献
42.
Basudev Shome Albert F. Parlow Wan-Kyng Liu Hyun S. Nahm Ted Wen Darrell N. Ward 《Journal of Protein Chemistry》1988,7(4):325-339
A collaborative study from two laboratories has been undertaken to re-evaluate the human follitropin -subunit sequence (hFSH), since areas of uncertainty remain in the wake of two earlier reports. The first report was by Shome and Parlow (1974). The second, by Saxena and Rathnam (1976), proposed revisions for sequence not definitively placed in the first study, as well as some differences in other placements. We have re-examined the sequence of the hFSH with more recent methodology. This has led to revision of certain areas of the sequence and resolution of differences between the two earlier proposals. Specifically, an-Ile-Ser- is established at 21–22, Asp at 41, Arg at 44, Lys at 46, and Glu at 111. These were areas of disagreement in the earlier proposals. A definitive placement of the residues around tryptophan-27 has now been obtained by three laboratories. C-terminal heterogeneity was observed with subunits ending at residue 107, 109, or 111. N-terminal heterogeneity has been observed in all preparations examined to date. A significant population of molecules with a proteolytic nick between residues 38–39 is noted. This is very likely an artifact of the collection and processing. The preparations examined in the present studies showed no evidence of residues 112–118 proposed by Saxena and Rathnam. 相似文献
43.
K. M. Song T. C. Osborn P. H. Williams 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1988,76(4):593-600
Summary Preliminary analysis using nuclear RFLPs provided evidence that subspecies within Brassica rapa originated from two different centers. One center is in Europe, represented by turnip and turnip rape from which the oilseed sarson was derived. A second center is in South China containing a variety of Chinese vegetables of which pak choi and narinosa seem to be the most ancient forms. Based on RFLP data, the accessions of B. oleracea examined could be divided into three distinct groups, represented by thousand head kale, broccoli and cabbage. Thousand head kale and Chinese kale appear to be the primitive types. Observations of parallel variation among subspecies of both species are discussed. 相似文献
44.
MacELISA、RPHI和IFAT用于流行性出血热早期诊断的比较 总被引:2,自引:0,他引:2
比较了IgM捕获ELISA(MacELISA)、反向间接血凝抑制试验(RPHI)和间接免疫荧光抗体试验(IFAT)检测流行性出血热(EHF)病人血清特异性抗体的结果。MacELISA对急性期血清IgM抗体的阳性检出率与RPHI对总抗体的阳性检出率相近,两法都具有较高的敏感性。而IFAT检测IgG抗体的阳性率则较低。总抗体滴度(RPHI)与IgG抗体滴度(IFAT)相关(r=0.542,P<0.01),而与IgM抗体滴度(MacELISA)无明显相关(r<0.1)。但进一步研究发现,3日内血清IgM抗体滴度与总抗体滴度(RPHI)存在相关关系(r=0.701,P<0.01),表明IgM抗体可能也与发病初期RPHI的较高的阳性检出率有关。本工作表明,MacELISA作为一种早期诊断方法具有高度的特异性和敏感性,而RPHI操作简便、快速、敏感性高,但存在一定的非特异性。研究还发现,流行区临床诊断为EHF的病人,IFAT(IgG)和RPHI检测均阳性,而MacELISA(IgM)阴性,提示用RPHI进行血清学诊断时,检查双份血清是必要的。 相似文献
45.
流行性出血热病毒R22株cDNA克隆及其特异性鉴定 总被引:3,自引:0,他引:3
用家鼠型流行性出血热病毒R22株RNA,经polyA接尾,以Oligo-dT做引物,合成cDNA。用pUC18为载体转染E.coli Mc1061,建立cDNA克隆。再经菌落杂交,选择病毒特异性的5个阳性克隆制成缺口翻译探针,与病毒RNA3个片段进行反杂交,确定RNA片段的特异性。结果表明,3个克隆为中(M)片段的cDNA,另两个分别为大(L)和小(S)片段cDNA。核苷酸序列分析证明,克隆的DNA中含病毒特异的核苷酸序列。 相似文献
46.
47.
Shiaw-Der Yang Jen-Shin Song Yao-Tsung Hsieh Hui-Wen Liu Wen-Hsiung Chan 《Journal of Protein Chemistry》1992,11(5):539-546
The ATP·Mg-dependent protein phosphatase activating factor (Fa) has been identified and purified to near homogeneity from brain. In this report, as evidenced on SDS-polyacrylamide gel electrophoresis followed by autoradiography, factorFa has further been identified as a cAMP and Ca2+-independent brain kinase that could phosphorylate synapsin I, a neuronal protein that coats synaptic vesicles, binds to cytoskeleton, and is believed to be involved in the modulation of neurotransmission. Kinetic study further indicated that factorFa could phosphorylate synapsin I with a lowK
m
value of about 2 µM and with a molar ratio of 1 mol of phosphate per mole of protein. Peptide mapping analysis revealed that factorFa specifically phosphorylated the tail region of synapsin I but on a unique site distinct from those phosphorylated by Ca2+/calmodulin-dependent protein kinase II and cAMP-dependent protein kinase, the two well-established synapsin I kinases. Functional study further revealed that factorFa could phosphorylate this unique specific site on the tail region of synapsin I and thereby inhibit cross-linking of synapsin I with microtubules. The results further suggest the possible involvement of factorFa as a synapsin I kinase in the regulation of axonal transport process of synaptic vesicles via the promotion of vesicles motility during neurotransmission. 相似文献
48.
Dr. Jian Wen Chen Lanping Zhang Jiantao Song Fen Hwang Qinghua Dong Jian Liu Yumin Qian 《Current microbiology》1992,24(4):189-192
The glycoproteins and glycolipids from membranes of virulent strain Z and avirulent strain M ofMycoplasma hyopneumoniae have been compared. The proteins and the glycoproteins were identified by SDS-polyacrylamide gel electrophoresis and concanavalin A-biotin labeling, respectively. The membrane preparation contained approximately 34 protein bands with molecular weights between 20 KD and 100 KD. The concanavalin A-biotin system reacted with a glycoprotein of a molecular weight of approximately 28,000 from avirulent strain M and did not react with the correspondent band from virulent strain Z. The membrane glycolipids of both strains consisted of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), and the percentages of 160, 180, and 181 fatty acids comprised more than 80% of the total fatty acids of membrane glycolipids. The 180 fatty acid of MGDG in avirulent strain M was twofold higher than that of virulent strain Z. 相似文献
49.
The PCR technique can use protein-derived oligonucleotide sequences as primers to develop probes for screening recombinant libraries. Here we report a method with highly degenerate mixtures of oligonucleotides as primers for the PCR that eliminates the need to identify or isolate the DNA sequences derived by PCR. The method uses the pool of PCR-generated DNA sequences radiolabeled during the extension reaction as a probe, combined with highly stringent hybridization and wash conditions that permit only homologous sequences to hybridize and therefore target desired clones. This technique was used successfully to clone the receptor for tumor necrosis factor. 相似文献
50.
脂质过氧化对人红细胞膜脂流动性的影响 总被引:20,自引:3,他引:17
研究枯稀过氧化氢/高铁血红素体系所产生的烷基过氧自由基对红细胞的损伤。测定了脂质过氧化的产物——丙二脂的生成,并证明阿魏酸钠对脂质过氧化的抑制。荧光偏振的结果指出,膜脂过氧化以后降低了膜脂的流动性。人红细胞用5DSA和16DSA标记并用ESR检测膜脂流动性,结果表明,序参数S几乎没有发生变化,旋转相关时间τ值的增加证明膜脂过氧化以后,疏水尾部的物理状态发生了改变。经脂质过氧化以后,红细胞膜中的不饱和脂防酸的减少,可能是降低膜脂流动性的原因之一。 相似文献