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121.
Adipose-tissue-specific increase in glyceraldehyde-3-phosphate dehydrogenase activity and mRNA amounts in suckling pre-obese Zucker rats. Effect of weaning. 总被引:2,自引:0,他引:2
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I Dugail A Quignard-Boulange R Bazin X Le Liepvre M Lavau 《The Biochemical journal》1988,254(2):483-487
The regulation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene expression was studied during the onset of obesity in the genetically obese (fa/fa) rat by determination of GAPDH activity and hybridizable mRNA amounts in adipose tissue and liver from suckling and weanling rats. GADPH activity remained low throughout the suckling period, and a burst of activity occurred after weaning in both lean and obese pups. As early as 7 days of age, adipose tissue from pre-obese rats displayed a significant increase in enzyme activity, whereas no difference could be detected in the liver. In both suckling (16 days of age) and weanling (30 days of age) obese rats a proportionate increase in GAPDH activity and mRNA amounts was observed in adipose tissue, but not in liver. It is concluded that the obese genotype influences GAPDH gene expression at a pretranslational level and in a tissue-specific manner. This phenomenon could partly contribute to the hyperactive fat accretion in the obese rat, since glycolysis is the major metabolic pathway for lipogenic substrates in adipose tissue. 相似文献
122.
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124.
M. Jane Ehrke Richard L. X. Ho Kazuyoshi Hori 《Cancer immunology, immunotherapy : CII》1988,27(2):103-108
Summary Recombinant murine (rMu) tumor necrosis factor (TNF), in a standard comitogenic assay with phytohemagglutinin, induced murine thymocyte proliferation, while up to 10,000-fold higher concentrations of recombinant human TNF did not. The induction of thymocyte proliferation was dependent upon TNF concentration in a biphasic manner. Thus, 100 to 1000 units/ml TNF were near optimal while concentrations 1,000 units/ml caused apparent down regulation. The effect was abrogated by neutralizing antibody to rMu-TNF but not by neutralizing antibody to rMu-interleukin 1 or . The rMu-TNF did not induce proliferation of the mature murine T-helper cell line, D10.G4.1, in the presence of mitogen. Taken together the results indicate that TNF, in a strictly species-specific manner, can regulate thymocyte proliferation independently of interleukin 1.Supported in part by Asahi Chemical Industry Co., Inc. and by USPHS Grants CA-24538, CA-15142 and CA-09072 awarded by the National Cancer Institute, Department of Health and Human Services 相似文献
125.
Robert S. Aronstam Michael W. Edwards John W. Daly X. Albuquerque 《Neurochemical research》1988,13(2):171-176
The interactions of eight piperidine derivatives with nicotinic receptor complexes fromTorpedo californica electric organ were studied using [125I]alpha-bungarotoxin ([125I]BGT) as a probe for the acetylcholine binding site and [3H]perhydrohistrionicotoxin ([3H]H12-HTX) as a probe for a site associated with the receptor-gated ion channel.Cis- andtrans-2-methyl-6-n-undecanyl piperidines (MUP), major constituents of fire ant venom, had a high-affinity for [3H]H12-HTX binding sites (Ki=0.08–0.24 M), but had no affect on receptor binding. MUP affinity for [3H]H12-HTX binding sites was approximately doubled in the presence of 1 M carbamylcholine. Introduction of a 2-hydroxyl group to the undecanyl side channel had little effect on activity of the alkaloid. The analog 2,6- (but not 3,5-) dimethylpiperidine was a moderately active inhibitor of [3H]H12-HTX binding (K
i-8.8 M). 2-Methylpiperidine was considerably less active (K
i=600 M), although it was more potent than either 3- or 4-methylpiperidine. The affinities of 2,6-dimethylpiperidine and 2-methylpiperidine for [3H]H12-HTX binding sites were decreased in the presence of 1 M carbamylcholine. Carbamylcholine affinity for the receptor was increased by up to 7 fold in the presence of 10 and 32 M MUP, but was decreased in the presence of 2,6-dimethylpiperidine and 2-methylpiperidine. Thecis- andtrans-isomers of MUP were equipotent in producing each of its effects. In these actions, MUP resembles a variety of other compounds derived from 2,6-disubstituted piperidines, including histrionicotoxins, gephyrotoxins and pumiliotoxins. These studies establish the importance of alkyl substitutions in theortho position of the piperidine ring in conferring ion channel specificity, and the importance of substantial alkyl side chains in conferring the ability of channel blockers to stabilize the nicotinic receptor complex in high affinity, desensitized conformations. 相似文献
126.
H X Lin T Kleinschmidt G Braunitzer H G Scheil 《Biological chemistry Hoppe-Seyler》1988,369(5):349-355
The hemoglobin of the Common Otter (Lutra lutra, Carnivora) contains only one component. The complete primary structures of the alpha- and beta-chains are presented. They were separated by high-performance liquid chromatography and the sequences determined by automatic liquid and gas-phase Edman degradation of the chains and their tryptic peptides. The alpha-chains show 18 and the beta-chains 13 substitutions compared to human alpha- and beta-chains, respectively. In the alpha-chains one heme- and two alpha 1/beta 1-contacts are exchanged. In the beta-chains the replacements involve one heme-, one alpha 1/beta 1-, and one alpha 1/beta 2-contact. The alpha- and beta-chains of the Common Otter are compared to those of other Carnivora hemoglobins. The unexpected low number of substitutions between Common Otter hemoglobin and that of Lesser Panda as well as of Harbor Seal is discussed. 相似文献
127.
128.
The presence of a binding site to (+)-(3H)SKF 10,047 was demonstrated in a guinea-pig myenteric plexus (MYP) membrane preparation. Specific binding to this receptor was saturable, reversible, linear with protein concentration and consisted of two components, a high affinity site (KD = 46 +/- 5 nM; Bmax = 3.4 +/- 0.5 pmole/g wet weight) and a low affinity site (KD= = 342 +/- 72 nM; Bmax = 22 +/- 3 pmole/g wet weight). Morphine and naloxone 10(-4) M were unable to displace (+)-(3H)SKF 10,047 binding. Haloperidol, imipramine, ethylketocyclazocine and propranolol were among the most potent compounds to inhibit this specific binding. These results suggest the presence of a non-opioid haloperidol sensitive sigma receptor in the MYP of the guinea-pig. 相似文献
129.
Hancai Chen James X. Gray Murali Nayudu Michael A. Djordjevic Michael Batley John W. Redmond Barry G. Rolfe 《Molecular & general genetics : MGG》1988,212(2):310-316
Summary R-prime plasmids were constructed from a derivative of Rhizobium strain NGR234 (ANU280) and were shown to contain overlapping genomic DNA segments involved in biosynthesis of exopolysaccharides (EPS). The R-primes originally constructed carried the mutant allele from Tn5-induced EPS-deficient (Exo–) mutant ANU2811. This plasmid-located mutant allele was dominant to the corresponding wild-type allele as merodiploid strains were Exo–. Exo+ revertants occurred at a low rate (1×10-7) and these were shown to result from double reciprocal recombination events, which led to the isolation of R-prime plasmids carrying functional wild-type exo alleles. R-prime plasmids that carry overlapping segments of DNA from parental strain ANU280 complemented 28 of the 30 group 2 Exo– mutants of strain ANU280. Complementation of these Exo– mutants also restored their symbiotic abilities of effective nodulation. Subsequent in vivo recombination between the wild-type alleles located on the R-prime and the corresponding mutated allele on the genome, was used to generate a new family of R-primes, which carried mutations in the exo genes. The 30 group 2 Exo– mutants were classified into 7 distinct genetic groups based upon complementation and physical mapping data. Five of the seven exo loci were gentically linked and located on a 15-kb region of DNA. Mutations at two loci were dominant only when the mutations were R-prime plasmid-located while a mutation at a second locus was cis-dominant to two other exo loci. At least five genes involved in the synthesis of acidic exopolysaccharide synthesis have been identified. 相似文献
130.
A developmentally regulated hydroxyproline-rich glycoprotein in maize pericarp cell walls 总被引:12,自引:3,他引:9
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![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We have studied the accumulation of peptidyl hydroxyproline in the pericarp of developing maize (Zea mays L., Golden cross Bantam sweet corn) kernels. Although this hydroxyproline accumulates throughout development, it is most soluble and its content per milligram dry weight greatest at midmaturation stages of development. Salt-soluble proteins containing this hydroxyproline from isolated cell walls of developing kernels were fractionated on a CsCl density gradient and on a Chromatofocusing column, resulting in the purification of an hydroxyproline-rich glycoprotein, PC-1. PC-1 is a basic protein of approximately 65 to 70 kilodaltons in molecular weight with an isoelectric point of at least 10.2 and a density of 1.38 to 1.39 in CsCl. Amino acid composition data indicate that it is rich in hydroxyproline, threonine, proline, lysine, and glycine. Its relation to dicot extensin is discussed. 相似文献