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921.
922.
The ataxia-telangiectasia gene (ATA) on chromosome II is distinct from the ETS-1 gene. 总被引:2,自引:2,他引:0
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P Concannon U Malhotra P Charmley J Reynolds K Lange R A Gatti 《American journal of human genetics》1990,46(4):789-794
We have studied the segregation of an RFLP detected with a human ETS-1 genomic probe in 25 families containing members affected with ataxia-telangiectasia (AT) and in 27 families from the Centre d'Etude du Polymorphisme Humain (CEPH) panel. We have recently mapped a gene for AT to 11q22-23 by linkage to the markers THY1 and D11S144. Multipoint linkage analysis of the CEPH families indicated that ETS-1 is located on chromosome 11q approximately 19.2 centimorgans telomeric to THY1. Analysis of the segregation of ETS-1 alleles in AT families yields strongly negative LOD scores, excluding an AT gene from a region extending 15 cM to either side of ETS-1. Multipoint mapping of ETS-1, D11S144, THY1, and AT also excludes the possibility that an AT gene is telomeric to ETS-1. 相似文献
923.
Colobus type C virus: molecular cloning of unintegrated viral DNA and characterization of the endogenous viral genomes of Colobus. 总被引:4,自引:2,他引:2
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E H Birkenmeier T I Bonner K Reynolds G H Searfoss G J Todaro 《Journal of virology》1982,41(3):842-854
The unintegrated viral DNA intermediates of colobus type C virus (CPC-1) were isolated from infected human cells that were permissive for viral growth. There were two major species of DNA, linear molecules with two copies of the long terminal repeat and relaxed circles containing only a single long terminal repeat. In addition, there was a minor species (approximately 10%) composed of relaxed circles with two copies of the long terminal repeat. A restriction endonuclease map of the unintegrated DNA was constructed. The three EcoRI fragments of circular CPC-1 DNA were cloned in the EcoRI site of lambda gtWES . lambda B and then subcloned in the EcoRI site of pBR322. Using these subgenomic fragments as probes, we have characterized the endogenous viral sequences found in colobus cellular DNA. They are not organized in tandem arrays, as is the case in some other gene families. The majority of sequences detected in cellular DNA have the same map as the CPC-1 unintegrated DNA at 17 of 18 restriction endonuclease sites. There are, however, other sequences that are present in multiple copies and do not correspond to the CPC-1 map. They do not contain CPC-1 sequences either in an altered form or fused to common nonviral sequences. Instead, they appear to be derived from a distinct family of sequences that is substantially diverged from the CPC-1 family. This second family of sequences, CPC-2, is also different from the sequences related to baboon endogenous type C virus that forms a third family of virus-related sequences in the colobus genome. 相似文献
924.
925.
The presence of a sodium-dependent, saturable uptake process is described in basolateral membranes of rat renal cortex for L-glutamine. Concentration-dependence studies indicate the presence of multiple transport systems withK
m
1 of 0.032 mM and V1 of 0.028 nmol/mg of protein per min, andK
m
2 of 17.6 mM and V2 of 17.6 nmol/mg of protein per min. Lysine completely inhibits the high-affinity, low-capacityK
m system and partially inhibits the low-affinity, high-capacity system. Cystine and other dibasic amino acids also affect glutamine uptake. 相似文献
926.
U. Trechsel G. Dew G. Murphy J.J. Reynolds 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1982,720(4):364-370
Collagenase secretion was studied in cultures of rabbit articular chondrocytes. Differentiation of the cells was assessed by characterizing the type of 3H-labelled collagen produced during treatment with (1) conditioned media from rabbit peritoneal macrophages and human blood mononuclear cells, and (2) with retinol, a potent cartilage resorbing agent in tissue culture. Conditioned media stimulated collagenase secretion. Total collagen synthesis was reduced due to a decrease of synthesis of α1 chains; the amount of α2 chains synthesized was unchanged. This is thought to be due to a reduction in type II synthesis. Retinol did not stimulate collagenase secretion. Total collagen synthesis was reduced by retinol. α2 chain synthesis, however, was significantly increased, suggesting a switch of collagen synthesis in favor of type I collagen and, therefore, dedifferentiation. These results demonstrate that dedifferentiation of chondrocytes with respect to collagen synthesis is not necessarily associated with a stimulation of collagenase secretion. 相似文献
927.
Tracey A. Chatterton C. Hugh Reynolds Norman R. Lazarus Christopher I. Pogson 《The Biochemical journal》1982,204(2):605-608
Pyruvate kinase in rat pancreatic islets was characterized immunologically and kinetically. It is concluded that this activity is predominantly if not totally of the M2 type. 相似文献
928.
A rapid fluorometric assay for erythrocyte pyridoxal kinase 总被引:1,自引:0,他引:1
929.
Transient decrease of liver cytosolic glutathione S-transferase activities in rats given 1,2-dibromoethane or CCl4 总被引:1,自引:0,他引:1
In vivo treatment of fasted male rats with 1,2-dibromoethane (DBE) (0.4 mmol/kg) or carbon tetrachloride (CCl4) (4 mmol/kg) was found to rapidly alter the activities of liver cytosolic and microsomal glutathione S-transferases. Microsomal activities towards chloro-2,4-dinitrobenzene (CDNB) were increased 2 h after either treatment. Cytosolic activities towards CDNB and 3,4-dichloronitrobenzene (DCNB), but not 1,2-epoxy-3-(p-nitrophenoxy)-propane (ENPP), were selectively and transiently decreased after either treatment. Time course studies in DBE animals indicated that the decrease in cytosolic activity was not evident until 2 h although liver glutathione (GSH) concentrations were diminished within 15 min. In contrast, in CCl4 animals the decrease in cytosolic activity was evident within 15 min and was not accompanied by diminished GSH concentrations. By 4 h, cytosolic activities had rebounded to control levels in both DBE and CCl4-treated animals. Kinetic studies of the enzyme in liver cytosol from animals 2 h after treatment with DBE or CCl4 indicated that both treatments decreased the apparent Vmax while neither treatment altered the apparent Km. This pattern of change allows exclusion of a simple competitive mechanism of enzyme inhibition, but cannot distinguish between reversible non-competitive inhibition and irreversible inhibition. It is possible that the observed decreases in the activities of the abundant cytosal enzyme are due to 'sacrificial' covalent linkages between the enzyme and reactive metabolites of DBE or CCl4. 相似文献
930.
Michael J. Boland Joanna F. Hanks Paul H. S. Reynolds Dale G. Blevins N. E. Tolbert Karel R. Schubert 《Planta》1982,155(1):45-51
Subcellular organelle fractionation of nitrogen-fixing nodules of soybean (Glycine max (L.) Merr.) indicates that a number of enzymes involved in the assimilation of ammonia into amino acids and purines are located in the proplastids. These include asparagine synthetase (EC 6.3.1.1), phosphoribosyl amidotransferase (EC 2.4.2.14), phosphoglycerate dehydrogenase (EC 1.1.1.95), serine hydroxymethylase (EC 2.1.2.1), and methylene-tetrahydrofolate dehydrogenase (EC 1.5.1.5). Of the two isoenzymes of asparate aminotransferase (EC 2.6.1.1) in the nodule, only one was located in the proplastid fraction. Both glutamate synthase (EC 1.4.1.14) and triosephosphate isomerase (EC 5.3.1.1) were associated at least in part with the proplastids. Glutamine synthetase (EC 6.3.1.2) and xanthine dehydrogenase (EC 1.2.1.37) were found in significant quantities only in the soluble fraction. Phosphoribosylpyrophosphate synthetase (EC 2.7.6.1) was found mostly in the soluble fraction, although small amounts of it were detected in other organelle fractions. These results together with recent organelle fractionation and electron microscopic studies form the basis for a model of the subcellular distribution of ammonium assimilation, amide synthesis and uredie biogenesis in the nodule.Abbreviations FH4
tetrahydrofolic acid
- PRPP
5-phospho--D-ribose 1-pyrophosphate
- PRPP synthetase
ribosephosphate pyrophosphokinase (phosphoribosylpyrophosphate synthetase) 相似文献