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31.
32.
Molecular cloning and sequence analysis of bovine T-cell receptor γ and δ chain genes 总被引:2,自引:2,他引:0
Nine bovine T-cell receptor (Tcr) chain (Tcrg) and three Tcr chain (Tcrd) cDNA clones were isolated from the cDNA libraries constructed from peripheral blood lymphocytes and thymocytes. Of nine Tcrg cDNA clones, only four were rearranged and contained specific V, J, and C gene segments, but the remaining five contained specific J and C or only C gene segments without the V gene segment. Three kinds of Tcrg-C, which were highly related at the nucleotide and amino acid levels, were found and designated as Tcrg-C1, Tcrg-C2, and Tcrg-C3. Compared with human and mouse Tcrg-C, bovine Tcrg-C sequences are much longer, with about 27–55 amino acids corresponding to the hinge and connector regions, where the characteristic repetitive 5-amino acid motif (TTEPP or TTKPP) exists in sheep Tcrg-C as previously reported. From three Tcrd cDNA clones, two Tcrd-V and three Tcrd-J segments were isolated. The nucleotide and deduced amino acid sequences of bovine Tcrd-C, especially the transmembrane and cytoplasmic domains, are well conserved among species. As in bovine Tcrg-C, diversity of amino acid residues in the Tcrd-C region is concentrated in the hinge regions. Southern blot analysis showed that there are at least three Tcrg-C genes and one Tcrd-C gene in the bovine genome. The analysis also revealed the presence of Tcrg-C- and Tcrd-C-associated restriction fragment length polymorphisms among bovine breeds.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers D90409-20. 相似文献
33.
Two new mutant loci (smhB and lytD) in Escherichia coli which confer temperature-sensitive growth and lysis phenotypes 总被引:1,自引:0,他引:1
A temperature-sensitive mutation in the murH gene of Escherichia coli confers a lysis phenotype at the restrictive temperature. An extragenic suppressor of murH apparently representing a new locus at 12.5 min on the linkage map and designated smhB is described. The smhB mutation by itself also conferred a temperature-sensitive lysis phenotype. A mutation in another new locus designated lytD which arose spontaneously in the smhB mutant was mapped close to smhB at 12.7 min on the linkage map. The lytD mutation by itself conferred a temperature-sensitive lysis phenotype indistinguishable from that of the murH mutant. Thus, the suppression of lysis in the smhB murH and the smhB lytD double mutants suggests a mechanism involving the reciprocal suppression of the two individual lysis-causing mutant alleles. The suppressor activity of smhB was apparently relatively specific in that smhB failed to prevent lysis induced by either mutational (murE or murF) or antibiotic-induced blocks in peptidoglycan synthesis. This suggests that murH, smhB, and lytD may be functionally related. 相似文献
34.
Regulation of D-alanine carboxypeptidase and peptidoglycan cross-linkage in amino acid-deprived Escherichia coli. 总被引:2,自引:2,他引:0
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The effect of amino acid deprivation on the activities of D-alanine carboxypeptidase (CPase) and peptidoglycan transpeptidase in Escherichia coli was determined. Enzymes were assayed in ether-treated bacteria (ETB) which were permeable to peptidoglycan nucleotide precursors. ETB were prepared at intervals from cultures grown in the presence and absence of a required amino acid. The specific activity of CPase in ETB decreased 50 to 85% during amino acid deprivation. This was paralleled by a 60 to 70% decrease in the specific activity of peptidoglycan transpeptidase. Both enzymes reached their lowest level of activity about 40 min after the onset of amino acid deprivation. The decrease in CPase activity apparently was not due to degradation of the enzyme, since full activity was restored after disruption of ETB by sonication. A decrease in CPase activity was associated with an enhancement of transpeptidation. The peptidoglycan synthesized in vitro by amino acid-deprived ETB was 1.7 times more cross-linked than the peptidoglycan synthesized by control ETB These results support the proposal that CPase may be involved in regulating transpeptidation in E. coli. 相似文献
35.
Isolation of calmodulin from the protozoan, Tetrahymena pyriformis, by the use of a tubulin-Sepharose 4B affinity column 总被引:3,自引:0,他引:3
We developed a simple new method for the isolation of calmodulin, a ubiquitous Ca2+-binding protein, by using tubulin-Sepharose 4B column chromatography, and succeeded in rapid isolation of calmodulin from Tetrahymena pyriformis. The procedure was also shown to be successfully applicable to the isolation of calmodulins from starfish ovary, porcine brain, and monkey brain and, therefore, may be of general use for the rapid isolation of calmodulin. 相似文献
36.
The citrate-utilizing ability of 19 out of 22 citrate-positive Escherichia coli strains isolated from pig sewage was transferred via conjugation to E. coli K-12. The conjugal transfer of citrate-utilizing (Cit) abilities was thermosensitive and concurrent with transfer of drug resistance. Weakly citrate-positive colonies were readily obtained in conjugation experiments. Their Cit characters could be transmitted to the other E. coli strains at a similar frequency in the retransfer experiments, and the transconjugants obtained still showed same characteristic growth on Simmons citrate agar plates. The 19 thermosensitive plasmids conferring citrate utilization and drug resistance were Fi-, and 16 of these plasmids belonged to incompatibility group H1. However, occasionally two conjugative plasmids (pOH3122-1 and pOH3124-1) carrying only the citrate utilization were also obtained in the conjugation experiments, and they were Fi+ and compatible with 19 reference R plasmids. In the two citrate-positive E. coli strains, it was suggested that the conjugative Cit plasmid showing Fi+ character and the more thermosensitive H1 plasmid conferring both the Cit character and drug resistance coexisted in the strain. The characterization of citrate utilization plasmids derived from pig farm sewage is discussed. 相似文献
37.
The effects of inhibition of protein synthesis on the cell size distributions of rel+ and relA- derivatives of Escherichia coli K-12 were determined. Amino acid deprivation resulted in a reduction in the cell sizes of rel+ strains but not of relA- strains. Treatment with chloramphenicol (CAM) did not alter the size distributions of either rel+ or relA- strains except when they were rel+ dap-. CAM treatment of rel+ dap- strains resulted in an increase in cell size. It is proposed that these results reflect differences in the structures of the cell envelopes of rel+ and relA- bacteria. 相似文献
38.
Poly-β-1-naphthylmethyl-L -aspartate and copolymers of β-1-naphthylmethyl-L -aspartate and γ-benzyl-L -glutamate were prepared. From the results obtained by a study of infrared and circular dichroism spectra, poly-β-1-naphthylmethyl-L -aspartate was found to be a left-handed α-helix both in the solid state and in solution. The fluorescence spectra of these polymers showed excimer emission of the naphthyl chromophores and gave some information about the arrangement of the side-chain chromophores. By optical titration experiments, it was found that an increasing amount of β-1-naphthylmethyl-L -aspartate residues in the copolymers induces a progressive instability of the helical structure. 相似文献
39.
Y. Ohta R. Shinohara I. Ishiguro 《Redox report : communications in free radical research》2013,18(5):339-344
SummaryThe role of the prosthetic groups (FAD and FMN) of NADPH-cytochrome P450 reductase (P450 reductase)in 3-hydroxyanthranilamide (3-OH An.Amide)-catalyzed, NADPH-dependent superoxide anion (O2-) production via the reductase was examined using the native and FMN-depleted preparations of P450 reductase which was partially purified from rat liver microsomes. NADPH-dependent O2-production by the FMN-depleted preparation was about 10% of that by the native preparation. 3-OH An. Amide-catalyzed, NADPH-dependent O2-production by the FMN-depleted preparation was less than 10% of that by the native preparation. FMN supplementation returned O2-production to near normal. We observed the same results for NADPH oxidation and hydrogen peroxide formation. O2-production, NADPH oxidation, and hydrogen peroxide formation were inhibited by native superoxide dismutase (SOD), but not by boiled, denatured SOD. These results indicate that the prosthetic groups, especially FMN, of P450 reductase play a critical role in 3-OH An.Amide-catalyzed, NADPH-dependent O2-production via the reductase. 相似文献
40.
Junpei Ishiguro Kenta Shibahara Yumi Ueda Kei Nakamura 《Molecular genetics and genomics : MGG》2013,288(1-2):63-75
TOR (target of rapamycin) signaling regulates cell growth and division in response to environmental stimuli such as the availability of nutrients and various forms of stress. The vegetative growth of fission yeast cells, unlike other eukaryotic cells, is not inhibited by treatment with rapamycin. We found that certain mutations including pmc1Δ (Ca2+-ATPase), cps9-193 (small GTPase, Ryh1) and cps1-12 (1,3-β-d-glucan synthase, Bgs1) confer a rapamycin-sensitive phenotype to cells under salt stress with potassium chloride (>0.5 M). Cytometric analysis revealed that the mutant cells were unable to enter the mitotic cell cycle when treated with the drug under salt stress. Gene cloning and overexpression experiments revealed that the sensitivity to rapamycin was suppressed by the ectopic expression of tyrosine phosphatases, Pyp1 and Pyp2, which are negative regulators of Spc1/Sty1 mitogen-activated protein kinase (MAPK). The level of tyrosine phosphorylation on Spc1 was higher and sustained substantially longer in these mutants than in the wild type under salt stress. The hyperphosphorylation was significantly suppressed by overexpression of pyp1 + with concomitant resumption of the mutant cells’ growth. In fission yeast, TOR signaling has been thought to stimulate the stress-response pathway, because mutations of TORC2 components such as Tor1, Sin1 and Ste20 result in similar sensitive phenotypes to environmental stress. The present study, however, strongly suggests that TOR signaling is required for the down-regulation of a hyperactivated Spc1 for reentry into the mitotic cell cycle. This finding may shed light on our understanding of a new stress-responsive mechanism in TOR signaling in higher organisms. 相似文献