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1.
DNA amplification in multidrug, cross-resistant Chinese hamster ovary cells: molecular characterization and cytogenetic localization of the amplified DNA 总被引:2,自引:0,他引:2 下载免费PDF全文
Vincristine-resistant (VCR) Chinese hamster ovary (CHO) cells have been established by stepwise selection in increasing concentrations of vincristine. These cells exhibit multidrug cross-resistance to a number of drugs that have no structural or functional similarities. Cytogenetic analyses of resistant cells revealed the presence of double minutes and expanded chromosomal segments, thus implicating gene amplification as a possible mechanism of resistance. An amplified DNA segment isolated from other multidrug cross-resistant CHO cell lines (Roninson, I. B., H. T. Abelson, D. E. Housman, N. Howell, and A. Varshavsky, 1984, Nature (Lond.), 309:626-628) is also amplified in our VCR lines. This DNA segment was used as a probe to screen a cosmid library of VCR genomic DNA, and overlapping clones were retrieved. All of these segments, totaling approximately 45 kilobases (kb), were amplified in VCR cells. Using in situ hybridization, we localized the amplification domain to the long arm of CHO chromosome 1 or Z1. Northern hybridization analysis revealed that a 4.3-kb mRNA was encoded by this amplified DNA domain and was over-produced in the VCR cells. Suggestions for the involvement of these amplified DNA segments in the acquisition of multidrug cross-resistance in animal cells are also presented. 相似文献
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3.
Structural gene and complete amino acid sequence of Pseudomonas aeruginosa IFO 3455 elastase. 总被引:21,自引:8,他引:13 下载免费PDF全文
J Fukushima S Yamamoto K Morihara Y Atsumi H Takeuchi S Kawamoto K Okuda 《Journal of bacteriology》1989,171(3):1698-1704
The DNA encoding the elastase of Pseudomonas aeruginosa IFO 3455 was cloned, and its complete nucleotide sequence was determined. When the cloned gene was ligated to pUC18, the Escherichia coli expression vector, bacteria carrying the gene exhibited high levels of both elastase activity and elastase antigens. The amino acid sequence, deduced from the nucleotide sequence, revealed that the mature elastase consisted of 301 amino acids with a relative molecular mass of 32,926 daltons. The amino acid composition predicted from the DNA sequence was quite similar to the chemically determined composition of purified elastase reported previously. We also observed nucleotide sequence encoding a signal peptide and "pro" sequence consisting of 197 amino acids upstream from the mature elastase protein gene. The amino acid sequence analysis revealed that both the N-terminal sequence of the purified elastase and the N-terminal side sequences of the C-terminal tryptic peptide as well as the internal lysyl peptide fragment were completely identical to the deduced amino acid sequences. The pattern of identity of amino acid sequences was quite evident in the regions that include structurally and functionally important residues of Bacillus subtilis thermolysin. 相似文献
4.
Evaluation of Superoxide Scavenging Activities of Hamamelis Extract and Hamamelitannin 总被引:2,自引:0,他引:2
Hamamelitannin, which is a component of bark extract of hamamelis (Hamamelis virginior L.), was found to be a potent scavenger of superoxide anion radicals. Superoxide anion scavenging activity of the compound was evaluated by ESR-spin trap method using DMPO (5,5'-dimethyl-1-pyrroline-N-oxide) as a spin trapping agent. The IC50 value (the concentration producing 50% inhibition of superoxide anion radicals) of hamamelitannin was found to be 1.38 ± 0.06 μM much lower than that of ascorbic acid (23.31 ± 2.23 μM). Supporting the superoxide scavenging activity of hamamelitannin, the compound showed both suppresive ability against depolymelization of hyaluronic acid and protective ability against cytotoxicity induced by superoxide anion radicals. Hamamelitannin increased the survival rate of fibroblast to 85.5 ± 3.3%, compared with that of control (27.2 ± 4.3%). 相似文献
5.
M Nakazato S Ikeda K Shiomi S Matsukura K Yoshida H Shimizu T Atsumi K Kangawa H Matsuo 《FEBS letters》1992,306(2-3):206-208
A novel variant transthyretin which contains a leucine-for-valine substitution at position 30 was isolated and identified in the serum of a patient with familial amyloidotic polyneuropathy (FAP). The amino acid substitution was proven to result from a guanine-to-cytosine change at the first base of codon 30 located in exon 2 in the mutated transthyretin gene by restriction fragment length analysis on the amplified transthyretin gene using Cfr13 I. The study indicates that the point mutation of the transthyretin gene is a cause of the disorder. 相似文献
6.
Toshiro Oridate Haruhisa Atsumi Satishi Ito Hajime Araki 《Plant Cell, Tissue and Organ Culture》1992,29(1):27-30
Significant differences in somatic embryogenesis from melon seeds were observed among 18 cultivars; especially, cultivars Earl's Favorite and Barnett which produced a large number of somatic embryos. F1 seeds were obtained by reciprocal crosses between cultivars. Some lines produced a large number of somatic embryos whereas others showed no or poor embryogenic response. Most of the F1 seeds formed somatic embryos. The frequency of somatic embryogenesis decreased as compared to the parents with the highest potential. Transfer of the frequency of somatic embryogenesis from superior responding cultivars to inferior cultivars was proved. It was difficult to determine the mode of inheritance of somatic embryogenesis because there was a large variation in the range of somatic embryogenesis from F2 seeds, and cytoplasmic effect was recognized in certain combinations.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- BAP
6-benzylaminopurine 相似文献
7.
Cultured crown gall cells were irradiated with gamma rays toinduce mutation in indoleacetic acid biosynthesis. The irradiatedcells were plated on a selection medium which contained auxin.Mutant cells adapted to selection media were characterized asauxin-heterotrophic and auxin-resistant cell lines. The auxin-heterotrophicmutants contained little auxin, whereas the auxin-resistantand -autotrophic mutants contained large amounts of auxin evenwhen cultured with 0.3 ppm of 2,4-dichlorophenoxyacetic acid.Each mutant cell line contained as much octopine as its parentalcells. The mutation rate was calculated as in the order of 108. (Received May 6, 1980; ) 相似文献
8.
Masatoshi Takeichi Tadao Atsumi Chikako Yoshida Kazuko Uno T.S. Okada 《Developmental biology》1981,87(2):340-350
The specificity of adhesion between embryonal carcinoma cells and fibroblastic cells of various origins was studied. Embryonal carcinoma cells have intercellular adhesion sites requiring Ca2+ (CDS). These sites were found to be sensitive to proteases but resistant to them in the presence of Ca2+. CDS with a similar protease sensitivity is present in fibroblastic cells. When embryonal carcinoma cells of different lines were mixed, they adhered to each other nonselectively by CDS. Nonselective adhesion by CDS occurred also between fibroblastic cells of various lines. When embryonal carcinoma and fibroblastic cells were mixed, they preferentially adhered to homotypic cells. Fab fragments of antibodies raised against F9 cells (a nullipotent line of embryonal carcinoma) inhibited the adhesion between embryonal carcinoma cells but not between fibroblastic cells. This inhibitory activity of Fab was absorbed with embryonal carcinoma cells with CDS, but not with fibroblastic cells with CDS or embryonal carcinoma cells from which CDS was experimentally removed. SDS-polyacrylamide gel electrophoresis of radioiodinated cell surface proteins showed that the presence of a 140K-dalton component correlated with the presence of CDS in embryonal carcinoma cells, while the presence of a 150K-dalton component correlated with the presence of CDS in fibroblastic cells. These results suggest that CDS in embryonal carcinoma and fibroblastic cells comprise distinct molecules. 相似文献
9.
Morphological features of an endangered Japanese strain of Cyprinus carpio: reconstruction based on seven SNP markers 下载免费PDF全文
Morphological analyses of 183 specimens of Japanese common carp Cyprinus carpio (171 from Lake Biwa and 12 from nursery ponds) using genetic hybrid indices demonstrated that the typical native Japanese strain of C. carpio has a more elongate body, more branched dorsal‐fin rays, fewer and shorter gill rakers, more developed pneumatic bulb, more coiled pneumatic duct, longer posterior swimbladder and shorter intestine than the typical introduced C. carpio. These results provide a basis for a better understanding of the ecological characteristics and taxonomic status of the endangered Japanese strain of C. carpio. 相似文献
10.
Incisor abnormalities such as loss of enamel color, hypoplasia of enamel, shortening and lengthening, irregular shape of edge, and fracture were often observed in SAM-P/2/Iw (senescence accelerated mouse-prone) more than 12 months old. On the other hand, for SAM-R/1/lw (control) mice more than 20 months old, there were only a few instances of loss of enamel color. The incidence of incisor abnormality was significantly different between P/2/Iw and R/I/Iw. The onset of abnormality was also earlier in P/2/Iw. Histologically, dens in dente and odontoma-like structures were occasionally found in the incisors of P/2/Iw. These findings add further supporting evidence that SAM-P/2/Iw is truly senescence accelerated. 相似文献