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101.
102.
Complete genome structure of the thermophilic cyanobacterium Thermosynechococcus elongatus BP-1. 总被引:6,自引:0,他引:6
Yasukazu Nakamura Takakazu Kaneko Shusei Sato Masahiko Ikeuchi Hiroshi Katoh Shigemi Sasamoto Akiko Watanabe Mayumi Iriguchi Kumiko Kawashima Takaharu Kimura Yoshie Kishida Chiaki Kiyokawa Mitsuyo Kohara Midori Matsumoto Ai Matsuno Naomi Nakazaki Sayaka Shimpo Masako Sugimoto Chie Takeuchi Manabu Yamada Satoshi Tabata 《DNA research》2002,9(4):123-130
103.
There are several pathways leading to apoptosis. It is not clear whether cells choose one of them or use multiple processes when they commit to apoptosis. MOLT-4 cells undergo apoptosis after X-irradiation through the p53-dependent pathway and/or ceramide signal. To evaluate the relative contribution of these pathways, we studied effects of the expression of various levels of transfected murine mutant p53 cDNA (TGC-->CGC of codon 173, corresponding to codonl76 in human p53) on the induction of apoptosis in X-irradiated or heated MOLT-4 cells. When survival was determined by the dye-exclusion test at 24 h after irradiation, the percentage of X-ray- or heat-induced dead cells was markedly decreased, depending on the expression level of mutant p53 protein in transfected clones. The appearance of apoptotic cells as determined by morphological changes was also decreased. These inhibitions were almost complete at 24 h after irradiation with X-rays in the case of the highest-expressing clone. p21 WAF1 protein was increased in MOLT-4 cells after X-irradiation, but not in the transfectant. These results suggest that murine mutant p53 protein has a dominant-negative effect against normal p53 in MOLT-4, and that the X-ray-induced apoptosis in MOLT-4 is fully p53-dependent. 相似文献
104.
The Native Form and Maturation Process of Hepatitis C Virus Core Protein 总被引:28,自引:5,他引:23 下载免费PDF全文
Kohichiroh Yasui Takaji Wakita Kyoko Tsukiyama-Kohara Shin-Ichi Funahashi Masumi Ichikawa Tadahiro Kajita Darius Moradpour Jack R. Wands Michinori Kohara 《Journal of virology》1998,72(7):6048-6055
The maturation and subcellular localization of hepatitis C virus (HCV) core protein were investigated with both a vaccinia virus expression system and CHO cell lines stably transformed with HCV cDNA. Two HCV core proteins, with molecular sizes of 21 kDa (p21) and 23 kDa (p23), were identified. The C-terminal end of p23 is amino acid 191 of the HCV polyprotein, and p21 is produced as a result of processing between amino acids 174 and 191. The subcellular localization of the HCV core protein was examined by confocal laser scanning microscopy. Although HCV core protein resided predominantly in the cytoplasm, it was also found in the nucleus and had the same molecular size as p21 in both locations, as determined by subcellular fractionation. The HCV core proteins had different immunoreactivities to a panel of monoclonal antibodies. Antibody 5E3 stained core protein in both the cytoplasm and the nucleus, C7-50 stained core protein only in the cytoplasm, and 499S stained core protein only in the nucleus. These results clearly indicate that the p23 form of HCV core protein is processed to p21 in the cytoplasm and that the core protein in the nucleus has a higher-order structure different from that of p21 in the cytoplasm. HCV core protein in sera of patients with HCV infection was analyzed in order to determine the molecular size of genuinely processed HCV core protein. HCV core protein in sera was found to have exactly the same molecular weight as the p21 protein. These results suggest that p21 core protein is a component of native viral particles. 相似文献
105.
Thyroid hormone directly induces hepatocyte competence for estrogen-dependent vitellogenin synthesis during the metamorphosis of Xenopus laevis 总被引:3,自引:0,他引:3
Hepatocytes competent for estrogen-dependent vitellogenin synthesis appeared and increased in number in the liver at the metamorphic climax of Xenopus laevis (A. Kawahara, S. Kohara, Y. Sugimoto, and M. Amano, 1987, Dev. Biol. 122, 139-145). The present study was conducted to determine whether cells competent for vitellogenin synthesis could be induced by thyroid hormone in a primary culture of larval hepatocytes. The thyroid hormone, triiodothyronine (T3), directly induced the competent cells in a primary culture of premetamorphic larval hepatocytes in a dose- and duration-dependent manner. The competency acquired in response to T3 persisted after removal of the hormone. Aphidicholin, an inhibitor of DNA synthesis, failed to block this induction, suggesting the presence of a "precursor cell fraction." This cell fraction in the hepatocyte population increased with the progress of metamorphosis. The thyroid hormone is thus considered the cause of competent cell formation at metamorphic climax. 相似文献
106.
Yasukazu Nakamura Takakazu Kaneko Shusei Sato Masahiko Ikeuchi Hiroshi Katoh Shigemi Sasamoto Akiko Watanabe Mayumi Iriguchi Kumiko Kawashima Takaharu Kimura Yoshie Kishida Chiaki Kiyokawa Mitsuyo Kohara Midori Matsumoto Ai Matsuno Naomi Nakazaki Sayaka Shimpo Masako Sugimoto Chie Takeuchi Manabu Yamada Satoshi Tabata 《DNA research》2002,9(4):135-148
107.
We determined map positions of the Escherichia coli K-12 portions of a subset of the hybrid E. coli-ColE1 plasmids constructed by Clarke and Carbon. The probe DNA of pLC plasmids was labeled with digoxigenine-dUTP, hybridized to the 476 phage clones of the E. coli ordered clone bank miniset, which was adsorbed on a strip of nylon membrane filters, and detected by enzyme-linked immunoassay and a subsequent enzyme-catalyzed color reaction. The total number of Clarke-Carbon plasmids we analyzed was 518, for which chromosomal locations of 297 clones were newly determined in the present study. Another 180 plasmids gave results that agreed with those reported previously, and the remaining 41 plasmids gave map positions different from those described in the previous report. A chromosome map of E. coli which shows the locations of 518 pLC plasmids on it is presented, as well as a table which correlates the pLC plasmids with the clones of the E. coli ordered clone bank miniset on the basis of the hybridization data. We estimate that approximately one-half of the entire genome of E. coli was covered by the pLC plasmids used in this study. 相似文献
108.
The mechanism of initiation of translation on hepatitis C virus (HCV) RNA was investigated in vitro. HCV RNA was transcribed from the cDNA that corresponded to nucleotide positions 9 to 1772 of the genome by using phage T7 RNA polymerase. Both capped and uncapped RNAs thus transcribed were active as mRNAs in a cell-free protein synthesis system with lysates prepared from HeLa S3 cells or rabbit reticulocytes, and the translation products were detected by anti-gp35 antibodies. The data indicate that protein synthesis starts at the fourth AUG, which was the initiator AUG at position 333 of the HCV RNA used in this study. Efficiency of translation of the capped methylated RNA appeared to be similar to that of the capped unmethylated RNA. However, a capped methylated RNA showed a much higher activity as mRNA than did the capped unmethylated RNA in rabbit reticulocyte lysates when the RNA lacked a nucleotide sequence upstream of position 267. The results strongly suggest that HCV RNA carries an internal ribosome entry site (IRES). Artificial mono- and dicistronic mRNAs were prepared and used to identify the region that carried the IRES. The results indicate that the sequence between nucleotide positions 101 and 332 in the 5' untranslated region of HCV RNA plays an important role in efficient translation. Our data suggest that the IRES resides in this region of the RNA. Furthermore, an IRES in the group II HCV RNA was found to be more efficient than that in the group I HCV RNA. 相似文献
109.
Identification of a homeobox-containing gene located between lin-45 and unc-24 on chromosome IV in the nematode Caenorhabditis elegans. 下载免费PDF全文
Using two primers corresponding to helix 1 and helix 3 regions in the homeodomain, we subjected genomic DNA from Caenorhabditis elegans to amplification by the polymerase chain reaction. Sequence analysis of the amplified products revealed a new homeobox-containing gene, designated ceh-19. This gene was located between lin-45 and unc-24 on chromosome IV where no homeogene has previously been mapped. 相似文献
110.
[16 alpha-2H]Pregnenolone was synthesized by catalytic deuteriation of 3 beta-hydroxy-5,16-pregnadien-20-one followed by base-catalyzed back exchange of the 17 alpha-2H atom, and [16 beta-2H]pregnenolone by catalytic hydrogenation of 3 beta-hydroxy-5,16-[16-2H]pregnadien-20-one, which had been synthesized from [16,16-2H]dehydroepiandrosterone. The labelled pregnenolones were incubated separately with the microsomal fraction of boar testis. The metabolites were analyzed by gas chromatography-mass spectrometry, and the isotope compositions of the following six metabolites were determined: 17-hydroxypregnenolone, dehydroepiandrosterone, 5-androstene-3 beta,17 alpha-diol, 5-androstene-3 beta,17 beta-diol,16 alpha-hydroxypregnenolone and 5,16-androstadien-3 beta-ol. The first four metabolites derived either from [16 alpha-2H]- or from [16 beta-2H]pregnenolone showed essentially the same isotope compositions as those of their respective precursors. The 16 alpha-hydroxypregnenolone and the 5,16-androstadien-3 beta-ol biosynthesized from [16 alpha-2H]pregnenolone lost the 2H label, while the same metabolites biosynthesized from [16 beta-2H]pregnenolone retained the albel. The result shows that the 16 alpha-hydrogen is stereospecifically removed with the retention of the 16 beta-hydrogen in the biosynthesis of 5,16-androstadien-3 beta-ol. 相似文献