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81.
82.
M Kuwabara K Tanabe W Hiraoka Y Tamura F Sato A Matsuda T Ueda 《Chemico-biological interactions》1991,79(3):349-358
The exposure of log-phase Chinese hamster V79 cells to 2-chlorodeoxyadenosine (CdA) for 3 h after X irradiation enhanced the lethal effects of X-rays in a concentration-dependent manner. The enhancement of the killing efficiency of X-rays by CdA was mainly observed in the reduction of quasi-threshold doses (Dq) of the dose-response curves. When the ability of CdA to inhibit the repair of X-ray-induced double- and single-strand breaks (dsb and ssb) of DNA was investigated by neutral- and alkaline-filter elution techniques, respectively, it was observed that 90% of dsb were rejoined in the absence of CdA within 30 min after X irradiation and 15-40% of dsb rejoining was suppressed by co-incubation of the cells with 5-10 microM of CdA for 3 h after X irradiation, whereas almost 100% of ssb were rejoined within 15 min regardless of the presence or absence of CdA. From these results it was concluded that CdA interfered exclusively with the repair of DNA dsb in X-irradiated Chinese hamster V79 cells and thereby increased the lethality of X-rays. 相似文献
83.
T Mizuno K Kaibuchi S Ando T Musha K Hiraoka K Takaishi M Asada H Nunoi I Matsuda Y Takai 《The Journal of biological chemistry》1992,267(15):10215-10218
The superoxide-generating NADPH oxidase system in phagocytes consists of at least membrane-associated cytochrome b558 and three cytosolic components named SOCI/NCF-3/sigma 1/C1, SOCII/NCF-1/p47-phox, and SO-CIII/NCF-2/p67-phox. p47-phox and p67-phox were isolated, and their primary structures were determined, but SOCI has not been well characterized. In the present study, we first purified SOCI to homogeneity from the cytosol fraction of the differentiated HL-60 cells. The purified SOCI was a small GTP-binding protein (G protein) with a M(r) of about 22,000. The guanosine 5'-(3-O-thio)triphosphate-bound form, but not the GDP-bound form, of this small G protein showed the SOCI activity. The partial amino acid sequence of SOCI thus far determined was identical to the amino acid sequence deduced from the cDNA encoding rac2 p21. None of the purified small G proteins, including Ki-ras p21, smg p21B/rap1B p21, rhoA p21, and rac1 p21, showed the SOCI activity. These results indicate that SOCI is a small G protein very similar, if not identical, to rac2 p21. The GDP/GTP exchange reaction of SOCI was stimulated and inhibited by stimulatory and inhibitory GDP/GTP exchange proteins for small G proteins, named smg GDS and rho GDI, respectively. The NADPH oxidase activity was also stimulated and inhibited by smg GDS and rho GDI, respectively. These results indicate that the superoxide-generating NADPH oxidase system is regulated by both smg GDS and rho GDI through rac2 p21 or the rac2-related small G protein in phagocytes. 相似文献
84.
Masashi Fujiwara Keiko Fukushi Mitsuo Takai Jisuke Hayashi Masahiro Fukaya Hajime Okumura Yoshiya Kawamura 《Biotechnology letters》1992,14(7):539-542
Summary Shuttle vector pUF106 was constructed by ligation ofAcetobacter xylinum plasmid pFF6 toEscherichia coli plasmid pUC18. It had unique restriction sites suitable for insertion of a foreign DNA fragment and conferred ampicillin resistance to a host. pUF106 transformed cellulose-producingA. xylinum ATCC10245 as well asE. coli JM109. 相似文献
85.
86.
Koji Sode Masahiro Tatara Haruko Takeyama J. Grant Burgess Tadashi Matsunaga 《Applied microbiology and biotechnology》1992,37(3):369-373
Summary Versatility of gene transfer by transconjugation in marine cyanobacteria was demonstrated. In this study, seven different marine cyanobacteria were used as recipient cells. First, transconjugation was carried out using the mobilizable transposon (Tn5) carrying plasmid pSUP1021. Transconjugants were observed in all marine cyanobacteria tested. Second, the broad-host-range vector pKT230 (IncQ) was tested for transconjugation. pKT230 has been successfully transferred in a marine cyanobacterium Synechococcus sp. NKBG15041C, and replicated as an autonomous replicon without alteration in the restriction enzyme pattern. A maximum transfer efficiency of 5.2 × 10–4 transconjugants/recipient cell was observed, when mating was performed on agar plates containing low salinity (0.015 m NaCl) medium. This is the first study to demonstrate gene transfer in marine cyanobacteria via transconjugation.
Correspondence to: K. Sode 相似文献
87.
88.
We report here about an antigen that is expressed in the central nervous system (CNS) of Drosophila only during the embryonic and metamorphic stages. In Drosophila, axonogenesis and synaptogenesis occur twice during the development: first in the embryonic and second in the metamorphic stages. We generated monoclonal antibodies (MAbs) in order to obtain molecular probes for analyzing axonogenesis or synaptogenesis in the CNS on the assumption that good candidates for molecules responsible for such phenomena must be present in the neuropil during those stages exclusively. As a result, we found MAb 66B2 whose intense immunoreactivity in the neuropil of the CNS was observed exclusively in the embryo and pupa, and not in the larva and adult. Immunoblot analyses showed that MAb 66B2 binds specifically to a protein with an apparent molecular weight of 350 K and neutral pl in the prepupal CNS. A significant amount of the antigen was isolated in forms that were soluble without detergent. Results of immunohistochemistry with MAb 66B2 in a primary culture of embryos showed that some live cells in the ganglion-like cluster were stained, and that neuronal cell bodies and neurites emanating from there were negative. These results strongly suggest that the 66B2 antigen observed in the CNS is an extracellular matrix component secreted from nonneuronal cells. These developmental changes in the 66B2 immuno-reactivity in the CNS presumably reflect dynamic changes of an extracellular matrix in the CNS that are accompanied by axonogenesis or synaptogenesis. © 1992 John Wiley & Sons, Inc. 相似文献
89.
A wasp venom, mastoparan, rapidly increased the cytosolic free Ca2+ concentration ([Ca2+]i) and activated phosphorylase in rat hepatocytes in a concentration-dependent manner. Mastoparan could increase [Ca2+]i even in the absence of extracellular Ca2+, but a larger increase was observed in the presence of extracellular Ca2+. Thus, mastoparan mobilized Ca2+ from intracellular and extracellular Ca2+ stores. It also activated inositol triphosphate (IP3) accumulation, but did not stimulate cAMP production. From these results, we conclude that mastoparan activates rat hepatic glycogenolysis mediated by the accumulation of IP3, which causes an increase of [Ca2+]i but not that mediated by cAMP. 相似文献
90.
Yoshiya Sato Hiromu Toma Masahiro Takara Yoshiyuki Shiroma 《International journal for parasitology》1990,20(8):1025-1029
The enzyme-linked immunosorbent assay was tested to evaluate whether it could be applicable in screening for mass examination of strongyloidiasis. A total of 2906 inhabitants in three areas (858 in Gushikawa Village, 849 in Nakazato Village and 1199 in Sashiki Town) were screened by the enzymatic assay and approximately 11–30% (11.8% in Gushikawa, 17.0% in Nakazato and 27.7% in Sashiki) were considered to be antibody positive. In the parasitological follow-up examinations of those who were antibody positive, actual infection was found in more than half (51%) the subjects. The overall infection rates estimated from the results reached 5.8% in Gushikawa, 9.1% in Nakazato and 14.0% in Sashiki (mean = 10.4%). The infection rates were significantly higher than those in previous surveys conducted in the same areas. The ELISA technique was found to be useful for strongyloidiasis screening and for seroepidemiological purposes in Okinawa. 相似文献