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排序方式: 共有637条查询结果,搜索用时 15 毫秒
1.
The effects of delayed mating on mouse preimplantation embryos (78 ± 1 hours) were studied by setting up different mating periods in relation to the estimated time of spontaneous ovulation. Copulation occurred even in the late morning and early afternoon after the night of spontaneous ovulation. However, females mated in the early afternoon had no viable embryos at the time of laparotomy. Although embryonic development was not affected in the groups mated 6 or 10 hours after estimated ovulation, the percentage of degenerated embryos was increased in these groups. These results suggest that prolonged intervals between the estimated time of ovulation and mating have some deleterious effects on preimplantation embryos. 相似文献
2.
Xiao-chun Liang Nobuyoshi Hagino Sai-shan Guo Taiki Tsutsumi Shinjiro Kobayashi 《Phytomedicine》2002,9(5):377-384
The present study was designed to examine therapeutic efficacy of the root extract of Stephania Tetrandra S. Moore (STMS) (traditional Chinese medicine; Han Fang Ji) for treatment of neovascularization of the retinal capillary (retinopathy) in streptozotocin (STZ)-induced diabetic rats (STZ diabetic rats) in culture. Recently we have established the culture system in which fetal bovine serum (FBS) in Dulbecco modified Eagle medium (DMEM) induced neovascularization of the retinal capillary and choroidal capillary in normal rats in culture. STZ diabetic rats showed more neovascularization of the retinal capillary and choroidal capillary than did normal rats in culture. In this study, the retinal tissue was removed for the posterior ocular region and cultured in DMEM containing FBS. The choroidal tissue of the posterior ocular region was also removed and cultured as an internal reference. Administration of STSM (0.91, 9.1 and 91 microg/ml) significantly suppressed neovascularization of the retinal capillary in both STZ diabetic rats and normal rats in a dose-dependent manner. Similar results were obtained with the choroidal capillary; administration of STSM suppressed neovascularization of the choroidal capillary in both STZ diabetic rats and normal rats. In order to determine the component of STSM inhibiting neovascularization of the retinal capillary, tetrandrine (a major chemical constituent of STSM) was administered and neovascularization of the retinal capillary was examined in culture. The effect of tetrandrine on the choroidal capillary was also examined as an internal reference. Administration of tetrandrine (0.1, 1.0 and 10 microM) suppressed neovascularization of the retinal capillary in both STZ diabetic rats and normal rats in a dose-dependent manner. Similar results were obtained with the choroidal capillary of both STZ diabetic rats and normal rats. We infer, therefore, that STSM has a direct effect on the retinal capillary of posterior ocular region and suppresses neovascularization of retinal capillary in STZ diabetic rats through the activation of tetrandrine. These results suggest that STSM may prevent for delay the progression of retinopathy in diabetic patients. 相似文献
3.
Satoshi Yamanaka Akiko Hagiwara Yukimasa Nishimura Hiroshi Tanabe Nobuyoshi Ishibashi 《Archives of microbiology》1992,158(6):387-393
The symbiotic bacterium strain, SK-1 isolated from Steinernema kushidai, a new species of entomopathogenic nematode, was compared with other strains of Xenorhabdus species. Like other Xenorhabdus nematophilus strains, this new strain is gram-negative, facultatively anaerobic, peritrichously flagellated rod and negative for catalase and nitrate reduction. It can be distinguished from the other Xenorhabdus spp. by differences in reactions to phenylalanine deaminase, no acid production from myo-inositol and utilizations of inosine, dl-malate, formate and methanol. Intra-haemocoelic injection of actual cells or liquid culture supernatant into sixth instar larvae of Spodoptera litura for either Phase I or II variants were not pathogenic. Other strains of X. nematophilus showed pathogenicity for whole cell injections. The supernatants of strain D-1 and ATCC 19061, which are symbionts of Steinernema carpocapsae were pathogenic, however pathogenicity decreased and then terminated by increases in temperature. 相似文献
4.
1-Aminocyclopropane-1-carboxylate (ACC) synthase, which formsAGC from S-adenosylmethionine (SAM), was purified to homogeneityfrom sliced and aged mesocarp tissue of Cucurbita maxima Duch.cv Ebisu fruits, and its enzymatic properties were determined.The specific activity of the purified enzyme was 220 mU/mg proteinat 30°C at 50 µM SAM. Native ACC synthase has a relativemolecular mass of 160 ± 10 kDa and consisted of two subunitsof about 84±3 kDa. S-adenosylhomocysteine (SAH), S-methylmethionine(SMM) and L-methionine did not serve as substrate. The enzymereaction was competitively inhibited by aminoethoxyvinylglycine(AVG) (Ki, 2.5 µM), aminooxyacetic acid (Ki, 40 µM)and SAH (Ki, 30 µM). The reaction was also strongly inhibitedby semicarbazide, and less effectively by homocysteine. Theenzyme was rapidly inactivated by its substrate, SAM in thepresence of pyridoxalphosphate (PLP), but in the absence ofPLP, SAM-induced inactivation was much slower. Inactivationdid not occur by SAH and SMM, SAM analogs without substrateactivity. Pyridoxal phosphate was an essential cofactor to beadded to a reaction mixture for maximum activity, but an enzymepreparation from which pyridoxal phosphate was removed by SephadexG-25 gel filtration exhibited one-eighth activity which wasinhibited by semicarbazide, this indicating that a small amountof pyridoxal phosphate is firmly bound to the enzyme. (Received May 6, 1986; Accepted May 20, 1986) 相似文献
5.
The properties and application of l-methionine γ-lyase [methioninase, l-methionine methanethiol-lyase (deaminating), EC 4.4.1.11], a pyridoxal 5′-phosphate enzyme, purified from Pseudomonas putida and Aeromonas sp. are presented. The enzyme has multicatalytic functions: it catalyses α,γ-elimination and γ-replacement reactions of l-methionine and its analogues (e.g. ethionine, homocysteine, O-acetylhomoserine and selenomethionine), α,β-elimination and β-replacement reactions of l-cysteine and its analogues (e.g. S-methylcysteine, O-acetylserine and Se-methylselenocysteine), deamination and γ-addition of vinylglycine, and deuterium labelling at the α and β positions of l-methionine and other straight-chain l-amino acids. These reactions are applicable to the synthesis of various optically active sulphur and selenium amino acids, preparation of deuterium or tritium labelled l-amino acids, and determination of sulphur amino acids. In addition, the enzyme shows potent anti-neoplastic activity. 相似文献
6.
7.
Ken-ichi Ishiwata Tadashi Suzuki Satoru Iwamori Setsuo Yoshino Nobuyoshi Makiguchi 《Biotechnology letters》1990,12(3):185-190
Summary The tryptophan synthase genes,trpA andtrpB, from a moderate thermophile,Bacillus
stearothermophilus IFO13737, were expressed efficiently inEscherichia
coli. The recombinant tryptophan synthase amounted to 22% of the soluble cellular protein, and was purified to homogeneity by three steps. The enzyme is more thermostable thanE.coli tryptophan synthase, especially the subunit. The enzyme is also more resistant to sodium dodecylsulfate and methanol thanE.coli enzyme. 相似文献
8.
Bae Gong Young; Nakajima Nobuyoshi; Ishizuka Kozo; Kondo Noriaki 《Plant & cell physiology》1996,37(2):129-134
The rate of evolution of ethylene by tomato plants was rapidlyincreased by O3 fumigation. The time course of the increasein 1-aminocyclopropane-1-carboxylic acid (ACC) synthase activitywas the same as that in the rate of evolution of ethylene, suggestingthat ACC synthase activity might be a rate-limiting step inthe evolution of ethylene that is caused by O3 fumigation. Therate of the O3-induced evolution of ethylene was increased bythe application of ACC to tomato plants, suggesting the involvementof ACC oxidase in the O3-induced evolution of ethylene. Treatmentof plants with tiron inhibited the evolution of ethane, butnot of ethylene. These results indicated that evolution of ethylenein O3-treated tomato plants might result from enzymatic reactionscatalyzed by both ACC synthase and ACC oxidase, but not fromstimulation by O3 of the peroxidation of lipids mediated byfree radicals. Pretreatment of leaves with aminoethoxyvinylglycine (AVG), aninhibitor of ACC synthase, significantly inhibited the evolutionof ethylene that was induced by O3 and concomitantly reducedthe extent of O3-induced visible damage to leaves. Treatmentwith 2,5-norbonadiene, an inhibitor of the action of ethylene,strongly reduced the extent of visible damage caused by O3,even though it did not suppress the evloution of ethylene. Theseresults indicate that ethylene acts on certain metabolic processesto cause visible damage. (Received September 7, 1995; Accepted December 18, 1995) 相似文献
9.
Takeuchi Yuichi; Murakami Mina; Nakajima Nobuyoshi; Kondo Noriaki; Nikaido Osamu 《Plant & cell physiology》1996,37(2):181-187
Photoinduced lesions in DNA, namely, cyclobutane pyrimidinedimers (CPDs) and pyrimidine-(6-4)-pyrimidone photoproducts[(6-4)photoproducts], in cucumber cotyledons that had been irradiatedwith naturally occurring levels of UV-B (290320 nm) werequantitated by enzyme-linked immunosorbent assays with monoclonalantibodies specific to each type of photolesion. Induction ofthese photolesions was dependent on temperature and their extentwas reduced by simultaneous irradiation with white light. Thedark repair of both types of photolesion was undetectable. Light-dependentremoval of (6-4)photoproducts was very slow, with 50% removalin 4 h. By contrast, 50% of initial CPDs were removed within15 min. Both photorepair processes were dependent on the intensityof white light and were sensitive to temperature. These resultsindicate that high photolyase activity is present in cucumbercotyledons and that repair activities in cucumber cotyledonsare different from those reported in Arabidopsis, in which (6-4)photoproductsare photorepaired more rapidly than CPDs. (Received October 13, 1995; Accepted December 28, 1995) 相似文献
10.
Hirobumi Suzuki Yasushi Sato Shizuo Fujiyama Nobuyoshi Ohba 《Biochemical genetics》1996,34(5-6):191-200
Japanese fireflies of the subfamily Luciolinae are biochemically analyzed using 13 allozymes, and the phylogenetic relationships obtained from this analysis are compared with their flash communication systems. As a result, the Japanese Luciolinae can be divided into three groups.Hotaria parvula andH. tsushimana together withLuciola yayeyamana andL. kuroiwae from the first group, and they use the same communication system.L. lateralis, Curtos okinawana, andC. costipennis make up the second group, and their communication systems are also the same.L. cruciata makes up the last one, and its communication system is different from the other fireflies of Luciolinae. Therefore, their taxonomical arrangement and communication systems are not congruent. However, the genetic similarity deduced by allozymic analysis of the members of the Japanese Luciolinae is highly consistent with their flash communication systems. 相似文献