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51.
Yahata Y Shirakata Y Tokumaru S Yamasaki K Sayama K Hanakawa Y Detmar M Hashimoto K 《The Journal of biological chemistry》2003,278(41):40026-40031
52.
Ohtaki A Iguchi A Mizuno M Tonozuka T Sakano Y Kamitori S 《Carbohydrate research》2003,338(15):1553-1558
Thermoactinomyces vulgaris R-47 produces two alpha-amylases, TVAI and TVAII, differing in substrate specificity from each other. TVAI favors high-molecular-weight substrates like starch, and scarcely hydrolyzes cyclomaltooligosaccharides (cyclodextrins) with a small cavity. TVAII favors low-molecular-weight substrates like oligosaccharides, and can efficiently hydrolyze cyclodextrins with various sized cavities. To understand the relationship between the structure and substrate specificity of these enzymes, we precisely examined the roles of key residues for substrate recognition by X-ray structural and kinetic parameter analyses of mutant enzymes and successfully obtained mutants in which the substrate specificity of each enzyme is partially converted into that of another. 相似文献
53.
Kiguchi K Ishiwata I Tokieda Y Iguchi M Ishiwata C Iwata M Ishizuka B Yoshikawa H Tachibana T Hashimoto H Ishikawa H 《Human cell》2002,15(2):97-102
A cell line designated HUUCLEC was established from a human uterine cervical lymphoepithelial carcinoma obtained from a 61-year-old Japanese woman. The cell line has grown slowly without interruption and serial passages were successively carried out 60 times within 3 years. The cultured cells were spindle or round in shape, showing anaplastic and pleomorphic features, a pavement cell arrangement and multilayering without contact inhibition. The population doubling time of the HUUCLEC line was 72 hours while the chromosomal number varied widely and showed aneuploidy. The modal chromosomal number was stable at the triploid range and marker chromosomes were present; the Ebstein-Barr virus was absent in the cultured cells. 相似文献
54.
Larvae of the bamboo borer, Omphisa fuscidentalis, enter larval diapause in September and pupate in the following June (Singtripop et al., 1999). We examined the changes in the responses of larvae to exogenous 20-hydroxyecdysone (20E) in order to estimate the progress of diapause development. In this respect, we adopted two terms, responsiveness and sensitivity of larvae to 20E. Responsiveness was estimated by the percentage of larvae that pupated, and sensitivity was evaluated by the duration from the day of 20E injection to pupation. The responsiveness of larvae declined gradually from September to November when larvae were least responsive to 20E, and then increased markedly from January to February. This indicates that the intensity of diapause increases from September to November and terminated gradually thereafter. Thus the sequence of events as the larval responses to 20E is characterized by a V-shaped curve. Sensitivity of larvae to 20E was at the same level from September to December, and increased remarkably from December to January. The abrupt increase in the sensitivity occurred one month earlier than the bottom of the V-shaped curve of larval responsiveness, suggesting that the increases in the responsiveness and sensitivity in the latter half of diapause may be brought about by respective mechanisms. 相似文献
55.
Osamu Katano Yoshimasa Aonuma Kei’ichiroh Iguchi Taiga Yodo Naoto Matsubara 《Ichthyological Research》2003,50(4):349-357
Response to predators may not be identical between different prey species with different life histories and body sizes, particularly when the threat of predation is not great. To clarify this hypothesis, we introduced two prey species (10 Japanese dace, Tribolodon hakonensis, and 10 pale chub, Zacco platypus) into each experimental pond (in total, 8 ponds×4 trials) in which benthic algae had been allowed to grow. The presence or absence of Far Eastern catfish, Silurus asotus, and a refuge for prey fish was used to produce four treatments. The presence of catfish and/or a refuge did not affect either the feeding behavior or growth rate of Japanese dace. In contrast, when catfish were present and no refuge was available, the incidence of bottom feeding for pale chub greatly decreased. Pale chub growth rate was low when catfish were present and a refuge was available, indicating that pale chub spent more of their time in the refuge and lost opportunities of acquiring food. Japanese dace can reach a threshold size at which the prey are safe from predation, but pale chub cannot, and this may explain the differences in response to predators of the two species. 相似文献
56.
Chiba T Li YH Yamane T Ogikubo O Fukuoka M Arai R Takahashi S Ohtsuka T Ohkubo I Matsui N 《Peptides》2003,24(5):773-778
In order to find the most effective antagonist for dipeptidyl peptidase III degrading enkephalin, we synthesized hemorphin-like pentapeptides with aliphatic or aromatic amino acids at the N-termini, such as VVYPW, LVYPW, IVYPW, YVYPW, FVYPW and WVYPW. Among those pentapeptides, IVYPW and WVYPW showed the strongest inhibitory activity toward rDPP III. The K(i) values of IVYPW and WVYPW were 0.100+/-0.011 and 0.126+/-0.015 microM (mean+/-S.E.), respectively. The order of K(i) values was Ile> or =Trp>Phe> or =Tyr>Leu>Ala>Val>Ser>Gly. rDPP III activity is inhibited in a non-competitive manner by these peptides. The peptide VYPW did not inhibit rDPP III activity, but the sequence is essential for the expression of inhibitory activity. 相似文献
57.
Organogenesis of heart-vascular system derived from mouse 2 cell stage embryos and from early embryonic stem cells in vitro 总被引:2,自引:0,他引:2
Regenerative medical treatment with embryonic stem cells (an ES cell) is a goal for organ transplantation. Structures that are tubular in nature (i.e. blood capillaries) were induced from early embryonic stem (EES) cells in vitro using embryotrophic factor (ETFs). In addition, cardiac muscle cells could be identified as well. However, differentiation of EES cells into a complete cardiovascular system was difficult because 3 germ layer primordial organs are directed embryologically in various ways and it is not possible to guide only cardiovascular organs. Thus, we introduced ETFs after the formation of an embryoid body and were successful in cloning cell clusters that beat, thus deriving only cardiovascular organs. The application of this to the treatment of various cardiovascular diseases is promising. 相似文献
58.
We induced acute skeletal muscle necrosis in rats using bupivacaine hydrochloride and found that both 2,5- and 2,3-dihydroxybenzoic acid significantly increased in skeletal muscle. A single administration of dimethyl sulphoxide, a free radical scavenger, significantly lowered concentrations of 2,5- and 2,3-dihydroxybenzoic acid. These results suggest that dimethyl sulphoxide is an effective hydroxyl radical scavenger and may be useful in the treatment of myopathy. 相似文献
59.
Masahiro Hiratochi Akiyori Fujiwara Hiroshi Kitani Taisen Iguchi Teruyo Sakakura Yasuhiro Tomooka 《Development, growth & differentiation》1998,40(1):59-65
Mouse neural precursor cells (NPC) were dissociated from fetal heads at the 10th day of gestation. When clumps of NPC were cultured in collagen gel, they grew and reorganized neural tube-like structures in medium containing fetal calf serum at 10% and supplemented with insulin, transferrin, cholera toxin and selenite. However, dissociated NPC died when they were cultured in collagen gel at low density in the same medium. Addition of fibroblast growth factor-2 (FGF-2) to this culture stimulated growth of NPC and formation of neural tube-like structures. The requirement for FGF-2 disappeared in high seeding density culture: they grew and formed neural tube-like structures without FGF-2. The structures formed in collagen gel were immunohistochemically positive against anti-FGF-2 antibody. The results show that the three-dimensional culture system provides a useful tool to study the roles of FGF-2 in morphogenesis of the central nervous system. 相似文献
60.
Keiko Unno Hiroyuki Yamamoto Masateru Toda Shiori Hagiwara Kazuaki Iguchi Minoru Hoshino Fumiyo Takabayashi Sanae Hasegawa-Ishii Atsuyoshi Shimada Masanori Hosokawa Keiichi Higuchi Masayuki Mori 《Biochemical and biophysical research communications》2014
The senescence-accelerated mouse prone10 (SAMP10) strain, a model of aging, exhibits cognitive impairments and cerebral atrophy. We noticed that SAMP10/TaSlc mice, a SAMP10 substrain, have developed persistent glucosuria over the past few years. In the present study, we characterized SAMP10/TaSlc mice and further identified a spontaneous mutation in the Slc5a2 gene encoding sodium-glucose co-transporter (SGLT) 2. The mean concentration of urine glucose was high in SAMP10/TaSlc mice and increased further with advancing age, whereas other strains of senescence-accelerated mice, including SAMP1/SkuSlc, SAMP6/TaSlc and SAMP8/TaSlc or normal aging control SAMR1/TaSlc mice, exhibited no detectable glucose in urine. SAMP10/TaSlc mice consumed increasing amounts of food and water compared to SAMR1/TaSlc mice, suggesting the compensation of polyuria and the loss of glucose. Oral glucose tolerance tests showed decreased glucose reabsorption in the kidney of SAMP10/TaSlc mice. In addition, blood glucose levels decreased in an age-dependent fashion. The kidney was innately larger than that of control mice with no histological alterations. We examined the expression levels of glucose transporters in the kidney. Among SGLT1, SGLT2, glucose transporter (GLUT) 1 and GLUT2, we found a significant decrease only in the level of SGLT2. DNA sequencing of SGLT2 in SAMP10/TaSlc mice revealed a single nucleotide deletion of guanine at 1236, which resulted in a frameshift mutation that produced a truncated protein. We designate this strain as SAMP10/TaSlc-Slc5a2slc (SAMP10-ΔSglt2). Recently, SGLT2 inhibitors have been demonstrated to be effective for the treatment of patients with type 2 diabetes (T2D). SAMP10-ΔSglt2 mice may serve as a unique preclinical model to study the link between aging-related neurodegenerative disorders and T2D. 相似文献