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排序方式: 共有376条查询结果,搜索用时 15 毫秒
1.
Latitudinal comparison of altitudinal changes in forest structure,leaf-type,and species richness in humid monsoon Asia 总被引:10,自引:0,他引:10
M. Ohsawa 《Plant Ecology》1995,121(1-2):3-10
A new template for mountain vegetation zonation along latitudinal gradients is proposed for examining geographical pattern of various forest attributes in humid monsoon Asia. The contrasting temperature regime in tropical and temperate mountains, i.e., the former is a non-seasonal, temperature-sum controlled environment, and the latter is a seasonal, low temperature limiting environment, leads to different altitudinal patterns of tree height distribution and species richness. In the tropical mountains, both tree height and species richness decrease steeply, and the tree height often stepwise. The decline of tree height and species diversity in the temperate mountains is far less pronounced except near the forest limit. Both trends are explained by their temperature regime. 相似文献
2.
Ayumi Fujisawa Takaharu Abe Ikuro Ohsawa Kouichi Kamogawa Yoshikazu Izumi 《FEMS microbiology letters》1993,110(1):1-4
Abstract Potassium-limited cultures of Candida utilis grown with ammonium chloride as the sole nitrogen source attained a higher dry weight than similar cultures grown with sodium nitrate as the sole nitrogen source. This increase depended on the extracellular ammonia concentration and was not due to accumulation of storage polymers. We conclude that in this yeast ammonium ions can fulfill to some extent the physiological role of potassium ions and that the intracellular concentration of ammonium ions is predominantly determined by the ammonia concentration in the culture medium. 相似文献
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Successful selection of an infection‐protective anti‐Staphylococcus aureus monoclonal antibody and its protective activity in murine infection models 下载免费PDF全文
Hiroyoshi Ohsawa Tadashi Baba Jumpei Enami Keiichi Hiramatsu 《Microbiology and immunology》2015,59(4):183-192
Recent clinical trials to develop anti‐methicillin‐resistant Staphylococcus aureus (MRSA) therapeutic antibodies have met unsuccessful sequels. To develop more effective antibodies against MRSA infection, a panel of mAbs against S. aureus cell wall was generated and then screened for the most protective mAb in mouse infection models. Twenty‐two anti‐S. aureus IgG mAbs were obtained from mice that had been immunized with alkali‐processed, deacetylated cell walls of S. aureus. One of these mAbs, ZBIA5H, exhibited life‐saving effects in mouse models of sepsis caused by community‐acquired MRSA strain MW2 and vancomycin‐resistant S. aureus strain VRS1. It also had a curative effect in a MW2‐caused pneumonia model. Curiously, the target of ZBIA5H was considered to be a conformational epitope of either the 1,4‐β‐linkage between N‐acetylmuramic acid and N‐acetyl‐D‐glucosamine or the peptidoglycan per se. Reactivity of ZBIA5H to S. aureus whole cells or purified peptidoglycan was weaker than that of most of the other mAbs generated in this study. However, the latter mAbs did not have the protective activities against S. aureus that ZBIA5H did. These data indicate that the epitopes that trigger production of high‐yield and/or high‐affinity antibodies may not be the most suitable epitopes for developing anti‐infective antibodies. ZBIA5H or its humanized form may find a future clinical application, and its target epitope may be used for the production of vaccines against S. aureus infection. 相似文献
6.
Cloning of the biotin synthetase gene from Bacillus sphaericus and expression in Escherichia coli and Bacilli 总被引:3,自引:0,他引:3
I Ohsawa D Speck T Kisou K Hayakawa M Zinsius R Gloeckler Y Lemoine K Kamogawa 《Gene》1989,80(1):39-48
Biotin synthetase (BS) catalyses the biotransformation of dethiobiotin (DTB) to biotin. Here we report the cloning, characterization and expression of the gene encoding BS of Bacillus sphaericus. A recombinant plasmid pSB01, containing an 8.2-kb DNA fragment from B. sphaericus, was isolated by phenotypic complementation of an Escherichia coli bioB strain. Nucleotide sequence analysis of this fragment and N-terminal sequence determination of the recombinant protein product revealed that the bioB gene of B. sphaericus consists of a 996-bp open reading frame which is closely associated with at least one other gene. E. coli cells transformed with a bioB expression vector performed efficient bioconversion of DTB to biotin under defined culture conditions. Biotin production from transformed Bacillus subtilis and B. sphaericus recombinant strains was also demonstrated. Comparison of the amino acid sequences of BS from E. coli and B. sphaericus revealed extensive similarity. 相似文献
7.
Expression of tumor necrosis factor at a specific developmental stage of mouse embryos 总被引:1,自引:0,他引:1
We investigated the expression of the tumor necrosis factor (TNF) gene during development of mouse embryos, and observed its transient expression on Days 9 and 10 of gestation. We also detected a 25-kDa protein showing immunological cross-reactivity with mouse TNF antibody in an extract of 10-day embryos. These results suggest that TNF plays a role in mammalian ontogenesis. 相似文献
8.
Ken-ichi Morishita Nobumasa Yakushiji Fuminori Ohsawa Kayo Takamatsu Nobuyasu Matsuura Makoto Makishima Masatoshi Kawahata Kentaro Yamaguchi Akihiro Tai Kenji Sasaki Hiroki Kakuta 《Bioorganic & medicinal chemistry letters》2009,19(3):1001-1003
Retinoid X receptor (RXR) ligands are attractive candidates for clinical application because of their activity against tamoxifen-resistant breast cancer, taxol-resistant lung cancer, metabolic syndrome, and allergy. Though several RXR ligands, especially RXR antagonists, have been reported, the rational molecular design of such compounds is not well advanced. 4-[N-Methanesulfonyl-N-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-2-naphthyl)amino]nicotinic acid (5a) is a moderately RXRα-preferential agonist, and we examined the feasibility of replacing the methyl group on the sulfonamide with a longer alkyl chain or an aromatic ring as an approach to produce new RXR antagonists. Several of the resulting benzenesulfonanilide-type compounds showed RXR antagonist activity. This design strategy should be a useful approach for addressing the lack of structure diversity of RXR antagonists. 相似文献
9.
Masato Maruyama Naomi Arisaka Yoshikuni Goto Yosuke Ohsawa Hideshi Inoue Hiroshi Fujiwara Akira Hattori Masafumi Tsujimoto 《The Journal of biological chemistry》2009,284(50):34692-34702
Human laeverin/aminopeptidase Q (LVRN/APQ) is a novel member of the M1 family of zinc aminopeptidases and is specifically expressed on the cell surface of human extravillous trophoblasts. Multiple sequence alignment of human M1 aminopeptidase revealed that the first Gly residue within the conserved exopeptidase motif of the M1 family, GXMEN motif, is uniquely substituted for His in human LVRN/APQ. In this study, we evaluated the roles of nonconserved His379, comprising the exopeptidase motif in the enzymatic properties of human LVRN/APQ. We revealed that the substitution of His379 with Gly caused significant changes in substrate specificity both toward fluorogenic substrates and natural peptide hormones. In addition, the susceptibilities of bestatin, a sensitive inhibitor for human LVRN/APQ, and natural inhibitory peptides were decreased in the H379G mutant. A molecular model suggested a conformational difference between wild-type and H379G human LVRN/APQs. These results indicate that His379 of the enzyme plays essential roles in its distinctive enzymatic properties and contributes to maintaining the appropriate structure of the catalytic cavity of the enzyme. Our data may bring new insight into the biological significance of the unique exopeptidase motif of LVRN/APQ obtained during the evolution of primates. 相似文献
10.
Renin binding protein (RnBP) was purified from porcine kidney using pepstatin affinity column chromatography, DEAE-Sepharose column chromatography, gel filtration on Ultrogel-AcA 34, aminohexyl-Sepharose 4B column chromatography, and high performance liquid chromatography (HPLC) on TSK-gel G-3000 SW. The purified preparation was homogeneous as judged by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, polyacrylamide disc gel electrophoresis and isoelectric focusing on polyacrylamide gel. The isoelectric point was at pH 4.85, and the apparent molecular weight of RnBP was estimated to be 42,000 by SDS-polyacrylamide gel electrophoresis. The preparation did not show any renin activity and was stable for 30 min at 37 degrees C between pH 5.0 and 9.0 or on storage for 4 weeks at 4 degrees C or -80 degrees C. The activity of renin was greatly inhibited by RnBP. From the kinetic analysis of the inhibition we roughly estimated the dissociation constant between renin and RnBP to be about 0.2 nM, assuming that the stoichiometry in the complex, i.e., high molecular weight (HMW) renin, is one to one, and that the complex is inactive. The inhibitory activity of RnBP was lost by acidification at pH 3.0 and the activity of renin was restored. The purified RnBP formed a single precipitin line with the antiserum prepared with the purified HMW renin as antigen, which is RnBP-renin complex (Takahashi, S., et al. (1983) J. Biochem. 93, 265-274), and this line fused with one of the two precipitin lines formed between HMW renin and anti-HMW renin antiserum. The other of the two lines was between renin and anti-HMW renin antiserum. The purified preparation was thus identified as RnBP. The HMW renin was reconstituted with the purified RnBP and renin, and the apparent molecular weight of the reconstituted specimen was estimated to be 60,000 by gel filtration on Ultrogel AcA 44. 相似文献