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1.
Kunitoshi Yamanaka Teru Ogura Kazuyoshi Murata Toshinobu Suzaki Hironori Niki Sota Hiraga 《FEMS microbiology letters》1994,116(1):61-66
Abstract The smbA gene of Escherichia coli is essential for cell proliferation. The smbA2 mutant shows cold-sensitive colony formation at 22°C. A novel morphological phenotype, formation of a translucent segment at midcell or at a cell pole, was observed by phase-contrastt microscopy at a high frequency in the smbA2 mutant cells incubated in L medium lacking NaCl at 22°C, but not observed in L medium containing 1% NaCl or 20% sucrose at the same temperature. No translucent segment was observed in the wild-type cells in any of the media used. Electron microscopic observation revealed that the translucent segments resulted from the enlargement of a periplasmic space by separation of the inner membrane from the peptidoglycan layer and the outer membrane. 相似文献
2.
Summary Spacing and kinship of the Formosan squirrel, Callosciurus erythraeus thaiwanensis, were studied in two different habitats. One, native habitat in the woods of Kenting, southern Formosa, was rich in available food throughout the year and had several species of predators. The other, a site in Kamakura, central Japan where squirrels had been introduced, had relatively scanty food and few potential predators. 1. Home ranges among males and between sexes overlapped extensively in both habitats. 2. Females occupied exclusive home ranges in Kamakura but had small overlapping home ranges in Ken-ting. 3. Most males disappeared from their natal areas at 1 year old in both habitats (86% in Kamakura and 93% in Ken-ting), but less females disappeared (36% in Kamakura and 35% in Ken-ting). 4. In Kamakura, daughters settled adjacent to the mother or inherited the home range of the mother, but never shared the mother's home range. In Ken-ting, 35% of daughters shared the home range with their mothers. 5. Tolerance among female kin in Ken-ting was probably facilitated by the richness of available food throughout the year, and functioned to reduce predation risk via alarm calling and mobbing. 相似文献
3.
Microfibrils (MFs) on the inner surface of the walls of Avenacoleoptile and mesocotyl cells and of Pisum epicotyl cells wereexamined by a replica method. In the elongating epidermis ofthese three organs, cells having MFs that were transverse, obliqueor longitudinal to the elongation axis were intermingled. Inthe elongating parenchymal tissues, all cells deposited MFstransversely. In non-elongating cells of Avena coleoptiles andPisum epicotyls, the orientation of MFs on the inner wall surfaceof both epidermal and parenchymal cells was more longitudinalthan in elongating cells. These observations on the orientationsof MFs are compatible with those our previously reported observationson the orientations of microtubules (MT) (Iwata and Hogetsu1988). Disruption of MTs of Avena coleoptiles by treatment withamiprophosmethyl caused changes in the orientation of depositionof MFs. These results support the idea that MFs are usuallyco-aligned with MTs in organ cells and that the orientationof MFs is controlled by MTs. The averaged direction of MFs, visualized under polarized light,showed a clear difference between the epidermal and inner-tissuecell walls in the elongating regions of the three organs. Inalmost all elongating and non-elongating epidermal cells, theaveraged direction of MFs was longitudinal, while it was transversein all inner-tissue cells. (Received December 16, 1988; Accepted April 28, 1989) 相似文献
4.
Identification of the cell surface molecule involved in sexual cell fusion of Dictyostelium discoideum 总被引:6,自引:0,他引:6
Kazuyoshi Suzuki Kaichiro Yanagisawa 《Differentiation; research in biological diversity》1989,40(3):159-165
Dictyostelium discoideum was used as a model system for elucidating the molecular mechanism of sexual cell fusion. In heterothallic strains NC4 and HM1 of D. discoideum, complements in mating type, amoeboid cells acquire fusion competence only under certain environmental conditions, such as the presence of excess water and a certain period of darkness, to fuse sexually. The surface of cells which acquired fusion competence was found to possess specific antigens. Monovalent antibodies prepared from rabbit antiserum against fusion-competent NC4 cells inhibit the sexual cell fusion of these cells completely. Two specific antigenic proteins, 39 and 138 k Da in relative molecular mass and specific for fusion-competent cells, were detected. Only one, the 138-k Da protein, was capable of neutralizing the fusion-inhibitory activity of the monovalent antibody. These results show that the 139-k Da protein is the one involved in the sexual cell fusion of NC4 and HM1 strains in D. discoideum. 相似文献
5.
M. Jane Ehrke Richard L. X. Ho Kazuyoshi Hori 《Cancer immunology, immunotherapy : CII》1988,27(2):103-108
Summary Recombinant murine (rMu) tumor necrosis factor (TNF), in a standard comitogenic assay with phytohemagglutinin, induced murine thymocyte proliferation, while up to 10,000-fold higher concentrations of recombinant human TNF did not. The induction of thymocyte proliferation was dependent upon TNF concentration in a biphasic manner. Thus, 100 to 1000 units/ml TNF were near optimal while concentrations 1,000 units/ml caused apparent down regulation. The effect was abrogated by neutralizing antibody to rMu-TNF but not by neutralizing antibody to rMu-interleukin 1 or . The rMu-TNF did not induce proliferation of the mature murine T-helper cell line, D10.G4.1, in the presence of mitogen. Taken together the results indicate that TNF, in a strictly species-specific manner, can regulate thymocyte proliferation independently of interleukin 1.Supported in part by Asahi Chemical Industry Co., Inc. and by USPHS Grants CA-24538, CA-15142 and CA-09072 awarded by the National Cancer Institute, Department of Health and Human Services 相似文献
6.
The electronic structures of newly designed polyimide systems (ethenetetracarboxylic 1,2:1,2-dianhydride-diaminoethyne (PI-A) and ethenetetracarboxylic 1,1:2,2-dianhydride-diaminoethyne(PI-B)) are studied in detail with respect to their optimized geometries on the basis of the one-dimensional tight-binding self-consistent field crystal-orbital method. The computational results have revealed that PI-B shows intriguing properties such as a very small band gap and a wide bandwidth near the frontier level, compared with PI-A and other polyimides. Since PI-B would be a promising candidate for a new electric conducting material, a reaction diagram for this polymer is also proposed.Also affiliated to Central Research Laboratories, Matsushita Electric Industrial Co., Moriguchi 570, Japan. 相似文献
7.
Two soluble cytochromes of the C-type, cytochrome c-551 andcytochrome c-550, were purified from the bacteriochlorophyll-containingcells of a facultative methylotroph, Protaminobacter ruber StrainNR-1, by ion-exchange chromatography and gel-filtration. Cytochrome c-551 had absorption maxima at 551, 522 and 416 nmin the reduced form, and at 525, 410 and 273 nm in the oxidizedform. This cytochrome was a slightly basic protein with an isoelectricpoint of 8.4. It had a mid-point redox potential of 272 mV atpH 7.0. The molecular weight of this protein was 13,500 and13,700 by sodium dodecylsulfate polyacrylamide gel electrophoresis(SDS-PAGE) and gel-filtration, respectively. Cytochrome c-550 had absorption maxima at 550, 522 and 415 nmin the reduced form, and at 527, 409 and 278 nm in the oxidizedform. This cytochrome was acidic, having an isoelectric pointof 4.3. It had a mid-point redox potential of 227 mV at pH 7.0.Its molecular weight was 19,500 and 22,000 by SDS-PAGE and gel-filtration,respectively. (Received August 4, 1984; Accepted October 22, 1984) 相似文献
8.
On the basis of an artificial defoliation experiment, a new growth model of soybean was formulated through a modification
of Rudd's (1980) model with regard to his equations for dry matter allocation. Compensatory growth for leaf damage was modelled
by a single process in which the dry matter allocation changes dynamically according to the severity of leaf damage. The sums
of squared differences between simulations and experimental soybean yields were much smaller in our modified model than in
Rudd's original model. The modified model gave a better simulation of yield loss due to defoliation that varied in time and
intensity. The relationship between various times and intensities of defoliation and yield loss was shown, which is essential
for establishing the dynamic economic injury level in IPM. 相似文献
9.
Role of Tween 80 and Monoolein in a Lipid-Sterol-Protein Complex Which Enhances Ethanol Tolerance of Sake Yeasts 总被引:7,自引:6,他引:1
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An exogenous ternary complex composed of Tween 80, ergosterol, and albumin increased the final ethanol concentration of fermentation by sake yeasts from 17.2 to 19.0% (vol/vol) and reduced the fermentation time from 30 to 25 days. Likewise, a complex of monoolein, albumin, and either ergosterol or ergosteryl oleate increased the final ethanol concentration of fermentation to 19.7 or 19.8% (vol/vol), respectively, and reduced the fermentation time to 25 days. Both Tween 80 and monoolein promoted the fermentative activity (QCO2) of cells, and the effect was enhanced by the presence of ergosterol. 相似文献
10.
An application ofHokyo andKiritani 's method (1967) was attempted to estimate the stage specific survival rates of the population with overlapping stages. This method can be written as follows assuming a constant daily survival rate (K) throughout the life: where, and F refer respectively to the total incidence of ith instar nymphs and that of individuals after ith instar inclusive, and αi refers to the developmental period of ith instar. Application of this model to caged and natural populations of the southern green stink bug, Nezara viridula, was made to test its validity. The estimates of the initial number of successive stages obtained from the present method were compared with those fromRichards andWaloff 's method (1954) for the caged populations of 1st, 2nd and 3rd generations. The superiority of the present method to theRichards andWaloff 's in estimating adult numbers was shown in all the generations examined. When different daily survival rates are involved in the course of population decrease, application of the revised method proposed byHokyo andKiritani (1967), gives much reliable estimate as compared with one before correction. The present method is useful in constructing life table of such species as scale insects which complete their life cycle within a defined space, but their successive stages overlap considerably. 相似文献