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71.
Sadaaki Iwanaga Takashi Morita Toshiyuki Miyata Takanori Nakamura Jun Aketagawa 《Journal of Protein Chemistry》1986,5(4):255-268
A hemocyte lysate from horseshoe crab produced a gel, when exposed to Gram-negative bacterial endotoxins. This gelation reaction of the lysate, so-called Limulus test, has been widely employed as a simple and very sensitive assay method for endotoxins. Recent biochemical studies on the principle of Limulus test indicate that the hemocytes contain several serine protease zymogens, which constitute a coagulation cascade triggered by endotoxins, and that there is a (1 3)--d-glucan-mediated coagulation pathway which also results in the formation of gel. Up to now, six protein components, designated coagulogen, proclotting enzyme, factor B, factor C, factor G and anti-LPS factor, all of which are closely associated with the endotoxin-mediated coagulation pathway, have been purified and biochemically characterized. Among these components, the complete amino acid sequences of coagulogens isolated from one American and three Asian species of horseshoe crabs have been established. Moreover, the reconstitution experiment using the isolated clotting factors, C, B, proclotting enzyme and coagulogen in the presence of endotoxin, leads to the formation of coagulin get. Based on these results, we propose here a mechanism for the Limulus coagulation cascade. 相似文献
72.
Determination of the complete nucleotide sequence of pNS1, a staphylococcal tetracycline-resistance plasmid propagated in Bacillus subtilis 总被引:1,自引:0,他引:1
Norihisa Noguchi Takashi Aoki Masanori Sasatsu Megumi Kono Kazuo Shishido Tadahiko Ando 《FEMS microbiology letters》1986,37(3):283-288
Abstract The complete nucleotide sequence of pNS1 (3879 bp), a tetracycline-resistance (TcR ) plasmid drived from staphylococcal plasmid pTP5, has been determined and compared with that of the staphylococcal TcR plasmid pT181 [6]. The nucleotide sequences of the 2 plasmids are in agreement, except for 18 nucleotides, but these differences are significant in that they give rise to new open reading frames (ORFs). A short ORF-D is found in the copy control region, and the TcR region contains a single large ORF-A, that encodes the Tet protein (50 kDa). The upstream region of ORF-A contains 3 inverted repeat sequences, which can generate structures very similar in conformation of the structure of the control region of the inducible erythromycin-resistance gene of pE194. 相似文献
73.
Takao Tsuji Akihiro Ogawa Takashi Miyata Tatsuya Iida Takeshi Honda Toshio Miwatani 《FEMS microbiology letters》1986,37(3):345-350
Abstract A mutant (TUH No. 9) of a porcine strain of enterotoxigenic Escherichia coli (ETEC) produces as abnormal B subunit (B') of heat-labile enterotoxin (LT), which has aspartate instead of glycine at residue 33 from the N-terminus and does not bind to the receptor, GM1 ganglioside. The antigenicities of the receptor-binding site of LT were analyzed.
The antibody, which could not bind to the B' subunit in the anti-B subunit of porcine LT(LTp)-serum, could bind to cholera toxin (CT), LTp and LT produced by a human ETEC strain (LTh), suggesting that it recognizes a common epitope of LTp, LTh and CT. Thus glycine at residue 33 from the N-terminus in the B subunit of CT, LTh and LTp may be related to the common epitope of these three toxins. The bindings of CT, LTh and LTp to the antibody were inhibited by the GM1 ganglioside.
These data indicate that the antibody recognizes a common epitope in the receptor (GM1 ganglioside)-binding site of CT, LTh and LTp. 相似文献
The antibody, which could not bind to the B' subunit in the anti-B subunit of porcine LT(LTp)-serum, could bind to cholera toxin (CT), LTp and LT produced by a human ETEC strain (LTh), suggesting that it recognizes a common epitope of LTp, LTh and CT. Thus glycine at residue 33 from the N-terminus in the B subunit of CT, LTh and LTp may be related to the common epitope of these three toxins. The bindings of CT, LTh and LTp to the antibody were inhibited by the GM1 ganglioside.
These data indicate that the antibody recognizes a common epitope in the receptor (GM1 ganglioside)-binding site of CT, LTh and LTp. 相似文献
74.
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
75.
Transformation of L cells with virus thymidine kinase genes introduced by red cell-mediated microinjection 总被引:2,自引:0,他引:2
Takashi Iino Mitsuru Furusawa Iwao Furusawa Masuo Obinata 《Experimental cell research》1983,148(2):475-480
Fusion of red cell ghosts containing foreign materials with cells results in the introduction of the materials into the cells (red cell-mediated microinjection). Until now, 'two-step dialysis' has mainly been used for trapping proteins in the ghosts. Large-sized materials such as DNA, however, are rarely trapped in the ghosts, since the holes in the red cell membrane caused by osmotic shock are too small for such materials to pass through. In this study, we improved the trapping technique. Some of the Hind III fragments of lambda phage DNA as well as proteins could be trapped in the ghosts when the mixture of these materials and red cells were frozen at -80 degrees C for a short period followed by quick thawing. Red cell-mediated microinjection using ghosts containing plasmid pBR322 linked with a Herpes simplex viral thymidine kinase (tk) gene brought about transformation of tk-defective L cells, the efficiency of transformation was 1 out of 20 000-60 000 cells fused with the ghosts. 相似文献
76.
Takashi Gojobori 《Genetics》1983,105(4):1011-1027
A mathematical model for codon substitution is presented, taking into account unequal mutation rates among different nucleotides and purifying selection. This model is constructed by using a 61 X 61 transition probability matrix for the 61 nonterminating codons. Under this model, a computer simulation is conducted to study the numbers of silent (synonymous) and amino acid-altering (nonsynonymous) nucleotide substitutions when the underlying mutation rates among the four kinds of nucleotides are not equal. It is assumed that the substitution rates are constant over evolutionary time, the codon frequencies being in equilibrium, and, thus, the numbers of synonymous and nonsynonymous substitutions both increase linearly with evolutionary time. It is shown that, when the mutation rates are not equal, the estimate of synonymous substitutions obtained by F. Perler, A. Efstratiadis, P. Lomedico, W. Gilbert, R. Kolodner and J. Dodgson's "Percent Corrected Divergence" method increases nonlinearly, although the true number of synonymous substitutions increases linearly. It is, therefore, possible that the "saturation" of synonymous substitutions observed by Perler et al. is due to the inefficiency of their method to detect all synonymous substitutions. 相似文献
77.
Estimates of Denitrification and Nitrification in Coastal and Estuarine Sediments 总被引:13,自引:5,他引:8 下载免费PDF全文
Denitrification and nitrification in sediments of Tama Estuary and Odawa Bay, Japan, were investigated by the combined use of a continuous-flow sediment-water system and a 15N tracer technique. At Odawa Bay, the nitrification rate was comparable to the nitrate reduction rate, and 70% of the N2 evolved originated from nitrogenous oxides (nitrate and nitrite) which were produced by the action of nitrifying bacteria in the sediments. At Tama Estuary, the nitrate reduction rate was 11 to 17 times higher than the nitrification rate, and nitrogenous oxides derived from ammonium accounted for only 6 to 9% of the N2 evolution by denitrification. 相似文献
78.
The effects of photoperiod on the sex expression of cucumberflowers were examined in relation to the endogenous GA and ethyleneproduction with short day (SD)- and long day (LD)-sensitivecultivars under controlled environmental conditions. Growth of plants was greatly reduced under LD in both typesof cultivars. Reflecting this, GA activity was greater and ethyleneevolution less in plants grown under SD than in those underLD. However, the number of pistillate flowers increased underSD and LD in SD- and LD-sensitive cultivar, respectively, indicatingthat a change in sex expression did not coincide with hormonalchanges in the SD-sensitive cultivar. Thus, the effect of photoperiodon the sex expression was found to be separate, at least inpart, from the effect of GA or ethylene in cucumber. (Received September 16, 1982; Accepted December 7, 1982) 相似文献
79.
Cortical microtubules are oriented transversely to the cellaxis in leaf sheath cells of onion plants (Allium cepa L. cv.Osaka-Okute) that have not started bulb formation. As the bulbdevelops and the leaf sheath cells swell, the microtubules becomedisoriented and scattered and finally disappear. The microtubuleinhibitors colchicine and cremart [O-ethyl O-(3-methyl-6-nitrophenyl)N-sec-butylphosphorothioamidate]cause swelling of leaf sheath cells and make the basal partof the plant bulbous. The cortical microtubules may have animportant role in regulating bulb development in onion plants. (Received August 21, 1982; Accepted December 6, 1982) 相似文献
80.
12-O-Tetradecanoylphorbol-13-acetate (TPA) is a well-known tumor promoter in mouse-skin carcinogenesis. Its effects on mutagenesis in a soybean test system were examined, and the effects were judged from the appearance of spots of various colors on the leaves. When soybean seeds were treated with TPA plus 0.03% caffeine, the frequency of spots per leaf decreased significantly and in proportion to the concentration of TPA. TPA alone at concentrations of 1–20 μg/ml did not induce any mutations. Mutations induced by γ-rays were not affected by administration of TPA either before or after exposure to γ-rays. The mechanism of suppression by TPA of mutations induced by caffeine is discussed. 相似文献