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81.
Equations expressing the theoretical frequencies of twelve ascus-types in the tetrad analysis of a triply heterozygous diploid are described. Using these equations, a mapping procedure for a gene X, is proposed. The procedure requires that two genes, X and Y, of the same phenotype be heterozygous and that the map position of Y be known, and that another standard gene, Z, show an independent phenotype from X and Y. This procedure does not require the laborious allelism test of the segregants to determine the allelic 2:2 segregation in tetrads for the X and Y genes, which is indispensable for mapping by the conventional procedure. The exact placement of the X gene on a chromosome is possible by the chi2 minimization procedure in comparison with the expected frequencies of the six ascus-types or four spore-types deduced from the twelve expected ascus-types to give the optimal fit with the observed data.  相似文献   
82.
By the method of differential scanning calorimetry, it was found that thermal stability of glucose oxidase was dependent on its redox states. The oxidized form showed an apparent denaturation temperature at 76°C and the denaturation enthalpy was approximately 865 kcal/mol. On reduction of the enzyme, the denaturation temperature increased by about 10°, but no significant change was seen in the denaturation enthalpy. The activation energies of the denaturation of the oxidized and the reduced enzymes were about 89 and 103 kcal/mol, respectively. These results may imply conformational changes in the catalytic turnover of this enzyme.  相似文献   
83.
Summary The dnaA gene product of Escherichia coli, identified as a weakly basic protein of about 48,000 daltons (Yuasa and Sakakibara 1980), can be separated from other celluar proteins by means of two-dimensional gel electrophoresis. Synthesis of the dnaA protein took place continuously during a cell growth cycle. The newly synthesized dnaA protein persisted stably for one generation. Thermosensitive dnaA protein produced by the dnaA167 mutant was stable at 30° C, but was disintegrated at 42° C. The amount of intact dnaA protein present in the mutant exposed to the high temperature for 60 min was less than a quarter of the amount at the time of the shift. The cells having the reduced amount of intact dnaA protein were capable of initiating a new round of chromosome replication at the low temperature without de novo synthesis of the dnaA protein. The potential of the mutant for initiation of DNA replication decreased with reduction in the amount of the thermoreversible dnaA protein. The mutations dnaA167 and dnaA46 had no significant effect on the syntheses of the dnaA mRNA and the protein product at the low and high temperatures.Abbreviations used SDS sodium dodecyl sulfate - kb kilobase pairs - TCA trichloroacetic acid  相似文献   
84.
Isolated tea chloroplasts utilized linoleic acid, linolenicacid and their 13-hydroperoxides as substrates for volatileC6-aldehyde formation. Optimal pH values for oxygen uptake,hydroperoxide lyase and the overall reaction from C18-fattyacids to C6-aldehydes were 6.3, 7.0 and 6.3, respectively. Methyllinoleate, linoleyl alcohol and -linolenic acid were poor substratesfor the overall reaction, but linoleic and linolenic acids weregood substrates. The 13-hydroperoxides of the above fatty acidsand alcohol also showed substrate specificity similar to thatof fatty acids. Oxygen uptakes (relative Vmax) with methyl linoleate,linoleyl alcohol, linolenic acid, -linolenic acid and arachidonicacid were comparable to or higher than that with linoleic acid.In winter leaves, the activity for C6-aldehyde formation fromC18-fatty acids was raduced to almost zero. This was due tothe reduction in oxygenation. The findings presented here provideevidence for the involvement of lipoxygenase and hydroperoxidelyase in C6-aldehyde formation in isolated chloroplasts. (Received July 11, 1981; Accepted November 5, 1981)  相似文献   
85.
Hydrophobic protein (H protein) was isolated from membrane fractions of Bacillus subtilis and constituted into artificial membrane vesicles with lipid of B. substilis. Glutamate was accumulated into the vesicle when a Na+ gradient across the membrane was imposed. The maximum effect of Na+ on the transport was achieved at a concentration of about 40 mM, while the apparent Km for Na+ was approximately 8 mM. On the other hand, Km for glutamate in the presence of 50 mM Na+ was about 8 μM. Increasing the concentration of Na+ resulted in a decrease in Km for glutamate, maximum velocity was not affected. The transport was sensitive to monensin (Na+ ionophore).Glutamate was also accumulated when pH gradient (interior alkaline) across the membrane was imposed or a membrane potential was induced with K+-diffusion potential. The pH gradient-driven glutamate transport was sensitive to carbonylcyanide m-chlorophenylhydrazone and the apparent Km for glutamate was approximately 25 μM.These results indicate that two kinds of glutamate transport system were present in H protein: one is Na+ dependent and the other is H+ dependent.  相似文献   
86.
A total of 604 samples of about 7 different types of beans was examined to determine their mycological profiles, and suitability for use as solid substrates for mycotoxin production.All of the samples were collected from bean jam makers in Tokyo by the official food examiners.Genera Penicillium and Aspergillus were predominant, and genus Wallemia was also found commonly in all types of beans.Mycotoxin-producing Aspergillus strains were isolated from 52 samples of beans, approximately 9% of the total. The highest incidence of toxigenic Aspergillus (14.1%) was found in kidney beans. Red beans and peas inoculated with Aspergillus ochraceus were found to produce about 7 to 8 times more toxin than was obtained in a liquid medium, and red beans inoculated with A. versicolor produced more toxin than was obtained in yeast extract sucrose broth. Green peas inoculated with Fusarium graminearum produced about 8 times more T-2 toxin than was obtained in 1% peptone containing Czapek solution under comparable culture conditions.  相似文献   
87.
Protoplasts were isolated from callus derived from a single homozygous seed of Oryza sativa L. var. Norin 8. Thirty protoclones were randomly selected and these showed variation in regeneration frequency ranging from 0–87% with an average of 52%. The potential for regeneration of each protoclone as reflected in the regeneration frequency was analyzed five times over a period of 250 days and showed that the protoclones can be classified into three types, namely: protoclones with high regeneration frequency; protoclones with low regeneration frequency, both of which maintained their respective levels of regeneration potential; and protoclones with gradually decreasing regeneration frequency. Secondary protoclones established from protoplasts isolated from some of these protoclones and regenerated 2–3 times for a period of 120 days also showed further reduction in regeneration frequency. The polypeptide composition analyzed by two dimensional gel electrophoresis suggests the presence of specific polypeptides related to regeneration potential. Analysis of ploidy level based on plant morphology and pollen size suggests the predominance of tetraploids among the regenerated plants.  相似文献   
88.
Satoshi Hoshina 《BBA》1981,638(2):334-340
Temperature-dependent spectral changes of chlorophyll a (Chl a) incorporated into liposomes of two types of phosphatidylcholine are studied. When Chl a incorporated into the liposomes is cooled down to 5°C from the temperature of the gel-to-liquid crystalline phase transition of the lipid, the red shift as well as the increase in half-bandwidth of the red peak of Chl a are only slight. By measuring the difference spectra produced by substracting the absorption spectrum at the phase transition temperature of the lipid from that at lower temperature, it is shown that the component absorbing at longer wavelength (675–685 nm) than the peak of the red maximum (about 670 nm) significantly increases at the expense of the component absorbing at shorter wavelength (657–668 nm). The positions of positive and negative peaks depend on the temperature and the molar ratio of the lipid to Chl a. The absorbance change is most pronounced on cooling below the phase transition temperature of the lipid. The temperature-induced absorbance change is almost completely reversible. The results indicate that the aggregated forms of Chl a in liposomes can be spectrophotometrically detected in the gel phase of the lipid.  相似文献   
89.
Summary Three infants with different types of Y-chromosome abnomalies, including short- and/or long-arm deletion and mosaicism, are reported. The karyotypes of these patients were: 45,X/46,X,del(Y)/47,X,del(Y), del(Y) on peripheral lymphocytes and 45,X/46,X, del(Y) on gonadal tissue (case 1), 45,X/46,X,del(Y) (case 2), and 45,X/46,X,r(Y) (case 3). In case 1 the euchromatic segment on the deleted Y was distinctly larger than that of the father's Y.The three infants had no gross phenotypic anomalies except ambiguous genitals and low birth weight, and they were small for date. The histologic diagnosis in two of them was mixed gonodal dysgenesis (cases 1 and 2).The relationship between structural abnormalities of the Y chromosome and ambiguous genitals as well as male-determining factors is discussed.  相似文献   
90.
Ca2+ transport was studied in membrane vesicles of alkalophilic Bacillus. When Na+-loaded membrane vesicles were suspended in KHCO3/KOH buffer (pH 10) containing Ca2+, rapid uptake of Ca2+ was observed. The apparent Km value for Ca2+ measured at pH 10 was about 7 μM, and the Km value shifted to 24 μM when measured at pH 7.4. The efflux of Ca2+ was studied with Ca2+-loaded vesicles. Ca2+ was released when Ca2+-loaded vesicles were suspended in medium containing 0.4 M Na+.Ca2+ was also transported in membrane vesicles driven by an artificial pH gradient and by a membrane potential generated by K+-valinomycin in the presence of Na+.These results indicate the presence of Ca2+/Na+ and H+/Na+ antiporters in the alkalophilic Bacillus A-007.  相似文献   
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