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11.
E Dubnau J Weir G Nair L Carter rd C Moran Jr I Smith 《Journal of bacteriology》1988,170(3):1054-1062
The DNA sequences of the spo0H genes from Bacillus licheniformis and B. subtilis are described, and the predicted open reading frames code for proteins of 26,097 and 25,447 daltons, respectively. The two spo0H gene products are 91% identical to one another and about 25% identical to most of the procaryotic sigma factors. The predicted proteins have a conserved 14-amino-acid sequence at their amino terminal end, typical of sigma factors. Antibodies raised against the spo0H gene product of B. licheniformis specifically react with RNA polymerase sigma factor protein, sigma 30, purified from B. subtilis. We conclude that the spo0H genes of B. licheniformis and B. subtilis code for sigma 30, now known as sigma H. 相似文献
12.
R C Frankis M J Weise R M Nair G V Paddock 《Archives of biochemistry and biophysics》1985,238(1):178-186
The red blood cells of normal adult ducks contain two main hemoglobins. The most abundant type, HbA, comprises approximately 80% of the total, with the remaining 20% being made up of HbD. An attempt was made to determine whether during hemolytic anemia a special alpha globin chain (alpha s) replaces the alpha chain of HbA found in normal animals. This special stress alpha globin, whose existence has been seriously questioned, was originally postulated to explain the sequence discrepancies obtained between alpha chains of normal and anemic chickens and ducks. Using gel electrophoresis, isoelectric focusing, and HPLC peptide mapping techniques no qualitative differences between the alpha A globins of normal and anemic animals were found. The nature of the beta globin chains present in adult ducks has also never been rigorously established. In this work, a variety of techniques, including HPLC, gel electrophoresis, and microcolumn amino acid analysis, were used to examine the beta chains from each hemoglobin. Using these methods, no differences were found between the beta globin chains of the two hemoglobins. 相似文献
13.
Partial purification and some properties of a latent CO2 reductase from green potato tuber chloroplasts 总被引:1,自引:0,他引:1
We have partially purified the CO2 reductase, present in green potato tuber chloroplasts, as a latent form. Illumination of the chloroplasts in the absence of substrate, bicarbonate, activated the enzyme, which could then be obtained in soluble forms. Purification of the enzyme was achieved by (NH4)2SO4 fractionation (0-30%) and adsorption and elution from a DEAE-Sephadex A-50 column. The final preparation showed 15-fold purification and 50% recovery of the activity. The pH optimum for CO2 reductase was 8.0. Hepes and Tricine buffers showed maximum activity whereas Tris/phosphate or borate failed to show any activity. The enzyme reaction was sensitive to the presence of metal ions like Fe3+, Hg2+, Cu2+, Mo6+ and Zn2+, however, a threefold activation was observed with Fe2+. The metal requirement for CO2 reductase was evident from the observed inhibition by metal chelators like o-phenanthroline, alpha, alpha'-dipyridyl, bathocuproine, 8-hydroxyquinoline etc. Out of these o-phenanthroline was the strongest inhibitor and its concentration for 50% inhibition was 40 microM. The presence of Fe2+ ions in the reaction mixture protected the enzyme from heat denaturation upto 50 degrees C. Maximum enzyme activity was observed at 15 degrees C. The enzyme activity showed a 30-s lag period and the maximum was reached in 90 s. Supplementation of sodium dithionite in the reaction activated enzyme activity threefold, suggesting involvement of dithiol groups in the catalytic activity. There was strong inhibition by -SH inhibitors like 5,5'-dithiobis(2-nitrobenzoic acid) and N-ethylmaleimide and -SH reagents like dithiothreitol, 2-mercaptoethanol and cysteine. Various nucleotide coenzyme tried inhibited the enzyme strongly. 相似文献
14.
Seasonal distribution of Vibrio parahaemolyticus in freshwater environs and in association with freshwater fishes in Calcutta 总被引:2,自引:0,他引:2
The seasonal distribution of Vibrio parahaemolyticus in freshwater environs and in association with freshwater fishes was studied in 1982 and 1983. The occurrence of this organism in water and sediments at the three sites studied was very infrequent and was restricted to the summer months, although it was not always isolated during these months. The association of V. parahaemolyticus with plankton was chiefly confined to the summer months and progressively declined with the onset of monsoons, remaining below detectable levels during the postmonsoon and winter months. The incidence and counts of V. parahaemolyticus were consistently higher in association with plankton than with water and sediment samples. V. parahaemolyticus could be recovered throughout the period of investigation from freshly caught and market samples of freshwater fishes. The highest recovery rate of this halophile from fishes was invariably from fecal samples. Most of the strains isolated in this study were untypable, and those which could be typed were predominantly serotypes encountered in the environment. All the isolates were Kanagawa negative. From this study, it could be concluded that the survival of V. parahaemolyticus in freshwater ecosystems is transient and dependent on a biological host. 相似文献
15.
Buspirone produces a dose-dependent but short-lived elevation in striatal dopamine (DA) metabolites in the rat. , buspirone possesses an affinity similar to sulpiride for DA receptors (3H-spiperone). A moderate affinity for α1 receptors was also observed while buspirone was inactive at α2, β, muscarinic and serotonin2 receptors. This pharmacological profile as well as previous behavioral data indicate that buspirone may be a potential “atypical” neuroleptic. 相似文献
16.
Ribonucleic acid extracted from the virions of two human rhinoviruses is infective and is similar in size to poliovirus ribonucleic acid. 相似文献
17.
Exposure of pregnant rats to 25 R of x-irradiation on the fourteenth gestation day has produced in the male offspring an impairment of the development of the hepatic microsomal enzyme system which metabolizes hexobarbital. However, irradiation did not suppress the increase of enzyme activity brought about by the administration of chemical inducers (pheno-barbital). Actinomycin, on the other hand, inhibited to varying degrees both the ontogenic and phenobarbital-induced increases in enzyme activity. The effects on the enzyme system have been supported by in vivo measurements of the duration of hexobarbital hypnosis. The ontogenic increase in enzyme activity is hormone-dependent, while that following phenobarbital administration is independent of hormonal regulation as evidenced by the response in hypophysectomized or sexually immature animals. It is concluded from these results that the inhibitory effect of x-irradiation on the hepatic enzyme system is mediated through an action on the hormonal regulation of enzyme activity. Evidence for this hypothesis is discussed. 相似文献
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Summary This paper presents the preliminary observations on the interstitial fauna of the south-west coast of India, made during the course of 1963–1964. Observations were made at four stations representing different ecological habitats. The influence of some factors, such as wave action, grain size, temperature and salinity on the fauna was studied. The occurrence, seasonal abundance and the nature of distribution of the different groups on the intertidal zone, were also studied at the four stations. 相似文献