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41.
Correlation between the virulence of Francisella tularensis in experimental mice and its acriflavine reaction was studied. The cultures derived from all four strains (Ebina, CMB2, Schu, and N9) that had long been subcultured on agar media yielded two types of colonies, i.e., acriflavine reaction-positive (acf+) and acriflavine reaction-negative (acf-) colonies. All acf+ colonies, regardless of their parent strains, were shown to be low virulent in mice. Acf- colonies were shown to be either high (Ebina, CMB2) or low (Schu, N9) virulent. The low-virulent acf- colonies gained virulence during several passages in mice, whereas the acf+ colonies remained low virulent even after the animal passages. 相似文献
42.
Yokoyama Eiichi; Murakami Akio; Sakurai Hidehiro; Fujita Yoshihiko 《Plant & cell physiology》1991,32(6):827-834
Stability of thylakoid components under supra-high irradiancewas studied with the cyanophyte Synechocystis PCC 6714. Theactivity of overall photosynthesis was quickly inactivated (T1/2=20min) under supra-high irradiance (300 W m2, white light).In parallel with the inactivation of photosynthesis, QA in PSII was also inactivated. Both inactivations were acceleratedby chloramphenicol (CAP) addition. The reactivation of PS IIrequired weak irradiation and was suppressed by CAP. However,PS I measured as P700 was very stable. The level of PS I measuredas P700 was not significantly reduced by the irradiation for12 h even in the presence of CAP while the level of Cyt b559,component of PS II, was decreased markedly. The function ofPS I before and after supra-high irradiation with CAP was examinedby comparing sizes of P700 oxidation induced by a short flash,by a continuous light, and by determination of O2-and ferredoxin-reduction.No difference was observed in PS I actions before and afterthe irradiation treatment. These results indicate that the PSI complex is very tolerant of supra-high irradiation. However,the cells grown under supra-high irradiance contained much fewerPS I and PS II complexes than Cyt b6f complexes. Theformer levels were reduced to a half to one fourth of thosebefore growth while the level of Cyt b6f complex wasnot reduced so much. A possible mechanism for changes in thylakoidcomposition under supra-high irradiation was discussed. (Received February 16, 1991; Accepted June 12, 1991) 相似文献
43.
Fujita Yuichi; Takahashi Yasuhiro; Shonai Fumio; Ogura Yutaka; Matsubara Hiroshi 《Plant & cell physiology》1991,32(7):1093-1106
The frxC gene, found in liverwort chloroplast DNA, encodes aprotein of unknown function. The deduced amino acid sequenceof the protein shows significant homology to that of ni-trogenaseFe-protein encoded by the nifH gene. We have cloned the frxCand nifH genes from the nitrogen-fixing cyanobacterium Plectonemaboryanum, using frxC- and nifH-specific probes, and have determinedtheir nucleotide sequences. The amino acid sequence deducedfrom the frxC gene of P. boryanum exhibits 83% homology to thatof the protein encoded by the/rxCgene from liverwort, whereasit exhibits only 34% homology to that encoded by the nifH genefrom the same organism, namely, P. boryanum. Northern blot analysisshowed that the frxC gene was transcribed more actively undernitrogenase-repressed conditions than under nitrogenase-inducedconditions, suggesting that the FrxC protein has a functiondistinct from nitrogen fixation. These results, together withthe phylogenetic relationship between the nifH and frxC genes,indicate that the frxC and nifH genes are derived from a commonancestral gene but have evolved independently to encode proteinswith different functions. (Received April 27, 1991; Accepted August 12, 1991) 相似文献
44.
Dissolved nutrient inputs in bulk precipitation and outputs in streamwater were measured during 3 years of contrasting hydrological conditions in a 6.3-ha, grazed heathland watershed on schists in the Montseny mountains (NE Spain), drained by an intermittent stream. On average, 39% of the precipitation became streamflow. Bulk precipitation delivered positive net alkalinity (mean 0.22 keq/ha/yr), sulphate input was moderate (9.0 kg SO4-S/ha/yr), and the mean input of inorganic N was not exceptionally high (6.6 kg/ha/yr). Ion concentrations were relatively low in streamwater; SO4
2- was the dominant anion. Most concentrations in streamwater varied seasonally, with maxima in late summer or early autumn and minima in spring. This pattern probably resulted from increased availability of ions for leaching due to decomposition of organic matter and chemical weathering during the warm period. Nitrate concentrations were relatively high in winter and dropped sharply in early spring, probably because of biological uptake. Annual element outputs in streamwater varied between years and seemed to be controlled by both the amount of annual streamflow and its seasonal distribution. Annual inputs exceeded outputs for dissolved inorganic N. The watershed accumulated H+ and Ca2+, had net losses of Na+ and Mg2+, and was close to steady state for K+, SO4
2-, Cl- and alkalinity. The chloride budgets gave no evidence of substantial dry deposition in this system. The cationic denudation rate was negative (-0.14 keq/ha/yr) because Ca2+ retention was higher than net exports of Na+ and Mg2+ from silicate weathering. Low nutrient export and little production of alkalinity suggest that this watershed has a low buffering capacity. 相似文献
45.
N. Maruo Y. Kobayashi H. Horiuchi M. Kondo S. Fujita 《Histochemistry and cell biology》1992,97(2):141-145
Summary A microcytofluorometrical DNA measurement was basically studied and was applied to single megakaryocytes previously identified on a Wright-Giemsa stained smear. The smear was first photographed and the location of each megakaryocyte was recorded on a cell map. The smear was then bleached with 50% acid ethanol and absolute methanol, and re-stained with 4,6-diamidino-2-phenylindole (DAPI) reagent (pH 7.4) at 4° C. Nuclear blue fluorescence was observed and the intensity of this fluorescence was proportional to the amount of DNA with the coefficient of variation (CV) of 3.6% when stained for 30 min. After 30 min DAPI staining, the DNA measurement was microcytofluorometrically performed in single megakaryocytes which had been morphologically classified into 4 groups on the basis of cytoplasmic maturation, Bessis' classification, assessed on Wright-Giemsa-stained bone-marrow smears from normal human beings. The histograms of the cells did not show any difference in DNA ploidy distribution among the classes: that is, the DNA histograms disclosed ploidy distribution from 4 N to 64 N with the largest population of 16 N. These findings suggest that nuclear DNA synthesis is completed before platelet production starts. This method is useful for comparing the morphological features and DNA content of single megakaryocytes. 相似文献
46.
47.
Bacillus subtilis inositol dehydrogenase-encoding gene (idh): sequence and expression in Escherichia coli. 总被引:2,自引:0,他引:2
The Bacillus subtilis inositol dehydrogenase (Idh)-encoding gene (idh) was cloned in the B. subtilis temperate phage, rho 11, and then in Escherichia coli plasmids (pBR322 and pUC118). The nucleotide sequence of the idh gene, which consists of 344 codons and whose product has an Mr of 38,351, was determined. E. coli, bearing pIOL05d15, in which expression of the idh gene is under the control of the lac promoter of pUC118, overproduced an active Idh to approx. 20% of total protein upon addition of isopropyl-beta-D-thiogalactopyranoside. This overproduced enzyme cross-reacted with an anti-Idh antibody, and exhibited the same Mr and substrate specificity as those of the B. subtilis enzyme. 相似文献
48.
K Kobayashi K Kiuchi A Ishii N Kaneda Y Kurosawa K Fujita T Nagatsu 《FEBS letters》1988,238(2):431-434
Alternative splicing from a single gene produces four kinds of human tyrosine hydroxylase (types 1-4), which have structural diversity only in the N-terminal region. We attempted expression of the type 1-4 enzymes in COS cells and performed kinetic analyses. All had enzymatic activities. The Km values of the four types for L-tyrosine and 6-methyl-5,6,7,8-tetrahydropteridine were similar, although their relative homospecific activities were clearly different. The type 1 enzyme displayed the highest activity. 相似文献
49.
Developmentally regulated alternative splicing of brain myelin-associated glycoprotein mRNA is lacking in the quaking mouse 总被引:5,自引:0,他引:5
Evidence is presented that expression of the two myelin-associated glycoprotein mRNAs is developmentally regulated in mouse brain. In quaking mouse, the mRNA without a 45-nucleotide exon portion was scarcely expressed throughout development. We conclude that the mechanism of splicing out the 45-nucleotide exon portion is lacking in quaking mouse. 相似文献
50.
Y Sugiyama S Taketomi H Tawada K Meguro H Ikeda T Fujita 《Hormones et métabolisme》1988,20(3):145-149
In the perfused pancreas from normal SD rats, AD-4610 (0.01-0.1 mM) potentiated biphasic insulin secretion induced by 7.5 mM of glucose. The concentration-response curve of insulin secretion to glucose was shifted leftwards with AD-4610 (0.1 mM) without altering either the threshold concentration of glucose to induce insulin secretion or the maximal insulin response to glucose, indicating increased sensitivity of the pancreatic B-cells to glucose. On the other hand, AD-4610 was 10-fold less effective in altering insulin secretion induced by arginine and glyceraldehyde. The effect of AD-4610 on insulin secretion and glucose metabolism was compared with that of tolbutamide in vivo. AD-4610 (100 mg/kg) potentiated insulin secretion induced by an intravenous glucose load, and also accelerated glucose metabolism without altering basal insulin secretion in normal rats. On the other hand, tolbutamide (20 mg/kg) increased basal insulin secretion, but slightly decreased glucose-induced insulin secretion. In yellow KK mice with hyperglycemia, AD-4610 (10-100 mg/kg) had a dose-dependent hypoglycemic action, but tolbutamide did not. Thus, AD-4610 stimulated insulin secretion in a glucose-dependent fashion and enhanced glucose metabolism in vivo. These results suggest that AD-4610 selectively potentiates glucose-induced insulin secretion by increasing the sensitivity of pancreatic B-cells to glucose and may be useful for treating human NIDDM through a different mechanism than that of tolbutamide. 相似文献