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951.
Subcellular localization and glycoprotein nature of the invertase from the fission yeast Schizosaccharomyces pombe 总被引:6,自引:0,他引:6
Sergio Moreno Teresa Ruíz Yolanda Sánchez Julio R. Villanueva Luís Rodríguez 《Archives of microbiology》1985,142(4):370-374
The subcellular localization of the enzyme invertase in Schizosaccharomyces pombe cells, both repressed and derepressed for synthesis of the enzyme, was studied. Most of the invertase was found to be located outside the plasma membrane and only a small percentage was found to be associated to membranes. A substantial portion of the external enzyme remained firmly bound to cell-wall material.All of the invertase recovered in soluble form from cellular extracts reacted with concanavalin A and with the lectin from Bandeiraea simplicifolia seeds, indicating the presence in the enzyme of a carbohydrate moiety which probably contains terminal mannosyl (or structurally related) and galactosyl residues.The possibility of the presence of two different forms of invertase in S. pombe was considered. An intracellular, soluble form of invertase, devoid of carbohydrate, similar to the small invertase of the budding yeast Saccharomyces cerevisiae, was not found in S. pombe. However, the Michaelis constant for sucrose of the enzyme present in repressed cells was smaller than that of the invertase synthesized under derepressing conditions, although this difference could also be the result of a different pattern of glycosylation of the invertase synthesized under different growth conditions. 相似文献
952.
DNA of 96 strains of the genera Nitrosomonas, Nitrosococcus, Nitrosospira, Nitrosolobus, and Nitrosovibrio was isolated and analysed spectrophotometrically. Percentages of guanine plus cytosine (G+C) content, genome sizes, and DNA-DNA homologies were determined. The results indicated the presence of eight Nitrosomonas species, three or four Nitrosococcus species, five Nitrosospira species, and two species of both Nitrosolobus and Nitrosovibrio. DNA homologies between strains of a separate species ranged from 56–100%. Average homologies between strains of different species were 33% in Nitrosococcus, 36% in Nitrosomonas, 37% in Nitrosolobus, 40% in Nitrosospira, and 42% in Nitrosovibrio. Average homologies between species of different genera were 33% and thus not significantly above the background value of 30% detected between DNA of ammonia-oxidizing bacteria and Escherichia coli. Genome sizes ranged from 1.90–2.74×109 dalton in Nitrosomonas, 2.09–2.37×109 dalton in Nitrosococcus, 1.87–2.15×109 dalton in Nitrosospira, 1.92–2.10×109 dalton in Nitrosolobus, and 1.91–2.15×109 dalton in Nitrosovibrio. Differences in genome sizes were in accordance with DNA homologies. 相似文献
953.
Antigenic variation is associated with DNA rearrangements in a relapsing fever Borrelia 总被引:47,自引:0,他引:47
Borrelia hermsii, an agent of relapsing fever, undergoes antigenic variation in its host. Surface-exposed proteins with differing primary structures determine the serotype of each organism. Using amino acid sequence data from two of these variable proteins, we synthesized two mixed-sequence oligonucleotides and then used the oligonucleotides to probe mRNA and DNA of three isogenic serotypes of B. hermsii. In Northern blots the probes were specific for the mRNA of the homologous serotype. Southern blots revealed two classes of hybridizing fragments: those common to the three serotypes and those specific for a particular serotype. A serotype-specific DNA fragment, which had hybridized to both oligonucleotide probes, was cloned. Subsequent use of the cloned fragment as a probe provided further evidence that antigenic variation in B. hermsii is associated with DNA rearrangements and with occurrence of expression-linked copies of all, or part, of an antigen-specifying gene. 相似文献
954.
Embryos at the morula, blastocyst and hatched blastocyst stage were obtained from superovulated and naturally ovulated Japanese native goats. They were bisected into halves with a glass needle, and transferred immediately or after culture (for morula) to recipients. None of five does which received bisected morula became pregnant. Three of nine goats became pregnant after transfer of bisected hatched blastocysts, six of eleven recipients became pregnant. Four of them produced monozygotic twins and the remaining two produced singles. The present study demonstrated that the hatched blastocyst is suitable for bisection in the goat. 相似文献
955.
Regulation of the loss of frost hardiness in Pinus radiata by photoperiod and temperature 总被引:2,自引:1,他引:1
Abstract. In controlled environments, the interactive effects of warm (16: 8°C, day: night) and cool (12: 4°C, day: night) temperatures and long (13.5 h) and short (10 h) photoperiods on the dehardening of seedlings of Pinus radiata D. Don were investigated. In another experiment, the effect of four photoperiods from 9 to 14 h was examined. In a third, dehardening at constant temperatures from 5 to 17°C was followed. There was no evidence for an interaction between photoperiod and temperature. Dehardening was temporarily delayed by photoperiods below about 10 h, but there was no other quantitative effect of photoperiod. At constant temperatures, the rate of dehardening was initially constant but declined as the minimum summer frost hardiness was reached. In the initial phase the rate of dehardening was a linear function of temperature, increasing from 0.05°C day−1 at 8°C to 0.30 °C day−1 at 17°C. Temperature controlled the loss of frost hardiness by regulating the rate of dehardening. 相似文献
956.
Achim Recktenwald Karl-Heinz Kroner Maria-Regina Kula 《Enzyme and microbial technology》1985,7(12):607-612
Flow injection analysis (FIA) has been employed to automate enzyme assays for formate dehydrogenase (FDH) and l-leucine dehydrogenase (l-LeuDH). Coupled to a special sampling device the FIA assays were used to monitor on-line downstream processes, e.g. disintegration of microbial cells and cross-flow filtration of cell homogenates. 相似文献
957.
Summary Mitochondrial creatine kinase (CK) purified from canine myocardium showed a single protein band on SDS-PAGE and was free of
MMCK. Its amino acid composition was different than MMCK or BBCK and did not react to antiserum to MMCK or BBCK. Using purified
mitochondrial, MM and BBCK, the velocity of reaction (V) was estimated for creatine phosphate (CP), creatine (C), adenosine
triphosphate (ATP) and adenosine diphosphate (ADP) over a wide range of concentrations including those at Vmax. The values for Km (mM/L) derived from Lineweaver-Burke plots are shown:
The affinity of mitochondrial CK for C is much greater than MMCK which is compatible with the energy shuttle hypothesis, namely
ATP is converted by mitochondrial CK to CP, and then diffuses to the myofibril for conversion to ATP for utilization. 相似文献
958.
Summary Gonadotropin releasing hormone enhanced guanylate cyclase [E.C.4.6.1.2] two- to threefold in pituitary, testis, liver and kidney. Dose response relationships revealed that at a concentration of 1 nanomolar, gonadotropin releasing hormone caused a maximal augmentation of guanylate cyclase activity and that increasing its concentration to the millimolar range caused no further enhancement of this enzyme. There was an absolute cation requirement for gonadotropin releasing hormone's enhancement of guanylate cyclase activity as there was no increase without any cation present. Gonadotropin releasing hormone could increase guanylate cyclase activity with either calcium or manganese in the incubation medium but more augmentation was observed with manganese. The data in this investigation suggest that guanylate cyclase may play a role in the mechanism of action of gonadotropin releasing hormone. 相似文献
959.
Restriction endonuclease EcoO109 from Escherichia coli H709c with heptanucleotide recognition site 5'-PuG/GNCCPy 总被引:1,自引:0,他引:1
A new restriction endonuclease, EcoO109, has been isolated from Escherichia coli H709c by polyethyleneimine (PEI) precipitation, DEAE-cellulose chromatography and heparin agarose chromatography. The yield was high, more than 3000 units/g of wet cells. The EcoO109 endonuclease recognizes and cleaves a nucleotide sequence of (formula: see text), in the presence of 10 mM Mg2+. The enzyme will be useful for structural analysis and molecular cloning of DNA because of the stability, high yield and easy handling of the producer strain. 相似文献
960.