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961.
We have studied the presence of a cloned fragment of DNA from Drosophila melanogaster in other organisms by means of nucleic acid hybridization analysis. The isolated region is localized in polytene chromosomes at the 63F subdivision. This region includes a puff that responds within minutes to ecdysone stimulation. We have found that 63F DNA from D. melanogaster hybridizes 'in situ' to both DNA and RNA from D. simulans, D. teissieri, and D. hydei. In all these species the isolated DNA remains associated with one early-ecdysone stimulated puff. The isolated Drosophila recombinant DNA is also complementary to polyadenylated RNA from foetal and adult rat liver but fails to hybridize to the nonpolyadenylated RNA classes from both sources and to polyadenylated RNA from rat mammary glands. 相似文献
962.
963.
Danley A. S. Callieri Carlos G. Núñez Juan C. Díaz Ricci Luis Scidá 《Applied microbiology and biotechnology》1984,19(4):267-271
Summary
Candida utilis var. major NRRL-Y-1084 was grown in a defined medium without a phosphorous (P) source. During the exponential phase, cells divided according to a specific growth rate of 0.32 h-1, which is lower than the usual rate for a balanced medium (0.4–0.6 h-1). The relative P content of the biomass decreased from 2.70% to 0.75% over a period of 6 h, including 2 h of cell division arrest. At the end of this period there was another interruption of cell division. After that, multiplication restarted at a considerably lower rate and it deviated slightly from the exponential pattern. The stationary phase began when biomass P content reached 0.4%–0.5%, slowly decreasing afterwards to 0.25–0.20%. Biomass synthesis was less affected than cell division by the relative decrease of endogenous P, the two processes differing partially in their kinetics. Cell lysis started shortly before the stationary phase and affected about 20% of the population by the end of the assay. RNA and P content of the resulting biomass were 2.4% and 0.25% respecitvely, P being mainly incorporated to RNA.The relationship of biomass production to glucose uptake was very low, probably because the marked P deficiency called for an increase in energy consumption for growth and specially for maintenance. Compared with yeasts grown in a balanced medium, 40% increase in glycogen was observed, whereas no mean changes in the content of cell wall carbohydrates (glucan and mannan) and that of true protein were found.Member of the Scientific Researcher's Career of the Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET). Agrentina 相似文献
964.
Shu’a Yagev Michael Heller Arié Pinson 《In vitro cellular & developmental biology. Plant》1984,20(12):893-898
Summary Postnatal rat heart cells in culture enriched with respect to muscle cells were obtained by either high density seeding or
by the replating technique. [3H]Thymidine incorporation to DNA and the enzymatic pattern of cytoplasmic and lysosomal enzymes have been studied as a function
of the culture’s age, of seeding density, and replating. It was shown that (a) replating maintains predominance of myocyte
population for at least 2 wk in culture; (b) heavy seeding density allows homogeneous myocyte population for the 1st wk in
culture; and (c) the enzyme profile of the culture may serve as an indicator for the type of cell population in culture and
its state of differentiation.
This study was done as partial fulfilment of the M.Sc. thesis in Biochemistry (SY). Supported by grants from The Chief Scientist,
Ministry of Health, State of Israel; The Ministry of Education and Sciences, State of Niedersachssen (FRG); and The Foundation
for Heart Research from Mr. and Mrs. D. Vidal-Madjar, Paris, France. 相似文献
965.
This paper presents the results of taxonomic investigation of 8 species of lichens with gyalectoid apothecia collected in North-India and Nepal. Four species are recognized as new:Dimerella isidiata (sp. nova),D. nepalensis (sp. nova),Gyalideopsis lithophila (sp. nova) andRamonia nepalensis (sp. nova). Four species are reported for the first time from Nepal:Coenogonium moniliforme, Gyalectidium caucasicum, Gyalidea lecideopsis andG. scutellaris. 相似文献
966.
The pH-dependent fluorescence excitation of fluorescein located intracellularly and in the vicinity of cells of the yeast Saccharomyces cerevisiae and Endomyces magnusii was used to obtain local pH values at a linear resolution 0.2 micron. Cells suspended in water or in a diluted (5 mM) acidic buffer had a relatively alkaline interior (about 7.0-7.5) with pH decreasing gradually toward the periphery and further out through the cell wall to the value of the bulk solution. In slightly alkaline weak buffers the cells also showed an alkaline center and a slightly acidic ring-shaped area, but the peripheral region close to the membrane was again alkaline with pH increasing toward the bulk solution. The heterogeneity of intracellular pH was reduced or nearly abolished in starved or antimycin-treated cell. Suspension of cells in strong (200 mM) buffer resulted within 15-20 min in a nearly homogeneous pH pattern throughout the cell, attaining pH values of 5.5-7.5, depending on the pH of the buffer. Addition of glucose with concomitant pH decrease of the extracellular medium did not change appreciably the intracellular pattern for 20-30 min, except with diethylstilbestrol (inhibitor of proton-extruding ATPase) when the cell became more acidic. It appears that the delta pH measurements between the cell as a whole and the bulk solution (as are used for the calculation of the electrochemical potential of protons in proton-driven transports) are not substantiated, the probable pH difference across the plasma membrane being substantially smaller than previously supposed. 相似文献
967.
The interactions between reducing agents and Ca2+ in the activation of Ca2+-dependent K+ transport have been studied in one-step inside-out vesicles. The artificial electron donor system ascorbate + phenazine methosulphate increases the apparent sensitivity to Ca2+ by about 5-times over control values (half activation constant, about 5 X 10(-8) M) while oxidized cytochrome c decreases the sensitivity to about 1/3 of the controls. Using redox buffers at a fixed pCa it is shown that the shift from the low to the high-affinity state can be accounted by the reduction of a membrane component accepting two electrons and with an apparent standard redox potential (pH 7.5) of 47 mV. The electrons can be transferred directly from reduced PMS or to oxidized cytochrome c, but not from ascorbate, NADH or reduced glutathione. 相似文献
968.
Antibodies were raised in rabbits against the outer membrane of Neurospora mitochondria. Antibodies were obtained that were specific for this membrane's major polypeptide () and its slower-migrating derivatives on SDS-polyacrylamide gels. These antibodies inhibited the insertion into phospholipid bilayers of voltage-dependent ion channels from detergent extracts of the mitochondrial outer membranes. The same antibodies bound preferentially to membranes containing crystalline surface arrays in outer mitochondrial membrane fractions. These results indicate that the 31 kDa polypeptide is a component both of the ion channels and of the membrane arrays, suggesting identity between the functional and structural entities. 相似文献
969.
970.
A simple procedure for the determination of the absolute configuration (i.e., assignment to the D- or L-enantiomeric series) of glucose, mannose, galactose, fucose, arabinose, and rhamnose is described, based on inhibition by these sugars of 125I-labeled lectin binding to the glycoconjugates immobilized on the wells of plastic microculture plates. The method works well with 10 to 100-micrograms amounts of the sugars isolated after paper chromatography of the glycoprotein or polysaccharide hydrolysates. 相似文献