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31.
Fatichenti Fabrizio Farris Giovanni Antonio Deiana Pietrino Ceccarelli Salvatore 《Applied microbiology and biotechnology》1984,19(6):427-429
Summary Fermentation tests in clearly defined laboratory conditions were carried out with eight functionally selected strains of Saccharomyces cerevisiae. Analysis of the data showed that there were no significant differences in malic acid production between the strains when the acid was initially present. When it was initially absent, however, significant differences were observed two strains (Nos. 1141 and 1083) showing marked productive superiority. With malic acid as the sole C source, two strains (Nos. 1109 and 1141) showed less acid consumption. 相似文献
32.
33.
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
34.
Juan Alberto Claver Irene von Lawzewitsch Orestes Jorge Colillas 《Primates; journal of primatology》1984,25(3):362-371
The microscopic structure of theAlouatta caraya ovary is studied in different ages and reproductive stages. The most significant feature seems to be the presence in adult
ovaries of abundant glandular interstitial tissue which occupies both the cortex and medulla. It seems to be derived from
the theca interna of atretic follicles. Discrete luteinized masses are present in the medulla in all the ovaries observed.
Invaginations of the surface epithelium are seen only in infant and juvenile ovaries. The development of cystic follicles
seems to be a common pathway of atresia. 相似文献
35.
Summary We present a quantitative theory that relates the fluorescence intensityvs. temperature (I vs. T) profile of a fluorescent-labeled two-component lipid bilayer to the phase diagram of the bilayer and the partition coefficientK of the fluorophore between fluid and solid phases of the bilayer. We show how the theory can be used to evaluateK from experimentalI vs. T profiles and the appropriate phase diagrams as well as to understand the different shapes ofI vs. T profiles obtained with particular fluorophores and phase diagrams. Using calculatedI vs. T graphs, we discuss the meaning of parameters, such as midpoint of the phase transition and onset and termination of a transition, which are often used to characterize phase transitions on the basis of fluorescence intensityvs. temperature profiles. 相似文献
36.
Summary Intermediate filaments of toad oxyntic cells were isolated and analysed by SDS-PAGE. The major proteins of the residue were identified as actin and a 51,000 dalton polypeptide. Immunological crossreactivity between toad oxyntic cell intermediate filament components and anti-prekeratin, was shown by double immunodiffusion tests and indirect immunofluorescence. The immunofluorescent decoration of oxyntic cells and the electron microscope images are coincident in locating the intermediate filaments mainly at the cortical and perinuclear basal zones. Furthermore, the cortical zone appears especially rich in prekeratin-like material at its adluminal third. This results in a cup-like structure that encloses the cell portion occupied by the tubulovesicular system, which does not contain intermediate filaments. The translocation of membranes occurring during the secretory cycle of the oxyntic cell, has been attributed to a system of contractile proteins. The disposition of the prekeratin-like material suggests a role for intermediate filaments in the generation of movement, produced by actin and myosin interaction, by providing a fixed plane for the anchoring of actin microfilaments. 相似文献
37.
p-Hydroxyphenylglyoxal reacts with arginine residues in proteins to give a single product which can be quantitated spectrophotometrically. The reaction takes place under mild conditions, pH 7–9 and 25°C. Under these conditions up to complete modification of Nα-citraconyl-l-arginine was obtained within 60 min with less than 5% modification of other common amino acid side chains. The extent of modification in a protein can be determined at 340 nm using the molar absorption coefficient of 1.83 × 104m?1 cm?1 for the product at pH 9.0 and 25°C following removal of excess reagent by gel filtration. Several proteins, previously shown to have essential arginines, were modified by p-hydroxyphenylglyoxal and the losses in arginines were determined spectrophotometrically. These results were in close agreement with those of previous investigators. Rhea ovomucoid, a glycoprotein without arginines but containing an essential lysine, was relatively unaffected. 相似文献
38.
Soledad Gaitán Elvira Cuenllas Pilar Sancho Juan A. Bueren Concepción Tejero 《Bioscience reports》1992,12(4):281-292
This paper analyzes the long-term (6 and 12 months) function of mouse granulocytes after total body irradiation with a single dose (5 Gy) of X-rays. Superoxide anion production has been investigated in granulocytes from peripheral blood, and also in those harvested from long term bone marrow cultures, with the aim of correlating the environmental damage induced by radiation with the functional properties of granulocytes. Anin vivo andin vitro enhancement of superoxide anion production and protein levels in granulocytes from irradiated mice is described. The presence of some colony stimulating factor in the supernatant of cultures from irradiated mice could play an important role in the priming of granulocytes. 相似文献
39.
Mario Díaz Antonio Lorenzo 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1992,162(2):189-196
Summary Bioelectrical parameters and unidirectional sodium and chloride fluxes were measured under voltageclamp conditions in groups of lizards submitted to single or chronic aldosterone treatment. Both acute (AT) and chronic (CT) treatment induced significant increases in the short-circuit current (I
sc), as well as in the mucosa-to-serosa (J
m-s
Na
) and net sodium flux (J
net
Na
). In AT tissues, aldosterone did not change net chloride flux (J
net
Cl
) but did so in CT tissues. Amiloride reduced the aldosterone-increased I
sc in AT and CT tissues, inhibited J
net
Na
in AT tissues and abolished it in CT colons. J
net
Cl
was also reduced by the diuretic in the group of AT colons, whereas no changes were observed in the CT tissues. Addition of luminal DIDS reduced Na+ absorption and totally inhibited Cl- absorption in the AT tissues, but did not change I
sc. However, in CT tissues neither Na+ nor Cl- transport were affected by DIDS. A good relationship between I
sc and J
m-s
Na
was apparent after DIDS treatment in AT tissues. In this group, simultaneous addition of DIDS and amiloride totally abolished J
net
Na
and reduced I
sc to untreated control values. Addition of serosal ouabain abolished I
sc and Na+ absorption in AT and CT colons, but Cl- absorption was only altered in AT tissues. These results support the hypothesis that aldosterone induces an electrogenic, amiloride-sensitive sodium absorption, and in a dose-dependent fashion suppresses electroneutral NaCl absorption in the lizard colon.Abbreviations AT
acutely treated
- CT
chronically treated animals
- DIDS
4-4-diisothiocyanatostibene-2-2-disulfonic acid
- DMSO
dimethylsulphoxide
-
G
t
tissue conductance
-
I
sc
short circuit current
- PD
transepithelial potential difference
- SITS
4-acetamido-4-isothiocyanatostilbene-2-2-disulfonic acid
- UC
untreated controls
Preliminary results of this paper were presented at the X
th meeting of the European Intestinal Transport Group (EITG), Askov Hojskole, Denmark, 16–19 September 1990 相似文献
40.
By priming female C57BL/6 mice with syngeneic male spleen cells and enriching inguinal and paraaortic lymph node cells in long-term culture (LTC) by repeated restimulations, H-Y-specific T helper cells can be produced. In response to male spleen cells carrying I-Ab antigens these cells activate antigenexpressing B cells to secrete polyclonal antibody. Before the end of the second week in LTC it was impossible to detect any helper activity. Induction of plaque-forming cells (PFC) also requires simultaneous recognition of antigen and I-A-encoded determinants in the stimulator-responder spleen-cell population. The testing of spleen cells fromH-2 recombinant strains as stimulator-responders to anti-H-Y helper T cells of C57BL/6 origin also revealed that other genes, telomeric toI-A, control the magnitude of both specific T-cell proliferation and helper-dependent B-cell activation. 相似文献