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131.
Influence of Calcium Ion on Ethanol Tolerance of Saccharomyces bayanus and Alcoholic Fermentation by Yeasts 总被引:1,自引:0,他引:1
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Regina C. Nabais Isabel S-Correia Cristina A. Viegas Júlio M. Novais 《Applied microbiology》1988,54(10):2439-2446
The addition of Ca2+ (as CaCl2) in optimal concentrations (0.75 to 2.0 mM) to a fermentation medium with a trace contaminating concentration of Ca2+ (0.025 mM) led to the rapid production of higher concentrations of ethanol by Saccharomyces cerevisiae, Saccharomyces bayanus, and Kluyveromyces marxianus. The positive effect of calcium supplementation (0.75 mM) on alcoholic fermentation by S. bayanus was explained by the increase in its ethanol tolerance. The ethanol inhibition of growth and fermentation followed the equation μxi = μoi [1 - (X/Xmi)]ni, where μoi and μxi are, respectively, the specific growth (i = g) and fermentation (i = f) rates in the absence or presence of a concentration (X) of added ethanol, and Xmi is the maximal concentration of ethanol which allows growth or fermentation. The toxic power is given by ni. In Ca2+ - supplemented medium (0.75 mM), ng = 0.42 for growth and nf = 0.43 for fermentation compared with 0.52 and 0.55, respectively, in unsupplemented medium; for both media, Xmg = 10% (vol/vol) and Xmf = 13% (vol/vol). For lethal concentrations of ethanol, the specific death rates were minimal for cells that were grown and incubated with ethanol in medium with an optimal concentration of Ca2+, maximal for cells grown and incubated with ethanol in unsupplemented medium, and intermediate for cells grown in unsupplemented medium and incubated with ethanol in calcium-supplemented medium. The effect of Ca2+ on the acidification curve of energized cells in the presence of ethanol was found to be closely associated with its protective effect on growth, fermentation, and viability. 相似文献
132.
Cartesio Favalli Teresa Jezzi Antonio Mastino Cristina Rinaldi-Garaci Carlo Riccardi Enrico Garaci 《Cancer immunology, immunotherapy : CII》1985,20(3):189-192
Summary A single injection of -interferon (-IFN) (30 000 units/mouse), a major biological modifier of natural killer (NK) cytolytic activity, strongly stimulated NK activity in normal mice, as expected, while the same treatment did not statistically alter the NK response in cyclophosphamide (CY)-suppressed animals.We investigated the possibility of thymosin 1 cooperating with -IFN in boosting NK activity in CY-suppressed animals.The results show that treatment with thymosin 1 (200 g/kg) for 4 days, followed by a single injection of -IFN 24 h before testing, strongly restored NK activity in CY-suppressed mice. Thymosin 1 was, moreover, able to accelerate the recovery rate of NK activity in bone marrow reconstituted murine chimeras.Taken together the data support the concept that the synergic effect between thymosin 1 and -IFN could be the result of effects on differentiation of the NK lineage at different levels. 相似文献
133.
Restriction cleavage maps of the DNAs of Streptococcus pneumoniae bacteriophages containing protein covalently bound to their 5'' ends 总被引:6,自引:0,他引:6
Rubens López Concepción Ronda Pedro García Cristina Escarmís Ernesto García 《Molecular & general genetics : MGG》1984,197(1):67-74
Summary Several pneumococcal bacteriophages showing a morphology similar to that previously described for Cp-1 (Ronda et al. 1981) have been isolated and purified from throat samples taken from healthy children. Three of these phages (Cp-5, Cp-7 and Cp-9) have been studied in detail and compared to Cp-1. The four phages differed in several respects, e.g. size, structural polypeptides, restriction enzyme cleavage patterns, etc. The DNA of Cp-5, Cp-7 and Cp-9 showed protease-sensitive transfecting activity. This, together with the results obtained by electrophoretic analyses as well as by isotopic labelling of these DNAs with [-32P] ATP and polynucleotide kinase indicated that all these new phages have a protein covalently linked to the 5 ends of their DNAs as in the case of Cp-1 (García et al. 1983). Restriction enzyme cleavage maps of Cp-1, Cp-5, Cp-7 and Cp-9 have been constructed. 相似文献
134.
Dose-response curves for several prostaglandins (PGI2; PGD2; PGF2 and PGE2); BaCl2 or prostaglandin metabolites (15-keto-PGF2 alpha; 13,14-diOH-15-keto-PGF2 alpha; 6-keto-PGF1 alpha and 6-keto PGE1 in quiescent (indomethacin-treated) uterine strips from ovariectomized rats, were constructed. All PGs tested as well as BaCl2, triggered at different concentrations, evident phasic contractions. Within the range of concentrations tested the portion of the curves for the metabolites of PGF2 alpha was shifted to the right of that for PGF2 alpha itself; the curve for 6-keto-PGF1 alpha was displaced to the right of the curve for PGI2 and that for 6-keto-PGE1 to the left. It was also demonstrated that the uterine motility elicited by 10(-5) M PGF2 alpha and its metabolites was long lasting (more than 3 hours) and so it was the activity evoked by PGI2;6-keto-PGF1 alpha and BaCl2, but not the contractions following 6-keto-PGE1, which disappeared much earlier. The contractile tension after PGF2 alpha; 15-keto-PGF2 alpha; 13,14-diOH-15-keto-PGF2 alpha and PGI2, increased as time progressed whilst that evoked by 6-keto-PGF1 alpha or BaCl2 fluctuated during the same period around more constant levels. The surprising sustained and gradually increasing contractile activity after a single dose of an unstable prostaglandin such as PGI2, on the isolated rat uterus rendered quiescent by indomethacin, is discussed in terms of an effect associated to its transformation into more stable metabolites (6-keto-PGF1 alpha, or another not tested) or as a consequence of a factor which might protects prostacyclin from inactivation. 相似文献
135.
Cristina Rinaldi-Garaci Enrico Garaci Vera Del Gobbo Cartesio Favalli Teresa Jezzi Allan L. Goldstein 《Cellular immunology》1983,80(1):57-65
The effects of thymosin-α1 on the stimulation of specific release of prostaglandin E2 (PGE2) from splenic lymphocytes and thymocytes were studied. Experiments were also performed to study in parallel the absolute levels of thymosin-α1 in the blood and the induction of serum FTS activity and of azathioprine sensitivity of spleen cells from adult thymectomized (ATx) mice. A significant difference in the release of PGE2 between normal splenocytes and splenocytes from ATx mice was observed. Thymosin-α1 at certain concentrations was able to stimulate PGE2 release from lymphocytes of ATx mice while inhibiting release in lymphocytes of normal mice. Also, thymocytes were stimulated to release PGE2 after incubation with α1 in a manner similar to that seen in spleen cells of ATx mice. Approximately the same concentration of α1 was found to also correct the low azathioprine sensitivity of splenocytes from ATx mice. Determinations of FTS-like activity in the blood and the pharmacokinetics of α1 after administration of this synthetic molecule show a clear dissociation. A maximum peak of α1 activity was obtained after 1 hr, while maximal FTS-like activity was observed after 24 hr. The inhibition of the induction by α1 of FTS-like activity and of Thy 1.2 antigen by indomethacin suggests that the action of α1 requires prostaglandin biosynthesis. 相似文献
136.
Sandro Cavicchi Daniela Guerra Vanna Natali Cristina Pezzoli Gianfranco Giorgi 《Journal of evolutionary biology》1989,2(4):235-251
From a laboratory stock of Drosophila melanogaster (Oregon), reared for more than 20 years at 18° C, a new population was derived and maintained at 28° C for 8 years. The chromosomal and cytoplasmic contribution to genetic divergence between the two populations was estimated. Six body traits and reproductive fitness were taken into account. The third chromosome is responsible for the adaptive difference for temperature between the two lines. Temperature-selected genes which control body size are located on the second and third chromosomes, although the contribution of each chromosome depends on the environment in which the flies develop. The correlation between the chromosomal and cytoplasmic contributions to different traits and fitness, changes with temperature. At 28° C the correlation between fitness and each body trait is proportional to the response to selection exhibited by each of them, but this is not true at 18° C. Body size has, therefore, an adaptive significance in relation to temperature, which is expressed only in the environment where selection occurs. Cytoplasmic genes affect almost all characters to an extent similar to that of chromosomal genes. Inter-chromosomal and nucleo-cytoplasmic interactions are present and also change with temperature. In general, genes selected in a given environment produce greater phenotypic changes in that environment than in another. The population that experienced both temperatures is fitter in both environments, suggesting that the capacity to adapt to warm temperatures depends on genes other than those which are involved in the adaptation to cold. 相似文献
137.
M A Gimeno M Chaud E T Gonzalez A M Franchi A L Gimeno 《Prostaglandins, leukotrienes, and essential fatty acids》1989,38(3):163-168
The uptake of arachidonic acid (AA) and of di-homo-gamma-linolenic acid (DGLA) and their incorporations into phospholipids (PLs) and into neutral lipids (NLs) of uteri isolated from spayed rats and the effect of inhibiting triglyceride (TG) metabolism with 4-pentenoic acid (4-PEA) on tissue TG levels and the output of prostaglandins (PGs), were explored. Attempts were also made to determine whether the acylation of labelled AA and of labelled DGLA into PLs and TGs is different and to confirm possible correlations between the synthesis of PGE1 and the degradation of TGs. Uterine PLs incorporated significantly less DGLA than AA (P less than 0.05). AA was acylated mainly into the phosphatidylinositol (PI) and into phosphatidylcholine (PC) subfractions of rat uteri, whereas the incorporation of DGLA into these two subfractions was significantly smaller than that of AA. The acylation of labelled DGLA into NL fractions, mainly into triacylglycerol, almost doubled that of labelled AA. The levels of TGs in isolated rat uteri suspended in glucose-free medium during a period of 60 minutes were significantly less than immediately after isolation (P less than 0.001). PGE1 released from uteri into the incubating solution, was significantly higher than that of PGE2. Moreover, the presence of 4-PEA (1.0 mM), added after tissue isolation, prevented the decrement of TGs observed following 60 minutes of incubation and simultaneously diminished significantly (P less than 0.001) the enhanced output of PGE1, without altering that of PGE2. Results presented herein suggest that PLs are not normal precursors for the synthesis of PGE1.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
138.
Dr. María Cristina Maldonado Ana María Strasser de Saad Danley Callieri 《Current microbiology》1989,18(5):303-306
Several recent reports have described large numbers of monoclonal antibodies that cross-react with toxins A and B ofClostridium difficile; this suggests that the toxins share major epitopes. Our results show that monoclonal antibodies (MAb) against other antigens bind nonspecifically to both toxins. Therefore, we believe that the cross-reacting MAb bind by this manner and not by a true immune reaction. 相似文献
139.
Pier Giorgio Borasio Carla Biondi Maria Enrica Ferretti Elena Fabbri Maria Cristina Pareschi 《Neurochemical research》1989,14(12):1181-1186
Agonists modulation of Mg2+-dependent adenylate cyclase activity has been studied in guinea-pig superior cervical ganglion crude membrane preparations. In the absence of receptors ligands, Mg2+ stimulates the enzyme in a concentration-dependent manner. The dose-activation curve shows heterogeneity and two components with higher and lower apparent affinity states, are extrapolated. In the presence ofD-Ala2-met-enkephalinamide only one component is present and the apparent affinity of the ganglionic adenylate cyclase system for the divalent cation as well as Vmax are inhibited. On the contrary, prostaglandin E2 increases affinity and Vmax values of the lower and, to a lesser extent, of the higher Km component. When the two drugs are tested in combination, not only the inhibitory effect of the opiate is overcome, but a large increase of the apparent affinities and Vmax values for both components is obtained, suggesting the involvement of the Mg2+-regulated subunits of the adenylate cyclase system in the supra-additive stimulation mechanism of the enzyme. 相似文献
140.
The protective effect of zinc against slight teratogenical action, exerted by low cadmium concentrations, was evaluated inBufo arenarum embryos treated simultaneously with both cations or preincubated with Zn before Cd treatment. Data on survival, malformations, and delay in development pointed out that Zn could prevent the-deleterous effects of Cd in previous and simultaneous treatments with that heavy metal. 相似文献