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1.
Abstract A mutant strain of Schizosaccharomyces pombe lacking dipeptidyl aminopeptidase yspI was isolated from a strain already defective in aminopeptidase activity by means of a staining technique with the chromogenic substrate ala-pro-4-methoxy-β-naphthylamide to screen colonies for the absence of the enzyme. The defect segregated 2+ :2− in meiotic tetrads, indicating a single chromosomal gene mutation, which was shown to be recessive. Gene dosage experiments indicated that the mutation resides in the structural gene of dipeptidyl aminopeptidase yspI, dpa 1+ . The dpa 1+ gene was located on chromosome III by using l m- fluorophen-ylalanine-induced haploidization and mitotic analysis. dpa1 mutants did not show any obvious phenotype under a variety of conditions tested. 相似文献
2.
Norfloxacin, a recently developed antimicrobial fluoroquinolone, was investigated for DNA-damaging activity in rat liver and kidney. After oral administration of single doses ranging from 1 to 8 mmole/kg, DNA fragmentation was absent in liver and kidney both 2 and 6 h after treatment. However, when administered to pregnant rats, the highest doses produced a detectable amount of DNA damage in fetal tissues. This damage appears to be an aspecific consequence of maternal and fetal toxicity rather than a specific genotoxic effect. 相似文献
3.
4.
N Zaffaroni R Silvestrini E Grignolio R Villa C DeMarco 《International journal of cell cloning》1988,6(6):392-403
Two assays based on the inhibition of 3H-thymidine incorporation into DNA were used to measure either the antimetabolic or the antiproliferative effects of anticancer drugs. A direct comparison of the two assays was made with cell suspensions obtained from 11 ovarian cancers and 22 malignant melanomas. Drugs with different effects on cell cycle phases were tested by both assays, for a total of 53 drug comparisons. When the sensitivity indices specific for each system was used, a significant association (p less than 0.01) was noted between the two assays. The agreement of both assays in defining in vitro sensitivity or resistance was 100% for ovarian cancer. For melanoma, 97% of samples resistant to the antimetabolic assay were also resistant to the antiproliferative assay; whereas, only 45% of samples sensitive to the antimetabolic assay were sensitive to the antiproliferative assay. 相似文献
5.
P. Calo J. Cansado J. B. Velázquez C. Sieiro E. Longo T. G. Villa 《Biotechnology letters》1991,13(11):781-786
Summary Four strains ofLactobacillus plantarum, were tested for malolactic fermentation under conditions of variations in temperature, pH and SO2, L-malate and ethanol levels. When the pH value was below 3.5, malolactic fermentation was lower and was more sensitive to temperature changes. Malolactic fermentation decreased when the SO2 and ethanol levels were increased. The effects of L-malate levels were not significant. 相似文献
6.
E. Longo J. Cansado C. Sieiro P. Calo J. B. Velázquez T. G. Villa 《World journal of microbiology & biotechnology》1992,8(2):147-150
Fermentative behaviour and cell growth have been studied in grape juice inoculated either with two killerSaccharomyces cerevisiae wild strains or with their Acridine Orange-cured isogenic counterparts. The number of viable cells/ml at the beginning of the fermentation, as well as during exponential growth, were higher in grape juices inoculated with the cured strains. The CO2 production, fermentative rate and ethanol and acetic acid production were also higher in the cured strains, particularly during the stage of active fermentation. These differences, however, were minimal at the end of the fermentations. 相似文献
7.
Summary Alcoholic fermentation cycle with Saccharomyces cerevisiae has been studied on beet molasses exempt from nitrite ions and containing added amounts of these ions from 200 to 400 ppm. Experimental results indicate that fermentation duration increases with increasing nitrite concentration in the molasses. A detailed kinetic study reveals that this increase occurs only during the latency period. Moreover, the biomass and the ethanol production curves drawn after this period appear to be quite linear, their slope being independent of initial nitrite concentration. It has also been shown that nitrite ions turn completely into nitrate ions during the latency period. We have proved that this oxidation must be ascribed to yeast action and not to any chemical reactions between nitrite ions and molasses components. 相似文献
8.
In the forebrain from male Wistar rats aged 5, 15 and 25 months, age-related putative alterations in the glutathione system (reduced and oxidized glutathione; redox index) were chronically induced by the administration in drinking water of free radical generators (hydrogen peroxide, ferrous chloride) or of inhibitors of endogenous free radical defenses (diethyl-dithio-carbamate, an inhibitor of superoxide dismutase activity). In hydrogen peroxide administered rats, both reduced glutathione and the cerebral glutathione redox index markedly declined as a function of aging, whereas oxidized glutathione consistently increased. In contrast, chronic iron intake failed to modify the reduced glutathione in forebrain from the rats of the different ages tested, whereas the oxidized glutathione was increased in the older brains. The chronic intake of diethyl-dithio-carbamate enhanced the concentrations of reduced glutathione in the forebrains from the rats of the different ages tested, the oxidized glutathione being unchanged. In 15-month-old rats submitted to chronic oxidative stress, ergot alkaloids (and particularly dihydroergocriptine) interfered with cerebral glutathione system, while papaverine was always ineffective. The comprehensive analysis of the data indicates that: (a) both the type of oxidative stress and the age of the animals modulate the cerebral responsiveness to the putative modifiers in the level of tissue free radicals; (b) aging magnifies the cerebral alterations induced by oxidative stress; the (c) cerebral glutathione system may be modified by metabolic rather than by circulatory interferences; (d) a balance between the various cerebral antioxidant defenses is present, the perturbation of an antioxidant system resulting in the compensatory modified activity of component(s) of another system. 相似文献
9.
Developmental and Regional Expression of NMDA Receptor Subtypes Containing the NR2D Subunit in Rat Brain 总被引:7,自引:3,他引:4
Abstract: The regional and developmental expression of NMDA receptors containing the NR2D subunit was analyzed on the level of the subunit mRNA and protein in rat brain. RNase protection experiments indicated that among two proposed splice variants of the NR2D subunit, only the NR2D-2 subunit is expressed. The regional distribution of the NR2D subunit protein was visualized with a newly developed NR2D-2 subunit-specific antiserum on brain sections using the histoblot technique. In adult brain, NR2D immunoreactivity was mainly restricted to diencephalic, mesencephalic, and brainstem structures. During postnatal development, the NR2D subunit was detected transiently in certain regions, such as the ventro-basal complex of the thalamus, hippocampus, inferior colliculus, and brainstem reticular formation, suggesting that NR2D subunit-containing receptors play a role in these brain areas only during development. The level of NR2D subunit mRNA and protein decreased during late postnatal development. However, significant levels of NR2D subunit mRNA and protein were present in adulthood, in particular, in the globus pallidus, thalamus, subthalamic nuclei, and superior colliculus. These results indicate a functional relevance for NMDA receptors containing the NR2D subunit in the developing and adult brain, although its expression in the adult brain is less prominent and restricted to a few brain areas. 相似文献
10.
G. Benzi A. Gorini B. Ghigini A. Moretti F. Dagani R. F. Villa 《Neurochemical research》1996,21(1):7-18
The changes in the Mg2+-dependent V-type ATPase activity and the Mg2+-ATP-dependent H+ pumping activity of the synaptic vesicles from the cerebral cortex of rats submitted to intermittent chronic (4 weeks) mild
or severe hypoxia were evaluated. The adaptation to the chronic severe hypoxia increases both the ATPase and the H+ pumping activities which are inhibited by NEM with an exponential relationship between the IC50 values and the in vivo O2 concentration. The Mg2+-dependent increase in H+ pumping activity of synaptic vesicles from the rats subjected to in vivo chronic hypoxia may be antagonized by nigericin
(dissipating ΔpH) and by FCCP (dissipating ΔpH and ΔΨSV). In contrast, valinomycin (dissipating the ΔΨSV and facilitating an enhancement in ΔpH) increases in vitro the H+ pumping activity that is inhibited by the addition of high concentration of K gluconate (reducing the rate of K+ efflux). The preincubation of vesicles from hypoxic rats with FCCP, but not with nigericin, inhibits the valinomycin-increased
H+ pumping activity.l-glutamate increases the H+ pumping activity in synaptic vesicles from the cerebral cortex of chronic hypoxic rats, whereas other amino acids (i.e.,l-aspartate andl-homocysteate) and glutamate analogs (i.e., quisqualate and ibotenate) are ineffective. The adaptation to both chronic intermittent
severe hypoxia and in vivo treatment with posatireline causes a decrease in the Mg2+-ATPase activity consistent with the decrease in the H+ pumping one of the synaptic vesicles. The addition of nigericin into incubation medium magnifies the decrease in the H+ pumping activity, while the addition of FCCP is ineffective, suggesting that the treatment with posatireline interferes with
the ΔΨSV component in the
of the synaptic vesicles from rats submitted to chronic hypoxia. The results of the in vivo and in vitro experiments suggest
that in the synaptic vesicles from hypoxic rats the ΔΨSV component in
may be most effective in increasing the Mg2+-ATP-dependent H+ pumping activity. 相似文献