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111.
Enkephalin-binding systems in human plasma 总被引:1,自引:0,他引:1
Roberta Possenti Valeria De Marco Ornella Cherubini L. Giorgio Roda 《Neurochemical research》1983,8(4):423-432
Three amino acid-containing fractions present in human plasma are shown to bind both leu and met-enkephalin: serum albumin and two species of a much lower molecular weight, in all likelihood polypeptides. The amount of enkephalin associated with serum albumin seems comparatively smaller than that associated with the two low molecular weight systems. These systems jointly are apparently capable of binding a significant part of the circulating enkephalins. The possibility is suggested that the interactions described may play a role in maintaining the integrity of circulating enkephalins. 相似文献
112.
Joyce M. Fisher Marco Rabinovitz 《Biochemical and biophysical research communications》1982,104(2):851-853
A specific copper chelator, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinedisulfonic acid substituted for mercaptoethanol to support growth of a L1210 lymphoma in primary culture. Added Cu++, but not Zn++ or Fe++ interfered with growth promotion by the chelator. It also can protect an established L1210 culture, which does not require mercaptoethanol, from cytotoxicity of two bis-thiosemicarbazones. Since these are known to require copper for cytotoxicity, the results indicate that 2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinedisulfonic acid acts by removing a source of endogenous copper in the tissue culture medium which prevents growth of the primary culture. 相似文献
113.
Sacco C. De Vries Marco C. Harmsen Martin T. R. Kuiper Hans J. M. Dons Joseph G. H. Wessels 《Plant molecular biology》1983,2(6):295-303
Summary The molecular cloning of cDNA corresponds to pea seedling mRNA sequences encoding a shoot-specific polypeptide, the small subunit of the ribulose 1,5 biphosphate carboxylase and a component of the light-harvesting chlorophyll a/b complex is described. cDNA prepared from polysomal poly(A)RNA of light-grown shoots was enriched for shoot-specific and light-induced sequences by heterologous liquid hybridization with mercurated polysomal poly(A)RNA of dark-grown roots, followed by sulfhydryl chromatography. Cloned shoot-specific sequences were identified by 2D electrophoretic analysis of hybrid release translation products. The cloned shoot-specific sequence corresponded to a mRNA of 850 nt present both in light-and dark-grown shoots, and produced anin vitro translation product of Mr27 500 and isoelectric point of 4.7. 相似文献
114.
Roberta Bertelli Fabrizio Ginevri Rosanna Gusmano Gian Marco Ghiggeri 《In vitro cellular & developmental biology. Animal》1991,27(10):799-804
Summary It has been suggested that the generation of toxic radicals plays an important role in toxicity by Adriamycin (ADR) on cancer
cell lines and in vivo. We have examined the role of free radicals in determining toxicity and resistance to ADR of rat glomerular
epithelial cells in culture; this method provides a good model for analyzing the mechanisms responsible for ADR experimental
nephrosis in rats. Three points were established: a) the intra- or extracellular site of ADR toxicity; b) the role of the
superoxide anion and of the hydroxyl radical in determining intra- and-extracellular cytotoxicity; and c) the implication
of oxido-reduction cycling as a potential route for ADR semiquinone transformation. Free ADR was found to induce the same
inhibition of [3H]thymidine incorporation into DNA as ADR bound to an agarose macroporous bed which prevents the intracellular incorporation
of the drug. Specific scavenging of free radical activity by the enzymes catalase and superoxide dismutase, the hydroxyl radical
inhibitors dimethyl sulfoxide and dimethylthiourea (DMTU) and by chelation of intracellular free iron with deferoxamine produced
only a partial restoration of [3H]thymidine incorporation into DNA, which was maximal for DMTU (30% of normal incorporation). DMTU treatment was unsuccessful
in preventing the extracellular cytostatic effect of ADR. Finally, glomerular epithelial cell killing (51Cr-release method) by 5-iminodaunorubicin, an ADR analogue with a modified quinone function that prohibits oxido-reduction
cycling, was higher than unmodified ADR. These results indicate that ADR may exert its cytotoxic effects on glomerular epithelial
cells by interaction at the cell surface, whereas the intracellular compartment, principally DNA, does not seem to be the
target of ADR effects. They also suggest that the free radicals are in part responsible for ADR intracellular cytotoxicity,
but other mechanisms should also be hypothesized. Finally, the participation of the ADR semiquinone radical in oxido-reduction
cycling seems not important for the induction of the cellular damage. 相似文献
115.
116.
Hassidim M Schwarz R Lieman-Hurwitz J Marco E Ronen-Tarazi M Kaplan A 《Plant physiology》1992,100(4):1982-1986
The rotA gene encoding peptidyl-prolyl cis-trans isomerase has been identified, sequenced, and shown to be transcribed in the cyanobacterium Synechococcus sp. PCC7942. Inactivation of the gene by replacement of a region containing the open reading frame with a gene conferring kanamycin resistance resulted in merodiploids containing both the wild type and the modified genomic region. We were not able to isolate a kanamycin-resistant mutant in which all the genomic wild-type copies were substituted, which suggests that such replacement could have been lethal. 相似文献
117.
A soluble protein isolated from mitochondria has been found to modulate the voltage-dependent properties of the mitochondrial outer membrane channel, VDAC. This protein, called the VDAC modulator, was first found inNeurospora crassa and then discovered in species from other eukaryotic kingdoms. The modulator-containing fraction (at a crude protein concentration of 20 µg/ml) increases the voltage dependence of VDAC channels over 2–3-fold. At higher protein concentrations (50–100 µg/ml), some channels seem to remain in a closed state or be blocked while others display the higher voltage dependence and are able to close at low membrane potentials. By increasing the steepness of the voltage-dependent properties of VDAC channels, this modulator may serve as an amplifierin vivo to increase the sensitivity of the channels in response to changes in the cell's microenvironment, and consequently, regulate the metabolic flux across the outer mitochondrial membrane by controlling the gating of VDAC channels. 相似文献
118.
Summary Androgenic plants have been obtained via anther culture in four natural populations of Hordeum spontaneum. Microscopic observations revealed that androgenesis started with the formation of two vegetative-type nuclei derived from the mitotic division of the uninucleate microspores. In this species androgenesis was affected by the type and concentration of the sugars added to the culture medium: the highest response (17% of callusing anthers) was observed on media containing 80 g l–1 maltose. The highest production of androgenic plants (per 100 anthers, 5.9 green and 4.3 albino plants) was obtained from callus grown on these same media. About half of the green plants regenerated were haploid, while the others were diploid and set seed.Abbreviations IAA
indolacetic acid
- BAP
6-benzylaminopurine 相似文献
119.
To lek or not to lek: mating strategies of male fallow deer 总被引:5,自引:1,他引:4
Apollonio Marco; Festa-Bianchet Marco; Mari Franco; Mattioli Stefano; Sarno Benedetta 《Behavioral ecology》1992,3(1):25-31
We studied the mating system of fallow deer (Dama dama) for6 years in central Italy. Males in this population could defendterritories that were either single, clumped in leks, or satelliteto leks. The most highly successful males in our study werein leks. When we considered all males, there were no significantdifferences in average copulatory success according to territorytype because many lek males did not achieve any copulations,which were seen in only a few lek territories. The variancein copulatory success, however, was much greater for leks thanelsewhere. Single territories were occupied for shorter timesduring the rut than lek territories. Fighting among males wasmore frequent in the lek, even when we excluded highly successfullek males from the analysis. Chases of nonterritorial malesand harem size were correlated with the number of copulationsachieved by individual males, but did not vary according toterritory type. Copulatory success of some individuals increasedwith age, but there were no age differences among males holdingdifferent types of territories. Satellite males switched tolek territoriality in the course of one rut, but switches fromsingle territory to lek territory were rare. We suggest thatmales in single territories are inferior competitors that selecta low-risk, lowbenefit strategy, whereas those in lek territorieswhere no copulations were seen may be attempting to establishthemselves on the lek to increase their copulatory success infuture years. 相似文献
120.