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61.
Glucocorticoids Potentiate the Prostaglandin E1 -Mediated Cyclic AMP Formation by a Cultured Murine Neuroblastoma Clone 总被引:2,自引:2,他引:0
The effect of steroid hormones on the prostaglandin E1 (PGE1)-mediated cyclic AMP formation by murine neuroblastoma clone N1E-115 was studied. Dexamethasone at submicromolar concentrations and corticosterone at micromolar concentrations (steroids with glucocorticoid activity) were able to modify the PGE1-mediated response whereas testosterone, progesterone, and estradiol each at 10 microM had no effect. Glucocorticoids added to the culture medium of N1E-115 cells produced an increase in the maximal response to PGE1 only after long-term (greater than or equal to 4 h) incubation with the hormone. Inhibitors of protein and RNA synthesis blocked this effect of glucocorticoids. Basal activity of adenylate cyclase in treated cells was twofold higher than that in control cells, and this enzyme seemed to be the primary target for the hormone action, since the activity of 3':5'-cyclic AMP phosphodiesterase and the binding of [3H]PGE1 to its receptors were not altered by glucocorticoid treatment. Our results indicate that glucocorticoids modulate receptor-mediated responses in cells of neural origin through a mechanism that involves induction of protein synthesis. 相似文献
62.
Edda De Rossi Giovanna Riccardi Anna Maria Sanangelantoni Orio Ciferri 《FEMS microbiology letters》1985,30(1-2):239-244
Abstract A Spirulina platensis gene library has been constructed using cosmid vector pMMB34. The cosmid bank was controlled for its random gene distribution by colony hybridization. Genes were identified using either homologous or heterologous probes of genes involved in photosynthesis (large and small subunit of d -ribulose 1,5-bisphosphate carboxylase, 32 kDa thylakoid protein, α, β subunits of C-phycocyanin) and protein synthesis (elongation factors EF-Tu, EF-G). 相似文献
63.
Guatteria, Guatteriopsis, Guatteriella andHeteropetalum share the same conspicuous pollen type which is new for theSpermatophyta. It is zonoaperturate with a folded aperture region and an extremely reduced exine. First chromosome counts and karyotype analyses forGuatteriopsis (4 species investigated) andGuatteriella (1 species) are identical with those ofGuatteria (19 species seen): 2n = 28. The genome is characterized by diploidization and partly telocentric chromosomes. Sequentially Giemsa C- and fluorochrome banded chromosomes and interphase nuclei are described. The cuticular folding pattern is distinct forHeteropetalum only. Growth forms and ecology are reported for many species. The evolutionary pattern of theGuatteria group is discussed and compared with other genera and families. 相似文献
64.
Lidia Sautebin Hans Kindahl Maria Kumlin Elisabeth Granstrm 《Prostaglandins & other lipid mediators》1985,30(3):435-456
Conjugates of prostaglandins and thromboxanes with tritium labeled amino acids were prepared and employed as labeled ligands in porstaglandin and thromboxane radioimmunoassays. Assays for PGF2α, 15-keto-13, 14-dihydro-PGF2α, TXB2 and 15-keto-13, 14-dihydro-TXB2 were evaluated in comparative studies using either these heterologous ligands or the corresponding homologus tritiated eicosanoid as tracers. Binding properties for the respective antibodies were found to be similar using either tracer.Three biological studies were also conducted, viz. study of the release of TXB2 during collagen induced platelet aggregation, of 15-keto-13, 14-dihydro-TXB2 during guinea pig pulmonary anaphylaxis, and of PGF2α (measured as 15-keto-13, 14-dihydro-PGF2α in peripheral plasma) during bovine luteolysis. The analyses gave comparable results using either the heterologous or the homologous assay.Thus, this type of labeled prostanoid conjugates may serve as a convenient alternative to homologous tracers in radioimmunoassay. Heterologous tracers may even in certain cases provide the only simple solution to the problem of preparing a labeled ligand of high specific activity. 相似文献
65.
Zbigniew Szot Małgorzata Rochalska Maria Wojewódzka Andrzej Chimiak Witold Przychodzen 《Radiation and environmental biophysics》1986,25(1):31-35
Summary Male mice SAS/4 were injected i.v. with239Pu citr(IV) 0.27 µCikg–1–9.99 kBqkg–1. After 1 h 30 µmol kg–1 of 3,4,3 LICAM(C), N, N, N, N-tetra-(2,3-dihydroxybenzoyl)-spermine or Na3CaDTPA as a reference compound was given intraperitoneally. After 4 days the animals were sacrified and the Pu content in livers, kidneys, femurs and carcasses was determined by the liquid scintillation method. It was found that, as compared with the control, 3,4,3 LICAM(C) removed 83% of the Pu activity deposited in the liver, 71% of that in the femur and 79% of the Pu in the whole body. The Pu content in the kidneys exceeded the control value by about 50%. Na3CaDTPA removed 96, 86, 40 and 72% of plutonium from the liver, kidneys, femurs and carcasses respectively.Tetra-DHB-spermine caused the excretion of 50, 57 and 39% of Pu from liver, bone and whole body respectively. The retention of Pu in the kidneys was increased to 400% of the control value. 相似文献
66.
The effects of methadone (METH) on serum levels of prolactin (PRL), growth hormone (GH), corticosterone (CS) and TSH were determined in developing rats. METH increased PRL, GH and CS and decreased TSH at all ages tested, but the time course and magnitude of these effects changed during ontogeny. METH effects on day 10 were lower in magnitude than those observed in adults. In 20 day old pups, METH effects on GH and CS were comparable to those of adults, but TSH effects were still blunted. METH effects on hormone secretion in both 10 and 20 day old pups lasted longer than those observed in adults. Naloxone blocked all hormonal responses in adults, but did not completely block METH effects on CS secretion in 10 day old pups. 相似文献
67.
Anna Maria Tagliasacchi Laura Maria Costantina Forino Manuela Frediani Silvana Avanzi 《Protoplasma》1983,115(2-3):95-103
Summary The pattern of DNA and RNA puffs in pair VII of polytene chromosomes has been investigated in the suspensor ofPhaseolus coccineus during early embryo development. The pattern of3H-TdR and3H-U incorporation has been also detected. Collected data indicate that: 1. both heterochromatic regions, p11 and q(111+112), of chromosome pair VII, organize large DNA puffs; 2. DNA puffs of both regions are specific of different embryo differentiation steps; 3. a seasonal influence on the DNA puffing seems also to be present, as demonstrated by the comparison of the results collected in two different crops; 4. the incorporation experiment by3H-TdR evidences that not all DNA puffs show clustered labeling; 5. the RNA puffing of the two regions seems also to be specific of determined embryo stages. 相似文献
68.
Carlos A. Braumann 《Bulletin of mathematical biology》1983,45(4):635-641
This paper reviews some recent advances in single population stochastic differential equation growth models. They are a natural way to model population growth in a randomly varying environment. The question of which calculus, Itô or Stratonovich, is preferable is addressed. The two calculi coincide when the noise term is linear, if we take into account the differences in the interpretation of the parameters. This clarifies, among other things, the controversy on the theory of niche limiting similarity proposed by May and MacArthur. The effects of correlations in the environmental fluctuations and statistical methods for estimating parameters and for prediction based on a single population trajectory are mentioned. Applications to fisheries, wildlife management and particularly to environmental impact assessment are now becoming possible and are proposed in this paper. 相似文献
69.
Carlos Gancedo 《Journal of bacteriology》1971,107(2):401-405
Fructose-1,6-diphosphatase was derepressed in Saccharomyces cerevisiae by incubation in media containing non-sugar carbon sources. Addition of glucose to a derepressed culture led to a rapid loss of the measurable activity of the enzyme. Fructose and mannose also produced inactivation, but 2-deoxyglucose was ineffective. Experiments with cycloheximide indicated that the inactivation does not require protein synthesis. It was also shown that the process is not energy-dependent. The reappearance of the enzyme was dependent on an energy source and was prevented by cycloheximide. These results suggest that fructose diphosphatase inactivation is irreversible and that reappearance of enzyme activity implies de novo synthesis. Screening of different genera of yeasts has shown that the inactivation of fructose diphosphatase is a relatively widespread phenomenon. 相似文献
70.
The fate of newly made DNA in Escherichia coli mutants thermosensitive in DNA synthesis 总被引:5,自引:0,他引:5
Summary
E. coli mutants exist in which DNA synthesis is thermosensitive. In one class of these mutants DNA synthesis stops immediately if a critical temperature (42°C) is reached. When DNA replication in such mutants is followed by 3H thymidine incorporation at 33°C, it is found that 1. only the newly made DNA is degraded at 42°C, 2. the discontinuously replicated DNA is lost predominantly at 42°C, 3. 1–3% of the chromosomal DNA is rendered acid soluble at 42°C without concomitant loss of viability of the cells at 33°C.Replication of phage DNA is inhibited in the same mutant at 42°C. However, when DNA synthesis is followed in infected cells at 33°C it is found that 1. no degradation of specific DNA seems to occur at 42°C in the early phase of infection, 2. replicating DNA molecules in the late phase of infection are completed at 42°C before DNA synthesis comes to a halt. 相似文献