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Evidence for a role of protein kinase C zeta subspecies in maturation of Xenopus laevis oocytes. 总被引:4,自引:1,他引:3 下载免费PDF全文
I Dominguez M T Diaz-Meco M M Municio E Berra A García de Herreros M E Cornet L Sanz J Moscat 《Molecular and cellular biology》1992,12(9):3776-3783
A number of studies have demonstrated the activation of phospholipase C-mediated hydrolysis of phosphatidylcholine (PC-PLC) both by growth factors and by the product of the ras oncogene, p21ras. Evidence has been presented indicating that the stimulation of this phospholipid degradative pathway is sufficient to activate mitogenesis in fibroblasts as well as that it is sufficient and necessary for induction of maturation in Xenopus laevis oocytes. However, the mechanism whereby PC-PLC transduces mitogenic signals triggered by growth factors or oncogenes remains to be elucidated. In this study, data are presented that show the involvement of protein kinase C zeta subspecies in the channelling of the mitogenic signal activated by insulin-p21ras-PC-PLC in Xenopus oocytes as well as the lack of a critical role of protein kinase C isotypes alpha, beta, gamma, delta, and epsilon in these pathways. 相似文献
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Thymosin-beta 4 gene. Preliminary characterization and expression in tissues, thymic cells, and lymphocytes 总被引:1,自引:0,他引:1
J Gómez-Márquez M Dosil F Segade X R Bustelo J G Pichel F Dominguez M Freire 《Journal of immunology (Baltimore, Md. : 1950)》1989,143(8):2740-2744
A cDNA for rat thymosin-beta 4 was used to investigate the expression of this gene in different tissues, thymic cells, and lymphocytes. Hybridization analysis of total RNA from 13 rat tissues demonstrated the presence of an 800 nucleotides-long mRNA in all the tissues surveyed, with the highest levels in spleen, thymus, and lung. Examination of thymic cells showed that the thymosin-beta 4 gene is predominantly expressed in thymocytes. The thymosin-beta 4 mRNA was also studied in Ig+ and Ig- lymphocytes, being fourfold more abundant in Ig- than Ig+ splenic lymphocytes, whereas similar levels were found in both types of blood cells. The analysis of RNA from T cells at different maturation stages evidenced slight differences in their thymosin-beta 4 mRNA content, indicating that thymosin-beta 4 gene expression is not clearly related to the differentiation process of T cells. All these results do not support the roles for thymosin-beta 4 in cellular immunity and differentiation of lymphoid cells, suggesting a more general function for this peptide. Preliminary characterization of the human beta 4 gene by restriction analysis disclosed a complicated pattern consistent with multiple genes and/or introns. The analysis of genomic DNA from different species ranging from humans to Escherichia coli showed that this gene is only highly conserved in mammals. 相似文献
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The R7 fate is specified during Drosophila eye development by an inductive signal transduced intracellularly via the Raf kinase. We have performed a genetic screen for dominant mutations that alter the efficiency with which cells respond to a constitutively activated Raf kinase. Such mutations may affect genes involved in signal transduction downstream of Raf. We have isolated 44 mutations that define eight genes. One of these encodes a mitogen-activated protein kinase homologue; another is a putative target gene of this signaling pathway. We present the results of this screen in detail, as well as a preliminary genetic analysis of the six loci still to be characterized molecularly. 相似文献
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Detecting non-neutral heterogeneity across a region of DNA sequence in the ratio of polymorphism to divergence 总被引:11,自引:4,他引:7
Natural selection, in the form of balancing selection or selective sweeps,
can result in a decoupling of the amounts of molecular polymorphism and
divergence. Thus natural selection can cause some areas of DNA sequence to
have greater silent polymorphism, relative to divergence between species,
than other areas. It would be useful to have a statistical test for
heterogeneity in the polymorphism to divergence ratio across a region of
DNA sequence, one that could identify heterogeneity greater than that
expected from the neutral processes of mutation, drift, and recombination.
The only currently available test requires that a region be arbitrarily
divided into sections that are compared with each other, and the
subjectivity of this division could be problematic. Here a test is proposed
in which runs of polymorphic and fixed sites are counted, where a "run" is
a set of one or more sites of one type preceded and followed by the other
type. The number of runs is smaller than otherwise expected if
polymorphisms are clumped together. By simulating neutral evolution and
comparing the observed number of runs to the simulations, a statistical
test is possible which does not require any a priori decisions about
subdivision.
相似文献
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The correlation between pollen/ovule (P/O) ratio and breeding system has generally been accounted for either on the basis that P/O reflects pollination efficiency, or in terms of the sex allocation theory. The following were assessed for taxa belonging to genus Astragalus subgenus Epiglottis: 1) Degree of correlation between P/O and the breeding system, measured by means of autofertility; 2) The absence or existence of correlation between P/O and pollen grain size; and 3) The ability of various theories to account for the results obtained. Results showed a minimal correlation between P/O and autofertility, and between P/O and pollen grain size in the taxa studied. Analysis of these results in terms of the sex allocation theory enabled this correlation to be explained as a function of the variation existing between taxa with respect to the resources invested in each pollen grain and in each ovule. The predictive capacity of this theory, which has moreover proven valuable in explaining the structural peculiarities of the androecium in these taxa, was also highlighted. The type of self-pollination applicable was also discussed, as was the phenotypic model of selection of self-fertilization considered most plausible for these taxa. 相似文献
10.
Modified carbon flux during oxygen limited growth of Corynebacterium glutamicum and the consequences for amino acid overproduction 总被引:1,自引:0,他引:1
Summary The amino acid producing bacterium Corynebacterium glutamicum accumulated lactate, succinate and acetate under oxygen-limited growth conditions. Significant restructuring of carbon flux through the central metabolic pathways occurred with a notable decrease in pentose pathway flux and the operation of the TCA cycle in a reductive mode. Simultaneous consumption of residual sugar and organic acids took place when oxygen sufficient conditions were restored though amino acids yields were significantly perturbed. 相似文献