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31.
Dominique Mouchiroud Christian Gautier Giorgio Bernardi 《Journal of molecular evolution》1988,27(4):311-320
Summary The compositional distributions of coding sequences and DNA molecules (in the 50-100-kb range) are remarkably narrower in murids (rat and mouse) compared to humans (as well as to all other mammals explored so far). In murids, both distributions begin at higher and end at lower GC values. A comparison of homologous coding sequences from murids and humans revealed that their different compositional distributions are due to differences in GC levels in all three codon positions, particularly of genes located at both ends of the distribution. In turn, these differences are responsible for differences in both codon usage and amino acids. When GC levels at first+second codon positions and third codon positions, respectively, of murid genes are plotted against corresponding GC levels of homologous human genes, linear relationships (with very high correlation coefficients and slopes of about 0.78 and 0.60, respectively) are found. This indicates a conservation of the order of GC levels in homologous genes from humans and murids. (The same comparison for mouse and rat genes indicates a conservation of GC levels of homologous genes.) A similar linear relationship was observed when plotting GC levels of corresponding DNA fractions (as obtained by density gradient centrifugation in the presence of a sequence-specific ligand) from mouse and human. These findings indicate that orderly compositional changes affecting not only coding sequences but also noncoding sequences took place since the divergence of murids. Such directional fixations of mutations point to the existence of selective pressures affecting the genome as a whole. 相似文献
32.
33.
Marie-Laure Yaspo Nathalie Crété Zoubida Chettouh Jean-Louis Blouin Zohra Rahmani Dominique Stehelin Pierre-Marie Sinet Nicole Créau-Goldberg Jean-Maurice Delabar 《Human genetics》1992,90(4):427-434
To generate new chromosome 21 markers in a region that is critical for the pathogenesis of Down syndrome (D21S55-MX1), we used pulsed field gel electrophoresis (PFGE) to isolate a 600-kb NruI DNA fragment from the WA17 hybrid cell line, which has retained chromosome 21 as the only human material. This fragment, which contains the oncogene ETS2, was used to construct a partial genomic library. Among the 14 unique sequences that were isolated, 3 were polymorphic markers and contained sequences that are conserved in mammals. Five of these markers mapped on the ETS2-containing NruI fragment and allowed us to define an 800-kb high-resolution PFGE map. 相似文献
34.
A macromorphological study is made on taxa of the genusOrnithogalum subg.Heliocharmos in North Africa, Spain, and France. The results obtained are consistent with data from cytogenetics, reproductive biology and strategies of reproduction. They allow the retention of two species:O. algeriense andO. umbellatum. A biogeographical and phylogenetic interpretation of the subgenus is proposed for the western Mediterranean. Theoretical views on phenetics are discussed. 相似文献
35.
Nicole Benhamou Pierre J. Lafontaine Dominique Mazau Marie-Thérèse Esquerré-Tugayé 《Planta》1991,184(4):457-467
An antiserum raised against deglycosylated hydroxyproline-rich glycoproteins (HPGPs) from melon (Cucumis melo L.) was used to study the relationship between Rhizobium infection and induction of HRGPs in bean (Phaseolus vulgaris L.) root nodule cells infected with either the wild-type or a C4-dicarboxylic acid mutant strain of Rhizobium leguminosarum bv. phaseoli. In effective nodules, where fixation of atmospheric dinitrogen is taking place, HRGPs were found to accumulate mainly in the walls of infected cells and in peribacteroid membranes surrounding groups of bacteroids. Internal ramifications of the peribacteroid membrane were also enriched in HRGPs whereas the peribacteroid space as well as the bacteroids themselves were free of these glycoproteins. In mutant-induced root nodules, HRGPs were specifically associated with the electron-dense, laminated structures formed in plastids as a reaction to infection by this mutant. The presence of HRGPs was also detected in the host cytoplasm. The aberrant distribution of HRGPs in infected cells of mutant-induced nodules likely reflects one aspect of the altered host metabolism in relation to peribacteroid-membrane breakdown. The possibility that the antiserum used for HRGP localization may have cross-reacted with ENOD 2 gene products is discussed in relation to amino-acid sequences and sites of accumulation. 相似文献
36.
A 126 bp fragment of a plant histone gene promoter confers preferential expression in meristems of transgenic Arabidopsis 总被引:3,自引:0,他引:3
Rossitza Atanassova Nicole Chaubet Claude Gigot 《The Plant journal : for cell and molecular biology》1992,2(3):291-300
The tissue-specific pattern of expression directed by the H4A748 Arabidopsis histone promoter was investigated by analysis of beta-glucuronidase (GUS) activity in transgenic Arabidopsis containing H4A748-GUS gene fusions. As determined by fluorimetric and histochemical tests, the H4A748 promoter directs preferential expression in meristems of young seedlings and adult plants. The low activity found in nonproliferating tissues may relate to basal constitutive expression of the histone promoter and/or to endoreduplication occurring in some tissues. The endogenous histone mRNA levels parallel the GUS activity found in different tissues. Analysis of the regulatory properties of 5' deleted promoters showed that multiple positive elements exist between -900 and -219 and that the proximal region of the promoter to -219 is sufficient to establish the full tissue-specific pattern of expression. Further deletion to -93 nearly abolished the promoter activity thus suggesting that the 126 bp fragment located between -219 and -93 contains the elements responsible for the specific expression pattern. The presence of several remarkable sequences within this fragment is discussed. 相似文献
37.
Cyclin B in Xenopus oocytes: implications for the mechanism of pre-MPF activation. 总被引:25,自引:9,他引:16
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Using a polyclonal antibody raised against B2 cyclin from Xenopus laevis, we show that prophase-arrested Xenopus oocytes contain a stockpile of cyclin B2 protein. During progesterone-induced maturation, an increase in the synthesis of cyclin B2 is observed, although Western blotting experiments show that this new synthesis does not significantly increase the mass of cyclin over the maternal stockpile. In the oocyte cyclin B2 is already present in two forms which differ in the extent of phosphorylation, but the phosphorylated form becomes predominant as oocytes progress towards germinal vesicle breakdown (GVBD), coincident with cdc2 protein kinase activation. These two events do not depend upon formation of a new complex between cyclin and cdc2 protein kinase, since these two proteins are already found associated in resting oocytes, prior to activation of the kinase. 相似文献
38.
Francisco Yegres Nicole Richard-Yegres Kazuko Nishimura Makoto Miyaji 《Mycopathologia》1991,114(2):71-76
Three strains of Cladosporium carrionii, two human isolates and one from a xerophilous plant, were used to study the effect of culture conditions in 106 newborn ddY mice. Growth in a complex medium (YPG) and a basal synthetic medium (BSM) was compared. Filamentous forms developed during static incubation while conidia were readily formed with shaking. Mice inoculated intraperitoneally were sacrified and autopsied after 4 weeks. Mortality was related only to sporulated exponential phase growing cells. Invasiveness ability was preserved in all experimental conditions. BSM medium that inhibited exopigment formation appeared more suitable than YPG to obtain intact cells for further studies.Biochemical and physiological alteration associated with shape changes during differentiation of vegetative cells into spores could play an important role in virulence of C. carrionii 相似文献
39.
Monique Berthelon Catherine Caillaud Françoise Rey Philippe Labrune Dominique Melle Josué Feingold Jean Frézal Marie-Louise Briard Jean-Pierre Farriaux Pierre Guibaud Hubert Journel Bernard Le Marec Nicole Maurin Jean-Louis Nivelon Henri Plauchu Jean-Marie Saudubray Philippe Tron Jean Rey Arnold Münnich Stanislas Lyonnet 《Human genetics》1991,86(4):355-358
Summary A total of 252 chromosomes from 126 patients with phenylalanine hydroxylase (PAH) deficiencies were analyzed for both mutant genotypes and restriction fragment length polymorphism (RFLP) haplotypes at the PAH locus. The mutant genes studied originated either from Western Europe (116 alleles) or from Mediterranean countries (136 alleles). Only 27% of all mutant alleles were found to carry identified mutations, particularly mutations at codon 252 (2.3%), 261 (7.5%), 280 (6.3%), 408 (3.5%) and at the splice donor site of intron 12 (6.3%). The mutant genotypes were associated with RFLP haplotypes 7, 1, 38, 2 and 3 at the PAH locus respectively. Except for the splice mutation of intron 12, these associations were preferential, but not exclusive, since the other four mutations were found on the background of at least two RFLP haplotypes. These results, together with the observation that 85% of PAH deficient patients are heterozygotes for their mutant genotypes, emphasize the great heterogeneity of PAH deficiencies in Mediterranean countries and hamper systematic DNA testing for carrier status in this population. 相似文献
40.
C Gautier D Bazile J Paoletti 《Biochemical and biophysical research communications》1988,154(1):252-257
We have investigated by means of absorbance measurements at 310 nm the binding of alpha-anomeric or beta-anomeric tetrathymidylates covalently substituted at their 3' end by an intercalating agent (oxazolopyridocarbazolium), to poly(rA). Taking into account the strong autoaggregation of the free ligands, we have derived the binding parameters corresponding to the [alpha] and the [beta] ligands. The affinity of the alpha-anomer for poly(rA) is higher than the affinity of the beta-anomer in accordance with the Tm studies conducted on such a system. 相似文献