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81.
The Saccharomyces cerevisiae DIS2S1/GLC7 gene encodes a type 1 protein phosphatase indispensable for cell proliferation. We found that introduction of a multicopy DIS2S1 plasmid impaired growth of cells with reduced activity of the cAMP-dependent protein kinase. In order to understand further the interaction between the two enzymes, a temperature-sensitive mutation in the DIS2S1 gene was isolated. The mutant accumulated less glycogen than wild type at the permissive temperature, indicating that activity of the Dis2s1 protein phosphatase is attenuated by the mutation. Furthermore, the dis2s1
ts mutation was shown to be suppressed by a multicopy plasmid harboring PDE2, a gene for cAMP phosphodiesterase. These results indicate that the Ras-cAMP pathway interacts genetically with the DIS2S1/GLC7 gene. 相似文献
82.
Hirai Nobuhiro; Kojima Yasuhiro; Koshimizu Koichi; Shinozaki Masateru; Takimoto Atsushi 《Plant & cell physiology》1993,34(7):1039-1044
Flowering of Pharbitis nil strain Violet is induced in continuouslight under poor nutritional conditions. High-performance liquidchromatography of extracts of the cotyledons revealed that twocompounds in addition to chlorogenic acid accumulate under suchconditions. The compounds were identified as pinoresinol glucosideand p-coumaroylquinic acid. The endogenous levels of these phenylpropanoidswere correlated with the flowering response when nutrition waspoor. However, activation of phenylpropanoid biosynthesis seemednot to be essential for the induction of flowering. (Received May 17, 1993; Accepted July 26, 1993) 相似文献
83.
84.
Full-grown amphibian oocytes that had been arrested at meiotic prophase I contained an activity that prevented the cell cycle from progressing beyond a G2 -like stage. Injection of the contents of germinal vesicles (GV-content) or cytoplasm obtained from oocytes of the frog Rana rugosa prevented fertilized eggs of Cynops pyrrhogaster or Bufo japonicus from cleaving. The nuclei in the arrested eggs consisted of thin chromosomes and nucleolus-like particles enclosed within clear nuclear membrane and their volume increased as a function of time after injection. Cycling of maturation-promoting factor (MPF) did not occur in the injected eggs, but DNA synthesis was not disturbed. The injection of exogenous MPF into the eggs induced the reinitiation of the cell cycle with progression to the M phase and subsequent cleavage. Furthermore, the injection into the full-grown oocytes of Bufo inhibited induction of the maturation of oocytes by progesterone. These results demonstrate that a factor that arrests the cell cycle either at a G2 -like stage of mitosis or at prophase in meiosis is present both in the GV and cytoplasm of frog oocytes. We refer to this factor as a G2 -specific cytostatic factor (G2 -CSF). G2 -CSF may play an important role not only in the physiological arrest at prophase I in meiosis, but also in regulation of the G2 /M transition in the cell cycle of early embryonic cells. 相似文献
85.
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87.
Group I introns in the liverwort mitochondrial genome: the gene coding for subunit 1 of cytochrome oxidase shares five intron positions with its fungal counterparts. 总被引:3,自引:0,他引:3
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E Ohta K Oda K Yamato Y Nakamura M Takemura N Nozato K Akashi K Ohyama F Michel 《Nucleic acids research》1993,21(5):1297-1305
The complete nucleotide sequence of the mitochondrial DNA (mtDNA) from a liverwort, Marchantia polymorpha, contains thirty-two introns. Twenty-five of these introns possess the characteristic secondary structures and consensus sequences of group II introns. The remaining seven are group I introns, six of which happen to interrupt the gene coding for subunit 1 of cytochrome oxidase (cox1). Interestingly, the insertion sites of one group II and four group I introns in the cox1 gene coincide with those of the respective fungal mitochondrial interns. Moreover, comparison of the four group I introns with their fungal counterparts shows that group I introns inserted at identical genomic sites in different organisms are indeed related to one another, in terms of the peptide sequences generated from the complete or fragmental ORFs encoded by these introns. At the same time, the liverwort introns turned out to be more divergent from their fungal cognates than the latter are from one another. We therefore conclude that vertical transmission from a common ancestor organism is the simplest explanation for the presence of cognate introns in liverwort and fungal mitochondrial genomes. 相似文献
88.
89.
Yasuhiro Takemon 《Ecological Research》1993,8(2):185-192
Water drinking habits during flight in adult mayflies ofEpeorus ikanonis Takahashi were observed and the effect of water intake on their longevity was examined. The study was carried out in a mountain
stream in western Japan. Adult males collected a water droplet under the head capsule while alighting on the water surface
and consumed it after moving to nearby riparian vegetation. The amount of water intake was experimentally estimated to be
9.7% of the bodyweight for males. Although females did not show the water drinking behavior in the field, they imbibed as
much as 5.5% of the bodyweight of water in an experimental situation. Morphological observation of the mouthparts revealed
that the water was drawn in through the pits at the base of the labrum. In the field caging experiment, males with a water
supply had a substantially longer life span than those without. Increase in adult life span by drinking water was less marked
in females. Multiple copulation was observed in both sexes during the experiment. The water drinking behavior of the males
may closely relate to mating success through increased longevity. Variation in the longevity of adult mayflies was discussed
with regard to the possibility of water intake.
This paper forms part of a PhD thesis submitted to the Department of Zoology in Kyoto University (1990). 相似文献
90.
A genomic fragment containing the dihydroflavonol 4-reductase B (DFR-B) gene was cloned from the sweet potato (Ipomoea batatas) and its nucleotide sequence was analyzed. The exons and flanking regions were highly homologous to those of previously reported DFR-B genes of the Japanese morning glory, whereas the introns and the intergenic region were less conserved. In addition to the sequences of three miniature inverted-repeat transposable elements (MITEs) and one direct repeat previously reported in the DFR-B gene of Japanese morning glory, two mobile element-like sequences were newly identified in the sweet potato DFR-B gene. At least four allelic sequences were found to exist by amplification of the DFR-B gene from various sweet potato cultivars. One of these allelic sequences had a 2-kb deletion in the intergenic region and was observed in the cultivars with high anthocyanin content in their storage roots. 相似文献