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91.
Autotrophic picoplankton in southern Lake Baikal: abundance, growth and grazing mortality during summer 总被引:5,自引:0,他引:5
Nagata Toshi; Takai Kenji; Kawanobe Kyoko; Kim Dong-Sup; Nakazato Ryoji; Guselnikova Nina; Bondarenko Nina; Mologawaya Oliga; Kostrnova Tatyana; Drucker Valentine; Satoh Yasuhiro; Watanabe Yasunori 《Journal of plankton research》1994,16(8):945-959
Autotrophic picoplankton were highly abundant during the thermalstratification period in late July in the pelagic area (waterdepth 5001300 m) of southern Lake Baikal; maximum numberswere 2 x 106 cells ml1 in the euphotic zone ({small tilde}15m). Unicellular cyanobacteria generally dominated the picoplanktoncommunity, although unidentified picoplankton that fluorescedred under blue excitation were also abundant (maximum numbers4 x 105 cells ml1) and contributed up to {small tilde}40%of the total autotrophic picoplankton on occasions. Carbon andnitrogen biomasses of autotrophic picoplankton estimated byconversion from biovolumes were 1484 µg C l1and 3.621 µg N l1. These were comparableto or exceeded the biomass of heterotrophic bacteria. Autotropicpicoplankton and bacteria accounted for as much as 33% of paniculateorganic carbon and 81% of nitrogen in the euphotic zone. Measurementsof the photosynthetic uptake of [l4C]bicarbonate and the growthof picoplankton in diluted or size-fractionated waters revealedthat 80% of total primary production was due to picoplankton,and that much of this production was consumed by grazers inthe <20 µ.m cell-size category. These results suggestthat picoplankton-protozoan trophic coupling is important inthe pelagic food web and biogeochemical cycling of Lake Baikalduring summer. 相似文献
92.
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
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Yoshihito Suzuki Noboru Murofushi Yun-Hui Zhang Yasutomo Takeuchi 《Journal of Plant Growth Regulation》1994,13(2):63-67
Endogenous gibberellins were analyzed from a parasitic plant, clover broomrape (Orobanche minor Smith), and its host, clover (Trifolium repens L.). Members of both the early-13- and the early-non-hydroxylation pathways were identified from both the parasite and the host (GA12, GA24, GA9 GA4, GA44, GA19, GA20, and GA1 from clover broomrape; GA9, GA4, GA44, GA19, GA20, and GA1 from clover). Quantitative analyses showed that GA44 was present at high levels in both host and parasite. The similarity in the gibberellins suggests the possibility that the major gibberellins in clover broomrape are transported from clover. However gibberellins such as GA58, GA38, and notably GA47 which was identified from a plant for the first time were detected only from clover broomrape, suggesting that the parasite may have the ability to produce at least those gibberellins 相似文献
95.
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
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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
100.
Shunya Sogon Shinji Imakawa Makoto Masutani Nobuyoshi Takeuchi Katsuhiko Kubo 《Journal of Ethology》1993,11(1):1-10
The purposes of this study were two-fold. First, it compared Japanese infants' (N=129) abilities to regulate emotions at 13
months and 18 months of age, using the Strange Situation procedure. Second, it examined the relationship between the development
of emotion regulation and the mother's emotion expression style as assessed by the Emotion Expression Style Questionnaire
(EESQ). The total number of subjects who successfully completed all 8 episodes of the Strange Situation procedure increased
significantly during the aging between 13 and 18 months of age, indicating that as a group these infants increased their ability
to cope with stressful situations. However, infants who had mothers with negative emotion expression styles did not show greater
capacity for emotion regulation at 18 months. These findings suggest that the development of emotion regulation is mediated
by the mother's emotion expression style. 相似文献