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181.
M. Kawabuchi M. Osame S. Watanabe A. Igata T. Kanaseki 《Cellular and molecular life sciences : CMLS》1976,32(5):623-625
Summary Administration of large dose of neostigmine caused very quickly marked myopathic changes at the motor end-plate region. With continued injections, however some recovery of the structural features did occur suggesting the reconstructive changes in the affected regions.Acknowledgment. We wish to express our profound thanks to Dr.T. Iwayama and Ass. Prof.H. Ishikawa for their comments and discussions. Our thanks go also to Miss.R. Yokomine for her untiring technical assistance. 相似文献
182.
A. Watanabe N. Hobara H. Nagashima 《Cellular and molecular life sciences : CMLS》1985,41(11):1421-1422
Summary A rise in blood and liver acetaldehyde concentrations following ethanol loading (1.5 g/kg b.wt) was significantly reduced when rats were pretreated orally with taurine (0.5 g/kg), a potent in vitro activator of yeast aldehyde dehydrogenase. This taurine pretreatment produced a 4-fold increase in liver taurine content. 相似文献
183.
The c-mos proto-oncogene product is a cytostatic factor responsible for meiotic arrest in vertebrate eggs 总被引:77,自引:0,他引:77
The c-mos proto-oncogene product, pp39mos, is present in unfertilized Xenopus eggs, and disappears on fertilization. Microinjection of synthetic mos RNA into two-cell embryos induces cleavage arrest at metaphase. By contrast, egg cytosol extracts, when immunodepleted of endogenous pp39mos, lose their cleavage-arresting activity in injected embryos. These results demonstrate that Mos protein is the cytostatic factor CSF, long known as an endogenous meiotic inhibitor in vertebrate eggs. 相似文献
184.
185.
Moran K Backman J Brinkhuis H Clemens SC Cronin T Dickens GR Eynaud F Gattacceca J Jakobsson M Jordan RW Kaminski M King J Koc N Krylov A Martinez N Matthiessen J McInroy D Moore TC Onodera J O'Regan M Pälike H Rea B Rio D Sakamoto T Smith DC Stein R St John K Suto I Suzuki N Takahashi K Watanabe M Yamamoto M Farrell J Frank M Kubik P Jokat W Kristoffersen Y 《Nature》2006,441(7093):601-605
The history of the Arctic Ocean during the Cenozoic era (0-65 million years ago) is largely unknown from direct evidence. Here we present a Cenozoic palaeoceanographic record constructed from >400 m of sediment core from a recent drilling expedition to the Lomonosov ridge in the Arctic Ocean. Our record shows a palaeoenvironmental transition from a warm 'greenhouse' world, during the late Palaeocene and early Eocene epochs, to a colder 'icehouse' world influenced by sea ice and icebergs from the middle Eocene epoch to the present. For the most recent approximately 14 Myr, we find sedimentation rates of 1-2 cm per thousand years, in stark contrast to the substantially lower rates proposed in earlier studies; this record of the Neogene reveals cooling of the Arctic that was synchronous with the expansion of Greenland ice (approximately 3.2 Myr ago) and East Antarctic ice (approximately 14 Myr ago). We find evidence for the first occurrence of ice-rafted debris in the middle Eocene epoch (approximately 45 Myr ago), some 35 Myr earlier than previously thought; fresh surface waters were present at approximately 49 Myr ago, before the onset of ice-rafted debris. Also, the temperatures of surface waters during the Palaeocene/Eocene thermal maximum (approximately 55 Myr ago) appear to have been substantially warmer than previously estimated. The revised timing of the earliest Arctic cooling events coincides with those from Antarctica, supporting arguments for bipolar symmetry in climate change. 相似文献
186.
Sulphur isotope evidence for an oxic Archaean atmosphere 总被引:1,自引:0,他引:1
The presence of mass-independently fractionated sulphur isotopes (MIF-S) in many sedimentary rocks older than approximately 2.4 billion years (Gyr), and the absence of MIF-S in younger rocks, has been considered the best evidence for a dramatic change from an anoxic to oxic atmosphere around 2.4 Gyr ago. This is because the only mechanism known to produce MIF-S has been ultraviolet photolysis of volcanic sulphur dioxide gas in an oxygen-poor atmosphere. Here we report the absence of MIF-S throughout approximately 100-m sections of 2.76-Gyr-old lake sediments and 2.92-Gyr-old marine shales in the Pilbara Craton, Western Australia. We propose three possible interpretations of the MIF-S geologic record: (1) the level of atmospheric oxygen fluctuated greatly during the Archaean era; (2) the atmosphere has remained oxic since approximately 3.8 Gyr ago, and MIF-S in sedimentary rocks represents times and regions of violent volcanic eruptions that ejected large volumes of sulphur dioxide into the stratosphere; or (3) MIF-S in rocks was mostly created by non-photochemical reactions during sediment diagenesis, and thus is not linked to atmospheric chemistry. 相似文献