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141.
With the help of a suction manometric device, the relation between the deformation of Xenonus laevis embryo at the gastrula and neurula stages and the value of the applied force has been studied. Stiffness modules of embryonic
tissues were in the order of several dozens of Pascal and they were inversely proportional during deformation from 40 to 20%.
At the gastrula stage, a uniform or an increasing rate of expansion of the embryo body in the suction capillary with the diameter
of approximately half that of the embryo was observed for 30 min after the action of the suction forces. The length of the
stretched portion of the embryo correlates with the value of its deformation at the first minute. As a result of the expansion,
the total body surface area of the deformed embryo increases more than twice compared to intact embryos. After expelling the
embryo from the capillary, its surface reduced and the deformation became smoothened within 5 min, which indicates the existence
of tensional force in the expanded embryo. These data confirm that, at the embryo gastrula stage, external mechanical forces
do not only passively deform the embryo but also initiate the active expansion of the embryo which takes place at zero external
force and overcomes the tensional resistance of tissues. The mechanism of active expansion and its link with the processes
of normal morphogenesis are discussed. 相似文献
142.
143.
R factors of compatibility group A 总被引:4,自引:0,他引:4
144.
Abstract— In contrast to mouse brain, the content of putrescine in fish brain considerably exceeds that of spermine and spermidine. While we observed constant protein, RNA and spermidine concentrations in fish brains of weights between 60 and 800 mg, DNA and spermine concentrations diminished with increasing brain weight, the content of spermine per cell being constant throughout life. It can be concluded from our results that growth of fish brain results both from cell enlargement and cell proliferation. The concomitant changes of spermine and DNA concentrations in the growing fish brain are the first example of a direct quantitative relationship between these cell constituents and provides evidence on their possible functional relationship in the cell nucleus. 相似文献
145.
N. G. Morozova M. A. Maslov V. V. Myagchenkov G. A. Serebrennikova 《Russian Journal of Bioorganic Chemistry》2010,36(5):657-662
An approach to the synthesis of cationic carbohydrate surfactants with potential antimicrobial and transfecting activities
is proposed. 相似文献
146.
Ferredoxin from Bacillus polymyxa 总被引:5,自引:0,他引:5
Y I Shethna N A Stombaugh R H Burris 《Biochemical and biophysical research communications》1971,42(6):1108-1116
147.
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