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991.
The age, growth, feeding habits and reproductive biology of Leuciscus svallize in artificial lake Kremasta (Greece), are described. There is a considerable similarity in the feeding and reproductive characteristics between L. svallize and L. cephalus and also a similarity in the life span, growth patterns and age of maturation between L. svallize and some southern L. cephalus populations, which may suggest similar responses of closely related taxa to similar conditions. 相似文献
992.
The effects of variations in temperature, salinity and water movement on the laboratory growth and reproduction of a single clone of the bougainvilliid hydroid Clavopsella michaeli were examined. Unfavourable conditions resulted in reproducible oscillations of growth rate. They ranged from overall stimulatory effects (hormesis) to irreversible inhibition and shrinkage of colonies. Exposure to low concentrations (0.1–5 µg l–1) of copper and mercury ions produced similar responses, which were therefore regarded as non-specific. A control mechanism, dampening these growth rate oscillations, supported higher colonial tolerance, that is adaptation, to environmental stresses of low intensity. When the counteractive capacity of the control mechanism was exceeded, inhibition occurred. Higher frequencies of gonozooids were observed in stressed colonies and were interpreted as an adaptive response. 相似文献
993.
Incorporation of the gene for a cell-cell channel protein into transformed cells leads to normalization of growth 总被引:13,自引:0,他引:13
Parmender P. Mehta Agnes Hotz-Wagenblatt Birgit Rose David Shalloway Warner R. Loewenstein 《The Journal of membrane biology》1991,124(3):207-225
Summary Incorporation of the gene for connexin 43, a cell-cell channel protein of gap junction, into the genome of communication-deficient transformed mouse 10T1/2 cells restored junctional communication and inhibited growth. Growth was slowed, saturation density reduced and focus formation suppressed, and these effects were contingent on overexpression of the exogenous gene and the consequent enhancement of communication. In coculture with normal cells the growth of the connexin overexpressors was completely arrested, as these cells established strong communication with the normal ones. Thus, in culture by themselves or in coculture, the connexin overexpressor cells grew like normal cells. These results demonstrate that the cell-cell channel is instrumental in growth control; they are the expected behavior if the channel transmits cytoplasmic growth-regulatory signals. 相似文献
994.
The influence of plant resistance on the size of individual root-knot nematodes was determined in greenhouse experiments. Five genotypes of alyceclover were inoculated with second-stage juveniles of Meloidogyne incognita race 3 or M. arenaria race 1. Plants were harvested at selected intervals and stained for detection of the nematodes, which were dissected from the roots. Length, width, and sagittal-sectional area of each animal were measured using an image-analysis system, and areas of nematodes in all stages were compared at different times and across alyceclover lines. Nematodes feeding on roots of resistant lines were consistently smaller than those on susceptible plants, with significant differences in growth detected after the final molt. Similar results were observed with both nematode species. 相似文献
995.
Stephen R. J. Salton 《Journal of neurochemistry》1991,57(3):991-996
A nervous system-specific mRNA that is rapidly induced in PC12 cells to a greater extent by nerve growth factor (NGF) than by epidermal growth factor treatment has been cloned. The polypeptide deduced from the nucleic acid sequence of the NGF33.1 cDNA clone contains regions of amino acid sequence identity with that predicted by the cDNA clone VGF, and further analysis suggests that both NGF33.1 and VGF cDNA clones very likely correspond to the same mRNA (VGF). In this report both the nucleic acid sequence that corresponds to VGF mRNA and the polypeptide predicted by the NGF33.1 cDNA clone are presented. Genomic Southern analysis and database comparison did not detect additional sequences with high homology to the VGF gene. Induction of VGF mRNA by depolarization and phorbol 12-myristate 13-acetate treatment was greater than by serum stimulation or protein kinase A pathway activation. These studies suggest that VGF mRNA is induced to the greatest extent by NGF treatment and that VGF is one of the most rapidly regulated neuronal mRNAs identified in PC12 cells. 相似文献
996.
本文对等温自由生长和强制性溶液生长的等电溶菌酶的晶体形态进行了研究,发现这些形态变化与溶液相的流动密切相关,指出生物晶体生长停止是由于生长晶体周围的溶质贫乏造成的;通过某些手段减薄或消除这一溶质贫乏区,就可以保证晶体的持续生长。本文的研究对改善大尺寸晶体的生长提供了一条途径。 相似文献
997.
葡萄籽油和饼粕的化学成分及特性研究 总被引:3,自引:0,他引:3
廖德胜;王敬勉;王章莉;粟巧功;陈基国 《武汉植物学研究》1991,9(2):181-184
本文报道了葡萄耔油和饼粕的化学组成及特性。经测定,葡萄籽中粗蛋白、脂肪和纤维素的含量分别为8.4%、15.0%和37.2%;葡萄籽油中,不饱和脂肪酸为89.6%,其中亚油酸占72—76%,碘值、皂化值和酸值分别为138.3、191.5和1.68。我们还对重要矿物元素Ca、Mg和K的含量进行了测定。在葡萄酿酒后的下脚料中,葡萄籽占20—26%,对其进行二次深加工,不仅可以减少环境污染,还可以增加社会经济效益。 相似文献
998.
一、概述内禀增长率(r_m)是一个最基本的种群参数,它的测定和计算在动物生态学的研究中占有十分重要的地位。从20年代开始,已发展出多种计算动物r_m值的方法,如下所述。 相似文献
999.
过去的研究资料充分证明,巨噬细胞和由巨噬细胞释放的可溶性因子在矽肺纤维化过程中起着重要的调节作用。然而,对这种调节矽肺纤维化过程的蛋白因子的理化特性迄今还知道得很少。本研究采用矽肺大鼠肺泡巨噬细胞体外培养的方法获得其培养上清液,实验证明,该上清液可以促进体外培养的成纤维细胞对~3H-TdR和~3H-脯氨酸的摄取。我们从巨噬细胞上清液中分离纯化出一种具有促进成纤维细胞增殖能力的蛋白质因子。该因子在聚丙烯酰胺凝胶电泳上显示单个带谱,在SDS-聚丙烯酰胺凝胶电泳上测得分子量为66kD,在pH3-11的等电聚焦电泳上测得该因子的等电点为4.72。我们认为这种具有成纤维细胞增生因子活性的蛋白质可能就是在矽肺纤维化过程中刺激成纤维细胞增殖和胶原合成的调节因子。 相似文献
1000.