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1.
Samples of marine pleuston were collected from the sea-surface along considerable sections of the track of Eye of the Wind during its 2-year circumnavigational expedition 'Operation Drake' from November 1978 to October 1980. One hundred and eleven of the tow samples contained insects of the genus Halobates . They were assigned to four oceanic species: H. micans, H. sericeus, H. germanus and H. splendens; two coastal species: H. maculatus, H. princeps, and one undescribed species. Various development stages of the oceanic species were found. The locations, time of collection and surface temperatures where sea-skaters were collected are tabulated. Distributional boundaries and population densities of the oceanic species collected are discussed. 相似文献
2.
Bing Xia Haiping Ke Wei Jiang Masayori Inouye 《The Journal of biological chemistry》2002,277(8):6005-6011
The 5'-end region of cspA mRNA contains a Cold Box sequence conserved among several cold-shock mRNAs. This region forms a stable stem-loop structure followed by an AU-rich sequence. Here we show that the Cold Box region is essential for the normal scale of cspA mRNA induction after cold shock because a deletion of the stem-loop significantly destabilizes the mRNA and reduces the cold shock-induced cspA mRNA amount by approximately 50%. The AU-rich track, however, slightly destabilizes the mRNA. The integrity of the stem is essential for the stabilizing function, whereas that of the loop sequence is less important. Overexpression of a mutant cspA mRNA devoid of both the AUG initiation codon and the coding sequence results in a severe growth inhibition at low temperature along with a derepression of the chromosomal cspA expression. Furthermore, the overexpressed RNA is stably associated with the 30 S and 70 S ribosomes. Our results demonstrate that the AUG initiation codon and the coding region containing the downstream box are not required for cspA mRNA to bind ribosomes and that the 5'-untranslated region by itself has a remarkable affinity to ribosomes at low temperature. 相似文献
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The effect of lysolecithin (lysophosphatidylcholine) on the relaxation of rabbit aortic strip closely resembled that produced by acetylcholine (ACh) which releases the endothelium-derived relaxing factor (EDRF). Relaxation induced by lysolecithin depended on the presence of endothelium and was inhibited by hemoglobin and methylene blue. It appeared to be mediated by the second messenger, c-GMP. Lysolecithin induced relaxation was slower but more persistent than that resulting from the endothelium-derived relaxing factor (EDRF) produced by acetylcholine (ACh). Like lysolecithin, Triton X-100, a non-ionic detergent, also preferentially relaxed aortic strips with intact endothelium. The results demonstrate the importance of phospholipids derived from cell membranes in vascular smooth muscle relaxation. Endothelium-derived relaxing factors appear as a group of heterogeneous substances. 相似文献
6.
Restructured beef steaks, formulated with different beef particle sizes, fat content and binder levels, were evaluated with selected marketing factors by 30 consumers. Conjoint analysis was applied to consumers’hedonic scores and statement of purchase intent for raw and cooked steaks. Product preference, packaging and brand had significant (P < 0.05) impacts on hedonic scores for raw products. Price was an additional important factor in purchase intent. Parcooked products, only product preference was important for both hedonic rating and purchase intent. When products were not present, conjoint measurement indicated that nutritional information, price and brand influenced (P < 0.05) hedonic responses. 相似文献
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取食雄蜂蛹粉对龟纹瓢虫和异色瓢虫卵黄发生的影响 总被引:1,自引:1,他引:0
本文比较了龟纹瓢虫Proylea japonica和异色瓢虫Harmonia axyridis取食蚜虫和取食雄蜂蛹粉时的卵黄发生情况.当取食雄蜂蛹粉时,体内卵黄蛋白出现迟,积累速度慢,产卵前期长.但用保幼激素类似物ZR512点滴处理后则能达到与食蚜对照相当的水平.ZR512对取食雄蜂蛹粉瓢虫的作用显著大于取食岈虫者.进一步的研究表明,ZR512能促进这两种瓢虫取食雄蜂蛹粉,但对成虫的体重没有明显的影响.因此推论,雄蜂蛹粉基本能够满足这两种瓢虫生殖的营养需要,但对其内分泌有一定的影响,使瓢虫处于类似生殖滞育的状态.本文根据不同食物条件对卵黄蛋白发生的影响不同,建议用卵黄蛋白的量作为生理指标,以快速初步筛选和评估人工饲料. 相似文献
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水生观赏植物的调查和研究 总被引:2,自引:0,他引:2
倪学明;赵家荣;於炳;周远捷 《武汉植物学研究》1992,10(1):92-100
水生绿化观赏植物是美化园林水景的重要植物材料,作者通过几年的调查研究和引种栽培,提出了28种(其中荷花含18个品种,睡莲含20个品种)水生绿化观赏植物,同时介绍了20种(其中荷花含6个品种)观赏价值较高的水生绿化观赏植物。 相似文献
10.
青龙河底栖无脊椎动物群落结构及其水质评价 总被引:17,自引:3,他引:14
本文论述了青龙河底栖生物种类、数量、分布和结构等特点及其与环境因子间的关系。应用Beck、Gleason、Shannon、Simpson等生物指数对水质状况进行评价。结果表明青龙河除个别断面受污染外,大部分河段属尚清洁水。 相似文献