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101.
Measurements of gill dimensions were carried out on two ecologically distinct active rheophilic teleost species, the curvina Plagioscion squamosissimus and the curimbatá Prochilodus scrofa , and were analysed in relation to body mass according to the equation Y=aWb . The gill respiratory areas of P. squamosissimus and P. scrofa were large as expected for active fish and increased with increasing body mass ( b =0.70 and 0.72, respectively) showing no significant difference between them. However, the large respiratory area of both species was realized in a different way revealing an adaptation to the plasticity of head components related to feeding habits. Consequently, significant differences were found between the number and average length of gill filaments and the bilateral area of secondary lamellae. The respiratory area of P. scrofa was due mainly to larger bilateral surface area of the secondary lamellae and its growth coefficient ( b =0.51) that was significantly higher ( P <0.05) than that found for P. squamosissimus ( b = 0.36). The frequency of secondary lamellae mm−1 of filament was similar in both species (22 ± 2 on one side of gill filament). The dimensions of gill components and the respiratory area of these species suggest a complex interaction between head form, and feeding habits related to the functional morphology of the gills to meet the oxygen requirements of each species. 相似文献
102.
鳜鱼消化器官的发育和食性的研究 总被引:21,自引:1,他引:20
本文对鳜鱼从仔鱼到成鱼期的消化器官发育作了一系列观察研究,主要观察了鳜鱼的口腔齿、鳃耙、消化道及消化腺的发育状况,并探讨了消化发育与其食性及摄食行为的关系。 相似文献
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The relationship between vernalization requirement and frost tolerance in substitution lines of wheat 总被引:1,自引:0,他引:1
Two sets of wheat (Triticum aestivum L.) substitution lines for the homoeologous group 5 chromosomes, 5A, 5B and 5D, carrying vernalization genes (Vrn-A1, Vrn-B1, Vrn-D1) were used to study the relationship between vernalization requirement and winter survival, with respect to the induction and maintenance of frost tolerance. Substitution lines carrying dominant Vrn loci substituted from the spring cultivars Zlatka (5A), Chinese Spring (5D) and the alternative cultivar eská Pesívka (5B) into three different winter wheat backgrounds, Vala, Koútka and Zdar, showed lower winter survival by 20, 36, and 41 % for substitutions of 5B, 5A and 5D, respectively, compared to the original winter cultivars. Reciprocal substitution lines between two winter cultivars Mironovskaya 808 and Bezostaya 1 carrying different recessive alleles, vrn-A1, vrn-B1, vrn-D1, did not exhibit a modified induction of frost tolerance, but the duration of good frost tolerance, as well as the ability to survive the whole winter, was changed. In accordance with the model suggesting that genes for vernalization act as a master switch regulating the duration of frost tolerance, substitutions of homoeologous group 5 chromosomes induced, at first, frost tolerance at a level equal to the parental cultivar, and then, relative to the different extent of saturation of vernalization requirement, they gradually lost both frost tolerance and their ability to re-induce significant frost tolerance with a drop in temperature following warm periods in the winter. 相似文献
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Pepsinogen levels in ape stomachs were comparable to those in macaques and significantly higher than those in the stomachs of other mammals, including carnivores and ruminants. The occurrence of multiple forms of pepsinogens was remarkable. Nine, sixteen, eight, and fourteen pepsinogens were purified or partially purified from the gastric mucosa of a gibbon, orang-utan, gorilla, and chimpanzee, respectively. Most of these were type-A pepsinogens, and only one type-C pepsinogen was identified in each ape. The two types could be readily distinguished by staining for proteolytic activity on polyacrylamide gel electrophoresis (PAGE) in the presence/absence of pepstatin. Type-A pepsinogens were further divided into two subtypes. One subtype, constituting a major group of pepsinogens in apes, exhibited high hemoglobin-digestive activity. The other subtype was specified by a relatively high content of Lys and low hemoglobin-digestive activity. It is likely that pepsinogen-A genes have been duplicated several times as hominoids, including humans, evolved in the primate lineage. The presence of multiple pepsinogens in apes might be advantageous in the efficient digestion of a wide variety of foods. 相似文献
108.
无锡太湖地区夜鹭及白鹭繁殖生物学研究 总被引:21,自引:2,他引:19
1999年 4~ 6月对分布在无锡地区的夜鹭 (Nycticoraxnycticorax)和白鹭 (Egrettagarzetta)的繁殖生物学进行了调查研究 ,调查地面积约 2 72 37 5m2 ,植被以马尾松 (Pinusmassoniana)和香樟树 (Cinnamomumhupehanum)为主。研究结果表明 :栖息地共有鹭巢近万个 ,平均密度为 0 36个 /m2 ,每棵树上平均巢数为1 0 6个 ,最多达 2 5个 /棵树 ;平均窝卵数夜鹭为 3 5 5枚 ,白鹭为 4 89枚 ;平均窝雏数夜鹭为 2 6 8只 ,白鹭为3 96只 ;孵化期白鹭为 1 9~ 2 1天 ,夜鹭为 2 2~ 2 3天 ;孵化成功率白鹭为 84 2 5 % ,夜鹭为 75 46 % ;白鹭雏鸟主要以小型鱼类和虾类为食 ,夜鹭雏鸟主要以鱼类和两栖类为食。 相似文献
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