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17-β雌二醇诱导鲻雌性化的机制   总被引:2,自引:0,他引:2       下载免费PDF全文
方永强 《水产学报》2004,28(2):113-118
用原位杂交和免疫细胞化学技术,对服用17 β雌二醇实验组和对照组幼年鲻脑各部和性腺进行芳香化酶的定位。结果发现,芳香化酶转录物和特异性蛋白在幼年鲻端脑(嗅球和大脑)、间脑、中脑和小脑是丰富的。在性别未分化时,芳香化酶免疫活性细胞在幼鲻脑各部的分布密度有显著的差异。在嗅球,对照组芳香化酶免疫阳性细胞的分布密度高于实验组,而在间脑、中脑和小脑实验组免疫阳性细胞数量比对照组多1~3倍,特别是下丘脑视前区芳香化酶的免疫阳性细胞数量尤占优势,提示芳香化酶在幼年鲻性分化中可能起关键的作用。另外,在性分化后,芳香化酶免疫活性还定位在卵巢颗粒细胞和精巢间质细胞与足细胞。同时,免疫阳性物质也定位在卵巢和精巢的生殖细胞。这些结果揭示了17 β雌二醇诱发幼鲻雌性化的机制可能是通过芳香化酶的介导,本研究首次提供形态学新的证据。最后,文中还讨论了芳香化酶在鲻性腺发育中可能的生理作用。  相似文献
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日本鳗鲡人工繁殖技术研究最新进展   总被引:2,自引:0,他引:2  
乔振国 《海洋渔业》2007,29(4):360-364
日本鳗鲡(Anguilla japonica)人工繁殖是至今尚未解决的世界性难题。2001~2003年日本水产综合研究中心在实施政府资助研究专项“生态保护型增养殖体系建设一种苗生产、放流技术开发”期间,对已有40余年研究历史的日本鳗鲡人工繁殖涉及的亲鱼选育、催熟、催产、优质卵判别、仔鱼培育等关键技术进行了比较系统的研究。经过270d培育,于2003年首次成功获得日本鳗鲡白仔鳗苗(体长52.6mm)。本文在主要介绍这一研究成果的同时,概要介绍我国在这一领域的最新研究进展,希望能为我国的日本鳗鲡人工繁殖研究提供参考。  相似文献
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This study investigated the effects of estrogens on sexual differentiation in sea bass (Dicentrarchus labrax L.), a gonochoristic marine teleost that under culture conditions has a histologically sexual undifferentiated period that covers most of the first year of life, after which most individuals develop as males. Sea bass that had no noticeable histological sign of sex differentiation were fed estrogens at two doses (5 or 10 mg kg-1 food) and for different periods ranging from 48 to 426 days post fertilization (DPF). Exposure to the synthetic estrogen 17-ethynylestradiol (EE2) at 10 mg kg-1 food from 60 to 260 DPF, including the sensitive period to equivalent doses of synthetic androgens previously determined for this species (126-226 DPF), significantly (p < 0.05) more than doubled the number of juvenile females to 80%, compared to the control value of 33%, and completely suppressed gonadal development in the remaining 20% of the population. This suggests that the period during which sea bass gonads exhibit high sensitivity to androgens is also very sensitive to estrogens. A comparable exposure to the natural estrogen estradiol-17 (E2) resulted in 13% of the fish having suppressed gonadal development, but induced 57% of the fish to develop gonads with germinal tissue of both sexes, suggesting a pivotal role for E2 during this sensitive period. Earlier exposure to EE2 at 10 mg kg-1 food from 48-88 DPF, significantly (p < 0.05) increased the number of females to 62% from 36% in the control group, allowing for the normal testicular development in the remaining fish. In contrast, a later chronic exposure (226-426 DPF) to E2, at either 5 or 10 mg kg-1 food, starting when the gonads showed no sign of sexual differentiation but past the critical sensitive period, had no effect on the resulting overall sex ratios, indicating that after this period responsiveness of the gonads to estrogens decreases as gonadal sexual differentiation progresses. However, the consequences of this apparently innocuous exposure were later manifested in adults, exemplified by a significant dose-dependent reduction in the number of mature males at 626 DPF, coinciding with the second reproductive season, the time when males normally reach sexual maturation in cultured sea bass. This suggests that chronic exposure to E2 past the critical sensitive period may not affect the sex ratio, but could result in alterations in the male reproductive organs. This was later verified by histological analysis which revealed a significant (p < 0.05) dose-dependent reduction of the surface of the testicular lobules in the remaining males that did not mature. Together, these experiments illustrate both readily observable and subtle effects of estrogens on sex proportions, gonadal morphology and maturation rates, providing evidence that estrogen exposure can have delayed action in a teleost in a manner similar to the effects described for mammalian species. The possible existence of effects of this latter type in adult fish could be considered when evaluating the consequences of deliberate or accidental exposure to estrogens or putative estrogenic chemicals, particularly if such exposure had taken place during sex differentiation.  相似文献
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During the last several years there has been rapid progress in the development and application of controlled reproduction and associated biotechnologies to the culture of salmonids. This review focuses on the development of those techniques for Pacific salmon (Oncorhynchus species) and rainbow trout (Salmo gairdneri). These include methodologies for the induction of ovulation, storage of gametes, chromosome set manipulation, i.e., induced gynogenesis and triploidy, hormonal feminization, hormonal sterilization and hormonal masculinization of genotypic females to produce milt containing only female spermatozoa.The current and future applications of these methodologies to the commercial mariculture of salmonids and to the enhancement and management of ocean and fresh water stocks are described. The implementation of each individual methodology for the control of reproduction can in itself have a significant impact on the efficiency of culture systems. It is, however, from the combination of specific complementary methods in production systems that the greatest gains will ultimately be made.It is concluded that the utilization of single or paired controlled reproduction techniques by themselves or in combination with other biotechnologies (e.g. sterilization plus growth acceleration) offer significant advantages for both the commercial mariculture of salmonids and the rearing of salmonids by government agencies for release into the oceanic or lacustrine environment.  相似文献
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采用FH激素诱导奥利亚罗非鱼(Oreochromis aurea)雌性化,结果显示:以鱼苗为起始材料,奥利亚罗非鱼雌鱼的转化率为76.5%~89.6%;以胚胎为起始材料,雌鱼的转化率可达到100%,ZZ型合子可完全变成生理雌鱼,卵巢发育正常,具有繁殖功能。  相似文献
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2009年7月12日至10月21日和2010年5月1日至11月6日,水温23~31℃范围下,