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91.
William S. Marshall Sharon E. Bryson David R. Idler 《Fish physiology and biochemistry》1989,7(1-6):331-336
The sperm duct epithelium of brook trout (Salvelinus fontinalis), mountedin vitro in Ussing-style epithelial chambers actively absorbs Na+ (measured as the short-circuit current, Isc) and secretes K+ (measured using86Rb+ as tracer). Dibutyryl-cyclic-adenosine monophosphate (db-cAMP) and 3-isobutyl-1-methylxanthine (IMX) produce a rapid, sustained
stimulation of both ion transport processes, but the hormone connected to the response is unknown. Purified sockeye salmon
CON A2 gonadotropin (GtH) produces a dose-dependent, rapid and sustained rise in Na+ uptake and K+ secretion. The time course, electrophysiological and transport characteristics are similar to those evoked by IMX. Carbohydrate-poor
(chum salmon CON A1) GtH is ineffective. Pretreatment of fish with 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-P) significantly
increases milt volume but is without effect on resting or stimulated (IMX + db-cAMP) levels of sperm duct ion transport. This
is the first indication of a direct, rapid action of GtH on ion transport by the vertebrate blood-testis barrier. The results
suggest direct involvement of GtH in control of later stages of sperm maturation. 相似文献
92.
Vitellogenin (Vtg) was purified from the plasma of 17-estradiol (E2)-injected male greenback flounder,Rhombosolea tapirina. The molecular weight of the native Vtg was estimated by gel filtration as 540 kD. SDS-PAGE and Western blotting analyses indicated that this protein consisted of three bands with molecular weights of 155, 104, 79 kD, respectively. A polyclonal antibody against the highest molecular weight band of putative Vtg was generated in sheep and an indirect antibody-capture competitive enzyme-linked immunosorbent assay (ELISA) was developed. The assay was validatedfor plasma Vtg measurement in greenback flounder. Serial dilutions of plasma from vitellogenic females parallelled the standard Vtg curve, whereas no cross-reaction was observed with the plasma of males in the ELISA. The Vtg ELISA was used to assess the induction of Vtg by E2
in vivo in males. The induction of Vtg in greenback flounder showed a time- and dose-dependent response as in other species. In E2-treated fish, detectable levels of Vtg were first found at 48 h, and reached a peak at 96 h post-injection. Plasma levels of Vtg increased as the E2 dose increased with a threshold of 0.1 mg kg–1. 相似文献
93.
A group of Atlantic salmon (Salmo salar) was followed through their first year of maturation and spawning. At monthly intervals, starting with juvenile fish in December, 5–7 fish of each sex were killed, and liver and plasma were sampled. The last sampling point was of spawning fish in November a year later. Variables in the cytochrome P450 (P450) system were studied in hepatic microsomes, and estradiol 17 was measured in the plasma of females to assess the maturational status. The P450 1A1-mediated 7-ethoxyresorufin O-deethylase (EROD) started at high levels in winter, but decreased to non-detectable activities in pre-spawning females. Decreases, but not to the same extent, were also observed during this period in total cytochrome P450, cytochrome b5, NADPH-cytochrome P450 reductase, and in the content of two immunochemically determined P450 isozymes. At the same time, LSI levels increased in maturing females (starting in July), and GSI levels increased in both sexes (starting in May). Sex specific differences were observed in pre-spawning fish in September and October, with levels of total P450, b5, NADPH-cytochrome P450 reductase, EROD and P450 isozymes significantly lower in females. At the same time, plasma estradiol-17 levels reached peak values in females. The results point to the important role of sex steroids such as estradiol-17 as major factors in the regulation of final sexual maturation. However, this study also indicates that there may be estradiol-17 independent events of equal importance in the early stages of gonadal maturation that may involve the P450 system. The changes observed in the P450 system (as a major drug and steroid metabolizing system) of Atlantic salmon during sexual maturation may be of importance both in the endogenous transduction of hormonal signals, and as a pharmacological basis for designing therapeutic treatment of diseases in the aquaculture industry.Parts of this work were presented at the 5th International Symposium on Responses of Marine Organisms to Pollutants, April 1989 in Plymouth, United Kingdom (Larsen and Goks\/oyr 1989). 相似文献
94.
The effects of temperature and salinity on the reproductive success of Arctic charr, Salvelinus alpinus (L.), were examined by holding broodstock under the following conditions from mid‐May until the end of September: fresh water at ambient temperature (NFW; 8–16 °C); salt water (25–30‰) at ambient temperature (NSW; 4–10 °C); fresh water cooled to saltwater temperature (CFW; 4–10 °C); or salt water heated to freshwater temperature (HSW; 8–16 °C). The relative fecundity of females was similar among groups (P > 0.05; 2685 ± 706 eggs), but females reared in NSW produced significantly larger eggs than those raised in NFW. The highest spermatozoa concentrations were found in milt from males reared in SW and the highest milt glucose concentration was from males kept under coldwater conditions (CFW, NSW). Eggs from NSW and HSW females contained more proteins than eggs produced by NFW females. Eggs from NSW females also contained 40% more lipids than was observed in the other groups, and total energy content was 27% higher in eggs from NSW females than in eggs from NFW females. When FW was cooled (CFW), females produced eggs with protein contents similar to those in NSW, but the lipid contents remained 30% lower. Finally, the best survival at the eyed stage and at hatch was observed in families produced by NSW broodstock. Intermediate values were observed in families from NFW or CFW while the highest mortality occurred in families from the HSW group. All these results suggest that, under the experimental conditions used in the present study, coastal seawater conditions offered the most favourable summer rearing conditions with respect to the reproductive success of Arctic charr. 相似文献
95.
96.
This study examines the effects of nonesterified fatty acids on the properties of the sex steroid binding protein (SSBP) in the plasma of goldfish (Carassius auratus). Scatchard analysis revealed a single class of high affinity (Kd 1.89±0.20 nM), low capacity (Bmax 302±17 nM) binding sites for [3H]17-estradiol in female goldfish plasma. The SSBP bound 17-estradiol and testosterone with similar affinity but had much lower affinity for estriol, 17,20-dihydroxy-4-pregnen-3-one and cholesterol. Nonesterified fatty acids inhibit the binding of [3H]17-estradiol to the SSBP as a function of dose, degree of unsaturation and fatty acid chain length. Polyunsaturated fatty acids (PUFAs) such as arachidonic acid (C20:4), eicosapentaenoic acid (C20:5) and docosahexaenoic acid (C22:6) strongly inhibit the binding of [3H]17-estradiol to the SSBP. By comparison, saturated fatty acids such as heptadecanoic acid (C17:0), palmitic acid (C16:0) and stearic acid (C18:0) were without effect. Scatchard analysis and Lineweaver-Burk plots showed that PUFAs act through a competitive mechanism whereby they reduce the affinity but have no effect on the binding capacity of the SSBP. Collectively, these studies suggest that in addition to their roles as metabolic energy sources and as precursors to eicosanoids, PUFAs can be potent modulators of steroid hormone interactions with the SSBP in goldfish plasma. 相似文献
97.
越来越多的环境内分泌干扰物( EDCs)不断释放到环境,并通过大气沉降、地表径流、土壤淋溶和直接排放等方式进入水体,从而使水体成为 EDCs 存在的主要场所之一。为引起社会对水体 EDCs 污染的广泛关注,并积极采取EDCs 危害防治措施,保护鱼类资源和水生态系统,本文介绍了 EDCs 的分类,详述了自然水体、饮用水源水以及自来水中EDCs 污染情况,阐明了 EDCs 对鱼类的生殖危害。资料分析显示,EDCs 能够扰乱生物体内分泌功能,导致生殖器官、生殖机能和生殖行为异常,引起生育力下降,甚至生物繁殖机能损害,并最终导致种群数量下降,以至物种灭绝。虽然国内外已经开展了一些关于 EDCs 对生物危害等方面的研究,但大都处于起步阶段,存在着基础研究薄弱、识别和鉴定困难或代价太大等问题,有关工作亟需全面、深入开展。 相似文献
98.
钙蛋白酶-钙蛋白酶抑制蛋白系统在多种细胞中发挥作用,在雌性生殖系统中其对卵母细胞、子宫与胎盘的调控也起着重要作用.对该系统在雌性生殖调控中的作用的研究进展进行了综述,为进一步了解该系统奠定基础. 相似文献
99.
100.