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Journal ArticleDOI

Relationship between seasonal plasma estradiol-17 beta and testosterone levels and in vitro production by ovarian follicles of amago salmon (Oncorhynchus rhodurus).

01 Sep 1983-Biology of Reproduction (Society for the Study of Reproduction)-Vol. 29, Iss: 2, pp 301-309
TL;DR: The seasonal pattern of plasma testosterone levels lagged behind and followed that of estradiol-17 beta during vitellogenesis, but levels remained high in mature and ovulated fish, and GSI values showed a linear increase, and reached a peak in October.
Abstract: Plasma estradiol-17 beta and testosterone levels were assessed by radioimmunoassay during the sexual maturation of female amago salmon (Oncorhynchus rhodurus). Estradiol-17 beta levels gradually increased during vitellogenesis (June to September), reached a peak in September (about 16 ng/ml) and rapidly decreased in mature and ovulated fish (about 3-4 ng/ml) in October. The seasonal pattern of plasma testosterone levels lagged behind and followed that of estradiol-17 beta during vitellogenesis, but levels remained high in mature and ovulated fish (90-110 ng/ml). Estradiol-17 beta levels and the gonadosomatic index (GSI) values correlated well during vitellogenesis: GSI values showed a linear increase, and reached a peak (29.9 +/- 1.4) in October. Values were extremely low in ovulated fish (1.2 +/- 0.2). In vitro production of estradiol-17 beta and testosterone by ovarian follicles in response to partially purified chinook salmon gonadotropin (SG-G100) was examined monthly using 18-h incubations. Throughout the vitellogenic period SG-G100 stimulated both estradiol-17 beta and testosterone production: the steroidogenic response of follicles increased from June (about 2 ng/ml estradiol-17 beta; 0.1 ng/ml testosterone) to September (about 10 and 14 ng/ml, respectively). In October full-grown immature follicles which could be induced to mature in vitro by hormone treatment produced large amounts of testosterone (about 130 ng/ml) but not estradiol-17 beta. Postovulatory follicles also produced testosterone but the values were low (10 ng/ml) compared with full-grown immature follicles. Very low levels of estradiol-17 beta were produced by postovulatory follicles.(ABSTRACT TRUNCATED AT 250 WORDS)

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Journal ArticleDOI
TL;DR: Reconditioning of post-spawned anadromous rainbow trout (steelhead kelts, Oncorhynchus mykiss) is being implemented as a recovery tool on the Yakima River in the mid-Columbia River Basin by measuring plasma E2 and VG levels, which showed that fish separated into rematuring and nonrematuring cohorts by October.
Abstract: Reconditioning of post-spawned anadromous rainbow trout (steelhead kelts, Oncorhynchus mykiss) is being implemented as a recovery tool on the Yakima River in the mid-Columbia River Basin. We assessed reproductive development in female Yakima River kelts by measuring plasma estradiol-17β (E2) and vitellogenin (VG) levels during reconditioning in 2009–2011. Plasma E2 and VG levels showed that fish separated into rematuring (consecutive spawning) and nonrematuring (presumed skip spawning) cohorts by October. Rematuration rates varied from 25% to 65%. Rematuring fish were consistently detected migrating toward spawning areas after release, whereas nonrematuring fish were occasionally detected on spawning migrations the following year. Rematuring fish grew more rapidly than nonrematuring fish over the reconditioning period and had higher muscle lipid levels and condition factor in October. Plasma E2 was elevated in rematuring fish by June–July, whereas plasma VG was elevated by June–August, suggesting that mat...

9 citations


Cites background from "Relationship between seasonal plasm..."

  • ...…high end of the ranges reported for other anadromous salmonids and non-339 anadromous rainbow trout, although assay and stock differences make comparison difficult 340 (Kagawa et al. 1983, Fitzpatrick et al. 1986, Eales et al. 1991, Crim et al. 1992, Slater et al. 1994, 341 Pankhurst et al. 2011)....

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Journal ArticleDOI
TL;DR: It is suggested that the water-soluble compounds formed in relatively high amounts in postspawned ovaries are excreted into the external environment, where they may function as sex pheromones during the spawning period.

8 citations

Journal ArticleDOI
TL;DR: The results indicate that with grayling broodfish there is greater efficacy in induction of reproduction when there is imposing of the controlled reproduction treatment regimen on 3- rather than 2-year-old broodfish.

8 citations

Journal ArticleDOI
TL;DR: Serum cortisol levels in farmed brown trout were significantly higher and showed a seasonal pattern opposite to that found in wild trout.
Abstract: Serum steroid profiles were investigated in order to evaluate the potential use of circulating sex steroid levels as a tool for sex identification in brown trout. Changes in the serum concentrations of testosterone (T), progesterone (P), 17-β-estradiol (E2), and cortisol (F) in wild and farmed mature female and male brown trout, Salmo trutta L., were measured in each season (January, May, July, and October) in six rivers and four hatcheries located in the north-west of Spain. Serum cortisol levels in farmed brown trout were significantly higher and showed a seasonal pattern opposite to that found in wild trout. Because levels of the hormones under study can be affected by disruptive factors such as exposure to phytoestrogens (which alters the hypothalamic-pituitary-gonadal axis) and infection with Saprolegnia parasitica (which alters the hypothalamic-pituitary-adrenal axis), both factors are taken into account.

7 citations