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B Truscott

Publications and source records attributed to B Truscott.

At least 19 recordsLinked to original sources
PubMed1992

Steroids involved with final oocyte maturation in the winter flounder.

A number of androgens and progestogens including 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17,20-P) were examined in female winter flounder as possible maturation inducing steroids (MIS). During final oocyte maturation serum levels of testosterone (T) and 17 beta-hydroxy-5 beta-androsten-3-one (5 beta-T) peaking at over 200 ng/ml and pregnenolone (PE) at 40 ng/ml were the predominant steroids found from each major group. High levels of T and 5 beta-T were correlated with oocyte stages characterized by germinal vesicle migration. Of the PEs measured, maximum serum levels of PE, 3 beta,17 alpha-hydroxy-5-pregnen-20-one (17-PE) and 3 beta,17 alpha, 20 beta-dihydroxy-5-pregnene (17,20-PE) were found during later oocytes stages associated with germinal vesicle breakdown. Levels of 17,20-P, an established MIS in most fish, were almost non-detectable (less than 0.1 ng/ml serum) in females throughout all stages of final oocyte maturation. Incubations of ovarian follicles in vitro with physiological concentrations of T and 5 beta-T indicated that these steroids could induce all stages of final oocyte maturation. Similar in vitro incubations showed that 17-PE and 17,20-PE were only effective on germinal vesicle breakdown. The principal conclusions are that T, 5 beta-T and the PEs can be considered as MISs in winter flounder and the PE pathway predominates during the final stages of oocyte maturation in winter flounder in contrast to progesterones which predominate in other fish species, mostly salmonids, studies to date.

Androgens↗
PubMed1986

Maturational steroids and gonadotropin in upstream migratory sockeye salmon.

The circulating serum concentrations of various steroid hormones in mature sockeye salmon were measured at four different developmental stages in their upstream migration to spawn at Adams River in British Columbia, Canada. In females, a high level of estradiol-17 beta was found in fish at the first location, and it persisted until immediately before reaching the spawning grounds, 485 km upstream, where it decreased to a minimal level. Free testosterone was extremely high throughout the migration but decreased significantly after spawning while its glucuronide changed reciprocally. Free and conjugated 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (17 alpha, 20 beta-P) peaked at the last location before spawning with the glucuronide only 20% of the free steroid in concentration. After spawning, the concentration of free steroid declined but the glucuronide remained constant. 17 alpha-hydroxyprogesterone increased significantly in serum before and after the fish had spawned. During the migration 11-deoxycortisol was present in the serum at all stages but maximal levels were found in postspawned fish. Throughout the migration, the males had high serum levels of 11-ketotestosterone. Lesser amounts of free testosterone were also consistently present but the ratio of free: conjugated decreased from 1.7 at the beginning of the migration to 0.15 on the arrival at the Adams River and 0.10 in postspawned fish. Only low levels of 11 beta-hydroxytestosterone were found except in the postspawned males where the value was equal to one-half that of free testosterone. As in the females, there was a substantial increase in the levels of 17 alpha, 20 beta-P and its glucuronide in the males captured at the spawning grounds. In both sexes gonadotropin levels were low during the migration and high in the postspawned fish.

Animals↗
PubMed1985

Epidermal cellular proliferation and differentiation in sexually mature male Salmo salar with androgen levels depressed by oil.

Sexually mature male Salmo salar exhibit epidermal thickening and an increase in goblet cell concentration during the spawning season. The ventral skin, which is likely to experience most abrasive contact during the spawning period, has the thickest epidermis and the greatest goblet cell concentration. Following exposure to crude oil there is inhibition of cellular proliferation and elongation associated with epidermal thickening, and also inhibition of mucigenesis. Data on the androgen levels in these fish, and data from earlier studies involving treatment with hormones, indicate that oil-related epidermal effects during the spawning period are most likely systemic in origin, probably arising from reduced plasmatic androgen levels.

Androgens↗
PubMed1985

Progestogens, androgens and their glucuronides in the terminal stages of oocyte maturation in landlocked Atlantic salmon.

Peripheral serum levels of free and conjugated steroids were correlated with seven terminal stages of oocyte maturation in female landlocked Atlantic salmon. Pregnenolone levels were maximal at stage 1, and there was a surge in testosterone after initiation of germinal vesicle migration. Testosterone remained high, above 25 ng/ml until ovulation, and its glucuronide was always lower than the corresponding free form. 17 alpha,20 beta-Dihydroxy-4-pregnen-3-one increased progressively from 0.71 to 68 ng/ml from oocyte stage 1 to 6, with the glucuronide predominating in stages 1 to 4 and the free steroid in stages 5 to 7. Thus, very low levels of free 17 alpha,20 beta-dihydroxy-4-pregnen-3-one were present when migration of the germinal vesicle was initiated but considerable free steroid was present at and after germinal vesicle breakdown. Negligible amounts of progesterone, 17 alpha-hydroxypregnenolone, 5-pregnene-3 beta,17 alpha,20 beta-triol were found in the serum during final maturation. In male salmon with expressible milt, 17 alpha,20 beta-dihydroxy-4-pregnen-3-one was present with a gradual increase of both free and conjugated form at the advent of spawning, suggesting that this steroid may also play a role in reproduction in male fish. The action of steroids in vitro on oocytes at various stages was consistent with conclusions based on blood levels.

Androgens↗
PubMed1983

Steroid metabolism in fish. II. Testosterone metabolites in the bile of the marine winter flounder Pseudopleuronectes americanus and the freshwater Atlantic Salmon Salmo salar.

Intraarterial injection of [3H]testosterone in the flounder Pseudopleuronectes americanus and the landlocked salmon Salmo salar resulted in the concentration of radioactive catabolites in the gall bladder bile. The catabolites were quantitatively conjugated with glucuronic acid. In flounder bile, three steroids, testosterone, 5 beta-dihydrotestosterone and 5 beta-androstane-3 alpha,17 beta-diol accounted for most of the radioactivity. Quantitatively the concentration of 5 beta-dihydrotestosterone usually exceeded that of the other two compounds. In salmon bile, 5 alpha-dihydrotestosterone was also present as a minor catabolite and the dihydrotestosterones accounted for approximately one-half the total radioactivity. In both species there was evidence for trace amounts of 5 beta-androstane-3 beta,17 beta-diol, 5 alpha-androstane-3 alpha,17 beta-diol, and 5 alpha-androstane-3 beta,17 beta-diol but no evidence for 5 beta- or 5 alpha-androstanolones, 4-androstene-3 alpha,17 beta-diol, or its 3 beta-epimer. There were no obvious sex-related differences in the composition of the biliary testosterone metabolites.

Androstane-3,17-diol↗
PubMed1983

Effect of acute exposure to crude petroleum on some reproductive hormones in salmon and flounder.

1. The concentration of total (free + conjugated) androgens in plasma of sexually mature male salmon and flounder was generally lower in oil-exposed fish. 2. Exposure to crude oil inhibited some testicular development of salmon during the final stages of maturation. 3. Oil exposure had no effect on levels of total plasmatic androgens or estradiol in male and female flounder during gonadal recrudescence. 4. Aryl hydrocarbon hydroxylase activity increased in liver and kidney of both species. 5. Sperm, collected from salmon exposed to oil, fertilized eggs from non-exposed females to produce normal alevins.

Androgens↗
PubMed1980

Identification and quantification of steroids in the serum of rainbow trout during spermiation and oocyte maturation.

17 alpha-Hydroxy-20 beta-dihydroprogesterone and 17 alpha-hydroxyprogesterone were found in higher concentrations in serum from female Salmo gairdneri undergoing final oocyte maturation immediately before ovulation than in serum from spermiating male trout. Other steroids (11-deoxycorticosterone, 11-deoxycortisol and progesterone) which have been implicated in oocyte maturation and/or ovulation in lower vertebrates were not identified at such high concentrations and the differences between the serum of both sexes were not so great. These results confirm that 17 alpha-hydroxy-20 beta-dihydroprogesterone and 17 alpha-hydroxyprogesterone, the most potent inducers of trout oocyte maturation in vitro, are present in the blood when oocyte maturation occurs. The concentration of testosterone was found to be higher in serum from female than from male trout indicating that testosterone is unlikely to be the principal androgen in trout. High concentrations of 11-oxotestosterone in male and barely detectable levels in female fish support the hypothesis that 11-oxotestosterone is an important androgen in the regulation of testicular activity.

Animals↗