Synthesis of 17,20β,21‐trihydroxypregn‐4‐en‐3‐one by ovaries of reproductively mature Atlantic cod Gadus morhua

Abstract

Atlantic cod Gadus morhua ovaries were incubated in vitro with tritiated 17-hydroxypregn-4-ene-3,20-dione (17-P) to determine whether 17,20beta-dihydroxypregn-4-en-3-one (17,20beta-P) or 17,20beta, 21-trihydroxypregn-4-en-3-one (17,20beta,21-P), or both, were more likely to be the steroid responsible for inducing oocyte final maturation (i.e. resumption of meiosis). Only 17,20beta,21-P was produced, in addition to 11-deoxycortisol (17,21-P), which is intermediate between 17-P and 17,20beta,21-P. Also, the 5beta-reduced forms of 17-P, 17,21-P and 17,20beta,21-P were all found. Some sulphation of 21-hydroxylated steroids was demonstrated. The ability of female G. morhua to make 17,20beta,21-P but not 17,20beta-P was confirmed by radioimmunoassay of plasma samples from spawning fish. Although small amounts of 17,20beta-P immunoreactivity were detected in a few plasma samples, this was shown, by thin-layer chromatography, to be mostly due to cross-reaction with other unidentified compounds. The evidence strongly suggests that 17,20beta,21-P is more likely than 17,20beta-P to be the maturation-inducing steroid in G. morhua.

Effect of the probiotic Lactobacillus rhamnosus on the expression of genes involved in European eel spermatogenesis

“…The main interests in DHP in male fishes origin from the discovery of a strong association in several species between blood plasma concentration of DHP and spermiation [48,49]. In fact, DHP is considered to be the steroid responsible for acquisition of sperm motility in the Japanese eel [17].…”

Sexually dimorphic transcription of estrogen receptors in cod gonads throughout a reproductive cycle

“…The timing of sexual maturation and the spawning period are strongly associated with a peak of the plasma E 2 levels in 2-and 3-year-old Atlantic cod under aquaculture conditions (Norberg et al 2004). However, molecular mechanisms underlying the direct effects of E 2 signaling on gonadal maturation and batch spawning have been poorly investigated, even if the final maturation process by maturation-inducing steroids has been studied ex vivo (Tveiten et al 2010). To deepen our understanding of the role played by estrogen regulation in gonadal maturation, we kept 2-year-old Atlantic cod in landbased tanks and examined their annual reproductive cycle throughout 1 year.…”

Exploring correlations between sex steroids and fatty acids and their potential roles in the induced maturation of the male European eel

“…Assay characteristics and cross-reactivities of the E2 and T antisera have previously been examined by Frantzen et al (2004) and further validated for eel plasma by Mazzeo et al (2014). The characteristics and cross-reactivities of the DHP assay have previously been described by Tveiten et al (2010) and validated for eel plasma by Peñaranda et al (2010). The cross-reactivities of a new 11-KT antiserum used in this work have previously been described by Johnsen et al (2013).…”