Comparing Sex Steroid Levels During the Annual Cycles of Rainbow Trout (Oncorhynchus mykiss) Diploid Female (XX) and Triploid Female (XXX) Genotypic Sex

Abstract

In this study, the annual cycle of the gonadal steroids testosterone (T), 11-ketotestosterone (11-KT), 17β-estradiol (E2) and 17α, 20β-dihydroxy-4-pregnen-3-one (DHP) was determined using radioimmunoassay and then compared for two populations of rainbow trout, XX diploid females (n = 40) and XXX triploid females (n = 15). In females, E2 and DHP levels were found to be significantly related to body weight (r = 0.22513; p < 0.0001 and r = 0.15831; p > 0.001, respectively). In this group, E2 concentrations peaked in November (25.05 ng/ml), while maximum DHP levels, only measurable from October to April, were attained in February (64.14 ng/ml). No significant differences in hormone ranges related to egg output ability were observed. Finally, sex steroid concentrations were low in the triploid female XXX fish compared to the female XX population. Nevertheless, maximum T (33.85 ng/ml) and 11-KT (32.35 ng/ml) levels were recorded in January, for XXX. The levels for these two hormones are relatively high and are also significantly associated (r = 0.8430; p < 0.0001). Diploid females showed significantly higher levels of E2 than triploids over the 12-month study period. The female triploid fish produced the lowest steroid hormone levels, such that these would be the most suitable for human consumption.

Cutthroat trout virus as a surrogate in vitro infection model for testing inhibitors of hepatitis E virus replication

“…Thus it may be possible that reasonably higher concentrations of the first are required to activate the cognate MIS receptor(s). On the other hand, the stimulation of CTV replication by testosterone and 17β-estradiol was most extensive at 0.5 µM, which is near physiological concentrations (Espinosa et al, 2013). Pronounced cytotoxicity was only observed for 17β-estradiol at 50 µM (figure 2B).…”

“…Concentrations of 5 and 50 µM are considerably above physiological levels (e.g. Espinosa et al, 2013). However, CHSE-214 cells are an embryo-derived continuous cell line (Lannan et al, 1984) that may be less sensitive to hormonal stimuli, as was observed for other piscine cell lines (Le Dréan et al, 1995, Fent, 2001, thus requiring increased concentrations of for instance progesterone to obtain notable differences in virus yields.…”

Seasonal changes of plasma sex steroids in captive longtooth grouper Epinephelus bruneus (Bloch) in subtropical regions

“…In this study, the seasonal changes of sex steroid levels (E2 in female and 11-KT in male) in LG were examined in a subtropical region (Figure 1). It is well known that the plasma levels of sex steroids (E2 and/or 11-KT) annually fluctuate with maturity in many species, such as the rabbit fish Siganus guttatus (Pham & Nguyen, 2019), rainbow trout Oncorhynchus mykiss (Espinosa et al, 2013), red-spotted grouper E. akaara (Li et al, 2007), chub Leuciscus cephalus L. (Guerriero, 2007), tench Tinca tinca (Pinillos et al, 2003), Arctic charr Salvelinus alpinus (Tveiten et al, 1998), red grouper E. morio (Johnson et al, 1998), and bambooleaf Psudolabrus japonicus (Morita et al, 1997).…”

Maturation Inducing Hormones in teleosts: Are progestogens always the first to be nominated?

“…Oncorhynchus mykiss DHP 10-40 70-380 GVBD|OV (Espinosa et al, 2013;Milla et al, 2006;Nagahama et al, 1983;Scott and Baynes, 1982…”