All-male populations are used in tilapia aquaculture because the culture of mixed-sex populations often results in precocious maturation and early reproduction (Mires, 1995). Early maturation shunts energy to gonadal rather than somatic growth. In addition, reproduction in ponds may lead to the harvest of many unmarketable fry. Individuals in mono-sex populations have increased somatic growth r...

BACKGROUND Concern that the use of exogenous testosterone may increase breast cancer risk coexists with rising use of this medication in the United States. We sought to examine the relationship between the use of estrogen plus testosterone (E + T) therapy (esterified estradiol plus methyltestosterone) and the occurrence of breast cancer. METHODS A total of 31,842 postmenopausal participants i...

The aim of the experiment was to compare the effectiveness of sex reversal in mature female rainbow trout using 17 -methyltestosterone (6 ppm-MT) and 11 -hydroxyandrostenedione (20 ppm-OHA). Hormones were administered with the first exogenous feed for up to 60 days. Among the fish treated with OHA, 95% females were reversed into mature neo-males and 1.6% to bisexual individuals. Among the fish ...

In most of the experiments previously reported on the metabolism of testosterone, reviewed by Dorfman (l), rather large quantities of this steroid have been administered to experimental subjects and the urine collected for the estimation of androgenic compounds. In general, metabolites amounting to about 20 per cent of the administered compound have been found in the urine of animals. However, ...

Estrogen plays key roles in vertebrate reproductive system via estrogen receptors (ERs) as mediating pathways. In the present study, three full-length ERs cDNA sequences were isolated from a protogynous teleost, the orange-spotted grouper (Epinephelus coioides), and were 2235bp for gERα, 1967bp for gERβ1 and 2158bp for gERβ2, respectively. Phylogenetic and amino acid alignment analyses showed t...

In most of the experiments previously reported on the metabolism of testosterone, reviewed by Dorfman (l), rather large quantities of this steroid have been administered to experimental subjects and the urine collected for the estimation of androgenic compounds. In general, metabolites amounting to about 20 per cent of the administered compound have been found in the urine of animals. However, ...

We examined the efficacy of androgens (1.0 mg/kg body mass), testosterone (T), 11-ketotestosterone (11-KT), 17alpha-methyltestosterone (MT), testosterone propionate (TP) or androgen mixture (T, MT and TP in an equal ratio), for induction of sex change in protogynous orange-spotted grouper, Epinephelus coioides. The spawning performance in sex-changed males was also investigated. MT and androgen...