Estrogen biosynthesis in the gonad of the frog Rana rugosa

Sexing Frogs by Real-Time PCR: Using Aromatase <b><i>(cyp19) </i></b>as an Early Ovarian Differentiation Marker

“…Generally, gonadal steroidogenesis is active before clear histological differentiation in many non-mammalian vertebrates. For example, as it has been demonstrated in chickens [Scheib, 1983] and turtles [Dorizzi et al, 1991], estrogens are synthesized by morphologically undifferentiated female gonads in frogs [Isomura et al, 2011]. This demonstrates that sex steroids also play an important role in frog sex differentiation.…”

“…The majority of these have focused on a single species, Glandirana (Rana) rugosa [Takase et al, 2000a, b;Sugita et al, 2001;Shibata et al, 2002;Aoyama et al, 2003;Ohtani et al, 2003;Oshima et al, 2005Oshima et al, , 2006Oshima et al, , 2007Oshima et al, , 2008Oshima et al, , 2009Yamamura et al, 2005;Iwade et al, 2008;Maruo et al, 2008;Nakamura et al, 2008;Sakurai et al, 2008;Yokoyama et al, 2009;Isomura et al, 2011;Suda et al, 2011a, b]. In this frog species, both genetic and phenotypic sex can be determined [Miura et al, 1998], and gene expression levels in differentiating GMCs can be studied separately in genetic males and females.…”

Sex Reversal in Amphibians

“…The enzymatic activity increased in females from stage 52, and at metamorphosis it reached 500-fold the activity measured in males [Chardard et al, 1995]. In G. rugosa tadpoles at stage I (prior to gonad differentiation), the rate of conversion of testosterone to 17β-estradiol was also higher ( ∼ 6-fold) in the indifferent gonad of females compared with males [Isomura et al, 2011]. This 17β-estradiol synthesis was inhibited by fadrozole.…”

Is a Sex-Determining Gene(s) Necessary for Sex-Determination in Amphibians? Steroid Hormones May Be the Key Factor

“…When the enzymatic activity of CYP17 and HSD17B was measured by HPLC analysis, indifferent male gonads converted progesterone to testosterone via androstenedione at a 2-fold higher rate compared to the indifferent gonads of females [Sakurai et al, 2008]. Estradiol-17 ␤ production is higher in the indifferent gonad of females than in that of males during sexdetermination in R. rugosa [Isomura et al, 2011]. It is evident, therefore, that the indifferent gonads of amphibians can synthesize steroid hormones.…”