The Expression of amh and amhr2 Is Associated with the Development of Gonadal Tissue and Sex Change in the Protandrous Black Porgy, Acanthopagrus schlegeli1

Abstract

The protandrous black porgy, Acanthopagrus schlegeli, has a striking life cycle, with sex differentiation at the juvenile stage, mono-male development, a bisexual gonad during the first 2 yr of life, and a male-to-female sex change (with vitellogenic oocytes) at 3 yr of age. In the present study, we investigated the possible roles of amh and amhr2 in gonadal development in a nonmammalian model organism (protandrous black porgy), especially in relation to sex differentiation, testicular and ovarian growth, and sex change. Fish of various ages were treated with estradiol or an aromatase inhibitor to induce the fish to become female. Furthermore, a natural sex change (2(+)-yr-old [>2 yr and <3 yr] fish) and a nonchemical method to surgically remove one of the pair of gonads to examine the possible roles of amh in the natural sex change were conducted. We present integrative in situ hybridization, immunohistochemical, cellular, and molecular data describing these phenomena. During gonadal sex differentiation, an increase in amh and amhr2 expression was detected. Higher levels of amh and amhr2 transcripts were observed in the testicular tissue when compared to the ovarian tissue in the bisexual gonad of 1(+)-yr-old (>1 yr and <2 yr) fish. Transcripts of amh reached peak levels in November (prespermatogenesis period) and then declined to the lowest levels in January (spawning period). Chemical-induced ovarian tissue had very low amh transcript levels but high levels of amhr2. Active testes had significantly higher amh and amhr2 expression levels as compared to inactive testes. In contrast, no difference in the expression of amh and amhr2 between active and inactive ovarian tissues was found. Transcripts of amh were expressed in the somatic cells of the spermatogonia and vitellogenic oocytes, and amhr2 was expressed in the somatic cells of the spermatogonia. Transcripts of amh decreased in the testicular tissue 5 mo before occurrence of the sex change into a female. In contrast, testicular amh expression remained high if the fish remained male. Human chorionic gonadotropin regulated amh and amhr2 expression in the testicular tissue but not in the ovarian tissue. The present results suggest that amh plays important roles in early testicular and ovarian development, late ovarian growth (e.g., vitellogenic oocytes), and natural sex change in the protandrous black porgy.

Epigenetic modification and inheritance in sexual reversal of fish

“…S8). Interestingly, we observed that amhr2, the receptor of amh (Wu et al 2010), and wt1a and wt1b, potential activators of amhr2 (Klattig et al 2007), also showed differential methylation between ZW/ZZ testes and ovaries (Supplemental Fig. S8).…”

“…3C), which might correspond to its approximately 23-fold up-regulated expression in testes compared with ovaries. amh (anti-Mullerian hormone) is another well-documented gene that mediates male sexual differentiation, whose expression is consistently higher in males than in females during sex differentiation in many vertebrates (Josso et al 2005;Wu et al 2010). The tongue sole amh showed a similar expression pattern (Supplemental Table S8) and harbored a DMR on the promoter region, which was up-methylated in ZW/ZZ testes in comparison with ovaries (Supplemental Fig.…”

Fsh and Lh direct conserved and specific pathways during flatfish semicystic spermatogenesis

“…The members of the Tgfb superfamily, such as Gsdf and Amh, produced by Sertoli cells are positive and negative regulators, respectively, of spermatogonial proliferation and early differentiation in adult teleosts (Miura et al 2002, Sawatari et al 2007, Wu et al 2010, Skaar et al 2011, Chen et al 2013. Accordingly, in Senegalese sole, gsdf and amh were localized exclusively in cortical Sertoli cells enclosing spermatogonia, and both transcripts were upregulated preferentially by Fsh during stages I-II.…”

Bending Genders: The Biology of Natural Sex Change in Fish

“…Most research has focussed on black porgy ( Acanthopagrus schlegeli , Sparidae), which reproduce as male for the first 2 years of life before roughly 50% of fish change sex to female [reviewed by Lee et al, 2001;Wu et al, 2010a;Wu and Chang, 2013]. Australian barramundi ( Lates calcarifer , Latidae) and gilthead seabream ( Sparus aurata , Sparidae) also sexually mature as male before becoming female at an older age and larger size [Guiguen et al, 1994;Liarte et al, 2007].…”