The switch of secondary sex determination in protandrous black porgy, Acanthopagrus schlegeli

Abstract

Hermaphrodites have both sexes during their life, including an initial primary sex determination and in later stage maintenance one of the sexual fates (secondary sex determination). Sex change (secondary sex determination) occurs in animals, but it is lost in amphibians through, mammals in vertebrates. Teleosts have various strategies and mechanisms of sex determination including genetic and environmental cues. However, the mechanisms by which the cues guide sex change are complicated in fish. This manuscript reviews our understanding of these processes in protandrous black porgy at the gonadal and neuroendocrine levels. Our studies addressed the process of sex change through brain-pituitary-gonad axis, and then secondary sex determination was switched by the fate of testis.

Cell fate commitment during mammalian sex determination

“…Many differentiated cells in other organs share a common bipotential progenitor, however, it is unclear whether the phenomenon of transdifferentiation between differentiated fates occurs naturally in other systems, or whether it is specific to gonadal cells. It could be an evolutionary remnant of the ability of some fish to switch sex in adult life [102] or of some vertebrates’ ability to function as ‘natural hermaphrodites’ by maintaining a gonad with seasonally expanding ovarian and testicular regions such as the mole and alligator [103,104]. It will be interesting to see how this plasticity of cell fate is related to the epigenetic landscape at the bipotential stage, and in Sertoli and granulosa cells during fetal and adult life.…”

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].…”

“…3 A). The reverse pattern is evident from numerous candidate gene studies in protandrous black porgy: male-related gene expression (e.g., dmrt1 , amh , amhr2 ) declines coincidentally with testis volume before expression profiles are increasingly feminised as the bisexual gonad becomes purely ovarian (e.g., cyp19a1a / b , foxl2 , wnt4 ) [reviewed by Wu and Chang, 2013]. Broadly speaking, the greatest shift in sex-specific gene expression occurs during mid-to-late sex change ( fig.…”

“…Dmrt1 expression in the male testis is thought to be maintained by androgens and gonadotropin signalling (e.g., LH) via the HPG axis [Herpin and Schartl, 2011b;Wu et al, 2012;Wu and Chang, 2013]. More detailed expression studies in the brain and gonad during early sex change are required to identify potential upstream regulators of dmrt1 .…”

The sex-specific transcriptome of the hermaphrodite sparid sharpsnout seabream (Diplodus puntazzo)

“…A recent study on the ancestral reconstruction of sexual patterns in sparids revealed both gonochorism and hermaphroditism in almost every group of the family [31]. Therefore, there is a great potential for understanding the molecular mechanisms underlying gonochorism and hermaphroditism within Sparidae [31, 35]. To date, considerable effort to unravel the genes involved in sex determination, sex differentiation and sex change have been conducted mainly on the protandrous black porgy, Acanthopagrus schlegelii [35–42].…”