Genetic regulation of sex determination and maintenance in zebrafish (Danio rerio)

Abstract

Over the last several decades zebrafish (Danio rerio) has become a major model organism for the study of vertebrate development and physiology. Given this, it may be surprising how little is known about the mechanism that zebrafish use to determine sex. While zebrafish are a gonochoristic species (having two sexes) that do not switch sex as adults, it was appreciated early on that sex ratios obtained from breeding lab domesticated lines were not typically a 1:1 ratio of male and female, suggesting that sex was not determined by a strict chromosomal mechanism. Here we will review the recent progress toward defining the genetic mechanism for sex determination in both wild and domesticated zebrafish.

Keywords: Androgen receptor; Anti-Müllerian hormone; Aromatase; Bmp15; Chromosomal sex determination; Cyp19a1a; Dmrt1; Environmental sex determination; Foxl2a; Foxl2b; Germ cell; Gsdf; Nr0b1; Oocytes; Sex determination; Sex differentiation; Sex maintenance; Somatic gonad; Wnt4a; Zebrafish.

Fig. 1

Sexually dimorphic phenotypes that distinguish adult female and male zebrafish. 6-month-old female (A–A‴) and male (B–B‴) zebrafish. Low magnification view shows that females (A) have a larger abdomen (arrow) then males (B). Low magnification view of the anal fins (A′ and B′) shows that females have lighter yellow pigmentation then males. High magnification view of the anal fins (A” and B”) shows that the yellow pigment stripes in females are narrower than those in males (brackets). The genital papilla protrudes from the ventral body surface in females (arrow in A‴), but not in males (arrow in B‴). Scale bar in A and B, 2mM.