Shedding new light on early sex determination in zebrafish

Abstract

In contrast to established zebrafish gene annotations, the question of sex determination has still not been conclusively clarified for developing zebrafish, Danio rerio, larvae, 28 dpf or earlier. Recent studies indicate polygenic sex determination (PSD), with the genes being distributed throughout the genome. Early genetic markers of sex in zebrafish help unravel co-founding sex-related differences to apply to human health and environmental toxicity studies. A qPCR-based method was developed for six genes: cytochrome P450, family 17, subfamily A, polypeptide 1 (cyp17a1); cytochrome P450, family 19, subfamily A, polypeptide 1a (cyp19a1a); cytochrome P450, family 19, subfamily A, polypeptides 1b (cyp19a1b); vitellogenin 1 (vtg1); nuclear receptor subfamily 0, group B, member 1 (nr0b1), sry (sex-determining region Y)-box 9b (sox9b) and actin, beta 1 (actb1), the reference gene. Sry-box 9a (Sox9a), insulin-like growth factor 3 (igf3) and double sex and mab-3 related transcription factor 1 (dmrt1), which are also known to be associated with sex determination, were used in gene expression tests. Additionally, Next-Generation-Sequencing (NGS) sequenced the genome of two adult female and male and two juveniles. PCR analysis of adult zebrafish revealed sex-specific expression of cyp17a1, cyp19a1a, vtg1, igf3 and dmrt1, the first four strongly expressed in female zebrafish and the last one highly expressed in male conspecifics. From NGS, nine female and four male-fated genes were selected as novel for assessing zebrafish sex, 28 dpf. Differences in transcriptomes allowed allocation of sex-specific genes also expressed in juvenile zebrafish.

Heterochiasmy and the establishment of gsdf as a novel sex determining gene in Atlantic halibut

“…Under this model, the sex-limited chromosome will accumulate deleterious mutations and lose genetic material not essential for the male or female phenotype in X/Y and Z/W systems, respectively. In contrast to heteromorphic sex chromosomes, several reptiles, amphibians and fishes show homomorphic sex chromosomes with little or no signs of degeneration or even multiple short sex-determining regions on different chromosomes [ 12 ] or recombining in only in the heterogametic sex [ 13 ]. In strong contrast to the model of physical recombination barriers, several recent studies have implicated that heterochiasmy, i.e.…”

Nutraceutical Screening in a Zebrafish Model of Muscular Dystrophy: Gingerol as a Possible Food Aid

“…In our experimental setting, we did not select a specific sex. Indeed, fish larvae sex was mixed, since the first indication of zebrafish sex differentiation occurs at 10–12 dpf, when the ovarian gonocyte proliferates and differentiates [ 20 ]. Handling of zebrafish embryos and larvae complied with the guidelines of our internal institutional animal care committee, and experiments were performed in accordance with, and under the supervision of, the Institutional Animal Care and Use Committee of the University of Pisa.…”

Notch-mediated re-specification of neuronal identity during central nervous system development

“…During this period zebrafish are not sexually differentiated. 70 The transgenic lines used are listed in the key resources table. Note that line Tg(vsx1:Gal4)q32 (Q32) was referred to as Tg(vsx1:Gal4)q26 (Q26).…”