Expression patterns of kiss2 and gpr54‐2 in Monopterus albus suggest these genes may play a role in sex reversal in fish

Abstract

Due to its exceptionally small genome size and protogynous hermaphroditism, Monopterus albus has been proposed as a model for vertebrate sexual development. The Kiss/GPR54 system is a central regulator of sexual development in most vertebrates, but its role in sex reversal remains hypothetical. In contrast to mammals, fishes often possess more than one copy of the kiss and gpr54 genes. Our objectives were to identify all kiss/gpr54 genes in the genome of M. albus and to assess their involvement in sex reversal via their expression patterns (qPCR) in females, males, and intersex specimens. We identified only two genes: kiss2 and gpr54‐2. kiss2 expression was extremely high in the gonads of males, intermediate in females, and low in intersex; and reduced in all tissues of intersex. gpr54 expression was also extremely high in the gonads of males, high in intersex, but low in females. gpr54 expression in brain was high in all three sexes. In conclusion, (a) kiss1 has been functionally replaced in M. albus; (b) the functions of gpr54‐2 in brain are not sex‐specific; (c) kiss2 appears to undergo a ‘reset’ in the expression during the sex change; and (d) sex‐specific expression patterns in the gonads indicate that these two genes may play a role in sex reversal in fish.

Chromosome-Scale, Haplotype-Resolved Genome Assembly of Non-Sex-Reversal Females of Swamp Eel Using High-Fidelity Long Reads and Hi-C Data

“…Previous studies have revealed multiple sex-related genes that might be involved in sex change, gonadal differentiation in M. albus , and other teleosts ( Zhang et al, 2008 ; Wu et al, 2012 ; Hu et al, 2014 ; Hu et al, 2015 ; Gao et al, 2016 ; Cai et al, 2017 ; Yi et al, 2019 ; Ding et al, 2020 ; Chen et al, 2022 ; Feng et al, 2022 ). To investigate a genomic survey of these genes in the assembled genome, these genes were directly searched in the annotated genome using gene name or identified with tBlastn (v2.9.0+) ( Camacho et al, 2009 ) in the annotated genome.…”