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

Edvardsen RB, Wallerman O, Furmanek T, Kleppe L, Jern P, Wallberg A, Kjærner-Semb E, Mæhle S, Olausson SK, Sundström E, Harboe T, Mangor-Jensen R, Møgster M, Perrichon P, Norberg B, Rubin CJ

PLoS Genet. 18 (2) e1010011 [2022-02-00; online 2022-02-08]

Atlantic Halibut (Hippoglossus hippoglossus) has a X/Y genetic sex determination system, but the sex determining factor is not known. We produced a high-quality genome assembly from a male and identified parts of chromosome 13 as the Y chromosome due to sequence divergence between sexes and segregation of sex genotypes in pedigrees. Linkage analysis revealed that all chromosomes exhibit heterochiasmy, i.e. male-only and female-only meiotic recombination regions (MRR/FRR). We show that FRR/MRR intervals differ in nucleotide diversity and repeat class content and that this is true also for other Pleuronectidae species. We further show that remnants of a Gypsy-like transposable element insertion on chr13 promotes early male specific expression of gonadal somatic cell derived factor (gsdf). Less than 4.5 MYA, this male-determining element evolved on an autosomal FRR segment featuring pre-existing male meiotic recombination barriers, thereby creating a Y chromosome. Our findings indicate that heterochiasmy may facilitate the evolution of genetic sex determination systems relying on linkage of sexually antagonistic loci to a sex-determining factor.

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PubMed 35134055

DOI 10.1371/journal.pgen.1010011

Crossref 10.1371/journal.pgen.1010011

pmc: PMC8824383
pii: PGENETICS-D-21-00885

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