RT Journal Article
SR Electronic
T1 A compendium of novel genomics technologies provides a chromosome-scale assembly and insights into the sex determining system of the Greenland Halibut
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.06.18.449053
DO 10.1101/2021.06.18.449053
A1 A-L Ferchaud
A1 C Mérot
A1 E Normandeau
A1 I Ragoussis
A1 C Babin
A1 H Djambazian
A1 P Bérubé
A1 C Audet
A1 M Treble
A1 W Walkusz
A1 L Bernatchez
YR 2021
UL http://biorxiv.org/content/early/2021/06/20/2021.06.18.449053.abstract
AB Despite the commercial importance of Greenland Halibut (Reinhardtius hippoglossoides), important gaps still persist in our knowledge of this species, including its reproductive biology and sex determination mechanism. In this study, we combined single molecule sequencing of long reads (Pacific Sciences) with Chromatin Conformation Capture sequencing (Hi-C) data to provide the first chromosome-level genome reference for this species. The high-quality assembly encompassed more than 598 Megabases (Mb) assigned to 1 594 scaffolds (scaffold N50 = 25 Mb) with 96 % of its total length distributed among 24 chromosomes. The investigation of its syntenic relationships with other economically important flatfish species revealed a high conservation of synteny blocks among members of this phylogenetic clade. Sex determination analysis revealed that flatfishes do not escape the rule applied to other teleost fish and exhibit a high level of plasticity and turnover in sex-determination mechanisms. A whole-genome sequence analysis of 198 individuals allowed us to draw a full picture of the molecular sex determination (SD) system for Greenland Halibut, revealing that this species possesses a very nascent male heterogametic XY system, with a putative major effect of the sox2 gene, also described as the main SD driver in two other flatfishes. Interestingly, our study also suggested for the first time in flatfishes that a putative Y-autosomal fusion could be associated with a reduction of recombination typical of early steps of sex chromosome evolution.