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Diversity of reptile sex chromosome evolution revealed by cytogenetic and linked-read sequencing

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posted on 21.09.2022, 01:29 authored by ZX Zhu, K Matsubara, F Shams, J Dobry, E Wapstra, T Gamble, SD Sarre, A Georges, Jennifer GravesJennifer Graves, Q Zhou, T Ezaz

Reptile sex determination is attracting much attention because the great diversity of sex-determination and dosage compensation mechanisms permits us to approach fundamental questions about mechanisms of sex chromosome turnover. Recent studies have made significant progress in better understanding diversity and conservation of reptile sex chromosomes, with however no reptile master sex determination genes identified. Here we describe an integrated genomics and cytogenetics pipeline, combining probes generated from the microdissected sex chromosomes with transcriptome and genome sequencing to explore the sex chromosome diversity in non-model Australian reptiles. We tested our pipeline on a turtle, two species of geckos, and a monitor lizard. Genes identified on sex chromosomes were compared to the chicken genome to identify homologous regions among the four species. We identified candidate sex determining genes within these regions, including conserved vertebrate sex-determining genes pdgfa, pdgfra amh and wt1, and demonstrated their testis or ovary-specific expression. All four species showed gene-by-gene rather than chromosome-wide dosage compensation. Our results imply that reptile sex chromosomes originated by independent acquisition of sex-determining genes on different autosomes, as well as translocations between different ancestral macro- and microchromosomes. We discuss the evolutionary drivers of the slow differentiation and turnover of reptile sex chromosomes. 

History

Publication Date

18/09/2022

Journal

Zoological Research

Volume

43

Issue

5

Pagination

(p. 719-733)

Publisher

Zoological Research

ISSN

2095-8137

Rights Statement

©2022 Editorial Office of Zoological Research, Kunming Institute of Zoology, Chinese Academy of Sciences This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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