Sharks and rays have the oldest vertebrate sex chromosome with unique sex determination mechanisms.

ABSTRACT: Sex determination has been investigated across vertebrate lineages to reveal the stepwise evolution of sex chromosomes and the diversity of responsible molecular mechanisms. However, these studies rarely include cartilaginous fishes, which diverged from the other vertebrates 450 Mya, hindering the comprehensive view of vertebrate sex determination. Here, we produced chromosome-scale genome assemblies of egg-laying shark species and comparatively investigated genome sequences and transcriptome profiles across diverse cartilaginous fishes. Sex chromosome identification, supported by cytogenetic experiments, elucidated the homology of X chromosomes between sharks and rays as well as an extensively degenerated Y chromosome harboring no detectable male-specific genes. Orthologs of documented se

SUBMITTER: Niwa T 

PROVIDER: S-EPMC12318234 | biostudies-literature | 2025 Jul

REPOSITORIES: biostudies-literature