B chromosome retrotransposed sequences persist through speciation, contributing to genomic and regulatory innovations in the fish genus Psalidodon (Characiformes, Acestrorhamphidae).

ABSTRACT: B chromosomes are supernumerary genetic elements rich in repetitive DNA. Many species within the fish genus Psalidodon possess a large metacentric B chromosome that exhibits signs of recent retrotransposon activity, resulting in truncated pseudogenic copies of standard A chromosomes genes, specifically sbno2 and simc1. We aimed to characterize the structure of the B chromosome pseudogenes sbno2-B and simc1-B and their evolutionary history in four B chromosome variants of three Psalidodon species, as well as their expression patterns in Psalidodon paranae individuals with a single B chromosome (1B). Our findings suggest that the retrotransposition process of each gene occurred in an ancestral B chromosome, which later diverged into distinct trajectories within each species following speciat

SUBMITTER: Lasmar LF 

PROVIDER: S-EPMC12758807 | biostudies-literature | 2026

REPOSITORIES: biostudies-literature