查看文章

Understanding the evolution and regulation of nucleolar organizing regions (NORs) is important to elucidate genome structure and function. This is because ribosomal gene (rDNA) copy number and activity mediate protein biosynthesis, stress response, ageing, disease, dosage compensation and genome stability. Here, we found contrasting dosage compensation of sex‐linked NORs in turtles with male and female heterogamety. Most taxa examined exhibit homomorphic rRNA gene clusters in a single autosome pair (determined by 28S rDNA fluorescence in situ hybridization), whereas NORs are sex‐linked in Apalone spinifera, Pelodiscus sinensis and Staurotypus triporcatus. Full‐dosage compensation upregulates the male X‐NOR (determined via silver staining—AgNOR) in Staurotypus (who lacks Y‐NOR) compared with female X‐AgNORs. In softshell Apalone and Pelodiscus, who share homologous ZZ …