Comparative genomics of using unsupervised AI reveals a high CG frequency.

The Japanese wrinkled frog () is unique in having both XX-XY and ZZ-ZW types of sex chromosomes within the species. The genome sequencing and comparative genomics with other frogs should be important to understand mechanisms of turnover of sex chromosomes within one species or during a short period. In this study, we analyzed the newly sequenced genome of using a batch-learning self-organizing map which is unsupervised artificial intelligence for oligonucleotide compositions. To clarify genome characteristics of , we compared its short oligonucleotide compositions in all 1-Mb genomic fragments with those of other six frog species (, , , , , and ). In , we found an Mb-level large size of repeat sequences having a high identity with the W chromosome of the African bullfrog (). Our study concluded that has unique genome characteristics with a high CG frequency, and its genome is assumed to heterochromatinize a large size of genome via methylataion of CG.