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bioRxiv · 10.1101/2023.10.20.563234

A novel amphibian sex determination candidate gene, evolved by structural variation in the regulatory region between X and Y

Kuhl, H.·Tan, W.-H.·Klopp, C.·Kleiner, W.·Koyun, B.·Ciorpac, M.·Feron, R.·Knytl, M.·Kloas, W.·Schartl, M.·Winkler, C. W.·Stoeck, M.
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Abstract

Most vertebrates develop distinct females and males, where sex is determined by repeatedly-evolved environmental or genetic triggers. Undifferentiated sex chromosomes and large genomes have caused major knowledge gaps in amphibians. Only a single master sex-determining gene is known in >8650 species, the dmrt1-paralogue (dm-w) of female-heterogametic clawed frogs (Xenopus; ZW[female]/ZZ[male]). Combining chromosome-scale female and male genomes of a non- model amphibian, the European green toad, Bufo(tes) viridis, with ddRAD- and whole genome pool-sequencing revealed a candidate master locus, governing a male-heterogametic system (XX[female]/XY[male]). Targeted sequencing across multiple taxa uncovered structural X/Y-variation in the 5-regulatory region of the gene bod1l, where a Y-specific non-coding RNA, only expressed in males, suggests that this locus may initiate sex-specific differentiation. Developmental transcriptomes and RNA in-situ hybridization show timely and spatially relevant, sex-specific ncRNA-Y and bod1l-gene expression in primordial gonads with coinciding differential H3K4me- methylation in pre-granulosa/pre-Sertoli cells, pointing to a specific mechanism of amphibian sex determination.

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Kuhl, H., Tan, W.-H., Klopp, C., Kleiner, W., Koyun, B., Ciorpac, M., Feron, R., Knytl, M., Kloas, W., Schartl, M., Winkler, C. W., Stoeck, M.. 2023-10-23. A novel amphibian sex determination candidate gene, evolved by structural variation in the regulatory region between X and Y. https://doi.org/10.1101/2023.10.20.563234

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