Sexually dimorphic reproductive defects in zebrafish with <i>spo11</i> mutation
Yunsheng Zhang, Zhiping Li, Yuan Nie, Guixiu Ou, Changzhi Chen, Shangye Cai, Liangguo Liu, Pinhong Yang
Abstract
Meiotic recombination is a key step in meiosis because it facilitates the pairing of homologous chromosomes and generates new combinations of genetic alleles, which results in the diversification of extant eukaryotes. Spo11, a meiosis-specific protein, catalyses the formation of double-strand breaks (DSBs) and initiates meiotic recombination in a wide variety of organisms, but the exact function of spo11 in the formation of gametes needs further study in fish. In this study, we knocked out the spo11 gene in zebrafish using CRISPR/Cas9 technology. Sexually dimorphic reproductive defects were found in the spo11-mutated zebrafish. The spo11-/- males were completely sterile, but spo11-/- females were fertile and there was no significant difference in relative fecundity and fertilisation rates compared with WT females; however, the offspring of spo11-/- females had severe developmental defects. In addition, we found that spo11 was expressed only in gonad tissue, and the level of expression in the testes was much higher than in the ovaries. Surprisingly, spo11 was also expressed in zebrafish embryos, especially at the dome stage. We compared amino acid sequences of Spo11 in ten different fish and found that Spo11 was highly conserved. Importantly, the results established zebrafish as a vertebrate model for understanding multiple roles of spo11 in meiosis.