Knockout of tac3 genes in zebrafish shows no impairment of reproduction.

Neurokinin B (NKB) plays a pivotal role in the regulation of reproduction in vertebrates. However, whether this neuropeptide is dispensable for reproduction in teleosts remains unknown. In order to reveal its authentic functions in fish, in this study, two tachykinin 3 (tac3) genes encoding Nkbs were functional mutated in zebrafish using the Transcription Activator-like Effector Nucleases (TALEN) technology. We established tac3a, tac3b and tac3a;tac3b mutant lines, and investigated their reproductive performance and ontogeny. According to our study, spermatogenesis and folliculogenesis were not impaired in tac3a, tac3b and tac3a;tac3b mutant lines, but changes in the expression of genes related to reproductive axis were observed after loss of Tac3, suggesting that possible compensatory response was activated to maintained the reproductive function in zebrafish. In summary, our results indicate that mutation of tac3 genes do not disrupt the reproduction in zebrafish unlike in mammals, revealing the plasticity of reproductive neuroendocrine system in the brain of zebrafish.