Sakai Group • Model Fish Genetics Laboratory

Analyses of developmental mechanisms in zebrafish germ cells


SAKAI, Noriyoshi

Associate Professor

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Research Summary

Spermatogenesis is characterized by sequential transitions of multiple processes: self-renewal of spermatogonial stem cells, mitotic growth of differentiating spermatogonia, and meiosis leading to the production of sperm. Molecular dissection of these complex processes and transitions could be facilitated by cell culture approaches. We have developed techniques to recapitulate the entire spermatogenesis process, from stem cell propagation to differentiation of functional sperm, solely in culture. In addition, we have already isolated several ENU-induced zebrafish mutants that have a defect in spermatogenesis. We are working on the molecular mechanisms to regulate spermatogenesis of vertebrates both in vivo and in vitro.

In human and zebrafish spermatocytes, meiotic recombination predominantly occurs near telomeres. Our studies in zebrafish showed that formation of meiotic chromosome axes and physical connection between homologous chromosomes (synapsis) begin near telomeres, and are required for proper recombination.

Selected Publications

Takemoto K, Nishimura T, Kawasaki T, Imai Y, Levy K, Hart N, Olaya I, Burgess SM, Elkouby YM, Tanaka M, Sakai N. In Vitro Storage of Functional Sperm at Room Temperature in Zebrafish and Medaka. Zebrafish. 2023 Dec;20(6):229-235.

Imai Y, Saito K, Takemoto K, Velilla F, Kawasaki T, Ishiguro KI, Sakai N. Sycp1 Is Not Required for Subtelomeric DNA Double-Strand Breaks but Is Required for Homologous Alignment in Zebrafish Spermatocytes. Front Cell Dev Biol. 2021 Mar 26;9:664377.

Imai Y, Olaya I, Sakai N, Burgess SM. Meiotic Chromosome Dynamics in Zebrafish. Front Cell Dev Biol. 2021 Oct 8;9:757445.

Takemoto K, Imai Y, Saito K, Kawasaki T, Carlton PM, Ishiguro KI, Sakai N. Sycp2 is essential for synaptonemal complex assembly, early meiotic recombination and homologous pairing in zebrafish spermatocytes. PLoS Genet. 2020 Feb 24;16(2):e1008640.

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