Chapter 15 - Cloning of Fish

Abstract

This chapter presents a study in which basic techniques of fish nuclear transplantation by using medaka embryonic cells are established. In the first step of the study, basic techniques of nuclear transplantation are developed. Single-blastula nuclei of an inbred strain with the wild-type body color are transplanted into nonenucleated unfertilized eggs of an outbred orange-red strain. The nuclear transplants grow to the adult stage, and they express the genetic markers of both the donor and the recipient nuclei; they are triploids and sterile. Foreign genes introduced into the donor nuclei are expressed normally in nuclear transplants when blastula nuclei derived from transgenic fish carrying the green fluorescent protein (GFP) gene, driven by the promoter of the medaka elongation factor gene, EF-1α-A, are transplanted into nonenucleated eggs. The gene expression pattern is the same as that in the transgenic fish. In the second step, embryonic cell nuclei from transgenic fish carrying the GFP gene are transplanted into unfertilized eggs enucleated by X-ray irradiation. Fertile and diploid nuclear transplants are successfully generated, and the natural and GFP markers of the donor nuclei are transmitted to the F1 and F2 offspring in a Mendelian fashion.