Production of biologically-active recombinant goldfish gonadotropins in transgenic rainbow trout

The feasibility of using rainbow trout Oncorhynchus mykiss embryos as an expression system for proteins was investigated. For model proteins, we selected two goldfish gonadotropins (GTHs), follicle-stimulating hormone (FSH) and luteinizing hormone (LH). To produce single-chain goldfish FSH (scgfFSH) and LH (scgfLH), cDNAs encoding glycoprotein hormone (GP) α and FSHβ were fused in tandem, and cDNAs encoding GPα and LHβ were fused in tandem. The fused cDNAs were ligated with β-actin promoter, and microinjected into fertilized rainbow trout eggs. After 4-days incubation, the embryos were subjected to western blotting and in vitro bioassays. The recombinant proteins produced by the embryos were immunoreactive to antisera against goldfish GPα, N-glycosylated, and biologically active. We conclude that scgfFSH and scgfLH were successfully produced in transgenic rainbow trout.