Cryopreservation of Germ Stem Cells in Fish

Abstract

Germ cells have drawn much attention as gamete precursors because of their exceptional potential for fundamental biological studies, as well as for being a potential alternative to gene resource banking for breeding and restocking purposes via surrogacy. Research has developed markers for germ cell identification, shedding light on their origin and specification mechanism. Then, pioneering studies focused on germ cell transplantation into the surrogate host with donor-derived gamete production have followed suit. The advent of transgenic technologies allowed the development of lines expressing green fluorescent protein (GFP) in their germ cells exclusively or the use of artificially synthesised mRNA conjugated with GFP to label and trace germ cells in vivo and facilitate studies on transplantation. The power of germ cell manipulation techniques was significantly enhanced by the development of a wide range of cryopreservation methods; with these approaches, valuable genetic material can be cryopreserved even during the blastula stage, as well as harvested from an adult specimen. In turn, the germ cells in the cryogenic storage can be recovered by transplantation in the surrogate host, producing donor-derived gametes after maturation. The aim of this chapter is to provide basic knowledge about a relatively novel biotechnological approach in fish reproduction and summarise performed studies on germ cell cryopreservation.