A molecular investigation of germ cell specification and migration within the tilapia Oreochromis mossambicus (Order Perciform)

This thesis reports on the investigation of gonad development in the tilapia, Oreochromis mossambicus. The project aimed to advance the field of reproductive development, aquaculture and pest management by understanding the molecular gene and protein components involved in germ cell specification and migration. Primordial germ cells (PGCs) are progenitors of the germ cell lineage, giving rise to either spermatogonia or oogonia after the completion of gonadal differentiation. Prior to this study, there was little information on the mechanism of PGCs migration leading to the formation of the primordial gonad in Perciform fish. This thesis presents the transcriptomes of ovary and testis, from which we identify the major germ cell components, including the Nanos-1, Vasa-1, Dead end, Oct-4, GFRa-1, SDF and CXCR4. Using a variety of molecular approaches, those components have been further investigated to reveal their conservation, spatial and temporal distribution within larvae and adult O. mossambicus.Submitted in the fulfilment of the requirements of the degree of Doctor of Philosophy, University of the Sunshine Coast, 2016