Germline Specific Expression of a Homologue Gene in the Viviparous Fish Black Rockfish () and Functional Analysis of the 3 Untranslated Region.

Germ cells play a key role in gonad development. As precursors, primordial germ cells (PGCs) are particularly important for germline formation. However, the origination and migration patterns of PGCs are poorly studied in marine fish, especially for viviparous economic species. The gene has been widely used as a germ cell marker to identify a germline because RNA is a component of germ plasm. In this study, we described the expression pattern of black rockfish () () in gonadal formation and development by hybridization. The results showed that failed in localization at the cleavage furrows until the late gastrula stage, when PGCs appeared and migrated to the genital ridge and formed elongated gonadal primordia at 10 days after birth. This study firstly revealed the PGCs origination and migration characteristics in viviparous marine fish. Furthermore, we microinjected chimeric mRNA containing EGFP and the 3'untranslated region (3'UTR) of into zebrafish () and marine medaka () fertilized eggs for tracing PGCs. We found that, although lacked early localization, similar to red seabream () and marine medaka, only the 3'UTR of 3'UTR of black rockfish was able to label both zebrafish and marine medaka PGCs. In comparison with other three Euteleostei species, besides some basal motifs, black rockfish had three specific motifs of M10, M12, and M19 just presented in zebrafish, which might play an important role in labeling zebrafish PGCs. These results will promote germ cell manipulation technology development and facilitate artificial reproduction regulation in aquaculture.