THE β-actin GENE PROMOTER OF ROHU CARP (Labeo rohita) DRIVES REPORTER GENE EXPRESSIONS IN TRANSGENIC ROHU AND VARIOUS CELL LINES, INCLUDING SPERMATOGONIAL STEM CELLS

We previously characterized the beta-actin gene promoter of Indian domesticated rohu carp (Labeo rohita) and made a reporter construct via fusion to green fluorescence protein (GFP) cDNA. In this study, the same construct was used to breed transgenic rohu fish. About 20% of the transgenic offspring showed ubiquitous expression of the reporter GFP gene. In a few of the transgenic fish, we documented massive epithelial and/or muscular expression with visible green color under normal light. The expression of GFP mRNA was higher in the muscle tissue of transgenic fish than in that of non-transgenic fish. A highly efficient nucleofection protocol was optimized to transfect proliferating spermatogonial cells of rohu using this reporter construct. The beta-actin promoter also drove expressions in HEK293 (derived from human embryonic kidney cells), K562 (human leukemic cells) and SF21 (insect ovarian cells) lines. These findings imply conserved regulatory mechanisms of beta-actin gene expression across eukaryotes. Furthermore, the isolated beta-actin promoter with consensus regulatory elements has the potential to be used in generating transgenic carp with genes of interest and in basic biology research.