Electroporation of salmon sperm for gene transfer: efficiency, reliability, and fate of transgene.

Uptake of exogenous DNA by electroporated salmon sperm for gene transfer is being investigated. Our studies show that electroporated salmon sperm cells were more efficient and more reliable than untreated sperm in picking up exogenous DNA and subsequently transferring the DNA into salmon embryos. Indirect evidence suggest that some of the exogenous DNA was internalized in the sperm nuclei. The taken up DNA retained its integrity as demonstrated by PCR. The foreign DNA was detected in 15-month-old fish, and had a mosaic pattern of distribution. Integration of the foreign DNA occurred infrequently, and the expression of the foreign genes was poor. The potential of sperm-mediated gene transfer as a routine protocol for mass gene transfer in salmon will be dependent on the improvement of integration and expression of the foreign gene.