Expression of porcine growth hormone gene in transgenic rabbits as reported by green fluorescent protein

Sperm-mediated gene transfer was used to produce transgenic rabbits that expressed the porcine growth hormone gene under the control of a metallothionein promoter. The gene that encodes the selectable marker green fluorescent protein (GFP) was inserted downstream of the transgene. After lipofectin-mediated gene transfer into sperm cells and after subsequent in vitro fertilization using the transfected sperm cells, 32% of the cultured blastocysts exhibited bright green fluorescence when stimulated with blue light. Of the 74 adult rabbits and five fetal rabbits (age, gestational day 15), 2 fetuses and 29 rabbits were GFP-positive as indicated by PCR analysis. Southern blot analysis of their genomic DNA showed that 13 of 21 GFP-positive rabbits were transgenic. GFP expression was observed in different tissues of transgenic rabbits and the growth rate of four GFP-positive rabbits was greater than that of controls. PCR analysis showed that one of six F1 offspring was transgenic. These results suggest that lipofectin-mediated gene transfer into sperm cells can be used to efficiently produce transgenic rabbits.