IN OVO TRANSFECTION OF CHICKEN EMBRYOS USING CATIONIC LIPOSOMES

It is reported that cationic liposomes are capable of transfecting emb ryos in unincubated fertile chicken eggs and that the cationic liposom e, TransfectAce(TM), has superior properties to Lipofectin(TM). In ord er to determine the duration of expression of genes introduced in this way, embryos were transfected with an expression vector encoding the firefly luciferase cDNA under the control of the Rous sarcoma virus lo ng terminal repeat (LTR). Luciferase activity could be observed consis tently in day 3 embryos and activity was detectable up to day 8 of inc ubation. The relative expression of luciferase under the control of di fferent viral promoters was compared in transfected chicken embryo fib roblasts and day 3 embryos. The cytomegalovirus immediate early promot er and the SV40 early promoter directed the highest amount of expressi on in fibroblasts while the Rous sarcoma virus LTR caused the highest amount of expression in embryos. Chicken embryo fibroblasts were trans fected with the luciferase vector in order to examine duration of repo rter gene expression in vitro. Luciferase expression was decreased exp onentially over a 24-day period after which point luciferase activity could no longer be detected. These data suggest that stable integratio n of transfected DNA using liposomes is a rare event. Nevertheless, li posome-mediated transfection of embryos is suitable for the examinatio n of promoter activity in vivo and may be a useful method to transfect genes to study embryonic development.