Effect of DNA loop anchorage regions (LARs) and microinjection timing on expression of beta-galactosidase gene injected into one-cell rabbit embryos.

The conditions favoring expression of a reporter gene microinjected into a male pronucleus of naturally ovulated and fertilized rabbit eggs have been studied. Injection of the reporter gene during S phase of the cell-cycle allows the highest level of expression of the gene. Incorporation of DNA loop anchorage regions (LARs) into constructs upstream and/or downstream of the reporter gene significantly increased the efficiency of expression.