DNA dose and sequence dependence in sperm-mediated gene transfer

We have tested three parameters in sperm-mediated gene transfer assays with mice and pigs: (i) the epididymal versus ejaculated origin of sperm cells, (ii) the primary structure, and (iii) the amount of the challenging foreig n DNA. We have found that the pVLCNhGH construct, of retrotransposon origin , causes a massive embryo lethality and yet increases the yield of genetic transformation among born animals of both species compared to viral constru cts. Arrest of embryonic development is a DNA dose-dependent effect, which is observed with high DNA doses, while lower doses are compatible with deve lopment. Finally, the overall efficiency of sperm-mediated gene transfer is higher when ejaculated, versus epididymal, spermatozoa are used. We sugges t that this difference is related to the highly efficient apoptotic respons e in epididymal compared to ejaculated spermatozoa, triggered by the intera ction of exogenous DNA molecules with the sperm membrane. (C) 2000 Wiley-Li ss, Inc.