![]() ![]() ; Balling, Rudi ![]() in Science (2001), 291(5507), 1251-5 Detailed reference viewed: 141 (7 UL)![]() ![]() ; ; et al in Nature (1987), 328(6127), 251-4 Data derived from both pronuclear transplantation experiments and classical genetic experiments indicate that the maternal and paternal genetic contributions to the mammalian zygote nucleus do not ... [more ▼] Data derived from both pronuclear transplantation experiments and classical genetic experiments indicate that the maternal and paternal genetic contributions to the mammalian zygote nucleus do not function equivalently during subsequent development. These observations have been interpreted as resulting from differential 'genome imprinting' during male and female gametogenesis. The molecular mechanism responsible for genome imprinting is unknown, but data gathered to date require that the mechanism fulfill at least four criteria: (1) the imprint must be physically linked to the pronucleus; (2) the imprint must persist through DNA replication and cell division; (3) the mechanism must be capable of affecting gene expression; and (4) the mechanism must be capable of switching the identity of the imprint from one sex to the other in successive generations. One molecular mechanism which could satisfy the first three criteria is differential DNA methylation during gametogenesis itself, or before formation of the zygote nucleus during embryogenesis. We present data indicating that the methylation patterns of exogenous DNA sequences in transgenic mice can be changed by switching their gamete of origin in successive generations. These data suggest that DNA methylation can also satisfy the fourth criterion for an imprinting mechanism. [less ▲] Detailed reference viewed: 151 (0 UL)![]() ![]() ; Balling, Rudi ![]() in Proceedings of the National Academy of Sciences of the United States of America (1985), 82(24), 8587-91 Using a Moloney leukemia virus vector containing the bacterial neo gene, we demonstrate that retrovirus vectors can be used to introduce genes into the mouse germ line. Infection of preimplantation ... [more ▼] Using a Moloney leukemia virus vector containing the bacterial neo gene, we demonstrate that retrovirus vectors can be used to introduce genes into the mouse germ line. Infection of preimplantation embryos with the vector MLV-NEO.1 resulted in integration of neo sequences in approximately equal to 10% of the progeny mice. One of these animals, mouse F.2, contained approximately six MLV-NEO.1 proviruses at independent integration sites, each present at less than a single copy per cell. This mosaic mouse transmitted one of these proviruses to her offspring, producing a line of transgenic mice carrying a full-length, unrearranged MLV.NEO.1 provirus at a single chromosomal integration site. Mice homozygous at this MLV-NEO.1 locus have also been produced. No expression of the neo gene has been detected in the transgenic mice, either by screening of primary bone marrow or lung cells for resistance to G418 or by RNA transfer blot analysis of RNA from several tissues. In addition, the neo gene was found to be extensively methylated in the transgenic mice; however, treatment of primary cells with 5-azacytidine did not induce G418 resistance. The inactivity of the MLV-NEO.1 provirus in transgenic mice and potential means of eliciting neo expression under these conditions are discussed. [less ▲] Detailed reference viewed: 145 (0 UL) |
||