Latham It is now recognized that the genetic material that is transmitted from gamete to zygote and from cell to cell contains the necessary information for progeny development not only in the base sequence of the DNA but also in, as yet, undefined coded messages termed epigenetic. Perhaps the most striking form of epigenetic inheritance in mammals is parental genomic imprinting, which renders maternal and paternal chromosomes functionally non-equivalent. It has been shown by this laboratory that genomic imprinting can involve post-fertilization modifications of the genome as well as gametic modifications. A combination of genetic and embryological methods will be used to characterize one class of modifiers that operates immediately after fertilization and mediates epigenetic modifications of the paternal genome function as revealed by the developmental capacity of androgenetic embryos (embryos with exclusively two paternal sets of chromosomes). The egg modifiers will be characterized genetically and functionally. Preliminary evidence suggests a two-locus model. That observation will be genetically verified and the loci mapped onto chromosomes at some level. Function will be investigated by egg cytoplasm transfer experiments to determine if the factors are acting in a positive or negative way. %%% It has become clear that knowing the base sequence of a genome is only a first step in understanding the generation of an organism. An understanding of the other parameters is essential for a basic understanding of life processes and also for more applied goals. ***
