Genetic conflict, genomic imprinting and establishment of the epigenotype in relation to growth

Genomic imprinting is the process that differentially modifies the parental alleles at certain genetic loci in the parental germlines. Such modifications of DNA and chromatin are somatically heritable and cause unequal expression of the parental alleles during subsequent development. In mammals, imprinted genes encode a relatively small number of functionally heterogeneous proteins. Nevertheless, imprinted genes exert important effects, primarily on fetal development, and their deregulation is implicated in a variety of pathologies including sporadic, inherited and induced growth disorders. Imprinted loci show several unusual structural and functional characteristics that may be related to mechanistic aspects of mono-allelic expression or to modes of evolution of imprinted genetic loci. Typically, imprinted genes are clustered in certain genomic regions and have relatively reduced intronic DNA content relative to non-imprinted genes. In addition, their regulatory regions frequently contain a combination of features including tandem repeats associated with differentially methylated CpG islands and overlapping transcription of coding or non-coding RNAs. The evolution of imprinting can be understood as the stable outcome of sexual selection acting differently on the parental alleles of genes that influence parental investment in offspring. Consistent with this explanation, imprinted genes are expressed predominantly during embryonic and postnatal development in mammals and in the developing endosperm of plants, and maternal or paternal expression at imprinted loci is associated with reduced or increased parental investment, respectively. Such selective forces have implications for understanding mechanistic aspects of genome reprogramming in the early mammalian embryo.

This article has been cited by other articles:

				C. Allegrucci, A. Thurston, E. Lucas, and L. Young Epigenetics and the germline Reproduction, February 1, 2005; 129(2): 137 - 149. [Abstract] [Full Text] [PDF]

				W. Mills and T. Moore Polyandry, Life-History Trade-Offs and the Evolution of Imprinting at Mendelian Loci Genetics, December 1, 2004; 168(4): 2317 - 2327. [Abstract] [Full Text] [PDF]

				T. Day and R. Bonduriansky Intralocus Sexual Conflict Can Drive the Evolution of Genomic Imprinting Genetics, August 1, 2004; 167(4): 1537 - 1546. [Abstract] [Full Text] [PDF]

				T. Moore and M. Ball Kaguya, the first parthenogenetic mammal - engineering triumph or lottery winner? Reproduction, July 1, 2004; 128(1): 1 - 3. [Full Text] [PDF]

				C. SPILLANE, C. BAROUX, J.-M. ESCOBAR-RESTREPO, D.R. PAGE, S. LAOUEILLE, and U. GROSSNIKLAUS Transposons and Tandem Repeats Are Not Involved in the Control of Genomic Imprinting at the MEDEA Locus in Arabidopsis Cold Spring Harb Symp Quant Biol, January 1, 2004; 69(0): 465 - 476. [Abstract] [PDF]

				C. E. Farin, P. W. Farin, and J. A. Piedrahita Development of fetuses from in vitro-produced and cloned bovine embryos J Anim Sci, January 1, 2004; 82(13_suppl): E53 - 62. [Abstract] [Full Text] [PDF]

				K. A. Maggert and K. G. Golic The Y Chromosome of Drosophila melanogaster Exhibits Chromosome-Wide Imprinting Genetics, November 1, 2002; 162(3): 1245 - 1258. [Abstract] [Full Text] [PDF]