Chicken orthologues of mammalian imprinted genes are clustered on macrochromosomes and replicate asynchronously.
In the chicken genome, most orthologues of mouse imprinted genes are clustered on macrochromosomes. Only a few orthologues are located in the microchromosome complement. Macrochromosomal and, to a lesser extent, microchromosomal regions containing imprinted gene orthologues exhibit asynchronous DNA replication. We conclude that highly conserved arrays of imprinted gene orthologues were selected during vertebrate evolution, long before these genes were recruited for parent-specific gene expression by genomic imprinting mechanisms. Evidently, the macrochromosome complement provides a better chromatin environment for the establishment of asynchronous DNA replication and imprinted gene expression later in evolution than microchromosomes.
Dünzinger
Ulrich
U
Institute of Human Genetics, Johannes Gutenberg University Mainz, Germany.
Nanda
Indrajit
I
Schmid
Michael
M
Haaf
Thomas
T
Zechner
Ulrich
U
D000818:Animals; D002645:Chickens; D002875:Chromosomes; D022202:Chromosomes, Artificial, Bacterial; D004261:DNA Replication; D019143:Evolution, Molecular; D016678:Genome; D018392:Genomic Imprinting; D006801:Humans; D051379:Mice