Monoallelic gene expression and mammalian evolution
Article first published online: 17 NOV 2009
Copyright © 2009 Wiley Periodicals, Inc.
Volume 31, Issue 12, pages 1318–1326, December 2009
How to Cite
Keverne, B. (2009), Monoallelic gene expression and mammalian evolution. Bioessays, 31: 1318–1326. doi: 10.1002/bies.200900074
- Issue published online: 17 NOV 2009
- Article first published online: 17 NOV 2009
Monoallelic gene expression has played a significant role in the evolution of mammals enabling the expansion of a vast repertoire of olfactory receptor types and providing increased sensitivity and diversity. Monoallelic expression of immune receptor genes has also increased diversity for antigen recognition, while the same mechanism that marks a single allele for preferential rearrangement also provides a distinguishing feature for directing hypermutations. Random monoallelic expression of the X chromosome is necessary to balance gene dosage across sexes. In marsupials only the maternal X chromosome is expressed, while in eutherian mammals the paternal X genes are silenced in the developing placenta and early blastocyst. These examples of epigenetic gene regulation commonly employ asynchrony of replication, the binding of polycomb proteins and antisense RNA, and histone modifications to chromatin structure. The same is true for genomic imprinting which among vertebrates is unique to mammals and represents a special kind of epigenetic modification that is heritable according to parent of origin. Genomic imprinting pervades many aspects of mammalian growth and evolution but in particular has played a significant role in the co-adaptive evolution of the mother and foetus.