From ScienceDaily:
Every gene in (almost) every cell of the body is present in two variants — so called alleles: one is deriving from the mother, the other one from the father. In most cases both alleles are active and transcribed by the cells into an RNA message. However, for a few genes, only one allele is expressed, while the other one is silenced. The decision whether the maternal or the paternal version is shut down occurs early in embryonic development — one reason, why for long it was thought that the pattern of active alleles is nearly homogeneous in the various tissues of the organism.
The new study (DOI:10.7554/eLife.25125), where CeMM PhD Student Daniel Andergassen is first author (now a PostDoc at Harvard University), uncovers a different picture. By performing the first comprehensive analysis of all active alleles in 23 different tissues and developmental stages of mice, the team of scientists revealed that each tissue showed a specific distribution of active alleles. Paper. (public access) – Daniel Andergassen, Christoph P Dotter, Daniel Wenzel, Verena Sigl, Philipp C Bammer, Markus Muckenhuber, Daniela Mayer, Tomasz M Kulinski, Hans-Christian Theussl, Josef M Penninger, Christoph Bock, Denise P Barlow, Florian M Pauler, Quanah J Hudson. Mapping the mouse Allelome reveals tissue-specific regulation of allelic expression. eLife, 2017; 6 DOI: 10.7554/eLife.25125 More.
It happens differently in different tissues of the body but it all somehow works. Hmmm.
See also: Did algae trigger complex cells before 650 million years ago?