Evolutionary Aspects of Cell Differentiation

Abstract

Publisher Summary This chapter examines how the changes that occurred in DNA during evolution may account for the modifications of a developmental stage of a cell, tissue, or organ during early embryonic development. The sequence of differentiations that occurred during the evolutionary history of an organism occurs in the same sequence during embryonic development. The differentiation of a particular cell type is attributable to modification(s) of a developmental stage of a more primitive cell type. These changes are because of an earlier production of more conservative messenger RNA molecules, followed by a quantitative and qualitative restriction of their transcription, and resulting in a relative increase of less conservative mRNA molecules. Evidence supports that the transcription initiation sequences that are enriched in A-T base pairs produce more copies of mRNA and that these abundant mRNA species are more conservative. Increasing amounts of H1 histone in the various cells react with the most A-T rich (the most conservative) initiation sequences and restrict their transcription. The molecular events may account for the temporal sequence of expression of the various families of genes during embryonic development and allow the evolutionary history of the organism to specify the course of embryonic development.