Microbiology, Developmental Genetics and Evolution

Abstract

The major elementary components of development in higher forms, i.e., cellular division, cellular differentiation and epigenetic homeostasis, are well established in microorganisms. Their existence and functional significance in modern microbes suggest that they may all have arisen in primitive unicellular forms and may have provided the "pre-adaptive" basis for the transition to multicellularity. The mechanisms underlying cellular differentiation in microorganisms appear to be similar to those operating in metazoa. In particular, nuclear differentiation-the regulation of genetic activities by chromosomal modifications, is wide-spread and of fundamental significance.