Epigenetics Connects the Genome to Its Environment

摘要

Comprehending the reasons for the natural variation and distribution of life-forms in different environments has been a major motivational force for biologysince antiquity. With Mendel's discoveries, Darwin's natural selection theories became armed with the concept of genotype.How a genotype is inherited, selected, and how this results in a phenotype have become a spirited debate that has ultimately led to our ideas of genetics and epigenetics. The concept of genetic memory that arose from developmental biology has underpinnedthe desire to understand the molecular basis of epigenetics. This has finally led to uncovering of many of the molecular building blocks and regulatory pathways of epigenetics. The possibility that the environment through epigenetic regulation may direct trait inheritance has even begun to question some of our fundamental paradigms of the function of the environment in shaping evolution. Some direct role of the environment in heritable phenotype variation cannot be ruled out now. This has blurred our concepts of transgenerational and developmental genetics so much that understanding the connections between these processes has taken an enormously important status in biology. The pace of growth of our knowledge of the biochemical participants in the epigenetic informational system has been truly impressive. Major epigenetic marks involve covalent chemical modifications to DNA and to histones. How these modifications and noncoding RNAs are organized into an epigenetic informational system is being intensively investigated.Understanding the way in which the environment controls the connections and use of epigenetic marks with the DNA sequence code promises to expose a rich new world of biology and new toolboxes that will afford stunning new capabilities in agriculture, medicine, and all practical applications of biology. This chapter discusses the sea change in our understanding of genome-environment interactions.