More and more studies are revealing systems that regulate DNA.  Here are some recent samples.

Stress response:  PhysOrg headlined, “Study finds stress triggers widespread epigenetic changes that aid in disease resistance reported.”  A study by the Salk Institute made it clear that epigenetics involves a code: “The scientists found that exposure to a pathogenic bacteria caused widespread changes in a plant’s epigenetic code, an extra layer of biochemical instructions in DNA that help control gene expression. The epigenetic changes were linked to the activity of genes responsible for coordinating a plant’s response to stress, suggesting that the epigenome may help organisms develop resistance to pathogens and other environmental stressors.”

A primer on PLoS Biology, similarly, emphasized the role of chromatin in stress response (Smith & Workman, “Chromatin: Key Responders to Stress,” PLoS Biology, July 31, 2012).

Developmental switches in lampreys:  Science Daily reported on a study that shows that lampreys have a way of sequestering genes after their use in development to prevent re-expression.  “In effect, by undergoing programmed genome rearrangement and gene loss during embryogenesis, the sea lamprey “seals” the genes away in the small germline compartment so they cannot be misexpressed and thereby create untoward problems (such as development of cancer, for example).”  This mechanism differs from epigenetic switching in mammals.  “The strategy removes the possibility that the genes will be expressed in deleterious ways,” the article stated.  “Humans, on the other hand, must contain these genes through other ‘epigenetic’ mechanisms that are not fool-proof.”  The authors probably did not intend to convey the notion that evolution is going downhill.

Caste system:  Epigenetics may be responsible for converting ants that have the same genetic code into workers and queens – the castes in an ant colony.  “The first ant methylomes uncover the relationship between DNA methylation and caste differentiation,” PhysOrg reported.  Methylation is one epigenetic mechanism whereby genes are tagged for repression by the addition of a methyl tag….

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