Epigenetic changes (not just methylation) alter gene expression to buffer the organism against environmental changes and support adaptability to the life-course conditions. A whole-organism epigenetic transcriptional reorganization appears to underlie different hormetic effects.
Caloric restriction increases life span, partly via hormetic mechanisms that increase cellular stress resistance by up-regulation of vitagenes. [1,2]
Exposure of human skin fibroblasts to a single dose of radiation changed the expression of more than 100 genes within 2 h. These included stress response genes that were different from those expressed in cultures exposed to a higher dose. Genome- wide changes in expression were observed in low-dose irradiated Drosophila with enhanced longevity. Approximately 13% of the genes exhibited changes in expression, along with a number of ageing-related genes. [3]
Mild stresses at a young age can protect from severe stresses at old age as well as delay ageing and increase longevity. Single or multiple exposures to low doses of otherwise harmful agents can cause a variety of anti-ageing and longevity-extending hormetic effects. [4–6]
In honey bees, the queen and worker female castes, although share the same genome, show different DNA methylation patterns as a result of differential intake of the royal jelly (environmental factor). [7–9] The queens live up to 500 times longer than males and 10 times longer than workers. [10]
References:
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2. Calabrese V, Cornelius C, Dinkova-Kostova AT, Calabrese EJ, Mattson MP. Cellular Stress Responses, The Hormesis Paradigm, and Vitagenes: Novel Targets for Therapeutic Intervention in Neurodegenerative Disorders. Antioxid Redox Signal [Internet]. 2010 Dec;13(11):1763–811. Available from: http://www.liebertpub.com/doi/10.1089/ars.2009.3074
3. Seong KM, Kim CS, Seo S-W, Jeon HY, Lee B-S, Nam SY, et al. Genome-wide analysis of low-dose irradiated male Drosophila melanogaster with extended longevity. Biogerontology [Internet]. 2011 Apr 9;12(2):93–107. Available from: http://link.springer.com/10.1007/s10522-010-9295-2
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8. Corona M, Hughes KA, Weaver DB, Robinson GE. Gene expression patterns associated with queen honey bee longevity. Mech Ageing Dev [Internet]. 2005 Nov;126(11):1230–8. Available from: https://linkinghub.elsevier.com/retrieve/pii/S0047637405001740
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10. Keller L, Jemielity S. Social insects as a model to study the molecular basis of ageing. Exp Gerontol [Internet]. 2006 Jun;41(6):553–6. Available from: https://linkinghub.elsevier.com/retrieve/pii/S0531556506001057