Look at you in those genes!: Potential epigenetic effects mediated by environment in Polydora cornuta
LE3 .A278 2012
Gibson, Glenys D.
Bachelor of Science
Environmentally induced variation in phenotype during development is referred to as developmental plasticity. Developmental plasticity is thought to be based on epigenetic processes, such as histone modifications and DNA methylation. The objectives of my thesis are to investigate whether epigenetic modifications are linked to developmental plasticity in the spionid polychaete, Polydora cornuta, and to determine if changes in histone modifications occur during metamorphosis. Adult P. cornuta were exposed to environmental treatments including those rich in methyl donors (e.g. Folate/vitamin B12) and methyl releasers (e.g. Bisphenol A). Adult sections and larval whole mounts were treated with antibodies for histone modifications and observed using fluorescent microscopy. In adults, hypomethylation of H3K9 and H3K4 and hypoacetylation of H3K14 were observed in females from each treatment (enhanced diet, folate/vitamin B12 diet, and BPA diet), relative to controls. Selected tissues of control adults and larvae showed comparable H3K9 me1 patterns. In contrast, adults from the BPA treatment showed H3K9 hypomethylation of the gut, whereas BPA larval gut cells were monomethylated. Results indicate that 1) the environment does affect histone modifications, which could ultimately produce alternative phenotypes, 2) all three modifications varied with treatment in adult tissues, 3) and while tissues of P. cornuta appear to have similar H3K9 me1 patterns prior to and following metamorphosis, this modification in adults appeared sensitive to treatment (BPA). This suggests that histone modifications are a potential mechanism by which the environment can influence developmental plasticity and that larvae respond differently to these factors than do adults.
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