Meeting Abstract
Parental environment plays a significant role in influencing offspring phenotype through epigenetic modifications. We tested two hypotheses: that methionine in the parental environment induces plasticity in offspring phenotype in the polychaete Polydora cornuta, and that methionine alters DNA methylation in spawning females. Methionine was tested as it is essential in the DNA methylation process and because it is considered limited in the diets of marine detritivores. Adults were cultured in seawater (controls) or at three concentrations (10-5, 10-7, 10-9M) of methionine. Control broods had the typical pattern of developmental plasticity and produced three morphs of offspring in equal proportions (i.e., small larvae, mid-sized larvae, and large juveniles). Parental exposure to methionine altered larval phenotype with the highest exposure (10-5M) increasing the production of small larvae, and the lowest exposure (10-9M) producing a range of larval morphs similar to controls. Differences in maternal methylation were demonstrated through total genome digestion with methyl-sensitive isoschizomers (HpaII, MspI), generating DNA smears with gel electrophoresis, and analyzing intensity plots with Image J. Exposure of females to all three concentrations of methionine significantly reduced DNA methylation relative to the controls. These results indicate that developmental plasticity in P. cornuta is epigenetic and is influenced by a potentially limiting nutrient (methionine) in the parental environment.
