Effects of temperature on global DNA methylation during early development in European sea bass

Abstract

Persistent epigenetic marks arise from early developmental environments and correlate with relevant biological processes later in life. Fish represent effective animal models for the purposes of studying these epigenetic marks, such as DNA methylation. Recently, we showed that adult European sea bass (Dicentrarchus labrax) exposed to high temperature during early development show higher levels of gonadal aromatase promoter DNA methylation than fish raised in natural temperature (Navarro-Martín et al. 2011. PLoS Genetics 7(12): e1002447). However, the effect of different temperatures and the sensitivity of distinct early developmental stages of the larvae remain unclear. In the present study, global DNA methylation patterns were measured by a modification of the Amplified Fragment Length Polymorphism (AFLP) technique called Methylation-Sensitive AFLP (MSAP), which allows the comparison of genome-wide DNA methylation profiles between treatments. Two types of comparisons by MSAP were studied in European sea bass sampled 15 days post fertilization: (1) three groups of larvae that were exposed to low (13.5oC), medium (17.5oC) or high (19.5oC) temperature, and (2) four groups of larvae that either were exposed to constant temperature (low or high) or that experienced a switch in temperature 5 days post fertilization, from low to high or vice versa. In the first comparison, significant differences in global DNA methylation patterns were detected among the temperature groups. In the second comparison, there was significant differentiation in DNA methylation between the four groups, as well as between groups compared pairwise. The differentiation was bigger between larvae which experienced constant temperature during their lifetime and larvae which experienced a switch of temperature at 5 days post fertilization. Together, these results reveal that temperature changes from 0–15 days post fertilization strongly affect the methylome of the European sea bass