Analysis of DNA methylation in tissues and development stages of pearl oyster Pinctada fucata

In this study, we developed a methylation-sensitive amplification polymorphism technique to investigate DNA methylation profiles in different tissues and in the early-development stages of the pearl oyster Pinctada fucata (P. fucata). Methylation levels in adductor muscle, digestive gland, axe foot, heart, and gill ranged from 11.71 to 14.71 %, and significant differences (P < 0.05) between methylation levels in different tissues were observed. The DNA methylation levels of sperm, egg cells, two-cell embryos, morula embryos, trochophore larvae and D-shaped larvae were 13.51, 11.80, 12.14, 12.60, 14.65 and 13.18 %, respectively. Development stages of two-cell embryos, morula embryos, trochophore larvae and D-shaped larvae indicated a higher number of identical DNA methylation status loci in the egg, compared to that in the sperm. It is probable that DNA methylation patterns of the progeny are mainly influenced by the egg, while the sperm may become increasingly important during the process of early embryo development. The observed differences in methylation levels in the tissues and the development stages of P. fucata suggest that DNA methylation may act as an epigenetic regulator during tissue differentiation, individual growth, and development.