LAUSR

For the purpose of studying the epigenetic characteristics of the mitochondrial genome of the ridgetail white prawn, Exopalaemon carinicauda (Holthuis, 1950) under Cd2+ and Cr6+ heavy metal stress, the mitochondrial DNA methylation of E. carinicauda was analysed by bisulfite sequencing PCR (BSP). Many methylation sites were found at the 3′ end sequence of COX3 and at the starting region sequence of ND3, while only a few methylation sites were found at the 3′ end sequence of ND5. The mitochondrial genome was inferred to regulate the energy metabolism through the methylation process. In addition, under Cd2+ stress, mitochondrial DNA methylation was more common, and found during all stress periods (3, 6, 12, 24, 48, 72 and 96 h), while under Cr6+ stress, mitochondrial DNA methylation was less common, mainly occurring after 48 hours of stress. The sensitivity of the mitochondrial genome response to Cd2+ stress was inferred to be greater than that to Cr6+. This study revealed for the first time that methylation occurs in the mitochondrial genome of E. carinicauda in response to heavy metal stress.