Valk Sophie, Engelsma Marc, Megens Hendrik-Jan, Kamermans Pauline, Murk Albertinka J, Nijland Reindert
Marine Animal Ecology, Wageningen University and Research, Wageningen, 6700 AH, the Netherlands.
Wageningen Bioveterinary Research, Wageningen University and Research, Lelystad, 8200 AB, the Netherlands.
BMC Genomics. 2025 Jun 6;26(1):567. doi: 10.1186/s12864-025-11736-1.
European flat oysters (Ostrea edulis) are sequential hermaphrodites that alternate sex in response to environmental change. Epigenetics, including DNA methylation, are often involved in sex reversal through influencing gene transcription. Knowledge on the epigenetic mechanisms underlying sex reversal in hermaphrodite bivalves is limited to gonadal tissue and previous studies have only compared DNA methylomes of males and females. Therefore, the aim of this study is to assess whether sex-specific DNA methylation can be identified in somatic gill tissue of the flat oyster.
By comparing whole-genome methylomes of 35 oysters of different sex phenotypes using nanopore sequencing, we demonstrate the presence of sex-specific DNA methylation patterns in somatic gill tissue. A total of 9,654 regions and 2,576 genes were differentially methylated between male, female, and hermaphrodite oysters. Functional analysis of differentially methylated genes indicated an association with energy homeostasis and metabolic processes, implying a remodeling of the energy balance.
This study is the first to characterize DNA methylomes of hermaphrodite oysters, providing new insights into the epigenetic mechanisms underlying sex reversal in a sequential hermaphrodite invertebrate. Additionally, this study characterizes sex-specific DNA methylation in somatic gill tissue, paving the way for non-lethal sex identification using epigenetic biomarkers.
欧洲扁蛎（Ostrea edulis）是顺序性雌雄同体生物，会根据环境变化改变性别。表观遗传学，包括DNA甲基化，常常通过影响基因转录参与性别逆转过程。关于雌雄同体双壳贝类性别逆转的表观遗传机制的知识仅限于性腺组织，并且之前的研究仅比较了雄性和雌性的DNA甲基化组。因此，本研究的目的是评估在扁蛎的体鳃组织中是否能鉴定出性别特异性的DNA甲基化。
通过使用纳米孔测序比较35个不同性别表型的牡蛎的全基因组甲基化组，我们证明了在体鳃组织中存在性别特异性的DNA甲基化模式。在雄性、雌性和雌雄同体牡蛎之间共有9654个区域和2576个基因存在差异甲基化。对差异甲基化基因的功能分析表明其与能量稳态和代谢过程相关，这意味着能量平衡的重塑。
本研究首次对雌雄同体牡蛎的DNA甲基化组进行了表征，为顺序性雌雄同体无脊椎动物性别逆转的表观遗传机制提供了新的见解。此外，本研究对体鳃组织中的性别特异性DNA甲基化进行了表征，为使用表观遗传生物标志物进行非致死性性别鉴定铺平了道路。
