Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, China.
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Gene. 2021 Feb 5;768:145331. doi: 10.1016/j.gene.2020.145331. Epub 2020 Dec 3.
Marine invasive species are constantly challenged by acute or recurring environmental stresses during their range expansions. DNA methylation-mediated stress memory has been proposed to effectively affect species' response and enhance their overall performance in recurring environmental challenges. In order to further test this proposal in marine invasive species, we identified genes in the DNA methylation and demethylation processes in the highly invasive model species, Ciona robusta, and subsequently investigated the expression patterns of these genes under recurring salinity stresses. After a genome-wide comprehensive survey, we found a total of six genes, including two genes of DNA methyltransferase 3a (DNMT3a1 and DNMT3a2), and one gene of DNA methyltransferase 1 (DNMT1), methyl-CpG-binding domain protein 2 (MBD2), methyl-CpG-binding domain protein 4 (MBD4) and ten-eleven-translocation protein 1 (TET1). Phylogenetic reconstruction and domain arrangement analyses showed that the deduced proteins of the identified genes were evolutionarily conserved and functionally similar with their orthologs. All genes were constitutively expressed in all four tested tissues. Interestingly, we found time-dependent and stress-specific gene expression patterns under high and low salinity stresses. Under the recurring high salinity stresses, DNMT3a1 and TET1 conformed to the definition of memory genes, while under the recurring low salinity stresses, two DNMT3a paralogues were identified as the memory genes. Altogether, our results clearly showed that the transcriptional patterns of (de)methylation-related genes were significantly influenced by environmental stresses, and the transcriptional memory of some (de)methylation-related genes should play crucial roles in DNA methylation-mediated stress memory during the process of biological invasions.
海洋入侵物种在其分布扩张过程中不断受到急性或反复环境压力的挑战。已提出 DNA 甲基化介导的应激记忆可有效影响物种的反应，并增强其在反复环境挑战中的整体表现。为了在海洋入侵物种中进一步检验这一假说，我们鉴定了高度入侵模式物种海鞘中的 DNA 甲基化和去甲基化过程中的基因，随后研究了这些基因在反复盐度胁迫下的表达模式。经过全基因组综合调查，我们发现了总共 6 个基因，包括 2 个 DNA 甲基转移酶 3a（DNMT3a1 和 DNMT3a2）基因和 1 个 DNA 甲基转移酶 1（DNMT1）基因、甲基-CpG 结合域蛋白 2（MBD2）、甲基-CpG 结合域蛋白 4（MBD4）和十号十一转位蛋白 1（TET1）基因。系统发育重建和结构域排列分析表明，鉴定基因的推导蛋白在进化上是保守的，与它们的同源物在功能上相似。所有基因在所有四个测试组织中均持续表达。有趣的是，我们发现高盐度和低盐度胁迫下存在时间依赖性和应激特异性的基因表达模式。在反复的高盐胁迫下，DNMT3a1 和 TET1 符合记忆基因的定义，而在反复的低盐胁迫下，两个 DNMT3a 同源物被鉴定为记忆基因。总之，我们的研究结果清楚地表明，（去）甲基化相关基因的转录模式受到环境胁迫的显著影响，一些（去）甲基化相关基因的转录记忆在生物入侵过程中 DNA 甲基化介导的应激记忆中可能起着关键作用。
