AUTHOR=Agwunobi Desmond Onyeka , Zhang Miao , Shi Xinyue , Zhang Shiqi , Zhang Meng , Wang Tongxuan , Masoudi Abolfazl , Yu Zhijun , Liu Jingze 

TITLE=DNA Methyltransferases Contribute to Cold Tolerance in Ticks Dermacentor silvarum and Haemaphysalis longicornis (Acari: Ixodidae)

JOURNAL=Frontiers in Veterinary Science

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2021.726731

DOI=10.3389/fvets.2021.726731

ISSN=2297-1769

ABSTRACT=<p>DNA methylation, mediated by DNA methyltransferases (Dnmts), is a typical epigenetic process that plays an important role in affecting organism acclimatization and adaptation to environmental changes. However, information about Dnmts and their associations with the cold tolerance of ticks remains meager. Hence, in the present study, the Dnmts in important vector ticks <italic>Dermacentor silvarum</italic> and <italic>Haemaphysalis longicornis</italic> were cloned and identified, and their functions in cold response were further explored. Results showed that the length of <italic>DsDnmt</italic> and <italic>DsDnmt1</italic> in <italic>D. silvarum</italic>, and <italic>HlDnmt1</italic> and <italic>HlDnmt</italic> in <italic>H. longicornis</italic> were 1,284, 549, 1,500, and 1,613 bp, respectively. Bioinformatics in protein analysis revealed that they were all unstable hydrophilic proteins and were mainly characterized with Dcm (DNA cytosine methyltransferase domain), Dnmt1-RFD (DNA methyltransferase replication foci domain), zf-CXXC (zinc finger-CXXC domain), and BAH (Bromo adjacent homology domain). The relative expression of these <italic>Dnmts</italic> was reduced after cold treatment for 3 days (<italic>P</italic> &lt; 0.05), and increased with the extension of treatment. Western blot revealed that Dnmt1 decreased first and then increased significantly (<italic>P</italic> &lt; 0.05) in both tick species, whereas other Dnmts fluctuated at varying degrees. RNA interference significantly silenced the genes <italic>Dnmts</italic> (<italic>P</italic> &lt; 0.01), and mortality increased significantly (<italic>P</italic> &lt; 0.05), when exposed to sub-lethal temperature, underscoring the important roles of Dnmts during the cold response of <italic>D. silvarum</italic> and <italic>H. longicornis</italic>. The above results lay the foundation for further understanding of the epigenetic regulation of DNA methylation in cold acclimatization and adaptation of ticks.</p>