Expression and function analysis of epigenetics-related genes during soldier differentiation in Zootermopsis nevadensis
Ryutaro Suzuki, Hajime Yaguchi , Kiyoto Maekawa
Graduate School of Science and Engineering, University of Toyama, Japan; Tropical Biosphere Research Center, University of the Ryukyus, Japan ; Graduate School of Science and Engineering, University of Toyama, Japan
Caste differentiation of eusocial insects is a great example of phenotypic plasticity. Recent studies indicate that epigenetic regulation, including DNA methylation and histone modification, affect morphological and behavioral polyphenism observed in caste differentiation of hymenopteran insects. A role of epigenetic regulation for termite caste differentiation, however, is still a mystery. Caste differentiation of termites, especially soldier differentiation, is usually associated with huge morphological changes. In this study, we performed expression and function analysis of epigenetics-related genes during soldier differentiation in Zootermopsis nevadensis, for which whole-genome sequence is available. In an incipient colony of this species, the first larva to become a 3rd instar (No. 1 larva) is certainly differentiated into a presoldier (intermediate stage of soldier), and the second larva to become a 3rd instar (No. 2 larva) molts into a 4th instar (function as worker). First, we conducted RNA-seq analysis between the No. 1 and No. 2 larvae, and detected eight epigenetic-related genes with significantly highly expression levels in the former. Then, function analysis of these eight genes was performed in the No. 1 larva. RNA interference of several genes involved in histone modification negatively affected on the presoldier molting period and infrequently presoldier specific morphogenesis. These results suggest that a histone modification is an important molecular regulator for the presoldier molting event and soldier formation in termites.