CpG methylation in the hexamerin 110 gene in the European honeybee, Apis mellifera

Takashi Ikeda1a, Seiichi Furukawa1b, Jun Nakamura2c, Masami Sasaki1, 2d, and Tetsuhiko Sasaki1, 2e*

1Brain Science Institute, Tamagawa University, Tamagawagakuen, Machida, Tokyo 194-8610
2Honeybee Science Research Center, Research Institute, Tamagawa University, Tamagawagakuen, Machida, Tokyo 194-8610
3Section of Molecular Biology and Cell Engineering, Department of Regenerative Medicine, Research Institute, National Center for Global Health and Medicine, Shinjuku, Tokyo 162-8655
4Biosphere Resource Science and Technology, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba, Ibaraki 305-8572

Abstract

The European honeybee, Apis mellifera L. (Hymenoptera: Apidae), has a full set of machinery for functional CpG methylation of its genome. A recent study demonstrated that DNA methylation in the honeybee is involved in caste differentiation. In this study, the expression and methylation of the hexamerin 110 gene (Hex110), which encodes a storage protein, was analyzed. High levels of the Hex110 transcript were expressed in both worker and queen larvae. Low levels of this transcript were also detected in adult fat bodies, and the expression level was higher in the queen than in the worker. Bisulfite sequencing revealed that the Hex110 gene is overall methylated at a low level, with a limited number of CpG sites methylated at relatively high levels. These highly methylated sites were exclusively located in the exon regions. The average methylation rate of the Hex110 gene was higher in the adult stage than in the larval stage. Furthermore, several CpG sites were differentially methylated between the worker and queen larvae. These observations suggest that the methylation of the Hex110 gene is regulated at the developmental stage and in a caste-dependent manner.

Keywords: bisulfite sequencing, caste differentiation, epigenetics, Hex110

Abbreviations: cds, coding sequence; Hex110, hexamerin 110; RACE, Rapid amplification of cDNA ends; RTPCR, reverse transcription-PCR; UTR, untranslated region

Correspondence: a tikeda6@yahoo.co.jp, b furukawa@agr.tamagawa.ac.jp, c njun@agr.tamagawa.ac.jp, d sasaki@agr.tamagawa.ac.jp, e* tsasaki@lab.tamagawa.ac.jp, *Corresponding author

Editor: Robert Jeanne was Editor of this paper

Received: 9 April 2010 | Accepted: 24 October 2010 | Published: 29 June 2011

ISSN: 1536-2442 | Volume 11, Number 74

Ikeda T, Furukawa S, Nakamura J, Sasaki M, Sasaki T. 2011. CpG methylation in the hexamerin 110 gene in the European honeybee, Apis mellifera. Journal of Insect Science 11:74 available online: insectscience.org/11.74


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