Epigenetic modifications and their relation to caste and sex determination and adult division of labor in the stingless bee Melipona scutellaris

Abstract

Stingless bees of the genus Melipona, have long been considered an enigmatic case among social insects for their mode of caste determination, where in addition to larval food type and quantity, the genotype also has a saying, as proposed over 50 years ago by Warwick E. Kerr. Several attempts have since tried to test his Mendelian two-loci/two-alleles segregation hypothesis, but only recently a single gene crucial for sex determination in bees was evidenced to be sex-specifically spliced and also caste-specifically expressed in a Melipona species. Since alternative splicing is frequently associated with epigenetic marks, and the epigenetic status plays a major role in setting the caste phenotype in the honey bee, we investigated here epigenetic chromatin modification in the stingless bee Melipona scutellaris. We used an ELISA-based methodology to quantify global methylation status and western blot assays to reveal histone modifications. The results evidenced DNA methylation/demethylation events in larvae and pupae, and significant differences in histone methylation and phosphorylation between newly emerged adult queens and workers. The epigenetic dynamics seen in this stingless bee species represent a new facet in the caste determination process in Melipona bees and suggest a possible mechanism that is likely to link a genotype component to the larval diet and adult social behavior of these bees.

Social context influences the expression of DNA methyltransferase genes in the honeybee

“…On the same day (5), dnmt3 expression also exhibited a peak in this group (with young adults). Interestingly, variation in dnmt3 expression, a de novo DNA methyltransferase, was shown to affect aging and alternative splicing in honeybee workers 29 , 31 , thus suggesting that fluctuations in dnmt3 transcript levels may represent a molecular signature of behavioral maturation through mRNA regulation. Therefore, it is possible that the expression of all three DNMTs encoding genes studied here is sensitive to external stimuli, especially early in a worker’s adult life.…”

DNMT1 Promotes Genome Methylation and Early Embryo Development in Cockroaches

“…This, along with a comparative analysis between hemimetabolan and holometabolan insects, led us ( Ylla et al., 2018 ) to hypothesize that DNA methylation could be instrumental in the type of embryo development, and the mode of metamorphosis. Many roles have been associated with DNA methylation in insects, including phenotypic plasticity and caste determination ( Bonasio et al., 2012 ; Glastad et al., 2016 ; Robinson et al., 2016 ; Cardoso-Júnior et al., 2017 ; Li et al., 2018 ), alternative splicing ( Bonasio et al., 2012 ; Glastad et al., 2014 , 2016 ), and reproduction ( Schulz et al., 2018 ; Bewick et al., 2019 ). However, there are few functional studies on the role of DNA methylation during early embryo development ( Schulz et al., 2018 ; Bewick et al., 2019 ), despite this being the period when de novo DNA methylation is expected to occur ( He et al., 2011 ).…”

Queen pheromone modulates the expression of epigenetic modifier genes in the brain of honeybee workers

“…food, pheromones) in honey bees and other social insects (Simola et al . 2013, 2016; Cardoso-Júnior et al . 2017).…”