Cardoso-Júnior Carlos A M, Fujimura Patrícia Tieme, Santos-Júnior Célio Dias, Borges Naiara Araújo, Ueira-Vieira Carlos, Hartfelder Klaus, Goulart Luiz Ricardo, Bonetti Ana Maria
Departamento de Genética e Bioquímica, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil.
Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
Genet Mol Biol. 2017 Jan-Mar;40(1):61-68. doi: 10.1590/1678-4685-GMB-2016-0242. Epub 2017 Mar 2.
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.
无刺蜂属的无刺蜂，长期以来因其种型决定模式而被视为社会性昆虫中的一个神秘案例，50多年前沃里克·E·克尔就提出，除了幼虫食物的类型和数量外，基因型也有影响。此后，人们多次尝试检验他的孟德尔双基因座/双等位基因分离假说，但直到最近，才证实蜜蜂性别决定的一个关键基因在无刺蜂的一个物种中存在性别特异性剪接，并且在种型上也有特异性表达。由于可变剪接常常与表观遗传标记相关联，且表观遗传状态在蜜蜂种型表型的形成中起主要作用，因此我们在此研究了无刺蜂盾无刺蜂的表观遗传染色质修饰。我们采用基于酶联免疫吸附测定的方法来量化整体甲基化状态，并通过蛋白质印迹分析来揭示组蛋白修饰。结果证明了幼虫和蛹中存在DNA甲基化/去甲基化事件，且新羽化的成年蜂王和工蜂之间在组蛋白甲基化和磷酸化方面存在显著差异。在这种无刺蜂物种中观察到的表观遗传动态代表了无刺蜂种型决定过程中的一个新方面，并提示了一种可能的机制，该机制可能将基因型成分与这些蜜蜂的幼虫饮食及成年社会行为联系起来。
