Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-Ku, Tokyo, 113-0033, Japan.
Laboratory of Entomology, Graduate School of Agriculture, Tamagawa University, Machida-Shi, Tokyo, 194-8610, Japan.
Sci Rep. 2020 May 12;10(1):7887. doi: 10.1038/s41598-020-64701-1.
Honey bees and bumble bees belong to the same family (Apidae) and their workers exhibit a division of labor, but the style of division of labor differs between species. The molecular and neural bases of the species-specific social behaviors of Apidae workers have not been analyzed. Here, we focused on two immediate early genes, hormone receptor 38 (HR38) and early growth response gene-1 (Egr1), and late-upregulated ecdysone receptor (EcR), all of which are upregulated by foraging flight and expressed preferentially in the small-type Kenyon cells of the mushroom bodies (MBs) in the honey bee brain. Gene expression analyses in Bombus ignitus revealed that HR38 and Egr1, but not EcR, exhibited an immediate early response during awakening from CO anesthesia. Both premature mRNA for HR38 and mature mRNA for Egr1 were induced during foraging flight, and mRNAs for HR38 and Egr1 were sparsely detected inside the whole MB calyces. In contrast, EcR expression was higher in forager brains than in nurse bees and was expressed preferentially in the small-type Kenyon cells inside the MBs. Our findings suggest that Kenyon cells are active during foraging flight and that the function of late-upregulated EcR in the brain is conserved among these Apidae species.
蜜蜂和熊蜂同属于蜂科（Apidae），其工蜂具有明显的分工行为，但不同物种的分工方式存在差异。蜂科工蜂的特定物种社会行为的分子和神经基础尚未得到分析。在这里，我们重点研究了两种即刻早期基因，即激素受体 38（HR38）和早期生长反应基因-1（Egr1），以及晚期上调的蜕皮激素受体（EcR），这些基因都受觅食飞行诱导，并且在蜜蜂大脑的蘑菇体（MB）的小细胞型 Kenyon 细胞中优先表达。在红火蚁（Bombus ignitus）中的基因表达分析表明，HR38 和 Egr1 而不是 EcR 在从 CO 麻醉中苏醒时表现出即刻早期反应。HR38 的过早 mRNA 和 Egr1 的成熟 mRNA 都在觅食飞行期间被诱导，并且 HR38 和 Egr1 的 mRNA 在整个 MB 帽中稀疏地检测到。相比之下，EcR 在觅食蜂脑中的表达高于护理蜂，并且在 MB 中的小细胞型 Kenyon 细胞中优先表达。我们的发现表明，Kenyon 细胞在觅食飞行期间是活跃的，并且大脑中晚期上调的 EcR 的功能在这些 Apidae 物种中是保守的。
