日本研究人员在新一期英国《自然》杂志网络版上报告说，他们发现蜂王浆中的一种蛋白质是蜜蜂幼虫变身蜂王的秘密所在。
蜂群中的工蜂和蜂王都是雌性且基因相同，但蜂王的体长约是工蜂的1.5倍，而寿命更是工蜂的约20倍。此前的研究表明，能成长为蜂王的蜜蜂幼虫的食物是蜂王浆，而其他幼虫的食物只是花粉和蜂蜜。但是，蜂王浆中的何种成分促使幼虫变身蜂王，一直是个谜。
日本富山县立大学讲师镰仓昌树分别用新鲜的蜂王浆和已经存放了30天的蜂王浆喂养蜜蜂幼虫，结果只有食用新鲜蜂王浆的幼虫成长为蜂王。进一步研究发现，新鲜蜂王浆中一种叫做“royalactin”的蛋白质能促进生长激素的分泌量，使幼虫出现体格变大、卵巢发达等蜂王的特征。
镰仓昌树用这种蛋白质喂养果蝇，果蝇也同样出现体长、产卵数和寿命等方面的增长。这说明这一蛋白质对生物特征的影响是跨物种的。
一个蜂群只有一个蜂王，随着时间推移，蜂王生殖率下降而需要淘汰更换。这项成果有助于人工大量培养产卵能力强的蜂王，可望在养蜂业中发挥作用。
原文出处：
Nature doi:10.1038/nature10093
Royalactin induces queen differentiation in honeybees
Masaki Kamakura1
The honeybee (Apis mellifera) forms two female castes: the queen and the worker. This dimorphism depends not on genetic differences, but on ingestion of royal jelly, although the mechanism through which royal jelly regulates caste differentiation has long remained unknown. Here I show that a 57-kDa protein in royal jelly, previously designated as royalactin, induces the differentiation of honeybee larvae into queens. Royalactin increased body size and ovary development and shortened developmental time in honeybees. Surprisingly, it also showed similar effects in the fruitfly (Drosophila melanogaster). Mechanistic studies revealed that royalactin activated p70 S6 kinase, which was responsible for the increase of body size, increased the activity of mitogen-activated protein kinase, which was involved in the decreased developmental time, and increased the titre of juvenile hormone, an essential hormone for ovary development. Knockdown of epidermal growth factor receptor (Egfr) expression in the fat body of honeybees and fruitflies resulted in a defect of all phenotypesinduced by royalactin, showing that Egfr mediates these actions. These findings indicate that a specific factor in royal jelly, royalactin, drives queen development through an Egfr-mediated signalling pathway.
