School of Life Sciences, Arizona State University, Tempe, AZ, USA.
J Exp Biol. 2011 Dec 1;214(Pt 23):3977-84. doi: 10.1242/jeb.061499.
Regardless of genetic makeup, a female honey bee becomes a queen or worker depending on the food she receives as a larva. For decades, it has been known that nutrition and juvenile hormone (JH) signaling determine the caste fate of the individual bee. However, it is still largely unclear how these factors are connected. To address this question, we suppressed nutrient sensing by RNA interference (RNAi)-mediated gene knockdown of IRS (insulin receptor substrate) and TOR (target of rapamycin) in larvae reared on queen diet. The treatments affected several layers of organismal organization that could play a role in the response to differential nutrition between castes. These include transcript profiles, proteomic patterns, lipid levels, DNA methylation response and morphological features. Most importantly, gene knockdown abolished a JH peak that signals queen development and resulted in a worker phenotype. Application of JH rescued the queen phenotype in either knockdown, which demonstrates that the larval response to JH remains intact and can drive normal developmental plasticity even when IRS or TOR transcript levels are reduced. We discuss our results in the context of other recent findings on honey bee caste and development and propose that IRS is an alternative substrate for the Egfr (epidermal growth factor receptor) in honey bees. Overall, our study describes how the interplay of nutritional and hormonal signals affects many levels of organismal organization to build different phenotypes from identical genotypes.
无论遗传组成如何，雌性蜜蜂都会根据其幼虫期所接受的食物成为蜂王或工蜂。几十年来，人们已经知道营养和保幼激素 (JH) 信号决定了个体蜜蜂的蜂群命运。然而，这些因素如何联系在一起在很大程度上仍不清楚。为了解决这个问题，我们通过 RNA 干扰 (RNAi) 介导的 IRS（胰岛素受体底物）和 TOR（雷帕霉素的靶标）基因敲低来抑制幼虫在蜂王饮食中接受的营养感应。这些处理影响了几个可能在不同蜂群之间的营养差异反应中起作用的生物体组织层次。这些包括转录谱、蛋白质组模式、脂质水平、DNA 甲基化反应和形态特征。最重要的是，基因敲低消除了一个标志蜂王发育的 JH 峰，导致工蜂表型。JH 的应用挽救了任何敲低中的蜂王表型，这表明幼虫对 JH 的反应仍然完整，即使 IRS 或 TOR 转录水平降低，也可以驱动正常的发育可塑性。我们在其他关于蜜蜂蜂群和发育的最新发现的背景下讨论了我们的结果，并提出 IRS 是蜜蜂中 Egfr（表皮生长因子受体）的替代底物。总的来说，我们的研究描述了营养和激素信号的相互作用如何影响生物体组织的许多层次，从而从相同的基因型构建不同的表型。
