Honeybees rely on nectar as their main source of carbohydrates. Sucrose, glucose, and fructose are the main components of plant nectars. Intriguingly, honeybees express only 3 putative sugar receptors (AmGr1, AmGr2, and AmGr3), which is in stark contrast to many other insects and vertebrates. The sugar receptors are only partially characterized. AmGr1 detects different sugars including sucrose and glucose. AmGr2 is assumed to act as a co-receptor only, while AmGr3 is assumedly a fructose receptor. We show that honeybee gustatory receptor AmGr3 is highly specialized for fructose perception when expressed in Xenopus oocytes. When we introduced nonsense mutations to the respective AmGr3 gene using CRISPR/Cas9 in eggs of female workers, the resulting mutants displayed almost a complete loss of responsiveness to fructose. In contrast, responses to sucrose were normal. Nonsense mutations introduced by CRISPR/Cas9 in honeybees can thus induce a measurable behavioral change and serve to characterize the function of taste receptors in vivo. CRISPR/Cas9 is an excellent novel tool for characterizing honeybee taste receptors in vivo. Biophysical receptor characterization in Xenopus oocytes and nonsense mutation of AmGr3 in honeybees unequivocally demonstrate that this receptor is highly specific for fructose.

中文翻译：

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CRISPR / Cas 9介导的突变是研究蜜蜂味道的新工具。

蜜蜂依靠花蜜作为碳水化合物的主要来源。蔗糖，葡萄糖和果糖是植物花蜜的主要成分。有趣的是，蜜蜂仅表达3种假定的糖受体（AmGr1，AmGr2和AmGr3），这与许多其他昆虫和脊椎动物形成了鲜明的对比。糖受体仅被部分表征。AmGr1可检测包括蔗糖和葡萄糖在内的各种糖。假定AmGr2仅充当辅助受体，而假定AmGr3被认为是果糖受体。我们表明蜜蜂味觉受体AmGr3是高度专门用于果糖感知时在非洲爪蟾卵母细胞中表达的。当我们将无意义的突变引入各自的AmGr3时在女性工人的卵中使用CRISPR / Cas9基因，产生的突变体几乎完全丧失了对果糖的反应能力。相反，对蔗糖的反应是正常的。CRISPR / Cas9在蜜蜂中引入的无意义突变可以引起可测量的行为变化，并表征体内味觉受体的功能。CRISPR / Cas9是表征蜜蜂体内味觉受体的优秀新工具。爪蟾卵母细胞的生物物理受体特性和蜜蜂中AmGr3的无义突变明确表明，该受体对果糖具有高度特异性。