Sucrose represents an important carbohydrate source for most bee species. In the Western honeybee (Apis mellifera) it was shown that individual sucrose responsiveness correlates with the task performed in the colony, supporting the response threshold theory which states that individuals with the lowest threshold for a task-associated stimuli will perform the associated task. Tyramine was shown to modulate sucrose responsiveness, most likely via the tyramine 1 receptor. This receptor is located in brain areas important for the processing of gustatory stimuli. We asked whether the spatial expression pattern of the tyramine 1 receptor is a unique adaptation of honeybees or if its expression represents a conserved trait. Using a specific tyramine receptor 1 antibody, we compared the spatial expression of this receptor in the brain of different corbiculate bee species, including eusocial honeybees, bumblebees, stingless bees, and the solitary bee Osmia bicornis as an outgroup. We found a similar labeling pattern in the mushroom bodies, the central complex, the dorsal lobe, and the gnathal ganglia, indicating a conserved receptor expression. With respect to sucrose responsiveness this result is of special importance. We assume that the tyramine 1 receptor expression in these neuropiles provides the basis for modulation of sucrose responsiveness. Furthermore, the tyramine 1 receptor expression seems to be independent of size, as labeling is similar in bee species that differ greatly in their body size. However, the situation in the optic lobes appears to be different. Here, the lobula of stingless bees is clearly labeled by the tyramine receptor 1 antibody, whereas this labeling is absent in other species. This indicates that the regulation of this receptor is different in the optic lobes, while its function in this neuropile remains unclear.
Brain Behav Evol

中文翻译：

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Corbiculate 蜜蜂大脑中酪胺 1 受体的分布指向一个保守的功能

蔗糖是大多数蜜蜂物种的重要碳水化合物来源。在西方蜜蜂（Apis mellifera) 表明个体蔗糖反应性与菌落中执行的任务相关，支持反应阈值理论，该理论指出，对于与任务相关的刺激具有最低阈值的个体将执行相关任务。酪胺显示调节蔗糖反应性，最有可能通过酪胺 1 受体。该受体位于对味觉刺激处理很重要的大脑区域。我们询问酪胺 1 受体的空间表达模式是否是蜜蜂的一种独特适应性，或者它的表达是否代表了一种保守性状。使用特定的酪胺受体 1 抗体，我们比较了这种受体在不同种类蜜蜂的大脑中的空间表达，包括真社会蜜蜂、大黄蜂、无刺蜜蜂和独居蜜蜂双角锇作为外群。我们在蘑菇体、中央复合体、背叶和下颌神经节中发现了类似的标记模式，表明受体表达保守。关于蔗糖反应性，这个结果是特别重要的。我们假设这些神经桩中酪胺 1 受体的表达为调节蔗糖反应性提供了基础。此外，酪胺 1 受体表达似乎与大小无关，因为在体型差异很大的蜜蜂物种中标记是相似的。然而，视叶的情况似乎有所不同。在这里，无刺蜜蜂的小叶清楚地被酪胺受体 1 抗体标记，而这种标记在其他物种中不存在。这表明该受体的调节在视叶中是不同的，
大脑行为进化