Department of Behavioral Physiology and Sociobiology, Biozentrum, University of Würzburg, Würzburg, Germany.
Dev Neurobiol. 2010 Mar;70(4):222-34. doi: 10.1002/dneu.20782.
In the leaf-cutting ant Atta vollenweideri, the worker caste exhibits a pronounced size-polymorphism, and division of labor is dependent on worker size (alloethism). Behavior is largely guided by olfaction, and the olfactory system is highly developed. In a recent study, two different phenotypes of the antennal lobe of Atta vollenweideri workers were found: MG- and RG-phenotype (with/without a macroglomerulus). Here we ask whether the glomerular numbers are related to worker size. We found that the antennal lobes of small workers contain approximately 390 glomeruli (low-number; LN-phenotype), and in large workers we found a substantially higher number of approximately 440 glomeruli (high-number; HN-phenotype). All LN-phenotype workers and some small HN-phenotype workers do not possess an MG (LN-RG-phenotype and HN-RG-phenotype), and the remaining majority of HN-phenotype workers do possess an MG (HN-MG-phenotype). Using mass-staining of antennal olfactory receptor neurons we found that the sensory tracts divide the antennal lobe into six clusters of glomeruli (T1-T6). In LN-phenotype workers, approximately 50 glomeruli are missing in the T4-cluster. Selective staining of single sensilla and their associated receptor neurons revealed that T4-glomeruli are innervated by receptor neurons from the main type of olfactory sensilla, the Sensilla trichodea curvata. The other type of olfactory sensilla (Sensilla basiconica) exclusively innervates T6-glomeruli. Quantitative analyses of differently sized workers revealed that the volume of T6 glomeruli scales with the power of 2.54 to the number of Sensilla basiconica. The results suggest that developmental plasticity leading to antennal-lobe phenotypes promotes differences in olfactory-guided behavior and may underlie task specialization within ant colonies.
在切叶蚁 Atta vollenweideri 中，工蚁表现出明显的体型多态性，并且分工依赖于工蚁的体型（异质社会性）。行为主要受嗅觉引导，并且嗅觉系统高度发达。在最近的一项研究中，发现 Atta vollenweideri 工蚁的触角叶有两种不同的表型：MG-和 RG-表型（有/无巨肾小球）。在这里，我们探讨了肾小球数量是否与工蚁的体型有关。我们发现，小工蚁的触角叶大约包含 390 个肾小球（低数量；LN 表型），而在大工蚁中，我们发现了数量显著更高的大约 440 个肾小球（高数量；HN 表型）。所有 LN 表型的工蚁和一些小 HN 表型的工蚁都没有 MG（LN-RG 表型和 HN-RG 表型），而剩下的 HN 表型的工蚁中大多数都有 MG（HN-MG 表型）。使用触角嗅觉受体神经元的大规模染色，我们发现感觉束将触角叶分为六个肾小球簇（T1-T6）。在 LN 表型的工蚁中，T4 簇大约缺失了 50 个肾小球。对单个感觉毛及其相关的受体神经元的选择性染色表明，T4 肾小球由主型嗅觉感觉毛（Sensilla trichodea curvata）的受体神经元支配。另一种嗅觉感觉毛（Sensilla basiconica）则专门支配 T6 肾小球。对不同体型工蚁的定量分析表明，T6 肾小球的体积与 Sensilla basiconica 的数量的 2.54 次方成正比。结果表明，导致触角叶表型的发育可塑性促进了嗅觉引导行为的差异，并可能为蚁群内的任务专业化提供了基础。
