Metabolic Enzymes in Glial Cells of the Honeybee Brain and Their Associations with Aging, Starvation and Food Response, 2017

The honey bee has been extensively studied as a model for neuronal circuit and memory function and more recently has emerged as an unconventional model in biogerontology. Yet, the detailed knowledge of neuronal processing in the honey bee brain contrasts with the very sparse information available on glial cells. In other systems glial cells are involved in nutritional homeostasis, detoxification, and aging. These glial functions have been linked to metabolic enzymes, such as glutamine synthetase and glycogen phosphorylase. As a step in identifying functional roles and potential differences among honey bee glial types, this project examined the spatial distribution of these enzymes and asked if enzyme abundance is associated with aging and other processes essential for survival. Using immunohistochemistry and confocal laser microscopy we demonstrate that glutamine synthetase and glycogen phosphorylase are abundant in glia but appear to co-localize with different glial sub-types. The overall spatial distribution of both enzymes was not homogenous and differed markedly between different neuropiles and also within each neuropil. Using semi-quantitative Western blotting it was found that rapid aging, typically observed in shortest-lived worker bees (foragers), was associated with declining enzyme levels. Further, enzyme abundance changes after severe starvation stress, and glutamine synthetase is associated with food response. Together, the data indicate that aging and nutritional physiology in bees are linked to glial specific metabolic enzymes. Enzyme specific localization patterns suggest a functional differentiation among identified glial types.

The data material consists of four files. The spreadsheat data allows to identify for each blot and lane the experiment/treatment.
- Experiment Starvation with ST=starved and SA=satiated for Fig. 4
- Experiment gustatory responsiveness/GRS with L=low and H=high responders for Fig. 5
- Experiment Aging with OF=old and YF=young foragers for Fig. 6

Data are freely available for downloading.

蜜蜂作为神经回路（neuronal circuit）和记忆功能的模型已被广泛研究，最近更成为生物老年学（biogerontology）领域的非常规模型。然而，蜜蜂大脑中神经处理的详细知识与神经胶质细胞（glial cells）相关的极少信息形成鲜明对比。在其他系统中，神经胶质细胞参与营养稳态（nutritional homeostasis）、解毒（detoxification）和衰老过程，这些功能与谷氨酰胺合成酶（glutamine synthetase）和糖原磷酸化酶（glycogen phosphorylase）等代谢酶相关。作为确定蜜蜂胶质细胞类型功能角色及潜在差异的一步，本项目研究了这些酶的空间分布，并探究酶丰度是否与衰老及其他生存必需过程相关。通过免疫组化（immunohistochemistry）和共聚焦激光显微镜（confocal laser microscopy），我们发现谷氨酰胺合成酶和糖原磷酸化酶在胶质细胞中含量丰富，但似乎与不同的胶质细胞亚型共定位（co-localize）。两种酶的整体空间分布并不均一，在不同神经纤维网（neuropiles）之间及每个神经纤维网内部均存在显著差异。通过半定量蛋白质印迹法（semi-quantitative Western blotting）发现，快速衰老——通常见于寿命最短的工蜂（觅食者，foragers）——与酶水平下降相关。此外，严重饥饿应激（starvation stress）后酶丰度发生变化，且谷氨酰胺合成酶与食物反应相关。综上，数据表明蜜蜂的衰老和营养生理与胶质细胞特异性代谢酶相关，酶的特异性定位模式提示已鉴定的胶质细胞类型间存在功能分化。

数据材料包含四个文件。电子表格数据可用于识别每个印迹（blot）和泳道（lane）对应的实验/处理：
- 饥饿实验：ST=饥饿（starved），SA=饱食（satiated），对应图4
- 味觉反应性实验（GRS，gustatory responsiveness）：L=低反应者，H=高反应者，对应图5
- 衰老实验：OF=老年觅食者，YF=年轻觅食者，对应图6

数据可免费下载。