Chemical Architecture of Arthropod Neuromuscular Junctions as Phylogenetic Characters

今天的生物体通过其蛋白质的氨基酸序列和核酸的组成来保留关于其过去的信息。因此，现代系统学现在主要基于DNA序列分析和比较。然而，严重缺乏其他具有系统发育意义的非分子特征，这些特征可用于确认或调整基于分子的遗传学，并有助于澄清任何不一致之处。由于细胞通信是重要的器官功能，系统发育分析的信息分子的分布可以提供这样一组独立的字符，可能有助于获得更多的见解进化史。在整个动物界，许多不同的物种使用乙酰胆碱作为骨骼肌神经肌肉接头的神经递质。与此相反，谷氨酸似乎是在一些节肢动物的神经肌肉突触兴奋性递质。该项目将测试的假设，在节肢动物门兴奋性运动神经元的骨骼肌是专门的martamatergic。使用电生理学以及细胞化学和免疫染色技术，我们将研究这一功能是否是真节肢动物或潜在的泛节肢动物（真节肢动物，Onychophora，缓步动物）的突触。外周抑制GABA能运动神经元广泛分布在无脊椎动物，但它似乎是在几个群体失踪。为了研究细胞特异性化学标记是否可以用作系统群的特征，该项目将联合收割机结合胆碱能、GABA能和谷氨酸能标记与节肢动物和选定外群物种神经肌肉接头的电生理学。因此，该项目旨在提供一组神经肌肉接头处的神经递质，可用作系统发育分析的独特特征。

Organisms today retain information about their past in terms of amino acid sequences of their proteins and in the composition of nucleic acids. Thus, modern systematics is now based largely on DNA sequence analysis and comparisons. There is however a severe shortage of other, non-molecular characters with phylogenetic significance that can be used to confirm or adjust molecular-based phylogenetics and help to clarify any inconsistencies. Since cellular communication is important to organismic functioning, a phylogenetic analysis of the distribution of informational molecules could provide such a set of independent characters that may be helpful to gain additional insights into the evolutionary history. Throughout the animal kingdom, many diverse species use acetylcholine as a neurotransmitter at the neuromuscular junction of skeletal muscles. In contrast, glutamate appears to be the excitatory transmitter at neuromuscular synapses in some arthropod species. The project will test the hypothesis that in the arthropod phylum excitatory motoneurons of skeletal muscles are exclusively glutamatergic. Using electrophysiology as well as cytochemical and immuostaining techniques, we will examine whether this feature is a synapomorphy of the Euarthropoda or potentially of the Panarthropoda (Euarthropoda, Onychophora, Tardigrada). Peripheral inhibition by GABAergic motoneurons is widely distributed within the invertebrates, but it appears to be missing in several groups. To examine whether cell-specific chemical markers can be used as features to characterize systematic groups, the project will combine labelling for cholinergic, GABAergic, and glutamatergic markers with electrophysiology of the neuromuscular junction in arthropods and selected outgroup species. As a result, the project aims at providing a set of neurotransmitters at the neuromuscular junction that can be used as distinct characters for phylogenetic analysis.