Reyes-Maldonado Roberto, Ramírez Alonso, Marie Bruno
Institute of Neurobiology, Medical Sciences Campus, University of Puerto Rico, Puerto Rico, USA.
Department of Biology, University of Puerto Rico, Puerto Rico, USA.
bioRxiv. 2025 Jun 3:2025.06.01.657287. doi: 10.1101/2025.06.01.657287.
Chironomids are important laboratory model organisms used to assess toxicity in freshwater environments. Cell and tissue features are not commonly used as chironomid markers to detect toxicity, but they could be extremely helpful in identifying acute and chronic effects of pollutants. The nervous system is an excellent cellular candidate since it is reactive to toxic substances. However, a detailed description of the chironomid nervous system is required prior to considering it as a candidate for a cellular toxicity marker. The present study describes the central ganglia, nerves, axons, and the neuromuscular system of (Freeman, 1961) to facilitate its use as a model organism in environmental studies. We find that the structure of the central nervous system is identical to that observed in other larvae. We then focused our study on the first abdominal segment and labeled the 31 hemi-segmental muscles according to a nomenclature based on their position and orientation. We also characterized their innervation and assigned the nerves a nomenclature based on their terminals' location in the muscle tissue. Finally, we investigated the neuromuscular junctions (NMJs) throughout this segment and defined four types of NMJs illustrating their great variability in size and shape. We selected a model NMJ, VEL 2, and quantified its mean bouton number and muscle size. Together with documenting a neurobiological system that could be informative to insects' comparative biology, these results could help establish the NMJ as an aquatic toxicity marker.
摇蚊是用于评估淡水环境毒性的重要实验室模式生物。细胞和组织特征通常不作为摇蚊检测毒性的标志物，但它们在识别污染物的急性和慢性影响方面可能极为有用。神经系统是一个很好的细胞候选对象，因为它对有毒物质有反应。然而，在将摇蚊神经系统视为细胞毒性标志物的候选对象之前，需要对其进行详细描述。本研究描述了（弗里曼，1961年）的中枢神经节、神经、轴突和神经肌肉系统，以促进其在环境研究中作为模式生物的应用。我们发现，[摇蚊名称]中枢神经系统的结构与在其他[摇蚊名称]幼虫中观察到的结构相同。然后，我们将研究重点放在第一腹节，并根据基于其位置和方向的命名法对31块半节段肌肉进行了标记。我们还对它们的神经支配进行了表征，并根据神经末梢在肌肉组织中的位置为神经赋予了命名法。最后，我们研究了整个节段的神经肌肉接头（NMJ），并定义了四种类型的NMJ，说明了它们在大小和形状上的巨大变异性。我们选择了一个模型NMJ，VEL 2，并对其平均突触小体数量和肌肉大小进行了量化。这些结果除了记录一个可能对昆虫比较生物学有参考价值的神经生物学系统外，还可能有助于将[摇蚊名称]NMJ确立为一种水生毒性标志物。
