Using a native insect species and its neuromuscular system as models for assessing water toxicity in Puerto Rico: <em>Chironomus</em> sp. "Florida" (Diptera: Chironomidae)

Abstract

Different species of chironomids have been used as laboratory models to detect toxicity in aquatic environments. This is achieved by studying the response of different molecular and morphological markers in the larvae of exposed animals. The use of cell markers is rarely applied to assess toxicity within these animal models, but their implementation could help to assess toxicity in a more cost-effective way and to detect toxicity before morphological responses appear. With the finality to contribute to the field of toxicology and to emphasize the advantages of using cellular markers to assess toxicity, this thesis seeks to determine the efficiency of the <em>Chironomus</em> neuromuscular junction (NMJ) as a cellular marker. In order to evaluate the NMJ as a marker, the larvae of a chironomid species native to Puerto Rico, <em>Chironomus</em> sp."Florida";, was studied. First, the life cycle of this chironomid was described and a rearing protocol was presented to manage the larvae under laboratory conditions. Then, the neuromuscular system of the last larval stage of this chironomid was described in order to identify a model NMJ. Once the model NMJ was identified, its effectiveness as a marker of toxicity was evaluated by exposing larvae to high doses of two toxic aquatic pollutants: dibutyl phthalate and lead. The obtained results in this work indicates that the <em>Chironomus</em> NMJ is an excellent model for assessing toxicity since quantifiable changes at the number of boutons, muscle area, and density of boutons were observable when the larvae were exposed to contaminants. It is hoped that all the descriptions provided in this thesis will encourage the development of additional studies in the field of toxicology, but also in the field of neuroscience and comparative biology.