Chapter 16 - Caenorhabditis elegans as a model to assess reproductive and developmental toxicity

Abstract

This chapter discusses the achievements realized in the field of toxicology through the use of the nematode Caenorhabditis elegans as an animal model. The entire lifecycle, from an egg to an adult producing more eggs, takes just 3.5 days. The hermaphrodite reproductive system consists of a symmetrically arranged bilobed gonad. The male gonad is a single lobed U-shaped structure. The developmental stages in C. elegans are very short, and its molecular and morphological pathways are well reported. The adult C. elegans has 302 neurons in two independent nervous systems: 282 in the somatic nervous system and 20 in the pharyngeal nervous system. These nervous systems control locomotion, feeding, defecation, reproduction and environmental sensing. Alterations in any of these functions may be indicators of neurotoxicity. Several studies have shown that some reproductive endpoints are controlled by the nervous system. Since the genome was first published, a plethora of molecular techniques have been developed for genetic manipulation and cellular and molecular observation that are particularly valuable for toxicological studies. Transgenic C. elegans have been employed as biomarkers of a variety of environmental exposures and provide valuable insight regarding the molecular bases of cellular stress and toxicity. Light microscopy is another valuable tool for the examination of toxicant effects in C. elegans. A variety of computer-based assays have been developed to assess outcomes of toxicant exposure in C. elegans. Genome-wide screening using C. elegans is a classical approach for studying the functional repercussions of a gene in a given molecular response. Developmental and reproductive toxicity are caused by metals like cadmium, zinc, mercury, lead, magnesium and other metals as well as pesticides