Reptiles as Animal Models: Examples of their Utility in Genetics, Immunology and Toxicology

Abstract

Historically, animals used as experimental models have contributed to the knowledgeof multiple aspects of organisms? biology and wildlife, providing valuable informationabout physiological processes, events, environmental situations, and even humaninteractions. Alternatives to animal testing are primarily based on biochemical assays orexperiments with cells/organs cultures, typically far more sophisticated and specific thanin vivo approaches. However, the whole organism allows for inferences about particularspecies and its situation in natural habitats. Sometimes, it is not possible to study directlythe species of interest, making it necessary to identify the closest related species that canbe used as a model organism. Reptiles may be good and interesting models as theyrespond both behaviorally and physiologically to environmental or experimentalconditions. This chapter specifically describes the utility of crocodiles, lizards, and turtlesas animal models in studies of genetics, immunology, and toxicology. The increasedinterest in reptile genomics is evident by newly sequenced genomes, by the establishmentof significant genomic resources for some reptile groups, and by the awareness thatgenomic diversity in Reptiles is substantially greater than that of mammals. Reptiles alsodemonstrate immune components with an apparently higher activity than othervertebrates. Their ability to resist serious injuries makes them interesting models toelucidate mechanisms within the defense system. In the same way, interesting studieswere performed to propose immune components to be used as indicators of toxicsexposure. Environmental contaminants can significantly affect many reptiles. However,these species are often excluded from toxicology studies and ecological risk assessments,even though they are important elements of ecosystems and show similar sensitivity tothat reported for birds and mammals. Genotoxicity, immunotoxicity and oxidative stresscompounds in reptile species, serving as early-warning signals of populationsenvironmentally exposed.