Chapter I: Epigenetic regulation has been implicated as an important factor in understanding the molecular mechanisms of drug addiction. This is due to the life -long behavioral changes that commonly afflict addicted individuals long after drug exposure has been extinguished. Invertebrates, such as crayfish, offer excellent model systems to study these molecular mechanisms because they retain the ancestral neural reward circuit that is evolutionarily conserved across taxa, possess relatively few, large neurons, and have an accessible, modularly organized nervous system. The marbled crayfish (Procambarus fallax forma virginalis), in particular, has potential as a model for epigenetic studies because it is parthenogenetic, and thus all individuals are genetic clones. To provide the foundation of this model system for parsing the epigenetic mechanisms of drug addiction, here I characterize the locomotor response of juvenile P. f. f . virginalis exposed to the psychostimulant, d-amphetamine sulfate. Custom video-tracking software was used to record the movement patterns of juveniles exposed to water infused with varying concentrations of d-amphetamine sulfate. ANOVA demonstrated that crayfish locomotion was significantly impacted by drug concentration. These psychostimulant effects, along with the non-invasive mode of drug delivery, which avoids potential epigenetic changes resulting from the stress of direct injection into the hemolymph, set the stage for using P. f. f . virginalis as an animal model for epigenetic studies.
Chapter II: With the rising interest in using invertebrate models for behavioral epigenetic studies, and the tissue- specific nature of epigenetic changes, there is a need for effective methods of extracting genomic DNA from neural tissue. Invertebrates, such as crayfish, represent useful models in which to parse out the basic underlying epigenetic changes because of the relatively simplified anatomical structure of their nervous system. The parthenogenetic marbled crayfish (Procambarus fallax forma virginalis) offers a particularly elegant system because it reproduces asexually and produces large numbers of genetically identical offspring. However, the low DNA yield of fatty neural tissue combined with small sample size represent technical challenges in using invertebrate brains. The present study seeks to support the use of the marbled crayfish as a model for studying the mechanisms of behavioral epigenetics by providing an optimized method for genomic DNA extraction from invertebrate neural tissue.