Meeting Abstract
S6.10 Monday, Jan. 5 Functional genomics of mammalian herbivores DEARING, M. D.*; MAGNANOU, E.; MALENKE, J.; SKOPEC, M. S.; University of Utah; CNRS – UniversitP et M Curie; University of Utah; Weber State denise.dearing@utah.edu
Mammalian herbivores with a narrow diet breadth, i.e., specialists, are predicted to utilize different hepatic biotransformation enzymes to process plant secondary compounds (PSC) compared to generalist herbivores. The large number of biotransformation enzymes (200-300) has limited the ability to comprehensively address this hypothesis. Genomic techniques offer unprecedented opportunities to address such hypotheses on biotransformation systems. In two separate experiments, we used microarrays designed for laboratory rats to investigate hepatic biotransformation of PSC in woodrat herbivores (Neotoma). First, we compared the expression profiles of biotransformation genes of specialist (N. stephensi) to generalist (N. albigula) woodrats fed juniper (Juniperus osteosperma) and control diets. Second, we examined biotransformation expression profiles in populations of N. lepida to identify gene candidates that permit populations in the Mojave desert to ingest greater quantities of the toxic shrub, creosote (Larrea tridentata) compared with populations outside of the Mojave. Crosshybridization of woodrat samples to rat arrays (70%) exceeded that for other crosshybridization studies. The number of biotransformation enzymes with adequate hybridization was 224. In the specialist and generalist comparison, we found large, dose dependent differences in gene expression. We found limited support for the hypothesis that specialists utilize Phase 1 enzymes to a greater extent than Phase 2. In our study examining the ability of N. lepida to feed on creosote, we found several gene candidates that may permit creosote feeding including Cytochrome P450 2B, catechol-O-methyl transferase and superoxide dismutase. We are sequencing the woodrat liver transcriptome and developing functional in vitro assays to test biotransformation rates of the gene candidates against particular PSC.
