SKOPEC, M.M.; HALEY, S.L.; DEARING, M.D.; University of Utah; University of Utah; University of Utah: Differential gene expression in the livers of a dietary specialist versus generalist species of woodrat.

Differential abilities to detoxify the plant secondary compounds present in juniper (Juniperus monosperma) are implicated as a major reason for the disparate juniper tolerances of two sympatric species of woodrats, Neotoma stephensi and Neotoma albigula. Neotoma stephensi is a dietary specialist that consumes juniper as 75-90% of its diet while N. albigula is a dietary generalist and is only able to consume a diet with a maximum of 25% juniper. Since the major site of detoxification is the liver we compared the difference in gene expression in the livers of N. stephensi versus N. albigula on control versus juniper containing diets using Agilent microarrays. By using microarray technology we were able to simultaneously asses the expression of over 20,000 genes. We found that there were large differences in gene expression between the species when on the control diet as well as the 25% juniper diet; 402 genes between species on the control diet and 1274 genes between species on the 25% juniper diet showed a 2-fold or greater difference in gene expression. There was much less difference in gene expression within species when on a control diet versus a 25% juniper diet; 111 genes within N. albigula and 91 genes within N. stephensi showed a 2-fold or greater difference in expression. However, there was a large within species difference in N. stephensi when on a 70% versus 25% juniper diet; 1734 genes showed a 2-fold or greater difference in gene expression. Further analysis will allow us to identify candidate genes for future study to help elucidate the mechanism by which N. stephensi is able to consume a toxic diet and also give us insights into the role plant secondary compounds have played in the evolution of mammalian herbivore livers.