Meeting Abstract
When herbivores consume plants with volatile plant secondary compounds (PSC), the only barrier between their nasal passageway and their brain is the nasal epithelium. While it is known that the nasal epithelium expresses biotransformation enzymes capable of metabolizing inhaled toxins, the regulation and role of these enzymes is poorly understood, especially in mammalian herbivores. We therefore sought to better understand how the presence of volatile PSCs may alter the expression of biotransformation enzymes in the nasal epithelium of woodrats (genus Neotoma). Using Western Blots we compared the expression of four enzymes, cytochrome P450 (CYP) 2B, CYP1A, catechol-O-methyl transferase and glutathione S-transferase in nasal epithelium and livers of woodrats consuming control and juniper diets. Two of the woodrat species were juniper specialists (N. stephensi and N. lepida from the Great Basin Desert), one species was a dietary generalist that can consume only small amounts of juniper (N. albigula) and the fourth species was a creosote specialist with evolutionary history consuming juniper (N. lepida from the Mojave Desert). We found that the expression patterns of biotransformation enzymes in the nasal epithelium of woodrats was species specific and that expression of the enzymes in the nasal epithelium was not correlated with the expression of the same enzyme in the liver. Of particular interest, N. stephensi showed either lower expression than the other species or downregulation of all four biotransformation enzymes in their nasal epithelium when consuming juniper. We propose that N. stephensi may forgo metabolizing the terpenes present in juniper at the nasal epithelium in order to use those terpenes for foraging cues.
