Title: | Strategies in herbivory by mammals revisited: The role of liver metabolism in a juniper specialist (Neotoma stephensi) and a generalist (Neotoma albigula) |
Author(s): | Orr TJ; Kitanovic S; Schramm KM; Skopec MM; Wilderman PR; Halpert JR; Dearing MD; |
Address: | "School of Biological Sciences, University of Utah, Salt Lake City, UT, USA. Department of Botany, Weber State University, Ogden, UT, USA. Department of Zoology, Weber State University, Ogden, UT, USA. School of Pharmacy, University of Connecticut, Storrs, CT, USA" |
ISSN/ISBN: | 1365-294X (Electronic) 0962-1083 (Linking) |
Abstract: | "Although herbivory is widespread among mammals, few species have adopted a strategy of dietary specialization. Feeding on a single plant species often exposes herbivores to high doses of plant secondary metabolites (PSMs), which may exceed the animal's detoxification capacities. Theory predicts that specialists will have unique detoxification mechanisms to process high levels of dietary toxins. To evaluate this hypothesis, we compared liver microsomal metabolism of a juniper specialist, Neotoma stephensi (diet >85% juniper), to a generalist, N. albigula (diet =30% juniper). Specifically, we quantified the concentration of a key detoxification enzyme, cytochrome P450 2B (CYP2B) in liver microsomes, and the metabolism of alpha-pinene, the most abundant terpene in the juniper species consumed by the specialist woodrat. In both species, a 30% juniper diet increased the total CYP2B concentration (2-3x) in microsomes and microsomal alpha-pinene metabolism rates (4-fold). In N. stephensi, higher levels of dietary juniper (60% and 100%) further induced CYP2B and increased metabolism rates of alpha-pinene. Although no species-specific differences in metabolism rates were observed at 30% dietary juniper, total microsomal CYP2B concentration was 1.7x higher in N. stephensi than in N. albigula (p < .01), suggesting N. stephensi produces one or more variant of CYP2B that is less efficient at processing alpha-pinene. In N. stephensi, the rates of alpha-pinene metabolism increased with dietary juniper and were positively correlated with CYP2B concentration. The ability of N. stephensi to elevate CYP2B concentration and rate of alpha-pinene metabolism with increasing levels of juniper in the diet may facilitate juniper specialization in this species" |
Keywords: | Animals *Herbivory *Juniperus Liver/*metabolism Sigmodontinae/classification/*metabolism Neotoma biotransformation diet switching enzyme assay herbivory mammalian herbivores metabolism terpenes trade-offs woodrat; |
Notes: | "MedlineOrr, Teri J Kitanovic, Smiljka Schramm, Katharina M Skopec, Michele M Wilderman, P Ross Halpert, James R Dearing, M Denise eng Research Support, U.S. Gov't, Non-P.H.S. England 2020/04/05 Mol Ecol. 2020 May; 29(9):1674-1683. doi: 10.1111/mec.15431. Epub 2020 Apr 22" |