title: Whole-body protein turnover reveals the cost of detoxification of secondary metabolites in a vertebrate browser.
abstract: The detoxification limitation hypothesis predicts that the metabolism and biotransformation of plant secondary metabolites (PSMs) elicit a cost to herbivores. There have been many attempts to estimate these costs to mammalian herbivores in terms of energy, but this ignores what may be a more important cost-increases in protein turnover and concomitant losses of amino acids. We measured the effect of varying dietary protein concentrations on the ingestion of two PSMs (1,8 cineole-a monoterpene, and benzoic acid-an aromatic carboxylic acid) by common brushtail possums (Trichosurus vulpecula). The dietary protein concentration had a small effect on how much cineole possums ingested. In contrast, protein had a large effect on how much benzoate they ingested, especially at high dietary concentrations of benzoate. This prompted us to measure the effects of dietary protein and benzoate on whole-body protein turnover using the end-product method following an oral dose of [(15)N] glycine. Increasing the concentration of dietary protein in diets without PSMs improved N balance but did not influence whole-body protein turnover. In contrast, feeding benzoate in a low-protein diet pushed animals into negative N balance. The concomitant increases in the rates of whole-body protein turnover in possums eating diets with more benzoate were indicative of a protein cost of detoxification. This was about 30 % of the dietary N intake and highlights the significant effects that PSMs can have on nutrient metabolism and retention.
authors: Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Canberra, 0200, Australia.
authors: Jessie
authors: J
authors: Au
authors: Karen J
authors: KJ
authors: Marsh
authors: Ian R
authors: IR
authors: Wallis
authors: William J
authors: WJ
authors: Foley
mesh_terms: D000818:Animals; D019817:Benzoic Acid / Q000494:pharmacology*; D003511:Cyclohexanols / Q000494:pharmacology*; D004044:Dietary Proteins / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects; D000077591:Eucalyptol; D060434:Herbivory / Q000502:physiology; D008297:Male; D039821:Monoterpenes / Q000494:pharmacology*; D009584:Nitrogen / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D048330:Trichosurus / Q000502:physiology*
chemical_list: D003511:Cyclohexanols; D004044:Dietary Proteins; D039821:Monoterpenes; D011506:Proteins; D019817:Benzoic Acid; D009584:Nitrogen; D000077591:Eucalyptol
references: Comp Biochem Physiol C Pharmacol Toxicol Endocrinol. 1999 Nov;124(3):239-46
references: 10661715
references: Clin Sci (Lond). 1985 Mar;68(3):271-82
references: 3918824
references: Br J Nutr. 2005 Aug;94(2):141-53
references: 16115347
references: Oecologia. 1978 Jan;33(1):71-86
references: 28309267
references: J Chem Ecol. 1995 Jun;21(6):721-43
references: 24234314
references: J Anim Sci. 2002 Dec;80(12):3154-64
references: 12542156
references: Proc Nutr Soc. 1981 Sep;40(3):317-20
references: 6795640
references: Pharmacol Ther. 1993 Oct;60(1):63-90
references: 8127924
references: J Comp Physiol B. 1988;158(2):237-46
references: 3170828
references: J Chem Ecol. 1995 Jun;21(6):693-719
references: 24234313
references: J Comp Physiol B. 2000 May;170(3):211-8
references: 10841261
references: J Chem Ecol. 2004 Jul;30(7):1409-29
references: 15503528
references: Clin Sci. 1969 Apr;36(2):283-96
references: 5772104
references: J Chem Ecol. 2005 Dec;31(12):2775-90
references: 16365704
references: Ecology. 2006 Aug;87(8):2103-12
references: 16937649
references: J Chem Ecol. 2005 Jan;31(1):123-38
references: 15839485
references: J Chem Ecol. 2006 Jun;32(6):1247-66
references: 16770716
references: J Biol Chem. 1949 Sep;180(2):715-26
references: 18147157
references: J Comp Physiol B. 2010 Feb;180(2):247-57
references: 19727760
references: Biochem J. 1970 Jun;118(1):47-51
references: 4990586
references: Ecology. 2009 May;90(5):1400-11
references: 19537559
references: Ecology. 2009 Mar;90(3):711-9
references: 19341141
references: Am J Med. 1960 Nov;29:832-48
references: 13788500