QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online January 18, 2008
Journal of Experimental Biology 211, 459-465 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.013219

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Tsahar, E. Articles by del Rio, C. M. Search for Related Content PubMed PubMed Citation Articles by Tsahar, E. Articles by del Rio, C. M.

Dietary protein influences the rate of ¹⁵N incorporation in blood cells and plasma of Yellow-vented bulbuls (Pycnonotus xanthopygos)

Ella Tsahar^1,*, Nathan Wolf², Ido Izhaki³, Zeev Arad¹ and Carlos Martínez del Rio²

¹ Department of Biology, Technion – Israel Institute of Technology, Haifa 32000, Israel
² Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA
³ Department of Biology, University of Haifa at Oranim, K. Tivon 36006, Israel

^* Author for correspondence (e-mail: elat{at}techunix.technion.ac.il)

Accepted 20 November 2007

The rate at which an animal's tissues incorporate the isotopic composition of food determines the time window during which ecologists can discern diet changes. We investigated the effect of protein content in the diet on the incorporation rate of ¹⁵N into the plasma proteins and blood cells of Yellow-vented bulbuls (Pycnonotus xanthopygos). Using model comparison analyses, we found that one-compartment models described incorporation data better than two-compartment models. Dietary protein content had a significant effect on the residence time of ¹⁵N in plasma proteins and blood cells. The diet with the highest protein content led to a ¹⁵N retention time of 21 and 5 days for cells and plasma, respectively. In contrast, average ¹⁵N retention time in the cells and plasma of birds fed on the diet with the lowest protein was 31 and 7 days, respectively. The isotopic discrimination factor ¹⁵N=¹⁵N_tissues–¹⁵N_diet was also dependent on dietary protein content, and was lowest in birds fed the diet with the highest protein content. Blood, plasma and excreta were enriched in ¹⁵N relative to diet. In contrast, ureteral urine was either significantly depleted of ¹⁵N in birds fed the diet with the lowest protein content or did not differ in ¹⁵N from the diets with the intermediate and high protein content. Thus, isotopic incorporation rates and tissue-to-diet discrimination factors cannot be considered fixed, as they depend on diet composition.

Key words: incorporation rate, stable isotopes, Yellow-vented bulbul, protein intake, diet reconstruction