title: Pythons metabolize prey to fuel the response to feeding.
abstract: We investigated the energy source fuelling the post-feeding metabolic upregulation (specific dynamic action, SDA) in pythons (Python regius). Our goal was to distinguish between two alternatives: (i) snakes fuel SDA by metabolizing energy depots from their tissues; or (ii) snakes fuel SDA by metabolizing their prey. To characterize the postprandial response of pythons we used transcutaneous ultrasonography to measure organ-size changes and respirometry to record oxygen consumption. To discriminate unequivocally between the two hypotheses, we enriched mice (= prey) with the stable isotope of carbon (13C). For two weeks after feeding we quantified the CO2 exhaled by pythons and determined its isotopic 13C/12C signature. Ultrasonography and respirometry showed typical postprandial responses in pythons. After feeding, the isotope ratio of the exhaled breath changed rapidly to values that characterized enriched mouse tissue, followed by a very slow change towards less enriched values over a period of two weeks after feeding. We conclude that pythons metabolize their prey to fuel SDA. The slowly declining delta13C values indicate that less enriched tissues (bone, cartilage and collagen) from the mouse become available after several days of digestion.
authors.affiliation: Department of Biology II, University of Munich (LMU), Luisenstrasse 14-16, D-80333 Munich, Germany. starck@uni-muenchen.de
authors.forename: J Matthias
authors.initials: JM
authors.lastname: Starck
authors.forename: Patrick
authors.initials: P
authors.lastname: Moser
authors.forename: Roland A
authors.initials: RA
authors.lastname: Werner
authors.forename: Petra
authors.initials: P
authors.lastname: Linke
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001837:Body Weights and Measures; D017821:Boidae / Q000502:physiology*; D002245:Carbon Dioxide / Q000032:analysis; D002247:Carbon Isotopes; D004063:Digestion / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D041981:Gastrointestinal Tract / Q000000981:diagnostic imaging; D010101:Oxygen Consumption / Q000502:physiology; D019518:Postprandial Period / Q000502:physiology*; D013997:Time Factors; D014463:Ultrasonography
chemical_list: D002247:Carbon Isotopes; D002245:Carbon Dioxide