Environmental temperature alters the overall digestive energetics and differentially affects dietary protein and lipid use in a lizard
Date
2019
Journal Title
Journal ISSN
Volume Title
Publisher
The Company of Biologists
Abstract
Processing food (e.g. ingestion, digestion, assimilation) requires
energy referred to as specific dynamic action (SDA) and is at least
partially fuelled by oxidation of the nutrients (e.g. proteins and lipids)
within the recently ingested meal. In ectotherms, environmental
temperature can affect the magnitude and/or duration of the SDA, but
is likely to also alter the mixture of nutrients that are oxidized to cover
these costs. Here, we examined metabolic rate, gut passage time,
assimilation efficiency and fuel use in the lizard Agama atra digesting
cricket meals at three ecologically relevant temperatures (20, 25
and 32°C). Crickets were isotopically enriched with 13C-leucine or
13C-palmitic-acid tracers to distinguish between protein and lipid
oxidation, respectively. Our results show that higher temperatures
increased the magnitude of the SDA peak (by 318% between 32 and
20°C) and gut passage rate (63%), and decreased the duration of the
SDA response (by 20% for males and 48% for females). Peak rate of
dietary protein oxidation occurred sooner than peak lipid oxidation at
all temperatures (70, 60 and 31 h earlier for 20, 25 and 32°C,
respectively). Assimilation efficiency of proteins, but not lipids, was
positively related to temperature. Interestingly, the SDA response
exhibited a notable circadian rhythm. These results show that
temperature has a pronounced effect on digestive energetics in A.
atra, and that this effect differs between nutrient classes. Variation in
environmental temperatures may thus alter the energy budget and
nutrient reserves of these animals.
Description
CITATION: Plasman, M., et al. 2019. Environmental temperature alters the overall digestive energetics and differentially affects dietary protein and lipid use in a lizard. Journal of Experimental Biology, 222:1-9, doi:10.1242/jeb.194480.
The original publication is available at http://jeb.biologists.org
The original publication is available at http://jeb.biologists.org
Keywords
Stable isotopes, Lizards (Agama atra) -- Digestion, Lizards (Agama atra) -- Nutrition, Digestive energetics in Agama atra -- Effect of temperature on, Specific dynamic action (SDA)
Citation
Plasman, M., et al. 2019. Environmental temperature alters the overall digestive energetics and differentially affects dietary protein and lipid use in a lizard. Journal of Experimental Biology, 222:1-9, doi:10.1242/jeb.194480