title: ANIMAL PHYSIOLOGY. Exceptionally low daily energy expenditure in the bamboo-eating giant panda.
abstract: The carnivoran giant panda has a specialized bamboo diet, to which its alimentary tract is poorly adapted. Measurements of daily energy expenditure across five captive and three wild pandas averaged 5.2 megajoules (MJ)/day, only 37.7% of the predicted value (13.8 MJ/day). For the wild pandas, the mean was 6.2 MJ/day, or 45% of the mammalian expectation. Pandas achieve this exceptionally low expenditure in part by reduced sizes of several vital organs and low physical activity. In addition, circulating levels of thyroid hormones thyroxine (T4) and triiodothyronine (T3) averaged 46.9 and 64%, respectively, of the levels expected for a eutherian mammal of comparable size. A giant panda-unique mutation in the DUOX2 gene, critical for thyroid hormone synthesis, might explain these low thyroid hormone levels. A combination of morphological, behavioral, physiological, and genetic adaptations, leading to low energy expenditure, likely enables giant pandas to survive on a bamboo diet.
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Nie
authors.affiliation: State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China. Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, Scotland, UK.
authors.forename: John R
authors.initials: JR
authors.lastname: Speakman
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wu
authors.affiliation: Beijing Key Laboratory of Captive Wildlife Technologies, Beijing Zoo, Beijing, China.
authors.forename: Chenglin
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Yibo
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Beijing Key Laboratory of Captive Wildlife Technologies, Beijing Zoo, Beijing, China.
authors.forename: Maohua
authors.initials: M
authors.lastname: Xia
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Li
authors.initials: L
authors.lastname: Yan
authors.affiliation: Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, Scotland, UK.
authors.forename: Catherine
authors.initials: C
authors.lastname: Hambly
authors.affiliation: State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Wang
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.affiliation: Beijing Key Laboratory of Captive Wildlife Technologies, Beijing Zoo, Beijing, China.
authors.forename: Jinguo
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China. weifw@ioz.ac.cn.
authors.forename: Fuwen
authors.initials: F
authors.lastname: Wei
mesh_terms: D000818:Animals; D001483:Base Sequence; D001831:Body Temperature; D002417:Cattle; D002884:Chromosomes, Human, Pair 15 / Q000235:genetics; D004032:Diet / Q000662:veterinary; D004285:Dogs; D000074623:Dual Oxidases; D004435:Eating; D004734:Energy Metabolism / Q000235:genetics / Q000502:physiology*; D041981:Gastrointestinal Tract; D014644:Genetic Variation; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009043:Motor Activity; D019255:NADPH Oxidases / Q000235:genetics*; D009929:Organ Size; D031787:Sasa; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D001503:Ursidae / Q000033:anatomy & histology / Q000235:genetics* / Q000502:physiology*
chemical_list: D014284:Triiodothyronine; D000074623:Dual Oxidases; D019255:NADPH Oxidases; C431515:DUOX2 protein, human; D013974:Thyroxine