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Atmospheric hypoxia increases bone robusticity in the American alligator
Author(s) -
Owerkowicz Tomasz,
Andrade Fernando,
Elsey Ruth,
Hicks James
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.988.4
Subject(s) - hyperoxia , hatchling , hypoxia (environmental) , alligator , anatomy , resorption , american alligator , biology , skeleton (computer programming) , zoology , chemistry , endocrinology , medicine , oxygen , lung , ecology , hatching , organic chemistry
During vertebrate evolution, atmospheric oxygen (O 2 ) level may have varied from as low as 12% to as high as 30%, but no studies to date have considered the effect of ambient O 2 on skeletal plasticity. We incubated eggs and subsequently grew alligator hatchlings under chronic hypoxia (12% O 2 ), normoxia (21% O 2 ) and hyperoxia (30% O 2 ). Animals received monthly injections of fluorescent dyes to determine bone deposition rates. After three months, animals were sacrificed and their femora either sectioned at mid‐diaphysis, or ashed. We found femora of hypoxic alligators to have significantly greater mass‐specific cross‐sectional area (+15%), second moment of area (+20%) and polar moment of inertia (+23%) than those of either normoxic or hyperoxic hatchlings. Mineral content was also significantly higher (+6%) in bones of hypoxic animals. This suggests that exposure to chronic hypoxia, but not hyperoxia, resulted in increased resistance to compressive, bending and torsional stresses on the skeleton. Furthermore, the relationship between body mass growth and periosteal deposition rate was different between treatments groups, with hypoxic animals accruing more bone per unit body mass. We suggest that prevalent atmospheric O 2 level need be considered when reconstructing size and growth curves of extinct vertebrates. Funded by the NSF IOB 04445680 and IOS 0922756 to JWH.