title: Developmental plasticity of mitochondrial function in American alligators, Alligator mississippiensis.
abstract: The effect of hypoxia on cellular metabolism is well documented in adult vertebrates, but information is entirely lacking for embryonic organisms. The effect of hypoxia on embryonic physiology is particularly interesting, as metabolic responses during development may have life-long consequences, due to developmental plasticity. To this end, we investigated the effects of chronic developmental hypoxia on cardiac mitochondrial function in embryonic and juvenile American alligators (Alligator mississippiensis). Alligator eggs were incubated in 21% or 10% oxygen from 20 to 90% of embryonic development. Embryos were either harvested at 90% development or allowed to hatch and then reared in 21% oxygen for 3 yr. Ventricular mitochondria were isolated from embryonic/juvenile alligator hearts. Mitochondrial respiration and enzymatic activities of electron transport chain complexes were measured with a microrespirometer and spectrophotometer, respectively. Developmental hypoxia induced growth restriction and increased relative heart mass, and this phenotype persisted into juvenile life. Embryonic mitochondrial function was not affected by developmental hypoxia, but at the juvenile life stage, animals from hypoxic incubations had lower levels of Leak respiration and higher respiratory control ratios, which is indicative of enhanced mitochondrial efficiency. Our results suggest developmental hypoxia can have life-long consequences for alligator morphology and metabolic function. Further investigations are necessary to reveal the adaptive significance of the enhanced mitochondrial efficiency in the hypoxic phenotype.
authors.affiliation: Faculty of Medical and Human Sciences, University of Manchester, Manchester, United Kingdom; gina.galli@manchester.ac.uk.
authors.forename: Gina L J
authors.identifier: 0000-0002-1023-915X
authors.initials: GL
authors.lastname: Galli
authors.affiliation: Developmental Integrative Biology Research Group, Department of Biological Sciences, University of North Texas, Denton, Texas; and.
authors.forename: Janna
authors.initials: J
authors.lastname: Crossley
authors.affiliation: Rockefeller Wildlife Refuge, Grand Chenier, Louisiana.
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Elsey
authors.affiliation: Developmental Integrative Biology Research Group, Department of Biological Sciences, University of North Texas, Denton, Texas; and.
authors.forename: Edward M
authors.initials: EM
authors.lastname: Dzialowski
authors.affiliation: Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
authors.forename: Holly A
authors.initials: HA
authors.lastname: Shiels
authors.affiliation: Developmental Integrative Biology Research Group, Department of Biological Sciences, University of North Texas, Denton, Texas; and.
authors.forename: Dane A
authors.initials: DA
authors.lastname: Crossley
mesh_terms: D000489:Alligators and Crocodiles / Q000196:embryology* / Q000502:physiology; D000818:Animals; D000066670:Cell Plasticity; D045222:Electron Transport Chain Complex Proteins / Q000378:metabolism; D047108:Embryonic Development / Q000502:physiology*; D005317:Fetal Growth Retardation / Q000503:physiopathology*; D000860:Hypoxia / Q000196:embryology / Q000503:physiopathology*; D008928:Mitochondria / Q000378:metabolism*
chemical_list: D045222:Electron Transport Chain Complex Proteins
keywords: developmental plasticity; ectotherm; heart; hypoxia; mitochondria; reptile