title: Paradoxical anaerobism in desert pupfish.
abstract: In order to estimate metabolic demands of desert pupfish for conservation purposes, we measured oxygen consumption in fish acclimated to the ecologically relevant temperatures of 28 or 33°C. For these experiments, we used fish derived from a refuge population of Devils Hole pupfish (Cyprinodon diabolis). Measurement of routine oxygen consumption (V̇O2,routine) revealed some 33°C-acclimated fish (10% of 295 assayed fish) periodically exhibited periods of no measurable oxygen consumption despite available ambient oxygen tensions that were above the critical PO2. We call this phenomenon paradoxical anaerobism. The longest observed continuous bout with no oxygen consumption was 149 min, although typical bouts were much shorter. Fish maintained normal posture and ventilation rate (>230 ventilations per minute) during paradoxical anaerobism. Fish rarely demonstrated a compensatory increase in oxygen use following a period of paradoxical anaerobism. In contrast, only one out of 262 sampled fish acclimated at 28°C spontaneously demonstrated paradoxical anaerobism. Muscle lactate concentration was not elevated during periods of paradoxical anaerobism. However, the amount of ethanol released by the 33°C-acclimated fish was 7.3 times greater than that released by the 28°C acclimation group, suggesting ethanol may be used as an alternative end product of anaerobic metabolism. Exposure to exogenous ethanol, in concentrations as low as 0.1%, produced periods of paradoxical anaerobism even in 28°C-acclimated fish.
authors.affiliation: School of Life Sciences, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154, USA.
authors.forename: Matt
authors.initials: M
authors.lastname: Heuton
authors.affiliation: School of Life Sciences, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154, USA.
authors.forename: Luis
authors.initials: L
authors.lastname: Ayala
authors.affiliation: School of Life Sciences, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Burg
authors.affiliation: School of Life Sciences, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154, USA.
authors.forename: Kyle
authors.initials: K
authors.lastname: Dayton
authors.affiliation: School of Life Sciences, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154, USA.
authors.forename: Ken
authors.initials: K
authors.lastname: McKenna
authors.affiliation: School of Life Sciences, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154, USA.
authors.forename: Aldo
authors.initials: A
authors.lastname: Morante
authors.affiliation: School of Life Sciences, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154, USA.
authors.forename: Georgina
authors.initials: G
authors.lastname: Puentedura
authors.affiliation: School of Life Sciences, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154, USA.
authors.forename: Natasha
authors.initials: N
authors.lastname: Urbina
authors.affiliation: School of Life Sciences, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154, USA.
authors.forename: Stanley
authors.initials: S
authors.lastname: Hillyard
authors.affiliation: School of Life Sciences, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154, USA.
authors.forename: Spencer
authors.initials: S
authors.lastname: Steinberg
authors.affiliation: School of Life Sciences, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154, USA frank.vanbreukelen@unlv.edu.
authors.forename: Frank
authors.initials: F
authors.lastname: van Breukelen
mesh_terms: D000064:Acclimatization; D000693:Anaerobiosis; D000818:Animals; D000431:Ethanol / Q000494:pharmacology; D007695:Killifishes / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology*; D013696:Temperature
chemical_list: D019344:Lactic Acid; D000431:Ethanol
keywords: Cyprinodon; Oxygen consumption; Thermal acclimation