Hopkins Marine Station Student Paper

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Title: Biochemical responses to Hypoxia in the Long-Jawed Mudsucker I: Metabolites
Student Author(s): Stonington, Scott
Faculty Advisor(s): Somero, George
Pages: 20
Location: Final Papers Biology 175H
Date: June 1999
Abstract: Gillichthys mirabilis (the long-jawed mudsucker, Family Gobiidae), acclimated to 14ºC, were exposed to different periods of hypoxia. I selected the hypoxia intensity based on critical oxygen concentration (Pcrit) data obtained from three fish, all of whom displayed Pcrit of 1.0 mg/L. I placed experimental fish in a consistent oxygen concentration of 0.8 mg/L, and sacrificed them after 0, 8, 24 and 72 hours of exposure by freeze-clamping in liquid nitrogen. I examined glycogen, lactate and ethanol concentrations in white muscle, liver, heart and brain. I found no ethanol in any tissue. Lactate accumulated significantly and similarly in all tissues throughout the time course. Glycogen changed significantly only in liver, which had very large initial stores (6.87 ± 1.46 mg/g), and drastically depleted stores by 8 hours (0.59 ± 0.22 mg/g). White muscle had consistently low glycogen (mean 0.27 ± 0.01 mg/g). Brain showed some hints of glycogen depletion (p = 0.053) by 72 hours. I conclude that during hypoxia in Gillichthys mirabilis, glycogen is mobilized from stores in the liver and transported to meet the energy demands of brain, heart and white muscle, which conserve their own glycogen.