Cold-induced mitochondrial degradation and cryoprotectant synthesis in freeze-tolerant arctic caterpillars |
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Authors: | Olga Kukal John G Duman Anthony S Serianni |
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Institution: | (1) Department of Biological Sciences, University of Notre Dame, 46556 Notre Dame, Indiana, USA;(2) Department of Chemistry, University of Notre Dame, 46556 Notre Dame, Indiana, USA;(3) Present address: Entomology Department, Ohio State University, 43210 Columbus, Ohio, USA |
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Abstract: | Summary The larvae ofGynaephora groenlandica, a long-lived moth endemic to the high arctic, are perennially freeze-tolerant and able to increase their freeze-tolerance by synthesizing glycerol. Cold-induced mitochondrial changes were correlated (using electron microscopy, DNA staining, cytochrome c assay, and oxygen uptake) with glycerol production (using NMR spectroscopy) in larvae under different acclimations and in the field. Hypometabolism in summer- or warm-acclimated larvae led to glycerol accumulation. Extended exposure to near-zero or freezing temperatures caused mitochondrial degradation and glycerol accumulation. Rapid freezing of warm-acclimated larvae did not result in mitochondrial breakdown. Mitochondrial reconstitution upon warm-acclimation occurred much more rapidly (<1 week) than did degradation (>2 months). Concomitant with mitochondrial breakdown was reduced oxidative metabolism, but the cytochrome c concentration remained independent of acclimation temperature. The adaptive response to cold by mitochondrial degradation and glycerol accumulation byG. groenlandica may be linked to diapause in other species of ectotherms. |
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