Cold-induced mitochondrial degradation and cryoprotectant synthesis in freeze-tolerant arctic caterpillars.
The larvae of Gynaephora 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 (less than 1 week) than did degradation (greater than 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 by G. groenlandica may be linked to diapause in other species of ectotherms.
Kukal
O
O
Department of Biological Sciences, University of Notre Dame, Indiana 46556.
Duman
J G
JG
Serianni
A S
AS
D000064:Acclimatization; D000818:Animals; D001921:Brain / Q000378:metabolism / Q000648:ultrastructure; D003081:Cold Climate; D003451:Cryoprotective Agents / Q000378:metabolism; D005216:Fat Body / Q000378:metabolism / Q000648:ultrastructure; D005615:Freezing; D005990:Glycerol / Q000378:metabolism*; D007915:Lepidoptera / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008928:Mitochondria / Q000378:metabolism* / Q000648:ultrastructure; D010101:Oxygen Consumption
D003451:Cryoprotective Agents; D005990:Glycerol