Freeze-tolerance adaptations,including haemolymph protein and lipoprotein nucleators,in the larvae of the cranefly Tipula trivittata |
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Authors: | John G Duman Lisa G Neven John M Beals Kenneth R Olson Francis J Castellino |
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Institution: | 1. Department of Biology, University of Notre Dame, Notre Dame, IN 46556 USA;3. Department of Chemistry, University of Notre Dame, Notre Dame, IN 46556 USA;5. Indiana University School of Medicine, South Bend Center, University of Notre Dame, Notre Dame, IN 46556, U.S.A. |
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Abstract: | The terrestrial overwintering larvae of the cranefly Tipula trivittata were freeze tolerant (able to survive the freezing of their extracellular body fluids) throughout the winter and spring of 1982–1983 until they pupated in mid-May. The larvae were most cold tolerant (24 h lower lethal temperatures of ?25 to ?30°C) in late January and early February. Sorbitol, at a maximal concentration of ~0.4 M, was the only polyol determined to be present at high levels and sorbitol accounted for most of the seasonal fluctuation in osmotic concentration. Haemolymph inorganic ion (Na+, K+, Ca2+, Mg2+, Cl?) concentrations did not vary seasonally.The supercooling points of the larvae remained constant at ?6 to ?7°C over the study period because of the presence of haemolymph ice nucleating factors. These ice nucleating factors consist not only of haemolymph proteins, as had been demonstrated previously in other insect species, but also lipoproteins. |
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Keywords: | Freeze tolerance cold tolerance ice nucleator proteins lipoproteins cranefly sorbitol haemolymph inorganic ions |
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