IAB Research Project Description
Collaborative Research: Deep Supercooling to -100°C, and Lower, in Alaska Beetle Cucujus clavipes
Kennan Jeanette and Todd Sformo collecting insects at Cache Creek March 2005 Credit: Franziska Kohl/IAB Research Professional
Insects exposed to subzero temperatures adapt by becoming either freeze tolerant (they survive if frozen) or they must become freeze avoiding, to prevent freezing. The freeze avoiding beetle Cucujus clavipes has a broad latitudinal range, from North Carolina to tree line in the Brooks Range in Alaska above the Arctic Circle (~68oN). Overwintering Alaska populations of larval C. clavipes supercool to a mean temperature of ~-40oC, with some individuals supercooling to –58oC before freezing. We refer to this level of supercooling as semi-deep supercooling (S-DSc).
However, in some cases we have been unable to freeze larvae even when cooled to –120oC. This deep supercooling (DSC) occurs sporadically in overwintering larvae from Interior Alaska. At certain times in winter all larvae collected deep supercooled, at other times only a few or none deep supercooled. Adaptations possibly contributing to DSc are production of antifreeze proteins (AFPs), accumulation of glycerol, diapause (reduced metabolism), and extensive cryoprotective dehydration. However, exactly how DSc to -120oC is accomplished is unknown, and is the major emphasis of this proposal. In contrast to the Alaska C. clavipes, larvae from northern Indiana (~41o45’ N) show mean winter SCPs of ~-23oC and, unlike the Alaska populations, they do not dehydrate or enter diapause in winter, although they do produce AFPs and glycerol. Winter concentrated hemolymph of Alaska larvae vitrifies, turns glassy and does not crystallize, at ~-100oC, but as winter temperatures do not get this low, the larvae would not vitrify naturally. However, it is possible that more dehydrated larvae, with further concentrated body fluids, might vitrify at natural temperatures.
The primary goal of this proposal is to identify the adaptations that result in DSc, and vitrification in Alaska C. clavipes. The intellectual merit of this proposal relates to identifying the integrated molecular, physiological, and behavioral adaptations that allow organisms to survive extreme winter environments and to describe, for the first time, the nature and conditions of animal vitrification. The broader impact of this study concerns its (1) potential applications to cryopreservation, and (2) its effects on biological education. Antifreeze proteins such as those found in C. clavipes are arguably the most active known, and their possible uses, along with other adaptations that result in DSc in C. clavipes, may allow the cryopreservation of biological and medical materials in a non-frozen state, thereby precluding the problems with preservation in the frozen state. There could also be applications in agriculture resulting in more cold tolerant crops, and in the frozen food industry. Students at levels ranging from high school to undergraduates to PhD will be involved in these studies, thereby receiving integrated training in techniques ranging from physiological ecology to biochemistry.
1 Jun 2006 – 30 May 2009
IAB Proposal #06-090
UAF Grant #G3400
IAB Project #82
302A Irving I
University of Alaska Fairbanks
Fairbanks, AK 99775-7000