Beetles that keep their supercool

A few days ago, I wrote about antifreeze proteins in overwintering plants, during which I mentioned in passing that there is a similar system in some insects, and that I might write about that too. So, here goes...

Winter conditions in southern England

One of the key concepts here is 'thermal hysteresis' (TH), the difference that antifreeze chemicals (usually proteins, but there are exceptions) create between the melting and freezing points, thus inhibiting ice formation and crystal growth. In fish this effect can reduce the freezing point by up to 1.5°C, and in plants the effect is weaker, but in insects, it is much stronger, reflecting the colder temperatures experienced on land than in water (plants don't show this, but are very differently organised both morphologically and biochemically). For example, despite being intolerant to freezing, the Spruce Budworm moth Choristoneura fumiferana (family Tortricidae) can survive to around –30 °C due to the presence of antifreeze proteins (e.g. Doucet et al. 2002, Qin et al. 2007). More impressively, the Alaskan beetle Upis ceramboides (family Tenebrionidae) survives conditions as cold as –60 °C using a non-protein TH chemical called xylomannan (Walters et al. 2009) which is a combination of sugars (sacchardies) and fatty acids (Ishiwata et al. 2011) in the cell membrane where it appears to function by suppressing the freezing of water molecules within cells. Interestingly, xylomannan was already known to be present in the red seaweed Nothogenia fastigiata, and research on this has shown it to have anti-viral effects by inhibiting replication, including types of herpes, influenza and (to a lesser extent) HIV, among others (Damonte et al. 1994).

The Alaskan-Canadian 'red flat bark beetle' Cucujus clavipes puniceus (family Cucujidae) is another that can survive extremely low temperatures (some individuals 'supercooling' to -100 °C in the lab!), in this case due to the more typical TH proteins and also losing 60-70% of its water content in winter (presumably reducing the among that has to be prevented from freezing) (Sformo et al. 2010, Carrasco et al. 2012).

I could go on - there are plenty of other examples even if some of the mechanisms and biochemistry are not fullt understood - but the point is that (1) there are processes here which require more study (anti-virals anyone!) and (2) wherever we look, life is more resilient than we imagine, with tardigrades and bacteria able to survive in space and much work being done on 'extremophiles' in places such as hot springs and hydrothermal vents as well as the frozen Arctic. Maybe time for a bet at Ladbrokes on life being found in the liquid interior of Europa...

References

Carrasco, M.A., Buechler, S.A., Arnold, R.J., Sformo, T., Barnes, B.M. & Duman, J.G. (2012). Investigating the deep supercooling ability of an Alaskan beetle, Cucujus clavipes puniceus, via high throughput proteomics. Journal of Proteomics 75(4):1220-1234.
Damonte. E., Neyts, J., Pujol, C.A., Snoeck, R., Andrei, G., Ikeda, S., Witvrouw, M., Reymen, D., Haines, H. & Matulewicz, M.C. (1994). Antiviral activity of a sulphated polysaccharide from the red seaweed Nothogenia fastigiata. Biochemical Pharmacology 47(12): 2187-2192.
Doucet, D., Tyshenko, M.G., Davies, P.L. & Walker, V.K. (2002). A family of expressed antifreeze protein genes from the moth, Choristoneura fumiferana. European Journal of Biochemistry 269(1): 38-46.
Ishiwata, A., Sakurai. A., Nishimiya, Y., Tsuda, S. & Ito, Y. (2011). Synthetic study and structural analysis of the antifreeze agent xylomannan from Upis ceramboides. Journal of the American Chemical Society
133(48): 19524-19535.
Qin, W, Doucet, D., Tyshenko, M.G. & Walker, V.K. (2007). Transcription of antifreeze protein genes in Choristoneura fumiferana. Insect Molecular Biology 16(4): 423-434.
Sformo, T., Walters, K., Jeannet, K., Wowk, B., Fahy, G.M., Barnes, B.M. & Duman, J.G. (2010). Deep supercooling, vitrification and limited survival to -100 °C in the Alaskan beetle Cucujus clavipes puniceus (Coleoptera: Cucujidae) larvae. Journal of Experimental Biology 213(3): 502-509.
Walters, K.R., Serianni, A.S., Sformo, T., Barnes, B.M. & Duman, J.G. (2009). A nonprotein thermal hysteresis-producing xylomannan antifreeze in the freeze-tolerant Alaskan beetle Upis ceramboides. Proceedings of the National Academy of Sciences of the USA 106(48): 20210–20215.