Winter is coming and with it comes the cold: the nose-nipping, coat-zipping, hot-chocolate-sipping cold. However, as we crank up the heat, consider that most of the insects of our climate are facing the cold head-on. Insects are ectotherms, meaning that the temperature of their body will follow that of the environment. Thus, when the temperature of the environment plunges, so does the body temperature of an insect. Although we know that insects are able to survive the cold, we don’t yet understand all of the mechanisms or the evolution behind their ability to do so. Never one to shy away from a challenge, Dr. Hiroko Udaka decided to investigate if and how the expression of particular genes may underlie the ability of insects to tolerate the cold.
Udaka was already aware that a particular gene, aptly named Frost, was expressed in fruit flies after they were allowed to recover from cold. This meant that she had a candidate gene that might be controlling the ability of flies survive the cold. In other words, if they couldn’t express this gene, would they be unable to tolerate a chilly environment? Using flies that were transgenically modified to suppress the expression of Frost, she was able to test the role of this gene in the ability for fruit flies to survive and recover from cold exposure. Udaka exposed her genetically modified flies to the cold and then measured how many flies survived and the time it took them to recover from the cold. What she found, however, was perplexing. Flies with the expression of Frost suppressed were seemingly unaffected, if not better able to recover from cold! It would seem that Frost was giving Udaka and her team the cold shoulder – but could Frost play a more indirect role in cold tolerance?
Far from discouraged, Udaka is one step closer to unraveling some of the mysteries of insect cold tolerance and now believes that Frost may instead be linked to cold-induced immune responses in insects. Continuing with these kinds of molecular manipulations, Udaka and her team will further investigate the role of Frost in the ability of insects to survive cold and its potential importance for insect immunity at low temperatures. Talk about catching the cold bug!
Udaka, H., Percival-Smith, A. and Sinclair, B. J. (2013). Increased abundance of Frost mRNA during recovery from cold stress is not essential for cold tolerance in adult Drosophila melanogaster. Insect Molec Biol 22, 541-550.
Written by Laura Ferguson, Sinclair Lab
Posted November 27, 2013