Freeze-tolerant larvae of Drosophila melanogaster

Evolutionary adaptations for freeze-tolerance are considered to be highly complex and uneasy to mimic in laboratory. Among vertebrates, only a few species of amphibians and reptiles tolerate the formation of ice crystals in their body fluids. Freeze-tolerance is much more widespread in invertebrates, especially in overwintering insects. We have previously revealed some of the basic mechanisms of freeze-tolerance in subarctic drosophilid fly, Chymomyza costata (Kostal et al., PNAS USA 108, 13 041-046).

            In our new paper we show that the "tricks" learned form C. costata can be applied to a fruit fly of tropical origin with a weak innate capacity to tolerate even mild chilling. We found that surprisingly simple laboratory manipulations can change the chill susceptible insect to the freeze-tolerant one.Larvae of Drosophila melanogaster can then survive at subzero temperatures when approximately 50% of their body water turns to ice crystals. To achieve this goal, synergy of two fundamental prerequisites is required: (a) shutdown of larval development, including all the chill sensitive processes linked to it, by exposing larvae to low but above-lethal temperatures (quiescence), and (b) incorporating the free amino acid proline in tissues by feeding larvae a proline-augmented diet (cryopreservation).

Košťál V., Šimek P., Zahradníčková H., Cimlová J., Štětina T. (2012) Conversion of the chill susceptible fruit fly larva (Drosophila melanogaster) to a freeze tolerant organism. Proceedings of the National Academy of Sciences USA doi:10.1073/pnas.1119986109