The insect cryoprotective mixture ─ composition, function and evolutionary history.
The cryoprotectants of C. costata were localized in larval tissues using MALDI-MS imaging and their metabolism, thermal behaviour, and protective functions were studied.
Fig.: The cryoprotectants of C. costata were localized in larval tissues using MALDI-MS imaging and their metabolism, thermal behaviour, and protective functions were studied.
The accumulation of specific metabolites, which include sugars, polyols, amino acids, and methylamines, has been observed in organisms of all taxa in response to various types of environmental stress (extreme temperatures, drought, hypersalinity and osmotic challenges, high hydrostatic pressure). In a series of three papers, we describe the composition of a native mixture of metabolites (cryoprotectants) that help larvae of the subarctic drosophilid fly Chymomyza costata survive during deep freezing or cryopreservation in liquid nitrogen. We identify the metabolic sources and pathways for synthesis of cryoprotectants, the tissues in which they accumulate, and changes in their distribution during freezing of most body fluids. We found that different components of the mixture play different roles and act in synergy. Trehalose stimulates the transition to an amorphous, glassy solid phase. Concentrated proline creates a viscoelastic solution that moves to the boundary between ice crystals and dehydrated tissue, where it can serve as a "thermomechanical buffer." By analyzing larval responses to various environmental factors (short-day signal triggering diapause, cold acclimation stimulus, desiccation stressor), we also gain deeper insight into the evolutionary history of metabolic response accumulation.
Moos M., Korbelová J., Štětina T., Opekar S., Šimek P., Grgac R., Koštál V. (2022) Cryoprotective metabolites are sourced from both external diet and internal macromolecular reserves during metabolic reprogramming for freeze tolerance in drosophilid fly, Chymomyza costata. Metabolites 12, 163, doi: 10.3390/metabo12020163
Kučera L., Moos M., Štětina T., Korbelová J.,Vodrážka P., Des Marteaux L., Grgac R., Hůla P., Rozsypal J., Faltus M., Šimek P., Sedlacek R., Koštál V. (2022) A mixture of innate cryoprotectants is key for freeze tolerance and cryopreservation of a drosophilid fly larva. Journal of Experimental Biology 225, jeb243934, doi: 10.1242/jeb.243934
Hůla P., Moos M., Des Marteaux L., Šimek P., Koštál V. (2022) Insect cross-tolerance to freezing and drought stress: role of metabolic re-arrangement. Proceedings of the Royal Society B 289, 20220308, doi: 10.1098/rspb.2022.0308