Metabolomic signatures associated with cold adaptation and seasonal acclimation of Drosophila: profiling of 43 species.

Cold tolerance is a key determinant of poleward colonization in insects. However, the physiological basis underlying interspecific differences in cold tolerance is not fully understood. Here, we analyzed cold tolerance and metabolomic profiles in warm- and cold-acclimated phenotypes of 43 Drosophila species representing a latitudinal gradient from the tropics to the boreal zone.

Insect cross-tolerance to freezing and drought stress: role of metabolic rearrangement.

The accumulation of trehalose has been suggested as a mechanism underlying insect cross-tolerance to cold/freezing and drought. Here we show that exposing diapausing larvae of the drosophilid fly, to dry conditions significantly stimulates their freeze tolerance. It does not, however, improve their tolerance to desiccation, nor does it significantly affect trehalose concentrations.

A mixture of innate cryoprotectants is key for freeze tolerance and cryopreservation of a drosophilid fly larva.

Insects that naturally tolerate internal freezing produce complex mixtures of multiple cryoprotectants (CPs). Better knowledge on composition of these mixtures, and on the mechanisms of individual CP interactions, could inspire development of laboratory CP formulations optimized for cryopreservation of cells and other biological material. Here, we identify and quantify (using high resolution mass spectrometry) a range of putative CPs in larval tissues of a subarctic fly, Chymomyza costata, which survives long-term cryopreservation in liquid nitrogen.

Transcriptional analysis of insect extreme freeze tolerance.

Few invertebrates can survive cryopreservation in liquid nitrogen, and the mechanisms by which some species do survive are underexplored, despite high application potential. Here, we turn to the drosophilid to strengthen our fundamental understanding of extreme freeze tolerance and gain insights about potential avenues for cryopreservation of biological materials. We first use RNAseq to generate transcriptomes of three larval phenotypic variants: those warm-acclimated in early or late diapause (weak capacity to survive cryopreservation), and those undergoing cold acclimation after diapause entry (extremely freeze tolerant, surviving cryopreservation).

Recovery from supercooling, freezing, and cryopreservation stress in larvae of the drosophilid fly, Chymomyza costata.

Physiological adjustments accompanying insect cold acclimation prior to cold stress have been relatively well explored. In contrast, recovery from cold stress received much less attention. Here we report on recovery of drosophilid fly larvae (Chymomyza costata) from three different levels of cold stress: supercooling to -10 °C, freezing at -30 °C, and cryopreservation at -196 °C.