Date: 25.10.2022

Winter-accumulated proline, trehalose, and protein stabilize plasma membrane integrity of the freeze-tolerant insect

Some insects survive winter with their body water frozen. In preparation for overwintering, they accumulate mixtures of different small molecules – most often sugars, amino acids and their derivatives, and also proteins, in their hemolymph. Based on in vitro assays and theory, insect physiologists hypothesized that these molecules protect insect enzymes and biological membranes against loss of viable structure during the freezing stress.

We have now tested the hypothesis empirically using the freeze-tolerant larva of drosophilid fly, Chymomyza costata that accumulates proline, trehalose and protein in hemolymph. We confirmed that the larval enzymes are indeed stabilized by accumulated compounds in vitro, but found that the enzymes likely are not primary targets of freezing injury in vivo, in their native biochemical context, and the seasonally accumulated compounds are not needed to stabilize them. In contrast, we proved that the fat body cell plasma membrane is highly sensitive to freezing injury but its integrity in winter larvae is protected by relatively high concentrations of proline, trehalose and protein working in synergy.

Grgac R., Rozsypal J., Des Marteaux L., Štětina T., Koštál V. (2022): Stabilization of insect cell membranes and soluble enzymes by accumulated cryoprotectants during freezing stress. PNAS USA 119, e2211744119, doi: 10.1073/pnas.2211744119






Biology Centre CAS
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