Molecular mechanisms and energetic costs of recovery from freezing in the polyextremophile midge, Belgica antarctica Jacobs.

Authors

Cleverson de Sousa Lima, Melise C Lecheta, Samuel Cecconi, Scott Hotaling, Paul B Frandsen, Peter Convey, Scott A L Hayward, J D Gantz, Yuta Kawarasaki, Jeramiah Smith, Nicholas M Teets

Published in

The Journal of experimental biology. Jul 14, 2026. Epub Jul 14, 2026.

Abstract

Extracellular freezing challenges insects in several ways, including mechanical damage from ice crystals, exposure to stressful levels of cold, and cellular dehydration. While stress-response mechanisms activated during and immediately after freezing are well-studied, less is known about how freeze-tolerant organisms recover from freezing in the longer-term and whether this recovery carries energetic costs. Here, we tracked changes in gene expression and energy stores over the course of 15 days following extracellular freezing using the world's southernmost insect, Belgica antarctica Jacobs (Diptera: Chironomidae), as a study system. We found that B. antarctica employed a coordinated "emergency" stress-response system during early-recovery (0-1 d), which includes the upregulation of genes involved in inhibiting cell death (e.g., Bcl-2, IAP-1) alongside mechanisms involved in damage repair and clearance of cell debris (e.g., heat shock proteins, autophagy, proteasome). Concomitantly, genes involved in ecdysone biosynthesis and juvenile hormone degradation were downregulated through the 1st day of recovery, and several genes involved in cuticle development were downregulated between the 3rd and 15th day of recovery, suggesting that homeostasis may not have been completely restored for two weeks after B. antarctica had thawed. These physiological changes did not lead to a detectable depletion of energy stores, indicating that this emergency response system does not incur significant energy drain. These results suggest that evoking a coordinated stress-response with minimal energy usage may be crucial for B. antarctica to persist in cold environments, and that blocking apoptosis and pausing development could provide sufficient time for freezing injury to be fully addressed.

PMID:
42444539
Bibliographic data and abstract were imported from PubMed on 14 Jul 2026.

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