Tissue- and temperature-dependent expression, enzyme activity, and RNAi knockdown of Catalase in a freeze-tolerant insect
Bibliographic record
Abstract
• Catalase expression and activity are elevated in freeze-tolerant cricket fat body. • RNAi knocks down Catalase in fat body and midgut at a warm temperature (22 °C). • RNAi is not effective at a cool temperature (15 °C) that preserves freeze tolerance. • Catalase knockdown has no impact on survival of a mild freeze treatment. • The role of antioxidants in freeze tolerance warrants further study. Organisms that overwinter in temperate climates may experience freezing and freezing-induced oxidative stress during winter. While many insect species can survive freezing, reverse genetics techniques such as RNA interference (RNAi) have not been used to understand the physiological mechanisms underlying freeze tolerance. The spring field cricket Gryllus veletis can survive freezing following a 6-week fall-like acclimation. We used RNAi to knock down expression of an antioxidant enzyme in G. veletis to test the hypothesis that minimizing oxidative stress is important for freeze tolerance. In fat body tissue, Catalase mRNA abundance and enzyme activity increased during the fall-like acclimation that induces freeze tolerance. Other tissues such as midgut and Malpighian tubules had more stable or lower Catalase expression and activity during this acclimation. In summer-acclimated (freeze-intolerant) crickets, RNA interference (RNAi) effectively knocked down production of the Catalase mRNA and protein in fat body and midgut, but not Malpighian tubules. In fall-acclimated (freeze-tolerant) crickets, RNAi efficacy was temperature-dependent, functioning well at warm (c. 22 °C) but not cool (15 °C or lower) temperatures. This highlights a challenge of using RNAi in organisms acclimated to low temperatures, as they may need to be warmed up for RNAi to work, potentially affecting their stress physiology. Knockdown of Catalase via RNAi in fall-acclimated crickets also had no effect on the ability of the crickets to survive a mild freeze treatment, suggesting that Catalase may not be necessary for freeze tolerance. Our study is the first to demonstrate that RNAi is possible in a freeze-tolerant insect, but further research is needed to examine whether other genes and antioxidants are needed for G. veletis freeze tolerance.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".