Combined Diel Cycles of Thermal Stress and Hypoxia Impact Parental Progeny Investment, Offspring Stress Responsiveness and Thermal Tolerance in Zebrafish (Danio rerio)
Bibliographic record
Abstract
Climate change increases the frequency and severity of environmental stressors in aquatic habitats including elevated temperatures and hypoxia. The maternal match hypothesis (MMH) predicts that parental exposure to environmental stressors may help offspring cope with similar stressors through altered parental investment but lacks empirical support. To address this, I investigated how zebrafish exposure to diel cycles of elevated temperatures and hypoxia affect parental progeny investment of cortisol and heat shock proteins (HSPs) and determined whether the combined stressor affects offspring stress response development, responsiveness, tolerance, and behaviour. \nFirst, to examine parental investment of stress-related signals in response to environmental stressors, I exposed adult zebrafish to individual or combined cycles of elevated temperature and hypoxia and quantified maternal and embryonic levels of cortisol and HSPs. The embryonic deposition of HSPs largely paralleled the ovarian cellular stress response. In contrast, the combined exposure simultaneously increased ovarian and decreased embryonic cortisol levels. \nNext, to determine how parental investment affects offspring stress responsiveness and tolerance, I exposed parents to cycles of elevated temperature and hypoxia, quantified offspring stress responses to a thermal and hypoxia challenge, and assessed larval thermal and hypoxia tolerance. Exposure to the combined challenge increased cortisol levels in control larvae but had no effect on larvae from exposed parents. In contrast, the combined challenge increased HSP levels in larvae from exposed parents only. The parental exposure also increased offspring thermal but not hypoxia tolerance. \nLastly, I assessed how altered parental progeny investment of stress-related signals affects stress response development, and the larval stress and behavioural responses to a sustained thermal stress. Offspring from exposed parents had lower cortisol and higher HSP levels prior to the larval stage. Following sustained thermal stress, larvae from exposed parents had blunted cortisol responses, and stronger HSP responses. Although thermal stress affected larval behaviours, the effects were independent of parental exposure. \nTogether, my thesis both supports and advances our understanding of the MMH. I demonstrate for the first time that combined environmentally relevant stressors affect parental progeny investment of endocrine and cellular stress-related signals with lasting effects on offspring stress response development, responsiveness, and tolerance.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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 source (direct Gemma or distilled Codex), 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".