The Influence of Hibernation Temperature on Deiodinase 2 in Red-Sided Garter Snakes (<i>Thamnophis sirtalis parietalis</i>)
Bibliographic record
Abstract
Environmental cues such as day length and temperature contribute to timing of biological rhythms in seasonal breeders. Life-history transitions such as spring emergence from hibernation, migration, or mating must be coordinated with environmental conditions or survival is compromised. Therefore, there must be chemical signaling pathways in the brain that transduce seasonally-changing sensory inputs into signals that initiate a hormonal cascade, culminating in reproductive behavior. The relative importance of environmental cues to reproductive timing varies with species, time of year, and sex, and the mechanisms driving these differences remain unknown. The role of photoperiod in regulating reproductive behavior has been explored in birds and mammals, but much less is known about the role of so-called supplementary cues such as temperature, which is crucial in the timing of ectotherm reproduction. This is a critical gap in our knowledge, because shifts in seasonal temperatures due to climate change could create a mismatch between peak reproductive behavior and resources necessary for gestation and offspring survival. Deiodinase 2 (DIO2) enzyme is a critical component of the pathway that mediates reproduction in photoperiod-activated seasonal breeders, but whether deiodinase 2 is sensitive to seasonal changes in environmental temperature is unknown. In this study, we used an ectothermic vertebrate known to be a temperature-activated seasonal breeder, the red-sided garter snake (Thamnophis sirtalis parietalis), to investigate changes in hypothalamic DIO2 in response to hibernation at 4°C and 12°C. We captured male and female snakes in Manitoba, Canada as they returned to their winter den site from summer feeding grounds. Snakes were hibernated in complete darkness at either 4°C or 12°C for up to 16 weeks. A subset of each sex and temperature group were euthanized at intervals, and the brains collected and processed for DIO2 immunohistochemistry. DIO2-specific staining was found in the anterior hypothalamus, in the periventricular hypothalamic nucleus and ventral pre-optic area, along the longitudinally central region of the olfactory tract, in the bed nucleus of the stria terminalis, caudally in the cortex and optic tectum, and in the lateral septal nucleus. DIO2-stained area in the anterior hypothalamus was quantified. Male T. sirtalis in both the 4°C and 12°C groups were found to have an increase in DIO2-specific staining in the anterior hypothalamus after 8 weeks in hibernation. Female T. sirtalis were found to have an increase in DIO2-specific staining in the anterior hypothalamus after 8 weeks in the 12°C group only. These findings shed light on the
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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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".