Spinal Oxygen Sensors in Larval Amphibians
Bibliographic record
Abstract
We have recently identified mammalian spinal preganglionic sympathetic neurons as spinal oxygen sensors (SOS). These cells are excited by hypoxia, silenced by hyperoxia, and contribute to oxygen‐sensitive sympathetic responses important for cardiovascular regulation. In general, terrestrial vertebrates experience acute or chronic hypoxia only during pathophysiological states. In contrast, aquatic vertebrates routinely experience environmental hypoxia and hypoxic sensitivity is critical to homeostatic regulation. The aim of the current study is to identify SOS neurons in aquatic larval amphibians. We test the hypothesis that endogenously hypoxia‐sensitive neurons are present in the spinal cords of larval bullfrogs ( Lithobates catesbeianus ). Spinal cords were isolated from bullfrog tadpoles and incubated for 8 hours in either artificial cerebrospinal fluid or high Mg/low Ca solution to synaptically maintain or isolate cells. Preparations were then exposed to either hyperoxia, normoxia or hypoxia (PO 2 of 700, 300 or 100 mmHg respectively) for 3 hours, after which tissues were fixed, sliced and stained to reveal early gene protein expression (c‐Fos) characteristic of cellular activation. Results illustrate the presence of hypoxia‐activated neurons in both synaptically intact and isolated preparations, indicating SOS neurons in amphibian spinal cords. We are characterizing the identities of these cells. Support or Funding Information Work reported in this publication was supported by the National Heart Lung and Blood Institute and National Institute of General Medical Sciences of the National Institutes of Health under awards 1R15HL126105, 1SC2GM112570 and three linked awards number RL5GM118990, TL4GM118992 and 1UL1GM118991. Additional support was provided by the Natural Science and Engineering Research Council of Canada, the Canadian Institutes of Health Research and Alberta Innovates ‐ Health Solutions (RJAW) and the Australian Research Council (MD). The work is solely the responsibility of the authors and does not necessarily represent the official view of the National Institutes of Health or any other funding body.
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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".