Validation of the use of phenylhydrazine hydrochloride (PHZ) for experimental manipulation of haematocrit and plasma haemoglobin in birds
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Bibliographic record
Abstract
The levels of haematocrit (Hct) and plasma haemoglobin (Hb) vary markedly through the annual cycle of birds, as well as among individuals at all life‐stages (embryos, chicks, adults). It is thus surprising that the functional, fitness‐related consequences of this variation are poorly understood. Putative ‘adaptive’ variation in these haematological traits has been associated with varying demands for aerobic capacity and oxygen transport, for example during migration, winter acclimatization, with increasing altitude, or during parental care. It has also been proposed that changes in Hct might reflect ‘costs’ of parental investment, for example during ‘reproductive anaemia’. However, almost all studies to date have been correlative. Here we describe a series of experiments that validate the use of phenylhydrazine hydrochloride (PHZ) for the transient, reversible experimental manipulation of Hct and Hb in birds. A single bolus injection (12.5 μg PHZ/g body weight delivered via intra‐muscular injection) caused a rapid decrease in Hct and plasma Hb within 24 h, from pretreatment values of 50–54% to 40–44% in non‐breeding Zebra Finches Taenipoygia guttata and European Starlings Sturnus vulgaris , and to 35% in breeding female Zebra Finches, changes within the normal physiological range. Hct and Hb returned to pre‐injection levels within 5–10 days of treatment. Changes in plasma Hb paralleled those for Hct. We suggest that PHZ treatment provides a widely applicable technique for use in experimental work to establish relationships between haematological status, aerobic capacity, workload (e.g. migration, parental care, thermoregulation), individual quality (of both adults and chicks) and trade‐offs such as costs of reproduction.
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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 it