The effects of 17α-ethynylestradiol (EE<sub>2</sub>) on gonadal development and differentiation in the estuarine killifish, <em>Fundulus heteroclitus</em>
Bibliographic record
Abstract
Endocrine disrupting substances (EDSs) comprise a wide variety of chemicals that perturb normal endocrine function including developmental and reproductive processes in vertebrates. The synthetic estrogen 17α-ethynylestradiol (EE2) is a commonly-used model EDS because of its environmental relevance and its effects on the reproductive endocrine system. Early life-stage exposure of fish to estrogenic EDSs causes effects such as intersex (ovotestes in males) and feminization. This study aims to confirm the period of gonadal differentiation in the estuarine killifish or mummichog (Fundulus heteroclitus) and to determine the sensitivity of gonadal development to EE2. Artificially-regressed mummichog were spawned, and fertilized eggs were collected and exposed to EE2 (0, 10, 50 and 250ng/L) within 8 h of spawning. Embryos and larvae were continually exposed in petri dishes and beakers (26˚C) and sampled weekly from hatch date to 10 weeks post-hatch (wph) to determine histologically the sensitivity of gonadal development to EE2. Exposure to EE2 (10-250ng/L) resulted in a concentration-dependent increase in skeletal abnormalities and mortalities; larval lengths proved insensitive to EE2 exposure. Complete gonadal differentiation in mummichog occurred by 3 wph in control groups, whereas exposure to EE2 accelerated gonadal differentiation as early ast 1 wph in all EE2 exposed groups. Sex ratios were skewed (>80% female phenotype) within all groups treated with EE2. This study demonstrates that early onset of exposure elicits effects on developing mummichog as exposure of EE2 prior to establishment of endogenous differentiation pathways influenced and altered sex differentiation, resulting in feminized groups of fish at environmentally-relevant and higher concentrations.
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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".