Characterization of mechanisms for Ca2+ and HCO3–/CO32– acquisition for shell formation in embryos of the freshwater common pond snail <i>Lymnaea stagnalis</i>
Why this work is in the frame
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Bibliographic record
Abstract
The freshwater common pond snail Lymnaea stagnalis produces embryos that complete direct development, hatching as shell-bearing individuals within 10 days despite relatively low ambient calcium and carbonate availability. This development is impaired by removal of ambient total calcium but not by removal of bicarbonate and/or carbonate. In this study we utilized pharmacological agents to target possible acquisition pathways for both Ca(2+) and accumulation of carbonate in post-metamorphic, shell-laying embryos. Using whole egg mass flux measurements and ion-specific microelectrode analytical techniques, we have demonstrated that carbonic anhydrase-catalyzed hydration of CO(2) is central in the acquisition of both shell-forming ions because it provides the hydrogen ions for an electrogenic vacuolar-type H(+)-ATPase that fuels the uptake of Ca(2+) via voltage-dependent Ca(2+) channels and possibly an electrogenic Ca(2+)/1H(+) exchanger. Additionally, CO(2) hydration provides an endogenous source of HCO(3)(-). Thus, hydration of endogenous CO(2) forms HCO(3)(-) for calcification while hydrogen ions are excreted, contributing to continued Ca(2+) uptake, as well as creating favorable alkaline internal conditions for calcification. The connections between Ca(2+) and HCO(3)(-) acquisition mechanisms that we describe here provide new insight into this efficient, embryonic calcification in freshwater.
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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