The <i>Drosophila Melanogaster</i> Homologue of an Insect Calcitonin-Like Diuretic Peptide Stimulates V-ATPase Activity in Fruit Fly Malpighian Tubules
Bibliographic record
Abstract
The Drosophila melanogaster homologue of an insect calcitonin-like diuretic hormone was identified in a BLAST search of the Drosophila genome database. The predicted 31-residue amidated peptide (D. melanogaster DH31; Drome-DH31) was synthesised and tested for activity on fruit fly Malpighian tubules. It increases tubule secretion by approximately 35 % of the response obtained with a myokinin from the housefly Musca domestica (muscakinin; Musdo-K) and has an EC50 of 4.3 nmol x l(-1). The diuretic activities of Drome-DH31 and Musdo-K were additive when tested at threshold and supra-maximal concentrations, which suggests that they target different transport processes. In support of this, Drome-DH31 increased the rate of secretion by tubules held in bathing fluid with a reduced Cl- concentration, whereas Musdo-K did so only in the presence of Drome-DH31. Stimulation with Drome-DH31 increased the lumen-positive transepithelial potential in the main secretory segment of the tubule. This was attributed to activation of an apical electrogenic proton-translocating V-ATPase in principal cells, since it was associated with hyperpolarisation of the apical membrane potential and acidification of secreted urine by 0.25 pH units. Exogenous 8-bromo-cyclic AMP and cyclic GMP increased tubule secretion to the same extent as Drome-DH31 and, when tested together with the diuretic peptide, their activities were not additive. Stimulation with Drome-DH31 resulted in a dose-dependent increase in cyclic AMP production by tubules incubated in saline containing 0.5 mmol x l(-1) 3-isobutyl-1-methylxanthine, whereas cyclic GMP production was unchanged. Taken together, the data are consistent with Drome-DH31 activating an apical membrane V-ATPase via cyclic AMP. Since the K+ concentration of the secreted urine was unchanged, it is likely that Drome-DH31 has an equal effect on K+ and Na+ entry across the basolateral membrane.
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How this classification was reachedexpand
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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".