Rescue of Light Responses in the Drosophila “Null” Phospholipase C Mutant, norpA, by the Diacylglycerol Kinase Mutant, rdgA, and by Metabolic Inhibition
Bibliographic record
Abstract
Light responses in Drosophila are reportedly abolished in severe mutants of the phospholipase C (PLC) gene, norpA. However, on establishing the whole-cell recording configuration in photoreceptors of the supposedly null allele, norpAP24, we detected a small ( approximately 15 pA) inward current that represented spontaneous light channel activity. The current decayed during approximately 20 min, after which tiny residual responses (<2 pA) were elicited by intense flashes. Both spontaneous currents and light responses appeared to be mediated by residual PLC activity, because they were enhanced by impairing diacylglycerol (DAG) kinase function by mutation (rdgA) or by restricting ATP but were reduced or abolished by a mutation of the PLC-specific Gq alpha subunit. It was reported recently that metabolic inhibition activated the light-sensitive transient receptor potential and transient receptor potential-like channels, even in norpAP24, leading to the conclusion that this action was independent of PLC (Agam, K., von Campenhausen, M., Levy, S., Ben-Ami, H. C., Cook, B., Kirschfeld, K., and Minke, B. (2000) J. Neurosci. 20, 5748-5755). However, we found that channel activation by metabolic inhibitors in norpAP24 was strictly dependent on the residual PLC activity underlying the spontaneous current, because the inhibitors failed to activate any channels after the spontaneous current had decayed. By contrast, polyunsaturated fatty acids invariably activated the channels independently of PLC. The results strongly support the obligatory requirement for PLC and DAG in Drosophila phototransduction, suggest that activation by metabolic inhibition is primarily because of the failure of diacylglycerol kinase, and are consistent with the proposal that polyunsaturated fatty acids, which are potential DAG metabolites, act directly on the channels.
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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) | 0.001 | 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 | 0.001 |
| 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".