Myosin waves and a mechanical asymmetry guide the oscillatory migration of <i>Drosophila</i> cardiac progenitors
Bibliographic record
Abstract
Abstract Heart development begins with the formation of a tube, as cardiac progenitors migrate from opposite sides of the embryo and meet medially. Defective cardiac progenitor movements cause congenital heart defects. However, the mechanisms of cell migration during early heart development remain poorly understood. We investigated the mechanisms of movement of the Drosophila cardiac progenitors, the cardioblasts. Using quantitative time-lapse microscopy, we found that cardioblasts did not advance monotonically. Instead, cardioblasts took periodic forward and backward steps as they migrated. The forward steps were greater in both amplitude and duration, resulting in net forward movement of the cells. The molecular motor non-muscle myosin II displayed an alternating pattern of localization between the leading and trailing ends of migrating cardioblasts, forming oscillatory waves that traversed the cells. The alternating pattern of myosin polarity was associated with the alternative contraction and relaxation of the leading and trailing edges of the cell. Mathematical modelling predicted that forward migration requires the presence of a stiff boundary at the trailing edge of the cardioblasts. Consistent with this, we found a supracellular actin cable at the trailing edge of the cardioblasts. When we reduced the tension sustained by the actin cable, the amplitude of the backward steps of cardioblasts increased, thus reducing the net forward speed of migration. Together, our results indicate that periodic cell shape changes coupled with a polarized actin cable produce asymmetrical forces that guide cardioblast migration.
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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".