Cellular Mergers Found to Kick-Start a Worm's Development

The merging of cells is a fundamental process in the development of many animals, but its exact influence on gene behaviour has remained unclear. Using the microscopic worm Caenorhabditis elegans as a model, researchers have now shed light on this mystery. The worm's skin, or epidermis, is formed by huge fused cells called syncytia, with one, hyp7, containing 139 individual nuclei.

This fusion is driven by a protein called EFF-1. Scientists investigated mutants with a defective EFF-1 protein, where these skin cells failed to merge. By analysing the genes being actively expressed—a process called transcriptomic analysis—they discovered widespread changes. The worms that could not fuse their cells failed to properly activate the genetic pathways needed to transition from embryo to larva.

The findings strongly suggest that the physical act of cell fusion is not just structural. It is a key event that helps to shape the transcriptional programmes which orchestrate an organism’s developmental journey, underscoring the significance of this cellular behaviour.