The study, to be published July 12 in Nature, focused on the developing nervous system of a favored experimental organism: the soil nematode worm Caenorhabditis elegans. Cell survival and cell death during development in this animal is highly stereotyped. Among different embryos, cells in corresponding positions virtually always share the same fate. Because the worms are transparent, the fate of all cellsliving, dead, or dyingcan be followed relatively easily and filmed by using a video camera attached to a microscope.
Under normal circumstances, dead cells are engulfed by neighboring cells to eliminate them from the embryo. Until now, the engulfment process was viewed as an after-the-fact, disposal operation. Cold Spring Harbor Laboratory researchers Daniel Hoeppner and Michael Hengartner, together with Ralf Schnabel of the Institute for Genetics (Braunschweig, Germany), studied how the death and "burial" (engulfment) processes are cordinated during development of the C. elegans nervous system. They made two interesting discoveries.
First, the scientists found that when they weakened the genetically programmed signal for cells to die, most cells still died (65%) and an expected cohort of cells survived (15%). Surprisingly, however, a few cells (5%) proceeded all the way to death's door but at the very last stage before death (stage 3 of 4), they reverted to a normal appearance and
Contact: Peter Sherwood
Cold Spring Harbor Laboratory