The Power of the Worm
Measuring 1 mm in length, the roundworm has 959 cells and a life cycle of only three days. Roundworm development is easy to trace as cells grow and move. The roundworm genome contains 100 million DNA base pairs.
Professor Daniel Starr, Department of Molecular and Cellular Biology, explores one of the most important parts of the cell, the nucleus. Since the nucleus is the control center, its proper positioning within the cell is essential to many developmental processes, like fertilization, cell movement and tissue development. This positioning process is called nuclear migration and Starr is at the forefront of identifying the cellular mechanics behind it. To do so, he’s getting big help from a little worm, the nematode Caenorhabditis elegans.
Transparent, C. elegans reaches only about 1 mm in length and doesn’t have a heart or circulatory system. Nine hundred and fifty-nine cells make up its entire body, and it’s this simplicity that makes it a valuable model. While nematodes and humans differ in many ways—namely, one doesn’t have a backbone—the genes and molecular pathways underlying both species are very similar.
“The big picture is that worms are little humans,” says Starr. “If you can understand how a cellular machine works in development in a worm, 95 percent of the time it’s going to work exactly the same in a human.”
Starr and his colleagues can watch the nuclear migration process live in C. elegans thanks to the worm’s transparent skin. The rapid and well-defined development of its cells, called a cell fate map, adds to its advantageousness as a model.
“We know where every cell is supposed to be at every time in development, and I can do a mutant screen to look for cells in the wrong place at the wrong time,” says Starr.
Starr is particularly interested in how the nucleus shifts and squeezes its shape to allow a cell to travel throughout an organism’s body. Dysfunction of the cellular mechanics involved in nuclear migration can lead to serious medical conditions, like sterility, blindness, autism and cancer.
“Even today, we don’t understand how this machine is put together or how it’s regulated during development,” he says.
Once these biological machines are defined in invertebrates, researchers can use those discoveries to run similar experiments in vertebrate model organisms, which bear a closer relationship to humans.
“These worms have the power to make fundamental contributions to human health,” says Starr.