Inelegant Worms Provide Clues About Development
The normal nematodes in Fern Finger’s lab move in beautiful S-shaped curves across their petri dish. In fact, it was these elegant movements that gave the tiny, clear worms the Latin name Caenorhabditis elegans. But the dish also contains worms with a very specific genetic defect, a mutant unc-85 gene, which are easily identified as the clumsiest dancers on the tiny dance floor.The mutant worms, which are unable to move backward or even mate with one another, hold valuable information in their genetic makeup that could help scientists better understand the role of specific genes in both normal and abnormal development. While studying unc-85, Finger, assistant professor of biology, discovered that the gene significantly impacted DNA replication in the nervous system.
Finger found that the unc-85 gene encodes what is known as a histone chaperone proteina protein that is essential for the packaging of DNA and the expression of different genes. In worms raised with a mutant unc-85 gene, the creation of new DNA strands is impaired during the last stages of development known as the post-embryonic stage. Specifically, DNA replication in cells that produce neurons is blocked, creating the ungainly worms.
Surprisingly, despite the presence of the genetic mutation, the worms still live to adulthood and are able to reproduce because they are hermaphrodites and can impregnate themselves. Under the microscope, unc-85 was found throughout nearly every cell nucleus in the worm during the earliest stages of development, but as development progressed, the protein became restricted to cells that replicate DNA, primarily in the neuronal precursors and reproductive organs. Finger is now looking to expand the research to better understand why and how the organism continues to undergo a certain level of normal cell division despite the genetic defect.