The team focused on fertilization of the alga, a process that requires a cilium to bind to a molecule on a cilium from a cell of the opposite mating type. They found that when the external molecule binds to a cilium, it activates an enzyme that signals the start of a chain of chemical reactions.
Although the cilia could move without IFT and bind to the molecules of the cilia of the opposite type, those cells were unable to respond to the signaling molecules. The failure to activate the chain of chemical reactions indicated that IFT was necessary for this function.
Analysis showed that the cilia signaling process was similar to that found in human cells, such as those in the nose involved in the sense of smell and those in the developing nervous system that sculpt our brains.
Uncovering this series of reactions will make it possible to test, for instance, drugs that can affect cilia, in the hope of finding substances that would also be effective in higher animals, Dr. Snell said.
"This is another example of how basic science research can have big results," he said. "Studies on Chlamydomonas will help us understand the unique qualities of cilia that have led to their use in chemosensory pathways in humans."