( By studying microscopic hairs called ci...)'Cellular antennae' on algae give clues to how human cells receive signals

Cilia perform many functions on human cells; they propel egg and sperm cells to make fertilization possible, line the nose to pick up odors, and purify the blood, among other tasks.

With such a range of abilities, cilia serve as both motors and "cellular antennae," said Dr. William Snell, a professor of cell biology at UT Southwestern and senior author of new research on cilia published in the May 5 issue of Cell.

Genetic defects in cilia can cause people to develop debilitating kidney disease or to be born with learning disabilities, extra fingers or toes, or the inability to smell.

But no one really knows how cilia work, or, in some parts of the body, what their function is.

"There are cilia all over within our brain, and we don't have a clue about what they're doing," Dr. Snell said.

He and his team use the microscopic green alga, Chlamydomonas reinhardtii, which has two individual cilia. This alga allows researchers to manipulate genes and study the resulting effects on cilia in a way that would be impossible in animals such as mice.

"Chlamy is one of the few model organisms in which it's possible to do these kinds of studies," Dr. Snell said.

Normally, cilia ?also called flagella ?are built and maintained by an internal bidirectional, escalator-like system that ferries molecules to and from the tips by a process called intraflagellar transport, or IFT.

The UT Southwestern researchers used a mutant temperature-sensitive strain of the alga that behaved normally at lower temperatures. At higher temperatures, however, the IFT process stopped, and its components disappeared from the cilia. The cilia themselves were still able to beat, or move back and forth, for about 40 m
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Source:UT Southwestern Medical Center