Boekhoff-Falk and her group have studied distal-less (dll) for years, previously investigating its role in the fruit fly hearing system and its limb development.
The current studies of the olfactory system were done in larvae rather than the more typically studied adult flies. Dissecting the younger, smaller flies demands the steadiest of hands, but the payoff is that larvae offer a substantially simpler view of brain development and wiring as well as insights into events occurring extremely early in development.
The researchers found dll was required for the development and growth of multiple cell types in the olfactory system, including those that receive, relay and process olfactory information. Dll must work for normal olfactory behavior to occur in larvae. And when dll is defective, the sense of smell is not present.
Zeroing in on the MB, the UW researchers also discovered an essential relationship between dll and the longest-living and most prolific neural stem cells found in fruit flies.
Boekhoff-Falk's team found that in flies with a mutated version of dll, these neural stem cells failed to proliferate. No other scientists have observed such strong defects in these cells at such an early stage.
The scientists identified markers that will allow them to learn how the stem cells decide which specialized cells they will become and how their growth may be regulated.
"We want to identify the niche, or the stem cell microenvironment, and the cells there that supply growth inputs needed to keep the stem-ness of the cells," she says.
Boekhoff-Falk believes the parallels to human stem cell biology may be strong. "Our model may be useful for further analysis of how this gene regulates stem cells," she says.
The experiments also opened the door to a better understanding of the evolution of the sense of smell.
"The prevailing view is that fly and mammal olfact
|Contact: Dian Land|
University of Wisconsin-Madison