1.   But these rhythms disappeared in fruit flies in which the clock genes in the antennas had been altered.

2.   Hekimi thinks the clock genes tie into the second theory.

3.   The first clock genes were discovered in bread mold and fruit flies, organisms that have highly periodic growth and reproductive cycles.

4.   They had discovered a clock gene.

5.   What researchers hope to determine is where the clock genes might fit in among the major theories of aging.