Testing the fitness of biologi...( ogaster were raised in constant illumi...)

When the algae strains were placed in a chamber with constant light, however, the researchers were surprised to discover that the shoe was on the other foot: The algae with the disrupted internal clock divided and grew at a slightly faster rate than their clockwatching cousins, both those with natural biological clocks and those whose clocks were damped.

"This was the most surprising result of our study," says Johnson. "Under constant conditions, the circadian clock system is of no benefit and, in fact, might even be bad for the algae."

The scientist doesn't know for certain why this happens, but he has some ideas. The microscopic plants use their biological clocks to turn their photosynthesis system on and off. In a normal 14-hour day/night cycle, this allows the microscopic plant to maximize the amount of chemical energy it can extract during daylight.

"In constant illumination, however, the biological clocks may keep shutting down photosynthesis in expectation of the darkness that never comes," says Johnson.

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Contact: David F. Salisbury
david.salisbury@vanderbilt.edu
615-343-6803
Vanderbilt University
23-Aug-2004