The nerve cells, called pacemaker neurons, contain a molecular clock that controls a 24-hour circadian rhythm in activity similar to the rhythms in sleep/wake cycles found in humans and many other organisms. It was previously known that pacemaker neurons receive visual signals to reset their molecular clocks, but scientists did not have any evidence that they transmitted information to their target cells, as most other neurons do.
The current study shows that pacemaker neurons do in fact transmit signals and are required for a rapid behavior, according to the paper, published in the January 20th issue of Neuron. The study was conducted by Esteban O. Mazzoni, a graduate student in NYU's Biology Department, Biology Professor Claude Desplan, and Assistant Biology Professor Justin Blau. The finding suggests it may be possible to identify genes that can be used to treat problems such as sleep disorders and jet lag.
The researchers examined the role that pacemaker neurons play in helping Drosophila larvae avoid light. Drosophila is a species of fruit fly commonly used in biological research. Fruit fly larvae foraging for food avoid light, presumably to keep away from predators. Unlike adult Drosophila, the larvae only have one structure for gathering visual cues, called Bolwig's Organ. This organ senses the amount of light in the environment and transmits that information to the pacemaker neurons to reset their molecular clocks.
In the experiments described by Mazzoni, Desplan, and Blau, fly larvae were placed in the center of a Petri dish with one side dark and the other illuminated. Normal larvae exhibited the natural behavior and clustered on the dark side. However, when the larvae had their pacemaker neurons disabled, they were as blind as larvae that had their light-sensing organs removed and
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Contact: James Devitt
james.devitt@nyu.edu
212-998-6808
New York University
25-Jan-2005