Fruitflies and the four seasons

A handful of central brain neurons help fruitflies adapt to different seasons, new research shows¹. These “clock neurons” drive the internal clock or circadian rhythms in fruitflies.

The research may throw light on how 24-hour circadian rhythms run in all animals, including humans.   

The tips of the axons of s-LNv “clock” neurons grow and retract every 24 hours. But what drives this neuronal plasticity had remained unknown until Justin Blau and his teammates from New York University Abu Dhabi and US-based New York University identified a specific protein that drove the plasticity of the clock neurons in fruitflies.

To investigate the roles of that protein, the researchers manipulated the growth and retraction cycles of the clock neurons. 

When the clock neurons were permanently retracted, the flies behaved normally during long days mimicking summer, but showed mistimed activity during short days mimicking winter. When the retraction cycles of the clock neurons were fully stopped, the flies failed to anticipate the earlier dawn of “summer” days but had normal activity on “winter” days. 

This suggests that the plasticity of the clock neurons helps flies adjust their behavior across seasons.

“This fruitfly study gives us a unique system to understand the molecular determinants of neuronal plasticity,” says Blau.

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