Data from: Sporadic feeding regulates robust food entrainable circadian clocks in blind cavefish

The circadian clock represents a key timing system that enables organisms
to anticipate the day-night cycle. To ensure synchronization with the
environment it is entrained by various periodic signals of which light is
the best studied. Many investigations have pointed to the existence of two
distinct circadian oscillators: one regulated by the light-dark cycle
(light-entrainable oscillator) and the other set specifically by feeding
time (food-entrainable oscillator) independently of light, and which
regulates various aspects of feeding behaviour. Blind cavefish have
evolved under extreme conditions where they completely lack light exposure
and also experience food deprivation. Furthermore, they are under
particular pressure to optimize the timing of their feeding behaviour.
Here, we have investigated feeding regulated clocks in two well-studied
cavefish species, the Somalian cavefish Phreatichthys andruzzii and the
Mexican cavefish Astyanax mexicanus, in comparison with the
surface-dwelling zebrafish Danio rerio. Our results reveal that feeding
represents an extremely strong synchronizer for circadian locomotor
rhythmicity in subterranean cavefish. Indeed, we showed that consuming
just one meal every 4 days is sufficient to entrain circadian rhythmicity
in both cavefish species, but not in zebrafish. These profound adaptations
to an extreme environment provide unique insight into the connections
between feeding and circadian clocks.