Publication Date:
2020-11-25
Description:
Antarctic krill (Euphausia superba) are high latitude pelagic organisms which play a key ecological role
in the ecosystem of the Southern Ocean. To synchronize their daily and seasonal life-traits with their
highly rhythmic environment, krill rely on the implementation of rhythmic strategies which might
be regulated by a circadian clock. A recent analysis of krill circadian transcriptome revealed that their
clock might be characterized by an endogenous free-running period of about 12–15 h. Using krill
exposed to simulated light/dark cycles (LD) and constant darkness (DD), we investigated the circadian
regulation of krill diel vertical migration (DVM) and oxygen consumption, together with daily patterns
of clock gene expression in brain and eyestalk tissue. In LD, we found clear 24 h rhythms of DVM
and oxygen consumption, suggesting a synchronization with photoperiod. In DD, the DVM rhythm
shifted to a 12 h period, while the peak of oxygen consumption displayed a temporal advance during
the subjective light phase. This suggested that in free-running conditions the periodicity of these
clock-regulated output functions might reflect the shortening of the endogenous period observed
at the transcriptional level. Moreover, differences in the expression patterns of clock gene in brain
and eyestalk, in LD and DD, suggested the presence in krill of a multiple oscillator system. Evidence
of short periodicities in krill behavior and physiology further supports the hypothesis that a short
endogenous period might represent a circadian adaption to cope with extreme seasonal photoperiodic
variability at high latitude.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf