Ricerc@Sapienza

Although the existence of circadian clocks is accepted as an ubiquitous feature of life, and their physiological mechanisms are becoming well understood, the role of circadian clocks in extreme environments, like the polar regions, has received very little attention. In polar environments the strength of the Zeitgeber is greatly reduced around the summer and winter solstices when the sun never sets or never rises. Polar organisms represent an excellent model in chronobiological studies.
Only a few studies have investigated activity patterns under polar conditions in the wild and the existing findings are inconsistent. Karl Stokkan and colleagues provide new molecular and behavioural evidence that suggests reindeer, living at high latitudes in the Arctic, lack the underlying biological clock necessary for generating circadian rhythmicity: they do not express 24-h locomotor activity rhythms in summer and winter, differently, during the equinoxes, animals express a circadian regulation of activity. The diversity of behavioural responses, even within the limited number of species tested, is surprising and suggests that a variety of genetic and physiological factors might be involved in regulating circadian plasticity
Lepidurus arcticus, an high Arctic invertebrate, is the ideal model (like drosophila) in which to develop this aspect because of its presence in all melt-water pools in Arctic, and because conspecifics can also be found at other latitudes, and gene expression and behaviour will be investigated.
Our aim is to understand the influence of the light on the biological clock of the high Arctic animals, and the adaptive significance of clocks and rhythms; moreover to develop a possible animal model for the study of the de-synchronization.