Adaptation of Drosophila melanogaster to Long Photoperiods of High-Latitude Summers Is Facilitated by the ls-Timeless Allele
03/21/2022Light-dark cycles are the most important Zeitgeber for animal's circadian clocks. The further north one goes, the more these clocks are challenged by longer photoperiods and - at very high Arctic latitudes - even by constant light-like conditions around the summer solstice.
In the fruit fly Drosophila melanogaster, a previously described naturally occurring polymorphism in the timeless-gene, called s-tim and ls-tim, gives rise to proteins that differ in their interaction sensitivity with the photoreceptor CRYPTOCHROME. We aimed to test, whether flies with the new ls-tim allele remain more rhythmic under constant light and whether their activity can better track the evening under very long photoperiods that it is the case in s-tim flies. For this purpose, different isofemale fly strains from Africa and Europe were sequenced for their tim-polymorphism and subjected to light-dark cycles with photophases of 16 and 20 hours as well as constant light conditions (LL).
Indeed, the activity of ls-tim flies could track the evening better than that of s-tim flies. Consequently, the phase difference Ψ between morning and evening activity was significantly larger in ls-tim flies.
Ls-tim lines additionally show higher rhythmicity values in constant light than s-tim flies, and rhythmicity in LL also correlates with the length of the morning-evening phase difference in fly strains.
In summary, the ls-tim allele facilitates behavioral adaptation of Drosophila melanogaster to high latitudes.
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Journal: Journal of Biological Rhythms
Autoren: Peter Deppisch, Johanna M. Prutscher, Mirko Pegoraro, Eran Tauber, Christian Wegener, Charlotte Helfrich-Förster
doi.org/10.1177/07487304221082448
