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Gewählte Publikation:

Publikationstyp: Zeitschriftenaufsatz
Dokumenttyp: Originalarbeit

Jahr: 2009

AutorInnen: Silverin, B; Gwinner, E; Van"t Hof, TJ; Schwabl, I; Fusani, L; Hau, M; Helm, B

Titel: Persistent diel melatonin rhythmicity during the Arctic summer in free-living willow warblers.

Quelle: Horm Behav (56), 1 163-168.



Autor/innen der Vetmeduni Vienna:

Fusani Leonida

Diese Publikation wurde nicht im Namen der Vetmeduni Vienna erstellt und ist deshalb ausschließlich der persönlichen Publikationsliste des/der Autors/Autorin zugeordnet!


Abstract:
Arctic environments are challenging for circadian systems. Around the solstices, the most important zeitgeber, the change between night and day, is reduced to minor fluctuations in light intensities. However, many species including songbirds nonetheless show clear diel activity patterns. Here we examine the possible physiological basis underlying diel rhythmicity under continuous Arctic summer light. Rhythmic secretion of the hormone melatonin constitutes an important part of the songbird circadian system and its experimental suppression, e.g., by constant light, usually leads to behavioral arrhythmia. We therefore studied melatonin patterns in a free-living migratory songbird, the willow warbler (Phylloscopus trochilus), that maintains diel activity during the Arctic summer. We compared melatonin profiles during late spring and summer solstice in two Swedish populations from the south (58 degrees N) and near the Arctic circle (66 degrees N). We found the northern Swedish population maintained clear diel changes in melatonin secretion during the summer solstice, although peak concentrations were lower than in southern Sweden. Melatonin levels were highest before midnight and in good accordance with periods of reduced activity. The maintenance of diel melatonin rhythmicity under conditions of continuous light may be one of the physiological mechanisms that enables continued functioning of the circadian system.

Keywords Pubmed: Animals
Animals, Wild
Arctic Regions
Circadian Rhythm/physiology*
Melatonin/blood*
Motor Activity/physiology
Periodicity
Photoperiod
Radioimmunoassay
Seasons*
Songbirds/physiology*


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