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dc.contributor.advisorWagner, Gabriela
dc.contributor.advisorWest, Alexander
dc.contributor.authorMelum, Vebjørn Jacobsen
dc.date.accessioned2018-11-19T10:32:23Z
dc.date.available2018-11-19T10:32:23Z
dc.date.issued2018-08-09
dc.description.abstractThe Svalbard rock ptarmigan displays a seasonal change of body mass as a selectively beneficial adaptation for survival in the high Arctic. This physiological change is sensitive to photoperiod (daylight duration in a 24h cycle) but little is known of the mechanism through which changes in photoperiod affects body mass in this species. We exposed winer adapted Sv. rock ptarmigan to a simulated lengthening natural photoperiod (NP), constant light (LL), and constant darkness (DD). As expected, increasing photoperiod rapidly reduced body mass (BM), likely as a consequence of increased activity which occurred without compensation of increased voluntary food intake (VFI). Expression of the thyroid hormone metabolising enzyme Dio2 was quantified within the mediobasal hypothalamus (MBH), as an indicator of seasonal status. Similar to other seasonal models, Dio2 was stimulated by lengthening photoperiods and spontaneously induced by extended exposure to constant darkness. Expression of Dio2 was positively correlated with expression of NPY (a crucial appetite regulating peptide) within the Arcuate nucleus (ARC). Conversely, the expression profile of the closely associated orexigenic factor AgRP was correlated with BM, but not Dio2 levels. Expression of the satiety factor POMC was unaffected by photoperiodic changes. Collectively these data demonstrate that although photoperiod affects central gene expression in the Sv. Rock ptarmigan their expression does not directly dictate changes in VFI or BM. Instead, a more complicated pattern of appetite regulation emerges, processing photoperiodic and metabolic signals as well as seasonal behavioural changes in the Svalbard rock ptarmigan.en_US
dc.identifier.urihttps://hdl.handle.net/10037/14208
dc.language.isoengen_US
dc.publisherUiT Norges arktiske universiteten_US
dc.publisherUiT The Arctic University of Norwayen_US
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2018 The Author(s)
dc.rights.urihttps://creativecommons.org/licenses/by-nc-sa/3.0en_US
dc.rightsAttribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0)en_US
dc.subject.courseIDBIO-3950
dc.subjectVDP::Mathematics and natural science: 400::Zoology and botany: 480::Zoophysiology and comparative physiology: 483en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Zoofysiologi og komparativ fysiologi: 483en_US
dc.subjectSvalbard Rock ptarmiganen_US
dc.subjectmediobasal hypothalamusen_US
dc.subjectDio2en_US
dc.subjectAgRPen_US
dc.subjectNPYen_US
dc.subjectPOMCen_US
dc.titleInfluence of photoperiod on central appetite regulation in captive Svalbard rock ptarmigan (Lagopus muta hyperborea)en_US
dc.typeMaster thesisen_US
dc.typeMastergradsoppgaveen_US


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Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0)
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