MSc in Biology/Animal Physiology and MD in General Medicine Jana Kalinová at the Department of Arctic and Marine Biology (AMB) will Thursday 26th of November 2026 hold her trial lecture and defend her thesis for the PhD degree in Natural Science.
Trial lecture on assigned topic will take place at 10:15: "Does adaptation to extreme environments make organisms more vulnerable to environmental change?"
Later, at 12:15 she will defend her thesis entitled: "Light perception and seasonal synchrony in the Arctic: Characterizing the non-visual opsin repertoire and photoperiodic response in Lagopus muta hyperborea"
Vice-Dean for Research at BFE Espen Holst Hansen will lead the disputation.
Popular Science Summary
Light is a key modulator of biological processes in organisms ranging from plants to higher vertebrates; it acts as a fundamental environmental cue in driving daily and seasonal rhythmicity in physiological functions and synchronizes endogenous biological timers. Animals use opsin-based photopigments as light detectors to perceive fluctuations in duration, spectral composition and intensity of their light environment and translate this external information into activation or suppression of internal neuroendocrine pathways. The ambient light climate dramatically changes with increasing latitude showing increased amplitude of day length cycles on a seasonal scale but reduced amplitude of solar elevation cycles on a daily scale. The seasonal changes in day length are a predictor for seasonal cycles of other environmental conditions, such as temperature and food availability. Thus, animals inhabiting high latitudes have developed strong seasonal programs to accommodate these extreme environmental fluctuations while using light as the primary cue to time their life history events. While considerable efforts have been undertaken to characterize the full cascade of events from light perception to expression of seasonal phenotypes, substantial knowledge gaps still exist. Timekeeping mechanisms in birds rely on a complex multiphotoreceptor system with deep brain photoreceptors located in the hypothalamus implicated as the main drivers of seasonality. Opsin expression has been identified within the medio-basal hypothalamus, a key anatomical region underpinning seasonal timekeeping in mammals and birds, and three opsins have been suggested as the primary candidates for synchronization of avian seasonal rhythms – Opsin 4, Opsin 5 and Vertebrate ancient (VA) opsin. However, several limitations exist in our knowledge of how the opsins aid in transduction of external photoperiodic information into its internal neuroendocrine representation, especially in the context of Arctic species residing in polar ecological niches with extreme light conditions throughout the year. This thesis used the Svalbard rock ptarmigan (Lagopus muta hyperborea), a galliform species residing year-round in the Arctic, as a model for seasonal synchrony to investigate the avian photoreceptor system, its role in driving seasonal cycles in physiology and its potential adaptations to the Arctic light environment.
Paper I presents the discovery of novel VA opsin transcript variants in the hypothalamus, retina and pineal gland of the Svalbard rock ptarmigan. The hypothalamus primarily expresses truncated VA opsin transcript variants which likely code for non-functional proteins. This result challenges the importance of VA opsin as a hypothalamic photoreceptor in this species. The pineal gland emerged as the only photosensitive structure with predominant expression of full-length VA opsin transcript capable of forming a functional opsin protein.
Paper II offers a comprehensive overview of the full repertoire of non-visual opsins in the Svalbard rock ptarmigan including their spectral sensitivity profile and tissue distribution. Estimation of peak spectral sensitivity aligned with those reported in other galliform species indicating that none of these opsins shows spectral tuning changes as an adaptation to life in the Arctic. Intriguingly, opsin expression was discovered in the pars tuberalis, a structure not traditionally considered photosensitive, which might constitute one of the missing links in the avian photoperiodic axis.
Paper III explores the possible role of the photoreceptor system in driving transitions between seasonal phenotypes in captive Svalbard rock ptarmigan and profiles the RNA expression in four different tissues implicated in the photoperiodic response. Using light- and temperature-controlled environments, the response to photostimulation and onset of photorefractoriness were investigated. Photostimulation altered expression of genes involved in the visual phototransduction cascade in the retina, whereas photorefractoriness showed no change in opsin gene expression in any tissue, supporting the current model that photorefractoriness is not dependent on changes in opsin-based light detection.
Paper IV serves as a foundation for future follow-up experimental work. In this pilot study, a customized protocol for stereotaxic neurosurgery in the Svalbard rock ptarmigan was developed with particular emphasis on safe and effective anesthesia and pain management. The establishment of this methodology allows for in vivo targeted manipulation of the photoperiodic axis while supporting animal welfare.
Evaluation Committee
Supervisors
Streaming
Both the trial lecture and defense and will be streamed:
Thesis
The thesis is avaliable in the Norwegian Research Information Repository (NVA)