Browsing Department of Biological Sciences by Author "Valen, Ragnhild"
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Molecular evidence that only two opsin subfamilies, the blue light- (SWS2) and green light-sensitive (RH2), drive color vision in Atlantic cod (Gadus morhua)
Valen, Ragnhild; Edvardsen, Rolf; Søviknes, Anne Mette; Drivenes, Øyvind; Helvik, Jon Vidar (Peer reviewed; Journal article, 2014-12-31)Teleosts show a great variety in visual opsin complement, due to both gene duplication and gene loss. The repertoire ranges from one subfamily of visual opsins (scotopic vision) including rod opsin only retinas seen in ... -
Spatial and temporal mRNA expression of key gastrointestinal peptide hormones in Atlantic salmon during processing of a single meal- towards an understanding of their roles in regulation of digestion and appetite
Valen, Ragnhild (Master thesis, 2009-11-27)Ghrelin (GRLN), Cholecystokinin (CCK) and the Neuropeptide Y (NPY) family member; PYY are gastrointestinal (GI) tract peptide hormones involved in the optimization of the digestive process and regulation of appetite in ... -
Transient photoreception in the hindbrain is permissive to the life history transition of hatching in Atlantic halibut
Eilertsen, Mariann; Valen, Ragnhild; Drivenes, Øyvind; Ebbesson, Lars O.E.; Helvik, Jon Vidar (Journal article; Peer reviewed, 2018)In nonmammalian vertebrates, photoreception takes place in the deep brain already early in development, but knowledge is lacking about the functions of these nonvisual photoreceptive systems. Prior to hatching, Atlantic ... -
The two-step development of a duplex retina involves distinct events of cone and rod neurogenesis and differentiation
Valen, Ragnhild; Eilertsen, Mariann; Edvardsen, Rolf; Furmanek, Tomasz; Rønnestad, Ivar; van der Meeren, Terje; Karlsen, Ørjan; Nilsen, Tom Ole; Helvik, Jon Vidar (Peer reviewed; Journal article, 2016-08)Unlike in mammals, persistent postembryonic retinal growth is a characteristic feature of fish, which includes major remodeling events that affect all cell types including photoreceptors. Consequently, visual capabilities ...