Non-visual opsin expression in the optic tectum of starry flounder (Platichthys stellatus)
Date
2026
Authors
Aveyard, Laurel
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Publisher
University of Victoria
Abstract
Non-visual opsins are light sensing proteins that are not associated with the typical image forming process and can be found not only in the retina, but across a wide variety of tissues such as brain and skin. Their expression in the brain specifically has been documented in several species, but the question remains as to whether these proteins are contributing to light sensitivity of the brain itself. The starry flounder (Platichthys stellatus) is a species of flatfish with several ecological and anatomical characteristics that allow for an indirect method of investigating the potential of brain light sensitivity. Because of their asymmetrical anatomy, their brains are located with one hemisphere pointing upwards and receiving more light stimulus than the other. They are found as both left sided and right sided individuals in the wild, meaning investigation of light sensitivity related to the upwards facing hemisphere in a given individual is possible. This study investigated expression of the specific non-visual opsin melanopsin in the optic tectum of the brain, which is the structure responsible for integration of visual stimuli. This was done using an immunohistochemical staining technique with antibodies designed to bind mammalian-like melanopsins. This provided a qualitative analysis of the levels of expression and how they differed between the hemispheres. There was no notable qualitative difference found between hemispheres in terms of expression, however there appeared to be pan-neuronal labelling throughout both hemispheres of the optic tectum. Further research is required to identify levels of protein expression, however this is an indication of melanopsin presence in the starry flounder brain and is a first step in understanding how these proteins may function in this asymmetric species.
Supervisor: Dr. John Taylor