Ege, M. (2020). The role of cilia on zebrafish olfaction & behaviour (Master's thesis, Norwegian University of Science and Technology).
The cilium is a ubiquitous organelle found across species on a wide range of cell types. It is a highly varied structure able to fulfil a plethora of functions; from motile cilia serving in cell motility and establishing flow within many different tissues, driving metabolite delivery and waste clearance to primary cilia, a crucial site of signalling driving some of the most crucial developmental and sensory processes within the cell. Since this relatively simple structure plays a role in so many functions within any organism, from early development to adulthood, their dysfunctions, collectively called “ciliopathies”, pose a complicated risk to human health, and understanding this wide and ever-expanding spectrum of diseases is crucial. Zebrafish larvae, with their exposed nose lined with cilia prove to be an ideal model organism for ciliary mutations. With the introduction of novel ciliary mutant lines that show no developmental defects and can survive up to adulthood, a new opportunity has emerged to test the impact of ciliary activity in adult zebrafish and relate it to behavioural response. Taking advantage of the cilia-mediated flow within zebrafish nose which was identified to be crucial in olfactant detection at the larval stage, my experiment investigates the properties of cilia, from the larval stage to adulthood, and how they affect olfactory behaviour and shows a loss of flow into the nose to significantly impact an adult zebrafish’s ability to detect food odour. Along with the impact on flow generation around the nose, my results indicate the effect ciliary mutations have on ciliated OSNs and propose that there is an added layer of impairment at the level of detection of the odorants at the olfactory epithelium. This, along with my investigation of the nose of ciliary mutant fish highlight the role of not only the motile cilia on MCCs but also the sensory cilia on OSNs. Additional experiments showcase that ciliary mutations are not limited to affect olfactory response, but also through an impact on the CSF-flow within the brain ventricles, lead to impairment in the ability to adapt to novel experiences. This phenotype I characterize lets us peer into the vast variety of processes cilia play an important role in.