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Transcriptomics and developmental plasticity of sensory systems in fishes
Lupše, Nik ; Musilová, Zuzana (advisor) ; Reichard, Martin (referee) ; Barluenga, Marta (referee)
Organisms depend on sensory input to survive and thrive. Vision is a key sensory system to many vertebrates, including ray-finned fishes (Actinopterygii). Sight is enabled by the retina composed of cone and rod photoreceptors, each characterised by its own set of opsin proteins that together with the chromophore form the photo-sensitive pigment. Vision is energetically very costly and so it is often adapted to specific photic conditions to best match available wavelengths of light. This Ph.D. thesis focuses on the evolution and development of opsin gene expression in ray-finned fishes. It mainly aims to explore how ontogenetic differences of visual capabilities across the fish phylogeny relate to ecological conditions. In some species, ecological shifts between developmental stages can affect their physiology, including vision. In this thesis I focused on the molecular differences of the visual system between developmental stages, mostly focusing on larvae and adults. The first chapter of the thesis focuses on developmental changes in deep-sea fishes, a unique group of organisms that has evolved unconventional adaptations to maximise photon capture in an otherwise photon- depleted environment. Most deep-sea fishes start their lives in the shallow, sun-lit, predator and food abundant epipelagic...
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Evolution of visual sensory system in the common barbel (Barbus barbus)
Konvičková, Zuzana ; Musilová, Zuzana (advisor) ; Pergner, Jiří (referee)
Vertebrates inherited five visual opsin classes from their common ancestor expressed in the rod and cone cells. While many vertebrate groups reduced the number of visual pigments they possess, opsins of teleost fishes have diversified. Today, teleosts outstand among all vertebrates in the number of visual pigments and photoreceptor types. This extraordinary development was also facilitated by the teleost- specific whole genome duplication that occurred approximately 350 Mya. Here I explored teleost species that recently underwent subsequent whole genome duplication - the common barbel (Barbus barbus). This event was accompanied by hybridization (i.e., it was allopolyploidization) and resulted in 14 opsin genes found in the genome, an unusually high number even among teleosts. In this thesis, I studied the effects of such an expanded opsin repertoire on the visual abilities of the common barbel. Based on the whole genome, I have completed the reference sequences of all opsin genes and revealed their positions on the chromosomes. I analysed retinal transcriptomes and constructed developmental series of opsin expression profiles. All opsin genes were preserved functional in the genome, even though one of them (green-sensitive, named RH2-4 in this thesis) was not found in the transcriptome and showed...
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