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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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Cone mosaic in the retina of ray-finned fishes and its function for vision
Konvičková, Zuzana ; Musilová, Zuzana (advisor) ; Němec, Pavel (referee)
Ray-finned fishes comprise more than half of the vertebrate diversity, and they developed many unique strategies and adaptations to inhabit miscellaneous water environments. This thesis is dedicated to vision, which is an indispensable sense for most fishes. Special focus is laid on photoreceptor morphology and their arrangement in a two-dimensional pattern - cone mosaic. There are three morphological types of photoreceptors commonly found in ray-finned fishes - rods, single cones, and double cones. Triple and quadruple cones that have never been observed in any other vertebrate group sometimes occur too. In this thesis, I discuss the structure and function of individual photoreceptors. While rods are randomly distributed across the retina, cones often form a regular mosaic. Several basic mosaic types can be distinguished according to the position of double cones. Row and square mosaics are the most prevalent. Basic patterns can be further modified in certain fish species. In this thesis, I describe basic patterns, I focus on mosaic development, and I investigate the reasons for regular photoreceptor arrangement. The type of mosaic partly reflects phylogeny, but it is also strongly influenced by the environment and life strategy of the fish. Active fishes inhabiting bright environments are likely...
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