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Detection of positive selection in reproductive genes of songbirds
Cakl, Lukáš ; Reifová, Radka (advisor) ; Těšický, Martin (referee)
Reproductive genes are assumed to play an important role in adaptive evolution and speciation, yet little is known about the patterns of molecular evolution in these genes within avian species. This thesis is focused on identifying reproductive genes under positive selection and analyzing their function in songbirds, the largest and most diverse suborder of modern birds. Using existing bioinformatic approaches and published genomic data of 14 songbird species, we have first constructed 12000 groups of orthologous genes and detected significant traces of recurrent positive selection within 385 of them. Using proteomic data, this genome wide set of genes was then filtered to obtain genes expressed within songbird spermatozoa and fluids from the female reproductive tract. Within spermatozoa 22 out of 940 expressed genes were positively selected, while female fluids were found to be more conserved, as only 6 out of 529 expressed genes have shown traces of positive selection. We have then computed the enrichment of gene ontology terms within the positively selected genes. The enriched terms suggest evolutionary pres- sures acting on spermatozoa cytoskeleton, molecular motors and energetic metabolism, highlighting the importance of sperm morphology and swimming speed. Furthermore, the enrichment results...
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Molecular basis of the sperm selection in the mammalian female reproductive tract
Šrámková, Adéla ; Krylov, Vladimír (advisor) ; Postlerová, Pavla (referee)
Internal fertilization is typical for all mammals. The male transfers sperm cells into the female reproductive tract, where usually one of them reach the oocyte and fertilize it. The female reproductive tract must be adapted to provide a suitable environment for the sperm cells to survive until fertilization. On the other hand, it must also be able to select developmentally competent sperm cells and prevent others to get into the close contact with the oocyte. Physical and molecular mutual communication of sperm cells with the female reproductive tract is ensured by sperm surface molecules and the receptors of the female epithelia lining. It appears that these interactions are required for key transformations, both on the sperm surface and in the cells of the female reproductive tract, where gene expression is affected. As a result of these changes, the most suitable sperm cell with all the required characteristics is allowed to fertilize the matured oocyte.
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