Polyploidy, or whole genome duplication (WGD), is a fundamental evolutionary mechanism for diverse organisms including many plants and some animals. Duplicate genes from WGD are a major source of expression and functional diversity. However, the biological and evolutionary mechanisms for gene expression changes within and between species following WGD are poorly understood. Using genome-wide gene expression microarrays and high-throughput sequencing technology, I studied the genetic and evolutionary mechanisms for gene expression changes in synthetic and natural allopolyploids that are derived from hybridization between closely related species. To investigate evolutionary fate of duplicate genes, I tested how duplicate genes respond to developmental and environmental changes within species and how ancient duplicate genes contribute to gene expression diversity in resynthesized allopolyploids. We found that expression divergence between gene duplicates was significantly higher in response to environmental stress than to developmental process. Furthermore, duplicate genes related to external stresses showed higher expression divergence between two closely related species and in resynthesized and natural allotetraploids than single-copy genes. A slow rate of expression divergence of duplicate genes during development may offer dosage-dependent selective advantage, whereas a high rate of expression divergence between gene duplicates in response to external changes may enhance adaptation. To investigate molecular mechanisms of expression diversity among allopolyploids, I analyzed high-throughput sequencing data of small RNAs in allopolyploids and their progenitors. Small interfering RNAs (siRNAs) induce epigenetic modification and gene silencing of repeats, while microRNAs (miRNAs) and trans-acting siRNAs (ta-siRNAs) induce expression modulation of protein coding genes. Our data showed that siRNA populations in progenitors were highly maintained in allopolyploids, and alteration of miRNA abundance in allopolyploids was significantly correlated with expression changes of miRNA target genes. These results suggest that stable inheritance of parental siRNAs in allopolyploids helps maintain genome stability in response to genome duplication, whereas expression diversity of miRNAs leads to interspecies variation in gene expression, growth, and development. Results from these research objectives show that genome-wide analysis of high throughput gene expression and small RNAs provides new insights into molecular and evolutionary mechanisms for gene expression diversity and phenotypic variation between closely related species and in the new allopolyploids. / text

This dissertation thesis deals with the work of three contemporary Czech artists - Josef Bolf, Jakub Špaňhel and Lubomír Typlt. The reason for choosing these three was the fact that all of the artists represent the same generation which entered the art scene in the late 1990s and their canvases can be equally described as expressive, although right at first glance there are noticeable differences in the intervention of the emotional and sense elements which participated in the creation process of the work of art, but also in its content. Contemporary expressive paintings are influenced by the development of art in the second half of the 20th century which is based on the continuous comparing of expressive subjectivity and its negation or intentional application and irony. That is why I decided to illustratively explore the movements which took place in terms of the foreign and Czech scene during the second half of the 20th century in the field of expressive painting. Because the Czech art arose in different conditions, I explored the changes of this phenomenon separately in these geographical areas, but at the same time I carried out a partial analysis of the works and comparisons with the work of the three chosen artists based on these findings. Subsequently, I analysed the work of the chosen...