Sturgeons (Chondrostei: Acipenseriformes) display markedly disjunct distributions with a wide occurrence in the northern hemisphere. Their unique benthic specializations, conserved morphology, evolutionary age, the variation in their basic diadromous life history, and the large public interest due to their near extinction or critically endangered status make sturgeons and paddlefishes one of the most interesting group of vertebrates. In addition to that, ploidy diversity of Acipenseriformes possessing three ploidy groups having ~ 120 chromosomes, ~ 240 ? 270 chromosomes and ~ 360 chromosomes provides unique model for investigation of evolutionary processes which were going through the genome duplication events. Sturgeons are also notoriously known for their strong propensity to interspecific and intergeneric hybridization which can result in hybrids with various ploidy levels. All these facts make sturgeon genetics and cytogenetics a thriving but also complicated area for research. In the present work, the role of genome duplication and functional reduction evens in evolution of sturgeon species as well as sturgeons? ploidy levels and ploidy relationships among Acipenseriformes were investigated using molecular markers. In addition to that, clarification of origin of abnormal ploidy levels and observation of segregation pattern of microsatellite alleles in the course of hybridization of polyploid sturgeon species were included into this study. With regard to the all considerations and observations provided by this study we concluded that evolution of sturgeon species is still widely dynamic and ongoing process which might goes through the allopolyplodization as well as autopolyplidization events.

Whole genome doubling (WGD) generates genetically unstable tetraploid cells that fuel tumorigenesis. Cells that undergo WGD must acquire adaptive characteristics to accommodate their tetraploid state, and these adaptations may confer unique vulnerabilities that can be exploited therapeutically. We analyzed the genomes of ~9,700 primary human cancer samples to uncover genetic alterations that are specifically enriched in WGD+ cancer cells. Through integrating our genetic analysis with gene essentiality data acquired from Project Achilles, we identified gene dependencies in WGD+ cells. Moreover, we identified genes that are essential for the viability of WGD+ cancer cells, but non-essential to non-transformed diploid cells. We demonstrated that the gene encoding for the mitotic kinesin KIF18A is dispensable for mitosis in diploid cells, but becomes critical for accurate chromosome segregation and viability in WGD+ cells, making it an attractive drug target. Collectively, this work revealed new strategies to specifically target WGD+ cancer cells, namely targeting the gene KIF18A, while sparing the normal diploid cells from which they arise. / 2022-06-04T00:00:00Z

Mixed-ploidy populations, consisting of multiple cytotypes, are an optimal system for studying genome doubling consequences in plants. The role of frequency dependent selection, known as minority cytotype exclusion principle, is very important in them, but there are many factors limiting this selection. In my thesis, I evaluate the changes in cytotype frequencies and pattern in permanent plots in natural mixed-ploidy populations of three plant species - Butomus umbellatus, Knautia serpentinicola and Tripleurospermum inodorum and I also experimentally analyze partial aspects of frequency dependent selection towards minority cytotype in artificially established mixed-ploidy arrays of two plant species - Arabidopsis arenosa and Tripleurospermum inodorum. Varied changes in frequencies of minority cytotype ware revealed in permanent plots. Usually there was decrease, but in two plots there was increase in minority cytotype frequency and in one case it became dominant. Observed changes depend on initial frequencies of minority cytotype in populations, biological properties of species and particular environment of permanent plot. Relative indexes describing the frequency and the strength of disturbances and also the amount of soil nutrients was used to compare the environment of permanent plots across...

A lot of the research has been made in the field of plant polyploidy since the discovery of this phenomenon. However, the more we know, the more questions arise. Overall, the most insistent questions remain: How did the polyploids arise and become established? Is it advantageous to be polyploid? We chose a perennial herb Vicia cracca L. to study the causes and consequences of polyploidisation on microevolution of a diploid-tetraploid complex in central European conditions. First, evidence from both flow cytometry and molecular markers (allozymes, DNA sequences, microsatellites) confirmed a hypothesised autopolyploid origin of tetraploids. Based on allozymes, we proved that tetraploids are genetically richer than diploid ancestors. However, we showed that the conclusions depend on statistics used for genetic variation measurements. Nevertheless, tetraploids of V. cracca suffered lesser reduction in seed production after artificial selfing than diploids. We thus infer that they profit from multiple allele dosage, which can mask deleterious alleles. We also corroborated an existence of a central European contact zone of diploids and tetraploids and discovered two other contact zones in south-western and south- eastern Europe. The central European contact zone with several mixed-ploidy populations served us as...

No description available.

No description available.

A lot of the research has been made in the field of plant polyploidy since the discovery of this phenomenon. However, the more we know, the more questions arise. Overall, the most insistent questions remain: How did the polyploids arise and become established? Is it advantageous to be polyploid? We chose a perennial herb Vicia cracca L. to study the causes and consequences of polyploidisation on microevolution of a diploid-tetraploid complex in central European conditions. First, evidence from both flow cytometry and molecular markers (allozymes, DNA sequences, microsatellites) confirmed a hypothesised autopolyploid origin of tetraploids. Based on allozymes, we proved that tetraploids are genetically richer than diploid ancestors. However, we showed that the conclusions depend on statistics used for genetic variation measurements. Nevertheless, tetraploids of V. cracca suffered lesser reduction in seed production after artificial selfing than diploids. We thus infer that they profit from multiple allele dosage, which can mask deleterious alleles. We also corroborated an existence of a central European contact zone of diploids and tetraploids and discovered two other contact zones in south-western and south- eastern Europe. The central European contact zone with several mixed-ploidy populations served us as...

No description available.

Carcinogênese é um fenômeno de múltiplas fases. A literatura recente aceita, baseada em evidências epidemiológicas, que a progressão neoplásica em direção ao carcinoma invasor da mama inicia-se em estados hiperplásicos do epitélio ductal, passando pelo carcinoma in situ. Questões abertas na literatura no que concerne à relação existente entre o carcinoma intraductal e o carcinoma ductal invasivo referem-se aos fatores envolvidos nos processos que levam à invasão tumoral. Quatro modelos de progressão de doença foram propostos baseados na morfologia dessas lesões. Três deles descreveriam diferentes vias de progressão direta do carcinoma intraductal para o carcinoma invasor. O quarto modelo propõe que a evolução do carcinoma intraductal e do carcinoma invasor se faz independentemente, \"em paralelo\", a partir de uma terceira lesão precursora comum que, na verdade, gera um tumor de colisão in situ e invasor. O presente trabalho estudou retrospectivamente o tecido tumoral da mama de 46 pacientes do sexo feminino que continham carcinoma intraductal associado ao componente invasor na mesma lesão. Foram determinados o conteúdo de DNA nuclear por citometria estática e o grau nuclear de ambas as lesões, assim como o padrão arquitetural do componente intraductal e o índice de formação de túbulos do componente invasor. Os resultados mostraram relação estatisticamente significante (kappa=0,713; p<0,001) para o grau nuclear entre os grupos, o mesmo acontecendo com o conteúdo de DNA nuclear (kappa=0,5018 p=0,0002). Ao compararmos o aspecto arquitetural do componente intraductal com o índice de formação de túbulos do componente invasor, não encontramos correlação estatisticamente significante (p=0,1033). Os resultados permitem especular que as características nucleares de um dado carcinoma invasor de ductos mamários são possivelmente determinados em fases pré-invasivas, enquanto que alterações arquiteturais provavelmente se desenvolvem em estágios avançados, após a célula tumoral adquirir o fenótipo invasor. / Carcinogenesis is a multiple stage phenomenon. Epidemiologic evidence indicates that progression to invasive breast cancer begins in hyperplastic states of the epithelium passing by in situ carcinoma. The actual relationship that exists between ductal carcinoma in situ and invasive ductal carcinoma of the breast and the factors that lead to the tumor invasion process are questions that remain unanswered in the literature. Four models have been developed to explain the progression of the neoplastic disease in the breast tissue. Three of them propose that there is a direct pathway of progression from ductal carcinoma in situ to invasive carcinoma. The fourth one suggests that there is a common precursor lesion and both carcinoma in situ and invasive carcinoma progress in an independent fashion with no relationship between each other. The present work retrospectively studied 46 tumor tissues of the female breast with coexisting ductal carcinoma in situ and ductal invasive carcinoma. DNA ploidy as well as nuclear were determined in both lesions. The architectural pattern of the in situ component and the degree of tubule formation of the invasive component were determined also. Our results showed that there are no statistically significant differences in both nuclear parameters studied (DNA ploidy, k=0,713,p<0,001; nuclear grade, k=0,5018, p=0,0002). When we compared the architectural features of ductal carcinoma in situ with the degree of tubule formation in the invasive component we found a statistically significant different between the groups (p=0,1033). The results lead us to conclude that the nuclear features of a given invasive breast cancer are possibly determined in a preinvasive level, while architectural changes probably develop in a late stage, after the acquisition of the invasive phenotype.

Die vorliegende Arbeit befasst sich mit züchtungsmethodischen Untersuchungen zur Schaffung blattvariegater Pelargonium x zonale-Hybriden auf tetraploidem Leistungsstand. Basierend auf dem Wirkstoff Trifluralin konnte eine effektive Behandlungsvariante zur somatischen Polyploidisierung periklinalchimärischer Pelargonium x zonale-Klone etabliert werden. Unter Ausnutzung biparentaler Erbgänge wurden fünf ausgewählte Plasmotypen an das Leistungsniveau moderner Sortimente herangeführt. Daneben erbrachten Kreuzungen innerhalb der Sektion Ciconium hybridvariegate F1-Pflanzen. Die Möglichkeit der Ausnutzung von Kern-Plasma-Wechselwirkungen in der Pelargonienzüchtung wird diskutiert. Im Hinblick auf den Aufbau eines Protoplastenregenerationssystems konnten Zellsuspensionskulturen etabliert werden. Im Anschluss an enzymatische Verdauungen wurde die Regeneration von Kallus beobachtet. Variegate Pflanzen aus Mutationsversuchen mit NMH (Nitroso-Methyl-Harnstoff), einer weiteren experimentellen Variante, erwiesen sich als steril, so dass eine weiterführende Züchtungsarbeit auf diesem Weg bisher noch nicht möglich war / The study analyzes breeding schemes concerning the development of variegated tetraploid Pelargonium x zonale-hybrids (Pelargonium x hortorum). With a focus on practical relevance breeding methods for periclinal chimeric leaf patterns are discussed. Trifluralin-induced tetraploid Pelargonium x zonale-hybrids were successfully crossed with modern cultivars. Via biparental mode of inheritance five defined plasmotypes were transfered to the karyological background of current high-performance Pelargonium series. In a crossing-program within the section Ciconium hybrid-variegation was detected. The possibility of using nucleo-plasmatic interactions in developing new Pelargonium cultivars is discussed. First steps concerning a biotechnological approach to create variegated plants included the establishment of cell-suspension-cultures as the base for a protoplast regeneration system. Following the enzymatic digestion of Pelargonium-liquid cultures up to now, callus regeneration was achieved. Variegated plants resulting from mutagenic treatments with NMU (Nitroso-methylurea) proved to be sterile.