|
|
Molecular Genetic Analysis in Patients Suspected of Cryptic Rearrangements.
Šolc, Roman ; Hirschfeldová, Kateřina (advisor) ; Vícha, Aleš (referee)
Such chromosomal rearrangements, which cannot be detected by using of cytogenetic banding of metaphase chromosomes, i.e. chromosomes smaller than 3 - 5 Mb, and therefore modern molecular genetic methods are used to detect them, are called "cryptic rearrangements". Their important role in human pathology is more and more significant. By using of the multiplex ligation-probe dependent amplification method (MLPA) we examined a group of 50 probands with idiopathic mental retardation. A cryptic rearrangement was found at 8 probands (16 %), at 6 of them it was demonstrably causal. Then we examined a group of 40 probands suspected of gene SHOX pathology. A cryptic rearrangement was found at 17 probands (42.5 %) and at 8 of them it was demonstrably causal. Presence of small deletion founded isolated at 7 probands was verified in a population set, but without a positive result. An analysis of mutations was made too.
|
|
|
Evolution of sex determination systems in toxicoferan reptiles
Augstenová, Barbora ; Rovatsos, Michail (advisor) ; Zrzavá, Magda (referee) ; Trifonov, Vladimir (referee)
(English) Sex determination plays an important role in the viability of populations and species evolvability. This is one of the reasons why sex determination has become an important subject of many studies during more than the last 100 years. The thesis focuses on the evolution of sex determination systems in toxicoferan reptiles. Toxicofera is a group of squamate reptiles containing more than 6000 species. Their species richness is also reflected in the diversity of their sex determination systems. The presence of environmental sex determination (ESD) as well as genotypic sex determination (GSD) with either XX/XZ or ZZ/ZW sex chromosomes, was reported among the toxicoferan species; however, the current knowledge on sex determination in toxicoferan reptiles is not equally distributed across their lineages. The main aim of the theses is to expand our knowledge on sex chromosome evolution using cytogenetic methods in snakes, chameleons and anguimorphan lizards. The first part of the thesis deals with the sex chromosome evolution in caenophidian and henophidian snakes. It is focused mainly on the variability in the distribution of repetitive content as well as heterochromatinization of the W chromosome of caenophidian snakes. While the sex chromosomes of Caenophidia are cytogenetically quite well...
|
|
|
Analysis of karyotype and sex chromosome differentiation in African annual killifish of the genus Nothobranchius (Teleostei: Nothobranchiidae)
Lukšíková, Karolína ; Sember, Alexandr (advisor) ; Zrzavá, Magda (referee)
Teleost fishes (Teleostei) encompass more than half of the extant vertebrate biodiversity. Their genomes display considerable plasticity and flexibility, going hand in hand with polyploidization events and repetitive DNA dynamics. Teleosts also display a striking diversity in mechanisms of sex determination and differentiation. The aim of the present thesis was to study the mechanisms underlying the karyotype and sex chromosome differentiation through cytogenetic mapping of repetitive DNA (by fluorescence in situ hybridization, FISH) in selected representatives of the African annual killifishes of the genus Nothobranchius (Teleostei: Nothobranchiidae). Nothobranchius spp. evolved a unique adaptation to freshwater temporary water pools whose existence is limited to periods of rainy season in African savannahs. Recent diversification, allopatric speciation in non-overlapping generations and small-sized populations together with known cytogenetics collectively suggest fast dynamics of chromosomal changes in Nothobranchius killifishes. The study took advantage of the availability of i) more populations of several closely related species for analysis and ii) data on specific repetitive DNA composition in selected Nothobranchius genomes as revealed by RepeatExplorer analysis. My work showed considerable...
|
|
|
Sex chromosome evolution in ray-finned fishes (Actinopterygii)
Pavlica, Tomáš ; Sember, Alexandr (advisor) ; Knytl, Martin (referee)
Ray-finned fishes (Actinopterygii) possess strikingly diverse sex sex differentiation strategies (including gonochorism, unisexuality and several types of hermaphroditism) and mechanisms of sex determination (both environmental and genetic), including frequent turnovers between abovementioned strategies and mechanisms. Although exhibiting remarkable diversity of sex determination mechanisms, only about 5% of analyzed teleost species possess cytologically recognizable (i.e. heteromorphic) sex chromosomes. Still, nine different male- or female- heterogametic sex chromosome systems at various stages of differentiation have been described along with high rate of inter- and intraspecific variability. Given that early sex chromosome evolution is best studied in evolutionarily young nascent sex chromosomes, ray- finned fishes and especially the teleost lineage (Teleostei) represent vital model group for these investigations offering new insights into the evolution of these rapidly evolving regions of vertebrate genomes. Moreover, handful of studies available so far has provided evidence for a role of emerging sex chromosomes and their turnover in processes such as ecologial adaptation, speciation or genomic conflict. Besides cytogenetic studies, which had a major impact on our current knowledge about fish...
|
|
|
Molecular Genetic Analysis in Patients Suspected of Cryptic Rearrangements.
Šolc, Roman ; Hirschfeldová, Kateřina (advisor) ; Vícha, Aleš (referee)
Such chromosomal rearrangements, which cannot be detected by using of cytogenetic banding of metaphase chromosomes, i.e. chromosomes smaller than 3 - 5 Mb, and therefore modern molecular genetic methods are used to detect them, are called "cryptic rearrangements". Their important role in human pathology is more and more significant. By using of the multiplex ligation-probe dependent amplification method (MLPA) we examined a group of 50 probands with idiopathic mental retardation. A cryptic rearrangement was found at 8 probands (16 %), at 6 of them it was demonstrably causal. Then we examined a group of 40 probands suspected of gene SHOX pathology. A cryptic rearrangement was found at 17 probands (42.5 %) and at 8 of them it was demonstrably causal. Presence of small deletion founded isolated at 7 probands was verified in a population set, but without a positive result. An analysis of mutations was made too.
|
guest ::
