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Sex reversal in cytogenomic world
Khomyn, Diana ; Drábová, Jana (advisor) ; Šolc, Roman (referee)
Sex development is a sophisticated regulatory system that is controlled by the activation and inhibition of specific genes. Gonadal differentiation is governed by the presence of the SRY gene on the Y chromosome. Expression of this gene triggers a cascade of events leading to the formation of testicular tissue; otherwise, in the absence of the Y chromosome and the SRY gene, the reproductive system develops towards the ovaries. As technologies in cytogenetics and molecular biology have advanced, diagnostic methods have improved and the molecular causes of DSD, which are both clinically and causally diverse, are being increasingly elucidated. There are several classification systems for DSD, and this thesis is based on the classification with three main diagnostic categories: 46,XX DSD; 46,XY DSD and sex chromosome anomalies. This system uses the patients' karyotype and histological characteristics of the gonads to identify and descriptively classify DSDs. This thesis briefly describes the categories of DSD, their characteristic features, and how they differ from each other. The main focus is on the categories 46,XX DSD and 46,XY DSD, previously referred to as sex reversals, which involves the development of phenotypic features that are contrary to the genotype of the individual. The 46,XX DSD...
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Uniparental disomy in the human karyotype
Koplíková, Patricie ; Drábová, Jana (advisor) ; Šípek, Antonín (referee)
Chromosome pairs affect how our body works. Normally, a baby gets one copy of each chromosome from each parent. This means one copy from mother, and the other copy from father. In rare cases, a baby may get two copies from the same parent and none from the other. This phenomenon is called uniparental disomy (UPD). Uniparental disomy is a major topic for molecular geneticists and cytogeneticists. There are several mechanisms that lead to UPD, for example: gamete complementation, monosomy rescue, trisomy rescue or post-fertilization error. The consequences of UPD can be diverse and depend on the specific chromosome and genetic content of the affected region. An abnormal phenotype is manifested if the UPD occurs on a chromosome that is subject to genomic imprinting. An abnormal phenotype can also occur due to mutations. Among the most common syndromes associated with UPD are Prader-Willi syndrome and Angelman syndrome, which I focus on in my theses. I consider the greatest contribution of my theses to be the creation of a comprehensive overview of the effects of UPD across all human chromosomes.
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Mechanisms of origin of cryptic rearrangements in human chromosomes and its clinical associations
Šenkyřík, Pavel ; Šolc, Roman (advisor) ; Drábová, Jana (referee)
Chromosomal rearrangements are one of the processes which leads to formation of genetic disorders. Among the mechanisms that cause the rearrangements belong NAHR, NHEJ, FoSTeS and MMBIR. They generate rearrangements of many types and have different requirements for their realization. NAHR is recombination-based mechanism responsible for recurrent rearrangements and operates mainly in repetitive sequences. NHEJ is used for repair of double-strand breaks and generates non-recurrent rearrangements due to its error rate. FoSTeS and MMBIR are replication-based mechanisms able to make both complex rearrangements and less massive non-recurrent rearrangements. Architecture of DNA has influence on all above-mentioned mechanisms. Structures that affect course or effectivity of mechanisms are microhomologies, double-strand breaks, tandem repetitions, hairpins, and loops causing stalling of replication fork.
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Analysis of mosaic chromosomal aberrations using various methods
Oroszová, Karin ; Drábová, Jana (advisor) ; Šolc, Roman (referee)
Mosaicism is represented by two or more chromosomally different cell lines in an individual. Mosaics are most often caused by chromosome malsegregation during mitosis, resulting in the gain or loss of chromosomes, known as aneuploidy, but structural aberrations can also occur in mosaic form. The problem is the limitation of detection with standart cytogenetic methods. The present study was carried out to compare the efficiency of FISH, array CGH and cytogenetic techniques in detection of mosaicism. In the practical part the results of 45 patients with mosaicisms of aneuplody of gonosomes (26 patients) and mosaicisms of autosomes (19 patients) were compared. The data show that we have different peripheral blood karyotype and FISH results in 23 of 37 patients (62%). There was a case of failure of detection of the mosaicism on the karyotype and the FISH method revealed a abnormal cell lines with a percentage of less than 5%. The array CGH method confirmed the karyotype and FISH results in 10 out of 12 patients (83%) in peripheral blood tests. The work also dealt with artificially made mosaics. From the results, it is obvious that the FISH method has a more accurate percentage of mosaic capture compared to the karyotype. The results indicate that using the techniques in parallel allow in clinical...
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Biological determinants of the origin and development of the opposite psychological and behavioral traits associated with autism spectrum disorders and Williams syndrome
Buriánková, Klára ; Šolc, Roman (advisor) ; Drábová, Jana (referee)
Williams syndrome is a genetical disorder caused by microdeletion on chromosome 7, specifically of 7q11.23 region. Its phenotype is characterized by typical facial features, mild mental retardation, cardiovascular problems (patients often suffer from supravalvular aortic stenosis), gastrointestinal problems and endocrine abnormalities. However, Willimas syndrome is best known for its unique behavioural-cognitive profile which leads to friendly, hypersocial and talkative personality. This specific neuropsychological profile is repeatedly considered to be the right opposite of the psychological profile, which is characteristic for people with autism spectrum disorder. Individuals with autism spectrum disorder often have severe impairments in social interaction, communication and they suffer from social anxieties. This contrasting cognitive-behavioural phenotype inspired many studies to examine possible biological causes, which might determine given personality features. Several results from these studies suggest that small genetical TFII-I family, which lies in the critical Williams syndrome region, could have a significant impact on the extent of personality qualities such as sociality and communication. Key words: Williams syndrome, autism spectrum disorder, duplication 7q11.23 syndrome, TFII-I...
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Inversions on human chromosomes
Košuthová, Klára Mária ; Šolc, Roman (advisor) ; Drábová, Jana (referee)
Lidské inverze jsou balancované strukturní variace, což způsobuje potíže při jejich analýze. Díky metodě PEM (paired-end sekvenování a mapování) došlo k obrovskému pokroku při studiu inverzí. Inverze mají důležitou roli jako evoluční činitel, přispěly ke vzniku gonozómů, speciaci šimpanzů a lidí a inv17q21.3 a inv 8p23.1 vykazují znaky přirozeného výběru. Inverze byly spojeny s patogenními změnami fenotypu, ať už přímým ovlivněním struktury genu (např. inv5p15.1q14.1), regulace genové exprese (inv7q21.3q35) nebo fungují jako predispozice k sekundárním genomovým přestavbám (inv7q11.23). Polymorfismus lidských inverzí je dokumentován databází InvFEST, avšak jen malá část z uvedených inverzí je validována a detailní analýzu komplikuje především častá lokalizace bodů zlomu v repetitivních oblastech. Klíčová slova: inverze, chromozom, gen, onemocnění, evoluce, PEM, polymorfismus Abstract Human inversions are a type of balanced structural variations, making it difficult to analyze them. Thanks to PEM (paired-end sequencing and mapping), there has been tremendous progress in studying inversions. Inversions plays an important role as an evolutionary factor, contributing to the formation of gonosomes, speciation of chimpanzees and humans, and inv17q21.3 and inv 8p23.1 exhibit natural selection features....
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Possibility of control of mammals group in the zoo trough modification of enrichment elements and its use in practice
DRÁBOVÁ, Jana
This experiment was conducted in two zoos - ZOO Troja in Prague and ZOO Ohrada in Hluboká nad Vltavou. The animals were presented the food enrichment of a puzzle type with different difficulties. Solving each levels of puzzles was being compared with the dominance of individuals in the group that was being observed by the aggression among all examinees. Nosal and their accession to the normal diet. All data were statistically evaluated. With the obtained results, the theory of "index of balance in the group" was tested.
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