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Turner syndrome and its relation with X chromosome inactivation
Kašíková, Lenka ; Schierová, Michaela (advisor) ; Král, Jiří (referee)
Turner syndrome (TS) is a genetic anomaly occurring in women with worldwide frequency 1:2,000. Turner syndrome's possible causes include X chromosome monosomy, mosaic karyotype (45,X/46,XX; 45,X/46,XY; 45,X/47,XXX), X isochromosome (46,X,i(Xq)), ring X chromosome (45,X/46,X,r(X)), and other X chromosome aberrations (deletion and translocation). Patients with Turner syndrome (with the exception of ring chromosome abnormalities) aren't diagnosed with mental retardation. Turner syndrome is closely related to the regulation of gene expression level, particularly with X chromosome inactivation. Genes escaping the X chromosome inactivation process in 45,X women are expressed in half the dose of a healthy woman. An example of such a gene is SHOX, which I decided to focuse on in this thesis. SHOX gene haploinsufficiency causes major Turner syndrome phenotype manifesting of short body and bone abnormalities. The research of other genes with possible roles in Turner syndrome is complicated by the absence of adequate model organism, which could be used for TS study with possibility to extrapolate the results to humans. In mice, both the inactivation process itself is different and the phenotypic manifestation of X monosomy (39, X) is also much milder than in 45,X women. This difference could be explained by...
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Karyotype analysis of mygalomorph spiders of the families Hexathelidae and Dipluridae
Hrubá, Barbora ; Král, Jiří (advisor) ; Sember, Alexandr (referee)
Cytogenetics of spiders of the infraorder Mygalomorphae is largely unknown. My thesis is focused on the karyotype evolution of spiders of families Hexathelidae Dipluridae, which are basal groups of the superfamily Avicularioidea. In this thesis the evolution of diploid chromosome number, chromosome morfology, and also sex chromosomes are studied. The karyotypes of the mygalomorphs are quite interesting for their diversity. Many members of the family Hexathelidae exhibit extreme systems of a chromosomal sex determination which are composed by many gonosomes X. The meiotic division of males is analyzed. Some species exhibit modifications of this division such as achiazmatic meiosis. Selected markers have been detected by fluorescence in situ hybridization. Keywords: evolution, fluorescent in situ hybridization, karyotype, nucleolus organizer region, sex chromosomes, spider
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Sequence analysis of SIX homeobox family in Craspedacusta sowerbyi
Vojta, Petr ; Pačes, Jan (advisor) ; Král, Jiří (referee)
Homeobox genes are generally known as key factors directing processes during the morphogenesis of organ systems. Recently, research of homeobox genes evolution has focused on evolutionary old groups of species, such as Cnidarians. ln Cnidarians, there are more homeobox genes compared with more complex organism, such as fruit flies. Several homeobox genes have also been described in plants and fungi. General opinion is that homeobox genes are a very old group of genes, originating even before the main kingdoms of multicellular organisms. Six homeobox genes that have been identified as homologues of Drosophila sine oculis, an important factor for compound-eye formation, take part in numerous developmental processes directed by the PAX-SIX-EYA signal pathway. ln Vertebratae, as representatives of Deuterostomes, there are six genes in three sub groups, whereas in Drosophila melanogaster, as a representative of Protostomes, three homologues have been described, always one for each subgroup. The ancestral six genes diverged even before the divergence of groups Bilateralia and Cnidaria. ln freshwater jellyfish Craspedacusta sowerbyi we distinguished both HD and SD regions for five SIX proteins. Four of these six genes of Craspedacusta sowerbyi belong to the established Six groups (Sixl/2, Six3/6 a Six4/5), where...
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Origin, degeneration and detection of sex chromosomes
Jílková, Klára ; Král, Jiří (advisor) ; Kratochvíl, Lukáš (referee)
Sex chromosomes evolved from a pair of autosomes and they are differentiated as a result of supression of recombination. This process leads to a successive degradation of odd sex chromosome (alosome), which is becoming genetically inert finally or even excluded. Fundamental processes taking part in degeneration of alosome are Muller's ratchet, genetic hitchhiking, background selection, accumulation of transposable elements and constitutive heterochromatin. Indeed, these processes take part in either degeneration of both Y or W chromosomes. Remarkably, these alosomes show different rates of degeneration, most probably due to 1) different structure of male and female gonads as well as 2) different course of gametogenesis in both sexes. Furthermore, rate of alosome degeneration is usually lower in plants because they are haploid during the major part of life cycle. Other mechanisms of sex chromosome evolution involve rearrangements between autosomes and gonosomes, nondisjunctions and fissions of original sex chromosomes, transformation of B chromosomes into sex chromosomes or non-random segregation of autosomes with sex chromosomes. Other phenomenon that appears in sex chromosome evolution is transition between XY/XX and ZW/ZZ systems or transition between chromosomal sex determination and epigamy. Actually,...
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Polyploidy with specific view to paleopolyploidy and its detection
Kotz, Matěj ; Král, Jiří (advisor) ; Rothová, Olga (referee)
Polyploidy is a significant phenomenon in the evolution of eucaryotic organisms. It has been a subject of interest of biologists for decades and it has been studied particularly largely in plants, where it most often occurs. This thesis handles occurrence of poylploidy in organims and a special emphasis is laid on old polyploidization events occurrence of polyploidy in animal taxa. Furthermore, the types of polyploidy and obstacles are discussed here, that a polyploid organism has to tackle to stabilize its genome. That also includes the need to ensure the correct chromosome segregation in a meiotic division. A special case of polyploidy is paleopolyploidy (sometimes refered to as "ancient polyploidy" in English), which is an evolutionary old polyploidization event, that is followed by the process of diploidization. This process is characterized besides others by a large number of structural changes in chromosomes and a loss of some DNA sequences and a gradual transition of the polyploid genome to the cytologically diploid state. Because of these changes, it is difficult to detect a paleopolyploidy and the main part of this thesis is dedicated to this problem, in which the main approaches that might lead to its detection are discussed. Key words: polyploidy, animal, plant, meiosis, paleopolyploidy,...
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Genetic factors affecting course of selected forms of nephrotic syndrome
Šafaříková, Markéta ; Štekrová, Jitka (advisor) ; Král, Jiří (referee)
Nephrotic syndrome (NS) is characterized by proteinuria, hypalbuminemia and edemas. It occurs during first and second glomerulopathies. This disease can be divided into two groups: primary (idiopathic) and secondary. The heredity of the familial nephrotic syndrome is autosomal dominant and autosomal recessive. There are four most important genes that condition the formation of hereditary nephrotic syndrome in adult patienst. These genes are ACTN4, CD2AP, NPHS2 and TRPC6. The gene ACTN4, which encodes protein α-actinin 4, is responsible for the autosomal dominant form of focal segmental glomerulosclerosis (FSGS). FSGS is included in first glomerulopathies. α-Actinin 4 was also researched for some types of carcinomas. There was performed the mutational analysis of the gene ACTN4 on the set of 48 patients with nephrotic syndrome in this diploma thesis. High resolution melting (HRM) analysis and sequencing selected samples were used during this mutation detection. During this process many published and unpublished SNPs and one unpublished candidate mutation that could have causal associations with FSGS were found.
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Evolution of the karyotype in two spider families, Atypidae and Pholcidae
Pastuchová, Markéta ; Král, Jiří (advisor) ; Kočárek, Eduard (referee)
Evolution of the karyotype in two spider families, Atypidae and Pholcidae (Araneae) Summary From cytogenetic point of view spiders are very diversified group, they exhibit great diversity in diploid chromosome number from 7 Ariadna lateralis (Segestriidae) up to 128 Cyclocosmia siamensis (Ctenizidae). Till recently karyotypes of almost all spiders were supposed to consist exclusively of acrocentric chromosomes including X1X20 sex chromosome system. However, this idea is based mostly on research of an advanced clade - entelegyne lineage of araneomorph spiders. Karyotypes of mygalomorph and haplogyne spiders remain nearly unexplored. Presented study is focused on cytogenetics of eight representatives of the family Pholcidae (Araneomorphae, Haplogyne) and Atypus piceus and A. affinis (Mygalomorphae, fam.Atypidae). Karyotypes, course of meiosis and distribution of nucleolar organizer regions (NOR) have been investigated in selected pholcid species and in one representative of the family Sicariidae (Araneomorphae, Haplogyne). Chromosomes of these groups are mostly biarmed (metacentric or submetacentric) and sex chromosome systems are diversified. Furthermore, distribution of constitutive heterochromatin and NOR has been analysed in A. piceus (2n0' = 41,XO) and A. affinis (2n0' = 14,XY). Key words: Atypidae,...
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Giardia intestinalis karyotypes
Hudosová, Lenka ; Nohýnková, Eva (advisor) ; Král, Jiří (referee)
Giardia intestinalis is a parasitic protist that causes one of the most common diarrheal disease of parasite origin. The cell of Giardia contains two nuclei with unknown number of chromosomes until recently. Karyotype was determined five years ago using conventional cytogenetic method by Tůmová and collaborators. In my work, I assessed karyotype of four isolates, six lines and three clonal lines by the same method. It was confirmed, that two nuclei within one cell could differ in chromosome number, the differences found were 1, 2 or 6 chromosomes. Aneuploid number of chromosomes was found too. In case that both nuclei within single cell contained the same number of chromosomes, there were 10 chromosomes indentified in each nucleus. It was also revealed, that karyotype is not specific feature for different genetic groups (in this work assemblages A and E). Karyotype can be different even among lines and clonal populations derived from the same isolate. Changes in karyotype in the course of in vitro cultivation were detected within three populations. Results are discussed in relation to known facts.
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Karyotype evolution of velvet spiders (Araneae: Eresidae)
Forman, Martin ; Král, Jiří (advisor) ; Rothová, Olga (referee)
Presented study is aimed to determine basic trends of karyotype evolution in velvet spiders (Eresidae; Araneae). Eresids are burrowing spiders; they includes also some social species. Karyotypes of 16 species of the family Eresidae as well as 2 species of the other families of the superfamily Eresoidea, Hersiliidae and Oecobiidae, are presented. Furthermore, DNA content and base proportion was determined in 14 species. In two species, DNA content of sex chromosomes was also measured. Obtained results revealed considerable variability of diploid numbers, and sex chromosomes systems in eresids. Obtained karyotype data allow to divide eresids into four groups. Karyotypes of the genera Gandanameno, Dresserus and S. lineatus are close to proposed ancestral karyotype of entelegynae spiders and they show the ancestral state of karyotype in velvet spiders. Karyotypes of S. lineatus and E. annulipes differ substantially from other representatives of the genera Stegodyphus and Eresus which indicates paraphyly of these genera. Karyotypes of basal forms are formed by acrocentric chromosomes. Further evolution of eresid karyotypes included considerable reduction of diploid numbers as well as changes of chromosome morphology. Social species of the genus Stegodyphus show tendency to reduce diploid numbers by...
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