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Evolution of sex determination in skinks and related lineages
Kostmann, Alexander ; Rovatsos, Michail (advisor) ; de Bello Cioffi, Marcelo (referee) ; Liehr, Thomas (referee)
6 Abstract Scincoidean lizards, i.e. cordylids, gerrhosaurids, skinks and xantusiids, are known for their remarkable ecological and morphological variability. It was hypothesized that, at least in skinks, sex determining systems are highly variable as well. In the other three families, evidence for presence or absence of sex chromosomes has been scarce, with two species of night lizards with ZZ/ZW sex chromosomes being the exception. In this thesis, conventional and molecular cytogenetic methods, including C-banding, fluorescence in situ hybridization (FISH) with probes for telomeric motifs and rDNA loci and comparative genomic hybridization (CGH) were used to identify cytogenetically distinguishable sex chromosomes. Although most studied species showed no sex-specific differences by cytogenetic examination, some did. Tracheloptychus petersi has accumulations of rDNA loci on a pair of macrochromosomes and a pair of microchromosomes in males, while again on a pair of macrochromosomes and a single microchromosome in females. This distribution suggests a ZZ/ZW system in this species, which is the first report of sex chromosomes in any gerrhosaurid lizard. In Zonosaurus madagascariensis, CGH was able to identify the W chromosome in females, which is the second report of sex chromosomes in this family....
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Cytogenetic characteristics of the genus Cimex (Heteroptera: Cimicidae)
Sadílek, David
The present thesis deals with the phenomenon of additional sex chromosomes in Cimex lectularius (Hemiptera: Heteroptera: Cimicidae) using genome size analysis combined with the classical cytogenetic approach. Also, five other cimicid species and 12 species from the family Nabidae were analysed identically for comparative purposes. The thesis also pursues a description of methodical approaches of cytogenetics and flow cytometry in the study of C. lectularius. Recently analysed European specimens of C. lectularius from human host exhibited 12 distinct cytotypes, with a variable number of chromosomes X from two to 20 (2n♂ = 26+X1X2Y to 26+X1-20+Y). The fragmentation hypothesis of C. lectularius additional chromosomes X origin was established in the second half of the 20th century. However, the present genome size measurements suggest that various chromosomal rearrangements as duplication or deletion besides the fragmentation could occur. Males with basic cytotype 2n = 26+X1X2Y had average genome size of 2C = 1.94 pg, in contrast male with 2n = 26+X1-7+Y yielded 2C = 2.26 pg and also specimens with genome size decrease 2C = 1.69 pg appeared. The most informative turned up to be the relative genome size of sperm cells n = 13+X1X2 and n = 13+Y, where specimens with higher chromosome number showed...
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Evolution of sex chromosomes in reptiles
Mazzoleni, Sofia ; Rovatsos, Michail (advisor) ; Zrzavá, Magda (referee) ; Liehr, Thomas (referee)
- ABSTRACT - Among vertebrates, reptiles represent the ideal group for the study of sex determination. Reptiles include lineages with environmental sex determination (ESD) as seen in crocodiles and tuatara, lineages with genotypic sex determination (GSD), like e.g. iguanas, chameleons, skinks, lacertid lizards and birds, and few groups which possess variability in sex determination mechanisms, i.e. geckos, dragon lizards and turtles. This thesis is focused on the evolution of sex chromosomes and sex determination in turtles. The majority of turtle species exhibit ESD, which is considered the ancestral sex determination system of this group, while GSD either as male or female heterogamety evolved independently at least five times. We investigated the presence of sex chromosomes in representative species of turtles by cytogenetic analyses. The analyses included the reconstruction of karyotypes, distribution of constitutive heterochromatin (C-banding, methylation analysis) and repetitive elements (fluorescence in situ hybridization) and comparative genome hybridization (CGH), which often characterize the degenerated Y or W and can be helpful in the identification of "cryptic" sex chromosomes. We described XX/XY sex chromosomes in seven previously unstudied Australasian chelids (Pleurodira) from the genera...
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Developmental defects and their examination in biochemical screening
TOMANOVÁ, Andrea
This thesis deals with the issue of congenital developmental defects, with the focus on the most frequently occurring chromosomal aberrations. The main focus is biochemical screening of pregnant women as an integral part of prenatal diagnostics. The aim is to produce summary statistics of the occurrence of the three most frequent chromosomal aberrations based on acquired data and to compare the results with the official statistics of the occurrence of these anomalies within the Czech Republic.
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Karyotype variability of harvestmen from Nemastomatidae family (Arachnida: Opiliones)
Alaverdyan, Argam ; Šťáhlavský, František (advisor) ; Symonová, Radka (referee)
This master's thesis is focused on cytogenetic analysis and karyotype variability of the Nemastomatidae family. This family comprises morphologically uniform harvestmen of small sizes, with low mobility, and with center of distribution in Europe. Karyotype differences could play an important role for detection of cryptic diversity in this family. The karyotype analysis is focused mainly on Alpine and Pyrenean endemic species but also on other taxons located in Central Europe. The goal was not only to identify the differences which occur between the specific genera and species, but also eventually between populations. For detection of the specific chromosomal alterations in evolution of the karyotype in Nemastomatidae the fluorescent in situ hybridization (FISH) was used, localizing the positions and amounts of gene clusters for 18S rRNA. From the results we can assume that the number of chromosomes in the family Nemastomatidae can range between 2n = 12- 30. Further it was found out that in Nemastomatidae the biarmed chromosomes are more prevalent, and that the species which have lower amounts of chromosomes contain chromosomes that noticeably differ in size (probably because of chromosomal fusions). These results indicate that with some morphologically uniform species, the knowledge of specific...
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Human multipotent mesenchymal stromal cells - bone differentiation and hematopoietic support
Pytlík, Robert ; Trněný, Marek (advisor) ; Filová, Elena (referee) ; Lesný, Petr (referee)
Human mesenchymal stromal cells (hMSC) are adult stem or progenitor cells, which physiological role is reparation of damaged tissues. This is achieved mostly by secretion of trophic, angiopoietic and immunomodulatory factors. Beside this, hMSC have potential to differentiate in vitro into specialized cells, especially of the mesodermal lineages. Human MSC also significantly support hematopoiesis in hematopoietic niche. This knowledge raised high hopes for therapeutic use of hMSC, especially in regenerative medicine and treatment of autoimmune diseases, including graft versus host disease (GvHD). As a proof of concept served initially crude preparations of bone marrow mononuclear cells (BMMC), which contain small numbers of hMSC. In our hospital, two pilot clinical studies with BMMC were performed: study of treatment of acute myocardial infarction (negative, prematurely terminated) and study of treatment of peripheral leg arthery disease (promising results). Further research was aimed on optimalisation of hMSC cultivation method for clinical use to obtain highest possible yield and get free from animal proteins. Human MSC were traditionally cultivated in research-grade media with fetal calf serum (FCS), which can lead to immunization of patients after repeated application of hMSC. We achieved...
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Analýza karyotypu vakonošů (Psychidae, Lepidoptera) metodami klasické a molekulární cytogenetiky
HEJNÍČKOVÁ, Martina
Due to their phylogenetic position, Psychidae play an important role in the investigation of the W chromosome origin in Lepidoptera. Several species of Psychidae were tested for the presence of sex-chromatin and investigated via comparative genomic hybridization. Furthermore, odd chromosome numbers and a Z univalent were observed in females. Overall, this study brings tangible evidence for the absence of the W chromosome in Psychidae, thus contributes to complex knowledge of the W chromosome evolution. In addition, karyotypes of the given species were analyzed using 18S rDNA and histone H3 probes. The results indicate relative stability of their karyotypes.
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Heteroploidy in bone marrow cells of children with acute lymphoblastic leukemia (ALL)
Matějčková, Nicole ; Zemanová, Zuzana (advisor) ; Krylov, Vladimír (referee)
Acute lymphoblastic leukemia is the most common type of cancer in children. It is a very heterogenous disease in which many recurrent chromosomal abnormalities have been described. The most important chromosomal abnormalities associated with a good prognosis are t(12;21)(p13;q22) which result in ETV6/RUNX1 fusion and hyperdiploidy. On the contrary findings suggesting a poor prognosis are t(9;22)(q34;q11) leading to fusion gene BCR/ABL1, MLL rearrangements or hypodiploidy. Heteroploidy is one of the most frequent findings in childhood ALL. It is characterised by nonrandom gain or loss of chromosomes from diploid cells. One of the most important findings in childhood ALL is hyperdiploidy where a non-random gain of chromosomes is present. Hyperdiploidy has a favorable prognosis and the impact of additional structural aberations requires further research. Another prognostically important group of heteroploidy is hypodiploidy. It is a quite rare finding and has a very poor outcome. There are non-random acquired chromosome losses observed in hypodiploid cells. Hypodiploid cell line may be masked with a doubled hyperdiploid clone which makes it difficult to identify. Proper and early cytogenetical analysis of heteroploid cells is very important as it contributes assigning correct diagnosis and risk stratification,...
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