|
|
Whole-genome analysis of the house mouse hybrid zone
Janoušek, Václav ; Munclinger, Pavel (advisor) ; Choleva, Lukáš (referee) ; Chan, Yingguang Frank (referee)
Hybrid zones provide a valuable opportunity to study the process of speciation in real time. Untested combinations of genes from diverging populations come to the contact here causing a breakdown of genetic interactions and giving rise to reproductive isolation. Two house mouse subspecies (Mus musculus musculus/Mus musculus domesticus) form a narrow zone of secondary contact across Central Europe which is thought to be maintained by a balance between selection against unfit hybrids and dispersion of individuals. During my PhD study my collaborators and I used an array of ~ 1400 SNP markers to study patterns of introgression on a genome-wide scale across two/three house mouse hybrid zone transects. Our aim was to identify the genomic regions putatively harboring genes which are involved in the reproductive isolation between the two subspecies, characterize their distribution in mouse genome and assess genomic features associated with them. We were able to confirm on a genome-wide scale the importance of the X chromosome in the evolution of reproductive isolation. This chromosome exhibited introgression corresponding to strong negative epistasis and the patterns were consistent between transects pointing out to a common basis of reproductive isolation playing a role in two transects. Contrary to the...
|
|
|
Changes in embryonal programing induced by diabetes mellitus
Landsmann, Lukáš ; Pavlínková, Gabriela (advisor) ; Tlapáková, Tereza (referee)
Embryonic development is sensitive to environmental changes. These changes may lead to changes in the embryonic programming. Changes in programming embryos can occur due to inadequate nutrition, stress, treatment with chemicals and also due to diabetes. Epigenome reacts sensitively to environmental factors regulating gene transcriptional activity. Changes in the epigenome lead to a changes in gene expression, which can have a negative impact on the physiology and metabolism of organism. Maternal diabetes may alter embryonic and fetal development and may result in diabetic embryopathy. Furthermore, maternal diabetic enviromental plays an important role in the predisposition of offspring to a number of chronic diseases later in life. The offspring of diabetic pregnancies demonstrate differences in metabolic, cardiovascular, and inflammatory variables, compared to the offspring of nondiabetic mothers. This thesis summarizes the genetic and epigenetic factors involved in the development of diabetic embryopathy and in the embryonic programming. Key words: Diabetes mellitus, diabetic embryopathy, transcriptional regulation, genetic and epigenetic factors , embryonic programming, genome
|
|
|
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....
|
|
| |
|
|
Mechanisms of papillomavirus genome integration into the human chromosome
Frčková, Tereza ; Šmahelová, Jana (advisor) ; Fraiberk, Martin (referee)
Human papillomaviruses (HPV) are small non-enveloped DNA viruses that can cause malignancies in the human population. They are often associated with carcinomas in anogenital area in both men and women, but also with part of head and neck cancer. In infected cells, the HPV genome is present as a circular molecule of DNA, called an episom. Certain circumstances result into the occurrence of a linearization of the HPV genome and a subsequent integration in the human chromosome. The integration plays a role in the cell behavior and contributes to immortalization and tumor transformation. The HPV genome integration is influenced by various viral or cell factors that affect the HPV genome stability in the cell. Interaction between viral and cell protein can often lead to activation of DNA damage response, that virus exploits for replication of viral genome. Viral genome integration is also more likely to occur in certain HPV types. Another factor is the area of infection, where the neoplastic progression was studied.
|
|
|
Evolution of nuclear and plastid genomes in euglenids
Hrdá, Štěpánka ; Hampl, Vladimír (advisor) ; Krajčovič, Juraj (referee) ; Škaloud, Pavel (referee)
Algae form a diverse group of simple photosynthetic eukaryotes of polyphyletic origin. Algae with a primary plastid (Archaeplastida) acquired it by ingesting cyanobacterium, a prokaryote; algae with a complex plastid acquired their plastid by ingesting another eukaryote with a primary or already complex plastid. Algae with a complex plastid are chimeras containing genes derived from the host genome, as well as genes derived from the genome of the endosymbiont, and also genetic material derived from genomes of their previous stable or transient endosymbionts. One of the groups with plastid derived from green algae are euglenophytes. This thesis deals with the genomes of three organisms that represent individual actors in the endosymbiotic process in euglenophytes. These are a heterotrophic host from the class Euglenida, a phototrophic endosymbiont from the class of green algae Prasinophyceae and the resulting phototrophic euglenid from the group Euglenophyceae. Knowledge of their genomes should illuminate the course of endosymbiotic gene transfer (EGT) in the formation of algae with a complex plastid. We annotated the plastid genome of a phototrophic euglenid Eutreptiella gymnastica and published it as the third plastome of Euglenophytes after the iconic and economically important Euglena gracilis...
|
|
|
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...
|
|
|
Study of genome of Metschnikowia yeasts by molecular methods
Schneiderwindová, Nicole ; Skoumalová, Petra (referee) ; Němcová, Andrea (advisor)
Yeasts of the genus Metschnikowia belonging to the family Metschnikowiacea are yeasts characterized by vegetative propagation through multilateral budding. These are yeasts widely distributed in nature. More than 35 species occurring have been defined in the wild. They most often occur on flowers, fruits, but also on insects or human skin. They have a wide range of uses due to their antifungal effects in agriculture and the cosmetics industry. This bachelor thesis deals with the study of usage of molecular methods to characterize selected species of yeasts of the genus Metschnikowia. It focuses on a detailed description of the yeast cell structure, karyotype and methods of reproduction in the theoretical part of the work. In the practical part on optimization and description of molecular methods including pulse gel electrophoresis methods used to separate the yeast genome and their subsequent observation of changes in individual parts of genome. First, the yeast was cultured under special conditions that are characteristic of Metschnikowia yeasts, then yeast DNA was isolated using methods suitable for DNA isolation, which was further examined by the PFGE molecular method. The DNA isolation procedure was first optimized for individual yeast strains, as it was necessary to verify the required ratio of low melting agarose to isolated DNA. That was because of it was important for the resulting gel blocks to be suitable for measurement by PFGE analysis. By optimizing the method was possible to create ideal blocks of isolated yeast DNA, which were subsequently subjected to PFGE analysis. Several measurements of PFGE analysis were performed at different time intervals in order to separate small and large yeast chromosomes. The CHEF standard of the yeast Hansenula wingei and the standard of the yeast Schizosaccharomyces pombe were used for the measurements. According to the measurement results, it can be determined that the yeast DNA isolation procedure and subsequent analysis by pulsed gel electrophoresis were successful, as the number of chromosomes of all used yeast species of the genus Metschnikowia was determined.
|
|
|
Evoluce genomů vlka a psa a jejich porovnání
Pazii, Oleksandra
The bachelor thesis deals with the study of the first and most common domesticated animal and its ancestors. The emphasis is put on the analysis of the current knowledge of the evolution of the gray wolf and the domestic dog genomes. Based on scientific publications are discussed origin, divergence, scenarios and influence of domestication on breeds. These are genetic fundamentals of phenotypic diversity, relationships between dog breeds, variations in morphology and behavior, and introgression between wolves and dogs. At the end of the thesis there are summarized several methods, used software and results from various molecular phylogenetic researches. A contemporary view of the evolution of all canines, molecular genetic research of the relationships between modern and origin species are key components for achieving the consensus about the place, time and reasons of diversification of dogs and wolves.
|
|
|
Robertsonian translocations and their involvement into genome evolution
Mlnáříková, Barbora ; Forman, Martin (advisor) ; Sember, Alexandr (referee)
Chromosome aberrations play an important role in human pathologenesis as well as in evolution of many organisms. Robertsonian translocation or centric fusion are the most frequent chromosomal rearrangements in mammals. The most investigated model for their research is house mouse Mus musculus. The standard karyotype of a mouse consists from 40 acrocentric chromosomes, notably there are more than one hundred wild populations that are characterized by various combination of metacentrics, formed by centric fusion of different acrocentrics. Several models have been proposed for the formation of metacentrics, taking account of the sequential structure of their centromeres and short arms in mouse. Segregation distortion in favor of metacentrics is present in female and/or male meiosis, such as meiotic drive can positively affect the degree of fixation of metacentric chromosomes in certain population. Centric fusions have been also presented in evolution of other organisms. Cytogenetic data in spiders indicate the possibility of similar phenomena in the most diversified group of spiders, Entelegynae. Spiders are notable for their unusual sex chromosome systems. Centric fusions also play an important role in the evolution of sex chromosomes and the formation of neo-sex chromosome systems. So far, there is...
|
guest ::
