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Molluscs as a new model system in molecular biology
Ber, Tobiáš ; Svoboda, Petr (advisor) ; Pergner, Jiří (referee)
Molluscs form the second largest animal phylum and are of great biological and economic significance. Their distinct evolutionary adaptations enabled them to inhabit a broad range of environments, with many of them invading new areas and becoming invasive pest species. Despite their importance, molluscan model systems have not received attention they deserve. In this bachelor thesis, I have reviewed the current state of molluscan model systems in molecular biology and analyzed their significance for more common use. From available data, it is apparent that the already established molluscan models are either marine or fresh-water, and therefore require more complex logistics and maintenance in order to set up a laboratory culture. To remedy the problem of aquaculture, the use of terrestrial gastropods was proposed. Here, I suggest that gastropods genus Deroceras have a good potential to become a new prominent molluscan model system in molecular biology.
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Characterization of Euglena gracilis and their role in metaboly movement
Šmída, Adam ; Hampl, Vladimír (advisor) ; Pergner, Jiří (referee)
Euglena gracilis is a free-living freshwater flagellate from the class Euglenida (Euglenozoa, Discoba, Excavata). The synapomorphy of Euglenida group is their pellicle, a firm layer underneath the surface of the cell which is composed of proteinaceous stripes (pellicle strips). The strips are locked into each other and run along the cell`s surface underneath the plasma membrane. In E. gracilis these strips can move by parallel sliding, therefore contracting the cell and changing its surface which results in a characteristic peristaltic euglenoid movement called metaboly. The mechanism behind this movement is still unresolved, however, it is expected that the force is generated by the cytoskeletal structures beneath the pellicle strips which consist of microtubules and other unknown cytoskeletal fibers. This thesis tests a hypothesis which proposes that centrins are involved in the pellicle contraction. Centrins are small proteins capable of binding calcium ions, they are very conserved throughout the eukaryotic tree and serve many purposes in the cell, of which one is to form contractile structures in ciliates species e.g., Vorticella or Paramecium. Sequences of centrins were searched for in the transcriptome of E. gracilis and after comparison with the available proteomic dataset of the isolated...
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Evolution of visual sensory system in the common barbel (Barbus barbus)
Konvičková, Zuzana ; Musilová, Zuzana (advisor) ; Pergner, Jiří (referee)
Vertebrates inherited five visual opsin classes from their common ancestor expressed in the rod and cone cells. While many vertebrate groups reduced the number of visual pigments they possess, opsins of teleost fishes have diversified. Today, teleosts outstand among all vertebrates in the number of visual pigments and photoreceptor types. This extraordinary development was also facilitated by the teleost- specific whole genome duplication that occurred approximately 350 Mya. Here I explored teleost species that recently underwent subsequent whole genome duplication - the common barbel (Barbus barbus). This event was accompanied by hybridization (i.e., it was allopolyploidization) and resulted in 14 opsin genes found in the genome, an unusually high number even among teleosts. In this thesis, I studied the effects of such an expanded opsin repertoire on the visual abilities of the common barbel. Based on the whole genome, I have completed the reference sequences of all opsin genes and revealed their positions on the chromosomes. I analysed retinal transcriptomes and constructed developmental series of opsin expression profiles. All opsin genes were preserved functional in the genome, even though one of them (green-sensitive, named RH2-4 in this thesis) was not found in the transcriptome and showed...
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Experimental system for the mouse polyomavirus life cycle study
Pergner, Jiří ; Španielová, Hana (advisor) ; Mašek, Tomáš (referee)
Experimental system for the mouse polyomavirus life cycle study Abstract: Murine polyomavirus (MPyV) is the prototype of the Polyomaviridae family. This family includes also some important human pathogens (BKV, JCV, Merkel cell polyomavirus). Due to their specific properties viruses within this family may serve as versatile vectors for gene therapy or recombinant vaccine production. New methodological approaches may help to understand some yet unknown facts about MPyV life cycle. Clarification of some processes during murine polyomavirus life cycle may be also important to fully exploit polyomaviruses for therapeutic purposes. The aim of this diploma thesis was to preparare two innovative experimental systems that extend possibilities of studying the life cycle of MPyV. The first part of the diploma thesis focusses on construction of recombinant MPyV which expresses yellow fluorescent protein (EYFP) in the early stages of infection. Such virus can be very useful for studying the infection spreading by live- cell imaging and Fluorescence-Activated Cell Sorting (FACS) and can be employed for co- localization studies of YFP-tagged LT antigen with certain cellular proteins. Second part of the diploma thesis describes preparation of a hybrid cell line prepared by fusion of mouse and monkey cells. This new cell...
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Evolution of light detection in chordates
Pergner, Jiří ; Kozmik, Zbyněk (advisor) ; Markoš, Anton (referee) ; Musilová, Zuzana (referee)
Light detection is one of the crucial abilities of all animals. The light cues are important e.g. for maintaining of circadian rhythms, regulation of spawning cycles, changes of pigmentation and arguably most importantly for vision. Most animals detect light by opsins, members of the G protein coupled receptors superfamily. Amphioxus belongs to earliest branching chordate clade, cephalochordates. Thanks to their phylogenetic position, physiology and morphology, cephalochordates became the most relevant model organism for understanding the evolutionary origins of vertebrate specific traits. Amphioxus evince various reactions to light throughout its development. In the presented thesis light detecting systems of amphioxus were studied thoroughly. More specifically characterization of the opsin gene repertoire of two amphioxus species Branchiostoma floridae and Branchiostoma lanceolatum and their comparison with opsins from other animals is presented. In addition, remarkable similarity on the gene expression level between one of amphioxus visual organs, so called frontal eye, and neurons and retinal pigmented epithelium in vertebrate retina was shown. These data confirm the long time ago proposed homology between amphioxus frontal eye and vertebrate lateral eyes. Taken together all the presented data...
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Comparative and evolutionary analyses of neurulation in non-teleost fishes
Matějková, Tereza ; Černý, Robert (advisor) ; Pergner, Jiří (referee)
Neurulation, i. e. formation of a neural tube, is a crucial event in embryogenesis of each vertebrate. This developmental process is rather stereotypical, generally comprising a transformation of a neural plate into a neural tube. In the majority of vertebrate groups, neurulation classically occurs by a folding process of bending neural folds, whereas in bony fishes (Teleostei), representing a crown group of ray-finned fishes (Actinopterygii), the neurulation occurs rather differently by a solid neural keel. The three stem groups of ray- finned fishes - bichirs, sturgeons and gars - might thus serve as unique models for understanding of evolutionary changes in the pattern of vertebrate neurulation. For that reason, detailed developmental series of bichir (Polypterus senegalus), sturgeon (Acipenser ruthenus) and gar (Atractosteus tropicus) were used, and their morphogenetic processes of neurulation were compared. I present here description of the outer morphology, and analyses of tissue and cellular changes, with a focus on intrinsic forces within the neural plate like apical constriction and convergent extension, as well as on some extrinsic forces. I also try to discuss possible mechanisms of an evolutionary transition from the bending of the neural plate to the neurulation via the neural keel,...
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The role of the Msx1 transcription factor in the intestinal epithelia and colorectal cancer
Šťastná, Monika ; Kořínek, Vladimír (advisor) ; Pergner, Jiří (referee) ; Doubravská, Lenka (referee)
The Wnt signaling pathway represents the principal evolutionarily conserved signaling cascade found in all multicellular organisms. It plays a key role not only in many processes during embryogenesis, but also in maintaining tissue homeostasis and regeneration. By contrast, mutations in genes encoding components of the pathway often result in increased activation of Wnt signaling and underlie onset of many human diseases, particularly cancer. The canonical Wnt signaling pathway is essential for proliferation and maintenance of the pluripotent state of intestinal stem cells and thus for homeostatic renewal of the intestinal epithelium. However, aberrant (hyper)activation of the Wnt signaling pathway is the initial step in development of intestinal neoplasia. Understanding the causes and identifying the consequences of the Wnt signaling hyperactivation is crucial for deciphering mechanisms leading to malignant transformation. Although the canonical Wnt signaling pathway has been the subject of scientific studies for several decades, all regulatory mechanisms and consequences of its hyperactivation have not been completely elucidated yet. During my PhD studies, I focused on understanding function(s) of some components and target genes of this signaling cascade. In this theses, results of my first...
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Comparative and evolutionary analyses of neurulation in non-teleost fishes
Matějková, Tereza ; Černý, Robert (advisor) ; Pergner, Jiří (referee)
Neurulation, i. e. formation of a neural tube, is a crucial event in embryogenesis of each vertebrate. This developmental process is rather stereotypical, generally comprising a transformation of a neural plate into a neural tube. In the majority of vertebrate groups, neurulation classically occurs by a folding process of bending neural folds, whereas in bony fishes (Teleostei), representing a crown group of ray-finned fishes (Actinopterygii), the neurulation occurs rather differently by a solid neural keel. The three stem groups of ray- finned fishes - bichirs, sturgeons and gars - might thus serve as unique models for understanding of evolutionary changes in the pattern of vertebrate neurulation. For that reason, detailed developmental series of bichir (Polypterus senegalus), sturgeon (Acipenser ruthenus) and gar (Atractosteus tropicus) were used, and their morphogenetic processes of neurulation were compared. I present here description of the outer morphology, and analyses of tissue and cellular changes, with a focus on intrinsic forces within the neural plate like apical constriction and convergent extension, as well as on some extrinsic forces. I also try to discuss possible mechanisms of an evolutionary transition from the bending of the neural plate to the neurulation via the neural keel,...
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Evolution of light detection in chordates
Pergner, Jiří ; Kozmik, Zbyněk (advisor) ; Markoš, Anton (referee) ; Musilová, Zuzana (referee)
Light detection is one of the crucial abilities of all animals. The light cues are important e.g. for maintaining of circadian rhythms, regulation of spawning cycles, changes of pigmentation and arguably most importantly for vision. Most animals detect light by opsins, members of the G protein coupled receptors superfamily. Amphioxus belongs to earliest branching chordate clade, cephalochordates. Thanks to their phylogenetic position, physiology and morphology, cephalochordates became the most relevant model organism for understanding the evolutionary origins of vertebrate specific traits. Amphioxus evince various reactions to light throughout its development. In the presented thesis light detecting systems of amphioxus were studied thoroughly. More specifically characterization of the opsin gene repertoire of two amphioxus species Branchiostoma floridae and Branchiostoma lanceolatum and their comparison with opsins from other animals is presented. In addition, remarkable similarity on the gene expression level between one of amphioxus visual organs, so called frontal eye, and neurons and retinal pigmented epithelium in vertebrate retina was shown. These data confirm the long time ago proposed homology between amphioxus frontal eye and vertebrate lateral eyes. Taken together all the presented data...
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