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Aktivita telomerázy u termita \kur{Prorhinotermes simplex}
JEHLÍK, Tomáš
Social insect is known for its unique caste system, coherence and effective division of labor, but also for the extreme longevity of reproductive individuals in comparison with asexual castes. Although mechanisms leading to lifespan differences between reproductive and non-reproductive castes of social insects are not sufficiently explained, one of the longevity determinants might be telomere length and activity of telomerase as the most common mechanism of telomere length maintenance. Telomere length belongs to general indicators of organismal lifespan. This work is focused on monitoring of telomerase activity in various stages, castes and organs of the termite Prorhinotermes simplex (Isoptera: Rhinotermitidae) showing up-regulation of telomerase in reproductive castes.
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Telomeres as indicators of chronological and functional age and ageing in birds
Kyliánková, Hana ; Albrecht, Tomáš (advisor) ; Aghová, Tatiana (referee)
The explanation of ageing processes belongs to the most challenging topics in evolutionary biology. This bachelor thesis provides a basic summary of evolutionary hypotheses of ageing, along with an overview of proximate ageing mechanisms. Main focus is on telomeres and the dynamics of their shortening. Telomeres are non-coding, repetitive sequences of DNA protecting the ends of eukaryotic chromosomes against degradation. They usually shorten with each cell division in most somatic cells until they reach the critical limit (the so called Hayflick limit), when the cell undergoes the replicative senescence and does not divide anymore. Various factors, such as physiological/oxidative stress, stage of reproduction/reproductive investments, and diseases/parasites, can influence telomere length dynamics. Recent studies indicate that telomere length is a useful biomarker for estimating functional, or biological age, but at the same time length of telomeres cannot be used to estimate chronological age. Molecular methods which can be used to measure telomere length, and their potential limitations, are also discussed in this thesis. Finally, I provide an overview of studies focusing on telomere dynamics in bird-oriented research. Key words: Telomeres, ageing, qPCR, birds, oxidative stress
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Non-resonant Raman Spectroscopic Study of Guanine Quadruplex Structures
Golan, Martin ; Mojzeš, Peter (advisor) ; Mašek, Vlastimil (referee)
Parts of human telomere sequences containing at least 4 guanine subsequences show the ability to form intrastrand quadruplexes of remarkable conformational diversity. Former studies using conventional Raman spectroscopy have revealed that the sequence G3(TTAG3)3 at milimolar concentrations in phosphate buffer solution doped with Na+ ions (ionic strength 150 mM) adopts antiparallel conformation regardless of the length of standing at room temperature or annealing, whereas K+ ions cause gradual transition to "3+1" or even parallel conformation. On the other hand, measurements carried out upon sequence AG3(TTAG3)3 at similar concentrations using Photonic Crystal Fibre-enhanced Raman Spectroscopy (PCFRS) suggest that in the respective presence of both Na+ and K+ (ionic strength 100 mM), a parallel structure is adopted. The hereby presented work employs conventional Raman spectroscopy and Drop Coating Deposition Raman spectroscopy to examine the sequence AG3(TTAG3)3 at concentrations ranging from units to hundreds of milimoles in strands. It concludes that the structure adopted in the presence of Na+, resp. K+ ions is antiparallel, resp. "3+1", and doesn't change over time despite both long standing and annealing. Two hypotheses about the cause of the differences between the results obtained by PCFRS and...
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Evolution of selected karyotype characters in tetrapulmonate arachnids
Jílková, Klára ; Král, Jiří (advisor) ; Marec, František (referee)
The class Arachnida is not thoroughly explored from the cytogenetic point of view. Previous studies suggest a high diversity of karyotypes and sex determination in arachnids. This study deals with the evolution of sex chomosomes, nucleolar organizer regions (NOR), and telomeric repeats in the tetrapulmonate clade of arachnids, particularly in groups of ancient origin. Sex chromosomes were detected in two orders. Detection of NORs in a large set of species supports the hypothesis that the ancestral karyotype of arachnids contained NOR on one pair of autosomes only. The number of NORs has increased during the evolution of some groups of Pedipalpi. The NORs are located in terminal or subterminal chromosomal regions in most tetrapulmonates. The occurrence of the "insect" telomeric motif was confirmed in majority of tetrapulmonates. Interstitital telomeric repeats were not detected with the exception of one species. Keywords: arachnids, meiosis, sex chromosomes, telomeres, nucleolar organizer, heterochromatin
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Evolution of karyotype and sex determination in iguanas (Squamata: Pleurodonta)
Altmanová, Marie ; Kratochvíl, Lukáš (advisor) ; Zrzavá, Magda (referee)
Squamate reptiles in general possess an unusual variability in karyotype and sex determining mechanisms. However, in these two aspects, iguanas (Pleurodonts) are considered as a relatively conservative group of lizards. So far only genotypic sex determination with male heterogamety has been detected in this lineage. However, the sex chromosomes have not been revealed in many species by classical cytogenetics, probably due to their homomorphy. Significant variability in karyotype was observed only in the species-rich genera Anolis, Sceloporus and Liolaemus. The aim of this thesis was to investigate the genome of available species from the main iguanid lineages using classical and molecular cytogenetic methods. As well as finding the karyotype characteristics, which may represent synapomorphies of main iguanid lineages, the other aim was to try to identify sex chromosomes. This study confirmed previously published karyotypes of 13 species and established new descriptions of karyotype for eight species. The chromosomes of all studied specimens were examined by methods of classical and molecular cytogenetics, 21 species covering eight iguanid families were analysed in this thesis. The majority of studied species shared the apparently ancestral karyotype of the group, with diploid chromosome number...
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Analýza promotorových sekvencí telomerického elementu \kur{HeT-A} u \kur{Drosophila melanogaster}
ŠVELLEROVÁ, Hana
Drosophila melanogaster extends its telomeres by transposition of special telomeric retroelements (HeT-A, TART and TAHRE) targeted specifically to chromosome ends. Retroelement HeT-A is the most studied of telomeric elements and recent studies revealed significant sequence variability of the element HeT-A, not only along its length but also in areas with regulatory activity. This thesis is focused on the activity of different HeT-A promotors during the whole Drosophila development and comparision of transgenic lines with HeT-A promotor and reporter Tomato transgen and it was confirmed the sequence variability of the promotor HeT-A element and its tissue and organ specificity.
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Effect of oxidative stress on telomere lenght in \kur{Drosophila melanogaster}
SZAKOSOVÁ, Klára
Oxidative stress is caused by an imbalance between high production of reactive oxygen species and ability of organism to detoxify them or counteract their effects. The chromosomal ends telomeres - are specialized nucleoprotein structures protecting chromosome ends from DNA damage. Telomeres of Drosophila melanogaster are arrays of specific non-long terminal repeated (LTR) retrotransposons HeT-A, TART and TAHRE. This thesis evaluates effects of exposure of paraquat, which is a strong oxidative stress inducer, on telomere length and transcription activity in Drosophila.
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