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Genome evolution of endosymbiotic bacteria in blood-sucking insects
ŘÍHOVÁ, Jana
The research on insect-bacteria symbiosis is experiencing a rapid burst leading to the identification of much higher complexity and dynamics of the insect-bacteria associations than ever before envisaged. The generally accepted concept of obligate bacterial symbionts as providers of essential compounds (vitamins, aminoacids) has been further developed into the framework of microbiomes, i.e. communities of microorganisms associated with the host. The majority of the knowledge has been derived from plant sap-feeders, while data on blood-feeding insects remain fragmented and even inconsistent. In this thesis, we employ amplicon, genomic and in-vivo approaches to investigate several symbiotic systems of obligate blood-feeders and address the following questions: What is the diversity of symbiotic bacteria in our studied systems? What are the metabolic capacities of these symbionts? What is the role of symbionts in the biology of their hosts? What are the possible sources of bacteria prone to establish symbiosis with obligate blood-feeders? Where these symbionts reside in the host´s body? What is the coevolutionary pattern of these bacteria with their hosts? As an answer to these questions, I present the results detailed in the course of this thesis, which are preceded by a comprehensive introduction to the studied topics and wraps up with a summary of the main results.
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Fylogenetické postavení rodu Polymastix a jeho prokaryotických symbiontů
Kubánková, Aneta ; Hampl, Vladimír (vedoucí práce) ; Kolísko, Martin (oponent)
Skupina Polymastigidae je jednou z pěti čeledí oxymonád (Metamonada, Preaxostyla). Zahrnuje drobné bičíkovce obývající trávící trakt hmyzu. V posledních letech byla získána molekulárně-fylogenetická data, která monofyletičnost této skupiny zpochybňují. Typovým rodem čeledi Polymastigidae je Polymastix. Fylogenetické postavení tohoto rodu zatím nebylo studováno, ačkoliv by právě tato informace mohla významně napomoci objasnit příbuzenské vztahy v rámci zmíněné skupiny. Tato práce poskytuje první sekvenční data zástupců tohoto rodu, která jsme získali pomocí metody single-cell genomové amplifikace a následné celogenomové sekvenace na Illumina HiSeq X Ten (Macrogene) ze tří jedinců P. melolonthae obývajících zadní střevo larvy tiplic. Fylogenetické analýzy založené na genu pro 18S rRNA, EF-1α a HSP90 přinesly dvě zhruba stejně pravděpodobné hypotézy o postavení tohoto rodu v rámci celé skupiny Oxymonadida. První z nich umisťuje rod Polymastix do nejbližší příbuznosti s rodem Streblomastix, dle druhé hypotézy je nejpříbuznější Termitimonas travisae. Charakteristickým znakem tohoto prvoka jsou ektosymbiotické bakterie napojené na jeho povrch. Tyto byly nutně amplifikovány a sekvenovány společně se svým hostitelem, což nám umožnilo získat data i pro tyto organizmy. Identifikace eubakteriálních symbiontů...
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Multilokusová charakteristika symbiontů entomopatogenních hlístovek rodu \kur{Steinernema}
FAKTOROVÁ, Lucie
During the evolution some groups of organisms have become coevolutionary associated with other groups, as is the case of host symbiont systems. To explore coevolutionary history of hosts and their associated symbionts, phylogenetic reconstruction of symbionts and phylogenetic reconstruction of hosts are usually compared. Coevolution is described by coevolutionary events (cospeciation, host switch, duplication, failure to diverge events and linage sorting events). The aim of this work was to test the suitability of MLST method for the complex of entomopathogenic nematodes from the genus Steinernema (with detailed analysis of Steinernema feltiae) and their symbiotic bacteria Xenorhabdus bovienii and subsequently use cophylogenetic comparative analysis to determine their level of cospeciation.
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Molecular phylogeny and genome evolution of insect symbiotic bacteria
NOVÁKOVÁ, Eva
Since the introduction of advanced molecular methods the research on insect bacterial symbioses underwent a major focus shift towards large scale phylogenetics and comparative genomics. These new fields provided answers to several fundamental questions of symbiont evolution, functional capabilities of the host-associated bacteria, and the role of symbionts in the host?s biology. However, the vast diversity and complexity of symbiotic relationships still leaves gaps in our understanding to a rich mosaic of various symbiont types, effects and transitions from facultative association to obligate mutualism. The presented study focuses on distribution, diversity, phylogenetic patterns, evolutionary transitions and genome evolution of two less known but ecologically diverse bacterial genera, Arsenophonus and Sodalis. The thesis also takes advantage of the knowledge on a well established symbiotic model between aphids and Buchnera and reveals several evolutionary patterns in the host and symbiont.
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RSS.