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Evoluce symbiotických bakterií dvoukřídlého krevsajícího hmyzu
JUHAŇÁKOVÁ, Eliška
This study is focused on bacterial symbionts of blood-sucking insects from the family Hippoboscidae (Diptera), namely Ornithomya biloba and Crataerina pallida. Bacterial symbionts are essential for blood-sucking insects because they provide nutrients absent in blood, particularly vitamin B and cofactors. In this study metagenomic data from Ornithomya biloba and Crataerina pallida were processed by bioinformatic tools and genome drafts were assembled. Genomes of two bacterial symbionts of the genus Arsenophonus were compared with their relatives and levels of genomic modification of these genomes were evaluated. Moreover, the presence of horizontally transferred genes in both Arsenophonus genomes was phylogenetically determined. Finally, metabolic pathways for essential B vitamins and cofactors were reconstructed and compared with other species of the genus Arsenophonus.
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Parasitic bacteria Arsenophonus in honeybee and its parasite Varroa destructor
Hejdánková, Sylvie ; Hubert, Jan (advisor) ; Smrž, Jaroslav (referee)
Arsenophonus is vertically and horizontally transmitted parasitic bacteria and strengthens its transfer through phenomenon called son killing. Arsenophonus has been detected in the arthropod hosts, insects, ticks and the garden spider Araneus diadematus. The aim of this study is detection parasitic bacteria Arsenophonus in honeybees and its parasite Varroa destructor. We find out that bacteria Arsenophonus is present in both hosts and it is identified as Arsenophonus nasoniae. Detection of bacteria Arsenophonus is discovered for the first time in Varroa destructor mites. We proved that the frequency of bacteria Arsenophonus in mites Varroa destructor is significantly higher than in honeybees. This study shows that the mite Varroa destructor could act as a vector for transmission parasitic bacteria Arsenophonus among honeybees. Results of this study could lead to the future application of Arsenophonus as a biological control for the mite Varroa destructor.
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Evolution and genomics of symbionts in Hippoboscidae
ŠOCHOVÁ, Eva
Obligately blood-sucking parasites harbour symbiotic bacteria providing them B-vitamins and cofactors missing from their blood diet. Within Hippoboscoidea group (parasites of birds and mammals), tsetse flies as medically important vectors have been studied extensively while bat flies and louse flies tend to be neglected. This thesis is composed of two complementary manuscripts focused on phylogeny and origin of bacterial symbionts in Hippoboscidae family (manuscript 1) and their genome evolution (manuscript 2). First, phylogenetic approach was employed to determine lineages of obligate and facultative symbionts present in this group. Second, genomic and phylogenomic analyses were carried out to better understand evolution of obligate endosymbionts from the Arsenophonus genus in this group. Results of the two studies indicate that relationships between Hippoboscoidea and their symbionts are extremely dynamic with frequent replacements of obligate symbionts. This hypothesis is supported by both phylogenetic and genomic evidence, in particular, Arsenophonus endosymbionts of Hippoboscidae represent several distinct lineages (of likely different ages) with noticeable differences in genome features and metabolic capabilities. The data presented in this thesis thus greatly extend our knowledge about evolution and genomics of symbiotic bacteria in Hippoboscidae and bloodsucking hosts in general.
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The intracellular symbionts of blood-feeding Diptera group Hippobosccoidea
ŠOCHOVÁ, Eva
Blood-sucking parasites from the Hippoboscoidea group (Insecta: Diptera) harbor symbiotic bacteria providing them with B-vitamins and cofactors missing from their blood diet. Although including medically important vectors such as tsetse flies, evolutionary history of symbiosis in the whole group is poorly understood. This thesis is focused on analysis of symbionts in the Hippoboscidae family (parasites of birds and mammals). Phylogenetic approach was employed to determine lineages of obligatory and facultative symbionts present in this group. Results of the study indicate that relationships between Hippoboscoidea and their symbionts are extremely dynamic with frequent replacements of obligate symbionts. To which extent is this dynamic evolutionary history of symbiotic systems in Hippoboscoidea caused by features of their parasitic lifestyle (e.g. host switches from mammals to birds) will be an interesting question for further studies.
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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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