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Effects of peripheral inflammation on gene expression modulation in passerines and parrots
Kuttiyarthu Veetil, Nithya ; Vinkler, Michal (advisor) ; Hyršl, Pavel (referee) ; Harazim, Markéta (referee)
(English) Birds have well-defined roles in maintaining the ecological balance as predators, seed dispersers, nutrient cyclers, and pollinators making them an integral part of many ecosystems. Birds are often the flag-ship species and are important for wildlife preservation. Some of the avian populations are very well connected across the globe through their annual migration, increasing risks of epidemics of infections. Birds also face different levels of existence encounters in challenging living conditions like deserts and cold mountains. To cope with these diverse environments not only need physiological adaptations, but also a very well-equipped immune system, optimised to challenges common to the environment they inhabit. How well a host immune system responds to pathogens determines the overall fitness of the organism and its survival. Insight into the avian immune system functions is of great significance as birds are reservoirs of innumerable pathogens. They have been the primary source of several major epidemics' onset leading to worldwide human and animal fatalities (e.g., COVID-19, Avian influenza, or West Nile virus outbreaks). Similar to all living beings, avian hosts and pathogens are always in a continuous adaptational arms race. This coevolution of hosts and their pathogens forms the...
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Interspecific and intraspecific variation in gastrointestinal microbiota composition of parrots and its association with incidence of selected disorders
Černá, Kateřina ; Vinkler, Michal (advisor) ; Rychlík, Ivan (referee)
Captive parrots are susceptible to various digestive, metabolic, and behavioural disorders. Recent research in other vertebrates has suggested that these disorders can be linked to the gut microbiota, directly or through the microbiota-gut-brain axis. Although many commercial probiotic products intended for the use in parrots advertise beneficial effects on digestion and mental well- being, these statements are not sufficiently supported with publicly available scientific evidence, but probably rather based on the extrapolation of the knowledge of microbiota-gut-brain interactions in poultry, mice, and humans. However, there are substantial differences in the gastrointestinal tract morphology and gut microbiota composition between parrots and these model vertebrates. This thesis aimed to describe the interspecific and intraspecific variation in the gut microbiota composition of parrots and to link the variation in microbial communities to the incidence of eight selected behavioural and physiological disorders. The gut microbiota composition of 491 individuals from 85 parrot species was analysed using 16S rRNA metabarcoding. The host species, type of feed, and housing environment were identified as the main factors influencing the diversity and composition of the gut microbiota of parrots. A...
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Fc receptor-like molecules: biological role and phylogenetic conservation of FcRL multigene family
Böhmová, Helena ; Komrsková, Kateřina (advisor) ; Vinkler, Michal (referee)
Fc receptor-like (FcRL) molecules are novel immunological receptors with intriguing proposed roles in the immune system. Phylogenetic studies revealed that FcRL genes are conserved in jawed vertebrates (Gnathostomata), and likely formed during adaptive system genesis. FcRLs have multiple extracellular immunoglobulin domains, and some representatives have newly documented specific ligands. Several FcRLs contain both ITIM and ITAM cytoplasmatic sequences, which provide them with dual signalling properties. These allow them to regulate intracellular signalling pathways. FcRLs are known to engage in B cell regulation. They are largely expressed on B cells, with some representatives preferentially expressed on cytotoxic T cells and NK cells. Their expression patterns are specific to distinct B cell subpopulations and also show different levels of expression during B cell differentiation, pointing to their possible involvement in this process. FcRL molecules have also been detected on the mammalian eggs, and they may potentially play role in gamete fusion. This thesis aims to introduce FcRL molecules in various aspects, including their relation to classical Fc receptors, their structural properties, genomic organisation, phylogenetic conservation and their roles in organism. Thesis also focuses on...
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Influence of avian Plasmodium on their hosts
Dulavová, Kristýna ; Svobodová, Milena (advisor) ; Vinkler, Michal (referee)
Avian malaria parasites of the genus Plasmodium are unicellular (and intracellular) protozoans of the group Haemospororida, using a blood-sucking insect (mosquito) as a vector and a bird as a vertebrate host. The effects of this disease, together with avian pox, have greatly influenced endemic populations of Hawaiian birds after introduction of a suitable vector to the islands by a human hand, leading to a drastic extinction of bird species; most of the remaining Hawaiian endemic species are now endangered. Apart from that, avian malaria is distributed nearly all over the world, infecting a variety of different hosts. This thesis is focused on the influence of avian malaria parasites mainly on their avian hosts. The most severe patologies caused by Plasmodium are associated with blood stages causing serious anemia in birds. More pathologies are connected with exoerythrocytic stages in the endothelial cells in various organs and are accompanied with external signs such as lethargy, respiratory distress, weakness, inappetence, sometimes weight loss and so on; different plasmodium species-bird host combinations have different outcomes. An interesting issue is the emerging tolerance against avian malaria in Hawaii Amakihi (Hemignathus virens), a species occupying low elevation areas of Hawaiian...
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Host-microbiota, pro-inflammatory immunity and physiological senescence in wild birds
Těšický, Martin ; Vinkler, Michal (advisor) ; Tschirren, Barbara (referee) ; Štěpánek, Ondřej (referee)
Triggered by microbial ligands, inflammation serves as a "double-edged sword" to fight infections on the one hand, but on the other hand causing tissue damage due to oxidative stress if it is dysregulated. For example, chronic inflammation can contribute to inflammaging, which is now widely regarded as one of the causes of ageing. In my interdisciplinary dissertation, my colleagues and I investigated three interrelated aspects of inflammation, using an evolutionary framework and various free-living birds as models: (1) ecological and evolutionary determinants of gut microbiota (GM) composition and diversity, a driver of wild bird immunity, (2) diversity in immune genes affecting inflammatory responses in wild birds and (3) inflammation-related physiological senescence in a free-living passerine bird, the great tit (Parus major). Firstly, using 16S rRNA gene metabarcoding, we revealed high intra- and interspecific variation in passerine gut microbiota (GM) dominated by the major phyla Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. Although in mammals GM depends strongly on host phylogeny and diet, in birds we found only moderate effects of phylogeny and very limited effects of host geography and ecology on GM composition. While microbiota diverged between the upper and lower...
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Effects of microbiota composition on emergence of depressions and behavioural disorders in animals
Bartková, Nikola ; Vinkler, Michal (advisor) ; Kubovčiak, Jan (referee)
The aim of this study is to summarize the current knowledge on the influence of gut microbiota composition on behavioural disorders in selected mammals and birds. Current research focuses on the influence of gut microbiota on the development of mental illnesses in humans and the potential therapeutic use of manipulating its composition. This paper briefly summarizes the main mechanisms of microbiota influence on the development of mental illnesses. The gut microbiota may also influence the development of behavioural disorders in animals. The literature suggests that changes in gut microbiota composition in humans with mental illnesses and animals with behavioural disorders share some similarities. In general, they are related mainly to a reduced abundance of selected genera of short-chain fatty acid producing bacteria and an increased abundance of gram-negative bacteria. The exceptions are destructive behavioural disorders in animals, which are associated with increased abundance of the Clostridia class and decreased abundance of the Lactobacillus genus. To prevent their development under stress, the thesis proposes the probiotic use of Lactobacillus rhamnosus. To manipulate the composition of the gut microbiota in the treatment of depressive disorders in humans, the administration of probiotics,...
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Evolution of molecular interaction between host and parasite
Bílková, Barbora ; Vinkler, Michal (advisor) ; Synek, Petr (referee)
Coevolution between host and parasite is a long-term object of scientific interest, mostly because of negative influence of parasites and human need to defend against it., The evidence concerning host-parasite coevolution mechanisms is, however, still incomplete and various models and theories are considered separately, out of the general concept. Beside generally well-known theories such as the "Red queen" theory or the coevolution "arms race" theory, several other models were proposed, e.g. the "gene for gene" model or the "matching allele" model, which describe detailed aspects of host-parasite coevolution and principles of genetic variability maintenance in their interaction. Although there are many studies mapping reciprocal evolution of hosts and parasites, the connection between empirical evidence and theoretical models is often missing. Therefore, this thesis covers theory on host-parasite evolutionary interactions and provides examples of host-parasite systems and molecules, which correspond to behavior of described models.
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Variability in selected haematological traits related to gastrointestinal microbiota in parrots (Psittaciformes)
Dlugošová, Sylvie ; Vinkler, Michal (advisor) ; Volf, Jiří (referee)
Thousands of parrots all over the world suffer from illnesses and medical complications that can result from interactions between their immune system and bacteria in their digestive tract. The aim of this master's thesis is to understand the link between symptoms of these medical issues, the composition of blood and gastrointestinal microbiota in parrots. Using the hematological methods, 198 blood samples representing 53 parrot species were analyzed. The composition of microbiome was defined by combination of a molecular approach using bacterial 16S rRNA gene sequencing in 132 fecal samples, 12 intestine samples, 228 cloacal swabs and 236 beak swabs representing in total 61 parrot species and a diagnostic approach by psittacine fecal Gram's stain method. Significant association of hematological parameters with individual, environmental and clinical factors was observed, as well as its considerable interspecific variability. Absolute heterophile and lymphocyte counts have been shown more useful for infectious and autoimmune disease monitoring than H/L ratio. Relative numbers of basophiles were the best indicator for behavioral disorders. In relation to hematological parameters, the effect of the bacterial family Flavobacteriaceae, as part of the oral microbiota, and the bacteria Escherichia or...
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Evolutionary implications of innate immunity receptors polymorphism
Bainová, Zuzana ; Vinkler, Michal (advisor) ; Zajícová, Alena (referee)
Interactions between hosts and their parasites are considered to be one of the major forces driving animal evolution. It can be assumed that the evolutionary changes will occur especially in host molecules directly involved in these interactions. The first line of host defense is formed by innate immunity receptors among which also pattern recognition receptors (PRRs) belong. PRRs detect the presence of parasites at the beginning of their invasion by binding characteristic structures of their bodies (so called pathogen-associated molecular patterns, PAMPs, e. g. lipopolysaccharide, flagellin or peptidoglycans) or abnormal self molecules (damage-associated molecular patterns, DAMPs, e.g heat shock proteins). Although this mechanism of immune system activation is based on the recognition of ligands that are relatively evolutionarily conservative in pathogens, growing body of evidence suggests that PRRs are highly polymorphic on both interspecific and intraspecific level. High frequencies of minority alleles can be observed in most populations studied. It has been proven that particular alleles of many PRRs may associate with increased or decreased resistance to various infectious or autoimmunity diseases. Relationship between polymorphic receptor and a disease could be the main force, which shapes the...
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