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Production and elimination of superoxide radical in relation to the compatibility of snails and trematodes
Cibulková, Lucie ; Skála, Vladimír (advisor) ; Nývltová, Eva (referee)
Almost all trematodes use snails as the intermediate host in their life cycles. To survive within the host, they have to efficiently avoid defense reactions of its immune system. The most important effector cells, haemocytes, produce reactive oxygen species with the first molecule known as superoxide radical. Various snail species produce different levels of these radicals in relation to the compatibility with the invasive trematode species. The parasite decreases the levels of toxic radicals by using antioxidant enzymes including superoxide dismutase which catalyzes transformation of superoxide radical into hydrogen peroxide. This dismutation reaction is the first step during the oxidative burst and likely influences survival of trematodes within the host. Based on the current knowledge the production and elimination of superoxide radical in relation to the compatibility between snails and trematodes have been described thoroughly for a few models such as for example Biomphalaria glabrata-Schistosoma mansoni. However, this interaction appears to play a key role and, therefore, it deserves more attention in another models as well. Key words: trematodes, snails, compatibility, haemocytes, oxidative burst, antioxidant enzymes, superoxide dismutase, superoxide radical
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Ontogenesis of trematode larval stages of the family Fasciolidae in the intermediate snail hosts.
Pankrác, Jan ; Kašný, Martin (advisor) ; Soldánová, Miroslava (referee)
The family Fasciolidae is an important group of trematodes including serious pathogens of humans and livestock. The life cycle is divided into two phases - sexual reproduction in the definitive host body (large land mammals) and an asexual reproduction in the intermediate host body (aquatic snails of the family Lymnaeidae and Planorbidae). Development within the snail host is characterized by production of large amounts of parasite larvae (sporocyst, rediae, cercariae). Cercariae released from the snail immediately start to transform into metacercariae, the larval stages infectious for definitive host. Snail phase of infection is generally accompanied by number of mostly negative symptoms (massive pathological changes, often followed by reduction of fertility). This summary reveals that current knowledge concerning the ontogenetic development of fasciolids in the intermediate host is uncomplete and unequally investigated. According to this summary is also obvious that some of the published findings are universally valid for all members of the family Fasciolidae and other are characteristic only for particular species.
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Migration and pathogenicity of neurotropic helminths
Pech, Václav ; Chanová, Marta (referee) ; Horák, Petr (advisor)
A neurotropism of helminths can be observed in their intermediate, paratenic and definitive hosts. Neurotropic helminths migrate through the nervous tissue, where maturation and reproduction can take place. The neurotropic helminths can be found in the family of trematodes (Diplostomum baeri, D. phoxini, Ornithodiplostomum ptychocheilus, Trichobilharzia regenti), cestodes (Taenia multiceps, T. solium) and nematodes (Angiostrongylus cantonensis, Elaphostrongylus cervi, Parelaphostronglus tenuis, Baylisascaris procyonis). Presence of these helminths in the nervous tissue can (usually with contribution of the immune system) lead to neurological or other pathological changes: the infected hosts can even die. Some of the neurotropic helminths (A. cantonensis, B. procyonis, T. solium, T. multiceps) can infect humans as well.
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Composition and structure of larval trematode communities in model freshwater pulmonate gastropods in eutrophic environments in Central Europe
SOLDÁNOVÁ, Miroslava
This work applies advanced sampling (mark-release-recapture) and comparative approaches addressing the patterns in composition, structure and variability of larval trematode communities in three species of gastropod molluscs (Lymnaea stagnalis, Planorbarius corneus and Radix auricularia) at two nested scales of community organisation in typical Central European eutrophic environments. Hypothesis-testing with the application of null-model analyses, logistic regression modelling and multivariate randomisation techniques, revealed determinants of transmission rates, levels of infection and community structure in freshwater snail hosts in Central Europe and elucidated the mechanisms linking the spatial and temporal environmental variability with the action of complex community assembly rules in freshwater pulmonate snails.
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