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Features and functions of glycocalyx of trematode cercariae
Chaloupecká, Jana ; Mikeš, Libor (advisor) ; Kašný, Martin (referee)
Trematodes are parasites from phylum Platyhelminthes which have compex life cycles involving two to four hosts. This work focuses especially on trematodes of the family Schistosomatidae. Their cercariae which leave the snail intermediate host, actively penetrate the skin of definitive hosts and transform into schistosomula. This is accompanied by detachment of cercarial tail and emptying of penetration glands. During transformation, cercarial bodies undergo extensive ultrastructural and molecular changes. One of these changes is the loss of surface glycocalyx which represents a protective coat in the aquatic environment. In glycocalyx shedding, participation of proteolytic enzymes from cercarial penetration glands is expected during invasion of the host. Glycocalyx has specific composition of saccharide molecules which are bound to lipids or proteins on the membrane of cercarial tegument. This work describes the origin, ultrastructure, saccharide composition, function and shedding mechanism of cercarial glycocalyx.
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Ultrastructural interactions of larval bird schistosome Trichobilharzia regenti and immune cells of hosts nervous system
Krčmářová, Veronika ; Bulantová, Jana (advisor) ; Hodová, Iveta (referee)
Trichobilharzia regenti is a neurotropic fluke belonging to family Schistosomatidae. Larvae called schistosomula migrate in the definitive hosts (anseriform birds) throuth the central nervous system (CNS) to their final location in nasal mucosa, where they mature and lay eggs. In contrast with that, the infection of accidental mammalian hosts (including human), is often stopped already in the skin immediately after entering the host. However, some schistosomula are able to reach CNS of experimentally infected mice, and survive there temporarily. Reaction to the CNS infection of mice is usually provided by microglia, astrocytes or the other immune cells infiltrated from the hosts blood. Parasite protects itself against the host reaction with its tegument. It does not serve only as mechanical barrier, but also as main secretoric organ that is capable of active immune evasion. Changes within CNS of the vertebrate hosts, caused by migrating schistosomula of T. regenti, were already described by routine histological and immunohistochemical methods. Till now, there was a lack of informations about interactions of immune cells of the host and the tegument of the parasite on ultrastructural level. To fill this gap in knowledge, two different methods were used: (1) imunohistochemistry in light and electron...
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In vitro cultivation of the trematode species Trichobilharzia regenti
Vrbová, Kristýna ; Kašný, Martin (advisor) ; Skelly, Patrick (referee)
The class Trematoda includes many pathogenic representatives. Main subject of this thesis, avian schistosome Trichobilharzia regenti, is a close relative to the important human pathogen Schistosoma mansoni (family Schistosomatidae). In vitro cultivation of trematodes enables closer understanding of their biology and parasite- host interactions; however, no trematode species has been successfully kept in vitro from the egg stage to the adults producing eggs. Many studies are focused on the problematic of S. mansoni cultivation, but data concerning T. regenti cultivation remain scarce. Only the ability of T. regenti cercariae to transform into schistosomula in vitro was documented, with following survival in a culture medium for a few days. Comparison of eight transformation methods was performed with T. regenti cercariae. Based on the number of tailless cercarial bodies obtained, five transformation methods were selected for further evaluation of the early schistosomula characteristics (glycocalyx shedding, penetration glands emptying and survival in vitro). It was observed that the largest quantity of cercarial bodies can be obtained by using a syringe needle or the BeadBeater cell disrupter. The largest quantity of schistosomula meeting the criteria of early schistosomulum was recorded after...
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Excretory-secretory proteins of schistosome intravertebrate stages in context of their biology
Konečný, Lukáš ; Mikeš, Libor (advisor) ; Kašný, Martin (referee)
Schistosomatidae is a family of blood-dwelling trematodes which cause serious disease in humans and warm blooded animals. Human schistosomiasis affects over 258 million people worldwide. The fundamental pathological manifestations of the disease are not caused by adult worms, but by responses to antigens released from eggs, which remain trapped in the tissues. All stages of these parasites release excretory-secretory products, which mostly comprise of proteins which are, to a certain extent, species- and stage-specific. These products have many functions that play roles in successful transmission of the parasite and its interactions with the host. Various approaches to the collection and analysis of these molecules do not always accurately reflect the secretory processes in vivo, because they always employ in vitro techniques. The research of these secreted molecules discovered many mechanisms, through which the parasite successfully modulates and evades host immune system. Despite the fact, that many of these molecules were identified as potential vaccine candidates, still no sufficiently effective vaccine has been developed. With great technological advances used for the identification of these proteins, this area is becoming more and more topical. This review focuses on composition of...
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Role of glial cells in the immune response of mice infected by neurotropic fluke Trichobilharzia regenti
Macháček, Tomáš ; Panská, Lucie (advisor) ; Kopecký, Jan (referee)
A central nervous system (CNS) can be invaded by plenty of parasites, including parasitic helminths. Host's immune response during such infections includes not only participation of peripheral lymphocytes, but also astrocytes and microglia, resident glial cells present in the CNS. Activation of astrocytes and microglia has been recently demonstrated also in mice infected by neurotropic avian trematode Trichobilharzia regenti (Digenea: Schistosomatidae) for which mammals represent accidental hosts. The parasite does not mature in them and elicits development of inflammatory reaction in the CNS which may take part in parasite's destruction. Employing in vitro experiments, this thesis aimed at evaluation of the possible role of astrocytes and microglia in murine immune response to T. regenti. For this purpose, primary astrocyte and microglia culture preparations were established and the cells were then stimulated by antigens of T. regenti (homogenate of transformed cercariae, recombinant cathepsins B1.1 and B2). After that, production of nitric oxide and proinflammatory cytokines (IL-1 beta, IL-6, TNF-alpha) was measured. The results revealed that in vitro stimulated astrocytes and microglia increase production of nitric oxide, IL-6 and TNF-alpha. Such response to parasite's antigens could influence...
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Chemoorientation of Trichobilharzia regenti schistosomula in vitro
Parolová, Lucie ; Horák, Petr (advisor) ; Kolářová, Libuše (referee)
The ability to orientate themselves in the definitive host body is very important in the life cycle of trematodes. Contrary to a number of data on trematode orientation in the external environment, migratory routes within the host and places of definitive localization, little is known about compounds serving as stimuli during migration. In this study we tested chemoorientation of Trichobilharzia regenti schistosomula in vitro. We tested fractions of the nervous tissue homogenate of domectic duck (Anas platyrhynchos f. domestica), various fractions of the duck blood serum, NaCl and KCl solutions, D-glucose, L-arginine and commercially available neuromediators and apolipoprotein A-I. The highest attractiveness was recorded in the case of the blood serum of domestic duck. Significant attractiveness also showed NaCl solution at concentrations of 188 and 205 mM, KCl solution at concentration of 205 mM and combination of NaCl, KCl and D- glucose at concentrations NaCl=136 mM, KCl=5 mM, D-glucose=5,5 mM As the attractiveness of NaCl and KCl solutions of the same osmolarity (410 mOsm/l) was equal, and D-glucose solution of the same osmolarity showed no attractiveness for schistosomula, we suggest that the chloride ions are the main stimulus for migration. When various molecular weight fractions of the duck...
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Features and functions of glycocalyx of trematode cercariae
Chaloupecká, Jana ; Mikeš, Libor (advisor) ; Kašný, Martin (referee)
Trematodes are parasites from phylum Platyhelminthes which have compex life cycles involving two to four hosts. This work focuses especially on trematodes of the family Schistosomatidae. Their cercariae which leave the snail intermediate host, actively penetrate the skin of definitive hosts and transform into schistosomula. This is accompanied by detachment of cercarial tail and emptying of penetration glands. During transformation, cercarial bodies undergo extensive ultrastructural and molecular changes. One of these changes is the loss of surface glycocalyx which represents a protective coat in the aquatic environment. In glycocalyx shedding, participation of proteolytic enzymes from cercarial penetration glands is expected during invasion of the host. Glycocalyx has specific composition of saccharide molecules which are bound to lipids or proteins on the membrane of cercarial tegument. This work describes the origin, ultrastructure, saccharide composition, function and shedding mechanism of cercarial glycocalyx.
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