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Cathepsins L of Diplostomum pseudospathaceum cercariae
Perháčová, Terézia ; Mikeš, Libor (advisor) ; Hartmann, David (referee)
This study is focused on cercarial cysteine peptidases of the trematode Diplostomum pseudospathaceum. It follows previous research which confirmed the presence of a 24kDa cysteine peptidase in cercariae biochemically and by mass spectrometry. It was postulated, that the function of this peptidase is histolytic, when cercariae penetrate the tissues. During an attempt to purify this peptidase and characterize its peptidolytic activity, it was found out that the cercarial homogenate containsmore different peptidases varying in their pI. Tests of peptidolytic activity and inhibition have shown that these peptidases are cathepsin L-like. They are active over a broad spectrum of pH with optima of activities in weakly acidicor neutral pH. Using degenerate primers based on conserved motifs of cysteine pepridases, partial sequences of three genes for cathepsin L of D. pseudospataceum (DpCL1, 2 a 3) were obtained. Then the complete sequences of DpCL2 and 3 genes and partial sequence (without 5'end) of DpCL1 were obtained by RACE PCR. To confirm function of these peptidases we tried to immunolocalize them. We assumed that they are localized in penetration glands. Preliminary results suggested that some of the cathepsins could be also localized in the gut of cercariae. For more detailed biochemical...
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Larval Stages of Flukes (Platyhelmintes: Trematoda) in Secondary School Education
Šulcová, Hana ; Říhová, Dagmar (advisor) ; Podroužková, Štěpánka (referee)
The parasites are one of the most important factors that shape relationships in the nature. This thesis deals mainly with developmental stages of trematodes (Platyhelmintes: Trematoda), especially the cercariae of so-called Schistosomes and sporocysts of Leucochloridium paradoxum, as well as with and their intermediate host - freshwater snails. Introductory chapters are focused on general introduction into the topic, such as basic terminology or occurrence issue of trematodes (mainly schistosomes) in the world and in the Czech Republic. In order to determine larval stages of flukes and their morphological types, the research was conducted in four Prague localities with known presence of aquatic snails. Only in one site, Kunratická tůň Pond, the constant presence of echinostomous cercariae (and in lesser extent also furcocercariae) in Radix labiata was recorded during summer season of 2015. In small pond in the Botanical Garden of the Natural Sciences Faculty of Charles University and in Modřanské tůně Ponds, xiphidocercarie in Lymnaea stagnalis were found. No cercarie were detected in the pond in the Genetic garden of Charles University. The presence of Leucochloridium paradoxum in the European Amber Snail Succinea putris was confirmed in the vicinity of Modřanské tůně Ponds. The verified...
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Orientation of helminths during host seeking
Vojtová, Terezie ; Mikeš, Libor (advisor) ; Horák, Petr (referee)
The parasitic helminths are often forced in the environment to search for their host quickly in order to continue the ontogenetic development, or else to finish it. To search for and indentify the host, they use various types of receptors which allow them to provoke a taxes corresponding to the oncoming stimulus and to react regarding the current situation. In respect to the concept relevant to the helminths, this work concerns trematodes, whose freely movable stadia are miracidium and cercacia, and then monogeneans which are viparous or oviparous with oncomiracidium larva, and nematodes during which the third larva stage moves. The representatives of the groups of Myxozoans and Ciliophorea are also mentionned, since they use similar mechanisms to look for hosts as helminths. This thesis includes the summary of the existing knowledge related to the orientation of helminths in the environment. On the basis of the data that is already known, it is possible to compare which mechanisms are used for host-seeking by particular species, and according to which signals from the surroundings they most often orientate themselves. Powered by TCPDF (www.tcpdf.org)
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Morphological and functional variability of secretory glands in cercariae of chosen trematode groups
Krčmářová, Veronika ; Bulantová, Jana (advisor) ; Mikeš, Libor (referee)
Trematodes are characterized by their complex life cycles that include definitive hosts and variable number of intermediate hosts. Transfer of the parasite from the first intermediate host to the other is usually realized by larval stage called cercaria. After finishing of their development within the first intermediate host, morphology and fate of these larval stages vary according to the way of infection of the next host. Some cercariae actively penetrate directly to their definitive hosts trough their body surface, other encystate in the outer environment where they wait in a form of metacercariae to be ingested by definitive host. Both of these ways can be combinated and cercariae encystate inside second intermediate host after they actively penetrate them. Exceptionally, cercariae do not leave the sporocyst in which they were developing inside the first intermediate host. They encyst there waiting for ingestion by the definitive host. Various types of secretory glands have been developed in cercariae for successful direct infection of next hosts, survival of parasite in adverse conditions of outer environment or for transformation of one larval stage to subsequent one. Variability in morphology and function of these secretory glands in cercariae is closely connected with differences in life...
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Orientation of helminths during host seeking
Vojtová, Terezie ; Mikeš, Libor (advisor) ; Horák, Petr (referee)
Helminths are often forced in the environment to search for their host quickly in order to continue the ontogenetic development, or else to finish it. To search for and indentify the host, they use various types of receptors which allow them to provoke a taxes corresponding to the oncoming stimulus and to react to the presence of the host. This thesis includes the summary of the existing knowledge related to the orientation of helminths, the comparison of the mechanisms used by the searching of a host and signals in the environment. In respect to the concept relevant to the helminths, this work concerns trematodes, whose freely movable stadia are miracidium and cercaria, and then monogeneans which are viparous or oviparous with oncomiracidium larva, and nematodes with the third infective larva stage. The representatives of fish parasites of Myxozoans and Ciliophorea are also mentionned, since they use similar mechanisms to look for hosts as helminths. Powered by TCPDF (www.tcpdf.org)
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Early embryonal development and morphogenesis of selected organ systems of the rediae and cercariae of Fascioloides magna.
Pankrác, Jan ; Kašný, Martin (advisor) ; Macůrková, Marie (referee)
Fascioloides magna (giant liver fluke) is a digenetic trematode with two-host life cycle and high veterinary importancy. Typical definitive host is a deer (Cervidae), but many other species from different families can be accidentally infected, for example sheep, goat or cattle. Very important role in the life cycle of F. magna has the first host - fresh water snail of the family Lymnaeidae. Three different life stages of F. magna, two of them with ability of reproduction - sporocysts and rediae develop in the body of snail. The third stage - cercaria is produced by rediae. Cercariae are able to escape from the snail, encyst and become infective for the definitive host. Since the second half of the 19th century many researchers studied the development of particular stages in the first intermediate host, but many characteristics of this process are still not fully understood. This thesis should reveal some of unanswered questions concerning to the reproduction and ontogenetic development of trematodes, which is presented on the examples of three organ systems - muscles, nerves and excretory system of rediae and cercariae of F. magna.
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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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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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Glycocalyx shedding by cercariae of bird schistosomes
Chaloupecká, Jana ; Mikeš, Libor (advisor) ; Štěrba, Ján (referee)
Trichobilharzia spp. are avian schistosomes related to medically important human parasites of the genus Schistosoma. Penetrating cercariae are well known as causative agent of cercarial dermatitis in humans. Cercariae actively penetrate the skin of definitive hosts and transform into schistosomula. This process is preceded by cercarial tail detachment and includes emptying of penetration glands and extensive surface changes. One of these changes is the loss of highly immunogenic glycocalyx which represents a protective coat in the aquatic environment. The glycocalyx has specific composition of saccharide molecules which are bound to lipids or proteins on the membrane of cercarial tegument. There is only limited information about the mechanism of shedding. Hypotheses based on indirect evidences suggest that peptidases or (phospho)lipases from penetration glands could be involved. This work describes the changes in surface glycosylation during transformation of cercariae into schistosomula by fluorescently labelled lectins and monoclonal antibodies against Lewis X antigen. Lectins UEA-I, LTA and PNA have been chosen as markers of transformation of T. regenti. Further, our experiments have been focused on shedding of cercarial glycocalyx. During in vitro induction of penetration gland emptying and...
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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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