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...

No description available.

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...

The commercial production of channel catfish (Ictalurus punctatus) is major industry in Mississippi. Infections of channel catfish with the digenetic trematode Bolbophorus damnificus have often been associated with heavy economic losses in the industry. To efficiently control transmission of this trematode, the avian hosts need to be identified. In the first study, two American white pelicans, two double-crested cormorants, two great blue herons, and two great egrets were fed channel catfish infected with B. damnificus metacercariae. The presence of Bolbophorus damnificus ova in pelican feces at three days post infection (dpi) indicated the pelicans had patent infections. Mature B. damnificus were recovered from the intestines of both pelicans at 21 dpi. No B. damnificus infections were observed in the other bird species. In a second study, 33 American white pelicans, 34 double-crested cormorants, 35 great blue herons, and 32 great egrets were collected in the Mississippi Delta. The prevalence of B. damnificus in the American white pelican was 93.9%, with an average of 158 B. damnificus found per bird (range 0-681). Bolbophorus damnificus was not found in any of the other bird species. The results of these two studies confirm that the AWPE is the only proven natural host for B. damnificus. In a third study, two previously undescribed cercariae were found infecting rams-horn snails in commercial catfish ponds. In challenge studies, channel catfish were exposed to both cercariae types. Only one type of cercariae (type I) was infective to channel catfish. The first evidence of type I metacercariae was seen histologically at 14 dpi and grossly at 21 dpi. Development continued until 120 dpi, when both gross examination and histology suggested that the metacercariae were mature. The type I metacercariae appeared to cause little host damage. Molecular analysis of the 18S rRNA gene region indicated that the type I cercariae and metacercariae may be a species of Clinostomum. The data generated in these three studies provides additional information that can be used in the development of efficacious management schemes to control digenetic trematodes infecting commercial catfish.