National Repository of Grey Literature 32 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Aporocotyle simplex fluke from the flounder Hippoglossoides platessoides in Svalbard.
In my bachelor thesis I studied trematodes from plaice Hippoglossoides platessoides obtained during expeditions to Svalbard in 2014 and 2018. My goal was morphological and molecular processing of the obtained material, which allowed me to confirm the identification of the flukes as Aporocotyle simplex Odhner, 1900. Aporocotyle simplex is a common parasite of plaice, ocurring mainly in Hippoglossoides platessoides, but also in Limanda limanda and Pleuronectes platessa. The species A. simplex is geographically distributed in the Gulf of St. Lawrence in Canada, off the west coast of Sweden, in the Barents Sea and Bering Sea, off the coast of Kamchatka and Greenland. My results showed that the species A. simplex is widespread in Svalbard. In the practical part, I dealt with methods that helped me to identify the studied specimens. I observed the trematode tegumental surface with aid of a scanning electrom microscope (JEOL JSM-7401F). The trematode internal organs were stained with Mayer-Schuberg carmine, which allowed me to observe and draw the mounted specimens using a light microscope (Olympus BX51) equipped with a drawing attachment. Furthermore, for molecular analysis, the DNA was isolated using the commercial Exgene Tissue SV mini kit (GeneAll). The isolated DNA (the gene for the large ribosomal subunit, 28S rRNA) was amplified by PCR, the obtained PCR products were sequenced on an automated sequencer (ABI Prism 3130xl or 3730xl, by SEQme). The newly acquired sequences (three in total) were aligned in the program Geneious 8.0.5with sequences available from GenBank (64 sequences). Phylogenetic analysis of the species relationships within the family Aporocotylidae was performed using the Maximum Likelihood method with TPM2u + F + G4 used as the best model. Aporocotyle simplex falls into a separate branch together with A. michaudi, from which however, it differs substantially by its morphology (distribution of tegumental spines on body and their number in the clusters, number of testes, ratio of esophagus length to body length) and geographical distribution (A. michaudi occurs in the South Atlantic Ocean).
Influence of bird schistosome Trichobilharzia regenti on haemocyte activity of lymnaeid snails
Skála, Vladimír
Gastropod molluscs are naturally exposed to various pathogens such as bacteria, or multicellular parasites that include digenetic trematodes (digeneans) which develop in snails. To combat these pathogens gastropods have evolved a sophisticated internal defence system that is composed of humoral and cellular arms. Lectins are probably the most important humoral components, whereas haemocytes represent the main effector cells. Immunity is one of the important factors determining compatibility/non-compatibility of gastropods and pathogens (particularly snails and trematodes). The introductory part of this thesis includes a review of literature focused on the components of the gastropod immune system and their reactions against pathogens represented by bacteria and digeneans. Additionally, selected immunomodulations caused by compatible digenean species are reviewed. Experimental work (presented in publications) focused mainly on the influence of the bird schistosome Trichobilharzia regenti on haemocyte activities of two lymnaeid snail species, Radix lagotis and Lymnaea stagnalis that are susceptible or refractory to the parasite, respectively. This schistosome parasite causes neuromotor disorders in specific definitive hosts (waterfowl), but it also causes cercarial dermatitis in accidental hosts...
Životní cyklus a diverzita motolic čeledi Opecoelidae na Svalbardu
The study was aimed to determine the diversity and species identification of trematodes family Opecoelidae (Digenea) in sculpins living in shallow waters of Billefjord (Svalbard). Second aim was to determine the affinity between the partenogenetic parasitic larval stages living in whelks (Buccinidae) and adult stages living in sculpins to describe their life cycle. During the work, there were used molecular methods using DNA and phylogeny analysis to identify the species of collected trematodes.
The effect of direct predation by fish on cercarial populations of selected trematode species (Digenea)
The predation effects of four fish species on the consumption of free-living cercariae of three trematode species (Plagiorchis elegans, Echinoparyphium aconiatum and Trichobilharzia szidati) were experimentally investigated with regard to specific life-history traits of both predator and parasite. The study provides evidence of a considerable consumption of trematode cercariae by fish and confirms that cercariae play an important ecological role in the energy flow in aquatic food webs.
Helminths as causative agents of vertebrate cancers
Schreiber, Manfred ; Horák, Petr (advisor) ; Kolářová, Iva (referee)
Opisthorchis viverrini, Clonorchis sinensis, and Schistosoma haematobium have been classified as the group 1 of carcinogens by the International Agency for Research on Cancer. Infections with opisthorchid flukes may lead to the development of cholangiocarcinoma of the liver, and those with schistosomes to the squamous carcinoma of the bladder. The link between helminth infections and carcinomas has been confirmed, and the exact mechanisms of carcinoma induction are at present intensively studied. There are some other representatives of helminths that are probably associated with cancers, but their direct effect on the process of carcinogenesis has not been confirmed yet. The formation of tumors can also occur via malignant transformation of totipotent parasite cells that become invasive and metastasize to different parts of the host body. However, some types of helminths may exhibit an opposite effect and show an anti-tumor activity. This review primarily focuses on the helminths associated with the development of cancer and the currently described mechanisms of carcinogenesis caused by such infections.
Složení společenstev larválních stádií motolic (Digenea) u vybraných zástupců plicnatých plžů čeledi Planorbidae
In the present study the species diversity, seasonal dynamics, composition of larval trematode communities and factors influencing their structure were studied in two species of planorbid gastropods (Gyraulus albus and Segmentina nitida) in typical eutrophic fishponds in South Bohemia, Czech Republic. The study significantly contributed to the present knowledge about the fauna of trematodes in small planorbids, provided evidence for validity of general rules affecting trematode community composition and structure and demonstrated the underestimated role of both snail species as first intermediate hosts for trematodes in the past.
Molecular and morphological characterisation of digeneans of the family Strigeidae Railliet, 1919 from Iceland
This study applies molecular and morphological procedures to identify larval and adult stages of trematodes of the family Strigeidae in Iceland. Intermediate hosts (snails and fishes) and definitive host (birds) from 11 freshwater lakes were sampled and examined for the presence of trematodes. Recovered species were subjected to study of morphology, sequencing and phylogenetic analyses. A total of seven species of three genera were identified via phylogenetical analyses based on mitochondrial (cox1) and nuclear (28S) sequences, and morphological data. The life-cycle of Apatemon gracilis was fully elucidated in Iceland, and those of Australapatemon burti and Australapatemon minor in part (cercariae and adults). The relationship of Cotylurus sp. 'Lin. 1I' and Cotylurus sp. 'Lin. 2I' could not be resolved.
Differentiation of totipotent germinal cells in larvae of bird schistosomes
Peštová, Jitka ; Horák, Petr (advisor) ; Chanová, Marta (referee)
This thesis aims to explore the larval development of a bird fluke Trichobilharzia regenti in its intermediate hosts, as well as the processes of differentiation of its embryonal cells and the differentiation between sporocystogenesis and cercariogenesis in sporocysts, with the ultimate goal to find out whether it is possible to find multiple generations of daughter sporocysts throughout the development of avian schistosomes in the intermediate hosts, just like in the case of human schistosomes of genus Schistosoma. Five developmental stages of daughter sporocysts, and ten developmental stages of cercariae have been defined. The first developmental stage in both larvae is the germinal cell. It divides and gives rise to a cell agregate. Afterwards an envelope (primitive epithelium) is formed around the embryo and subsequently, the embryo elongates. At this stage, the development of the two larvae undergoes different pathways. We can distinguish daughter sporocyst from cercaria in the phase, when the tegument is completed. The daughter sporocyst acquires characteristic vermiform appearance, and its body cavity contains plenty of germinal cells. For cercariae with an developed tegument, presence of the penetration glands is characteristic. Key words: Trichobilharzia regenti, germinal cells, mother...
Inhibitors of proteolytic enzymes of Trematodes
Šteiger, Vladimír ; Kašný, Martin (advisor) ; Salát, Jiří (referee)
i Abstract Trematodes are important parasites possessing various localization in the bodies of invertebrate and vertebrate hosts, including human; therefore they are subject of long time intensive worldwide research. Trematodes developed various adaptations and strategies (some of them have also molecular background) enable them to survive in the host bodies. Trematodes produce large amount of different molecules, which are involved in various physiological processes. Inhibitors of proteolytic enzymes form a large group of biologically active compounds, e.g. they regulate the activity of peptidases or modulate host immune response. Many of these inhibitors are investigated as potential candidates in chemotherapeutic fight against trematodes. This thesis reviews the information concerning the natural inhibitors produced by trematodes and also synthetic inhibitors. Key words: Inhibitor, trematode, peptidase, serpin, cystatin i
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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