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PubMedDate not supplied

[Comparative morphofunctional analysis of the gastropod-trematode interactions].

A morphofunctional aspect of pathogenesis in various mollusc--trematode combinations is very different. To evaluate the level of antagonism between the host and parasite, it is reasonable to use a summarized parameter of general physiological state of infected individuals. The somatic growth of the host could be used for that purpose. Analysis of original and reference data has shown, that the gastropod growth response to the trematode infection depends on the longevity of molluscs. The growth acceleration (gigantism) in infected individuals is common for snails with the intermediate longevity (3-4 yr), such as Hydrobia, Onobia and Bithynia (Prosobranchia: Rissoacea). As an exception, the gigantism is observed in the short-living species, which do not change the growth rate when they are parasitized: Biomphalaria, Bulinus, Helisoma and Lymnaea (Pulmonata: Basomathophora). Earlier, it was assumed that the single trend manifested in the infected long-living species (6-27 yr), such as Littorina (Prosobranchia: Littorinacea) and Cerithidea (Prosobranchia: Cerithiacea), in the decrease of the growth rate. The only case of the growth acceleration within the long-living molluscs was detected in the Littorina littorea from the White Sea infected with low pathogenic partenits of Cryptocotyle lingua (Heterophyidae). Based on the groups of snails with different longevity and being phylogenetically distant from each other, we can presume that the growth response to the infection correlates with the morphological peculiarities of hosts. The morphofunctional distinction in the system formed by trematodes and molluscs of different taxa are expressed in the parthenit localization in the host body and in the degree of digestive gland and/or gonad destriction. From the viewpoint of general physiological status of the host organism, the results of disfunctions in these organs are not similar. The destruction of digestive system ("energy power station" of organisms) is more fatal for infected individuals than a parasitic castration. Therefore, the localization of parasites in the mollusc gonad can be recognized as a parasitic adaptation to decrease the probability of a premature host's death and respectively to prevent the elimination of parasites. Phylogenetically distant gastropods with different life cycles use a diverse reproduction strategy, which implies a different proportion of gonad and digestive gland volume. Thus, snail species from different taxa are not similar in relation to the life space, which could be "granted" to the parasite without any risk to reduce a viability of the host. The space lack forces the parthenits parasitizing in the molluscs with the longer life span to occupy the digestive gland tissues, that increases their pathogenicity and decreases the host's growth rate.

Animals↗

PubMedDate not supplied

[The effect of trematode invasion and chromium sulphate on the crude protein content in the haemolymph of Viviparus viviparus (Mollusca: Gastropoda: Pectinibranchia)].

The combined effect of the trematode infection (Echinoparyphium sp.) and various concentrations of chromium sulphate (0.01, 1, 100 mg/l) onto the crude protein content in the haemolymph of the mollusc Viviparus viviparus was investigated. The normal contents of the crude protein is 0.7-1.22%. In adult specimens its concentration is 20-80% higher than in molluscs of junior age group. Sex difference by this index, which is higher in females, begins to manifest in four year old individuals only. The contents of crude protein in the haemolymph of pregnant females is 1.5 times higher than in latent ones. Under the low intensity of the trematode infection, the contents of crude protein in the haemolymph remains normal, while in the case of heavy infection, it decrease 100 times or lower. In the cases of 0.01-1 mg/l concentrations of chromium sulphate, the content of protein in the haemolymph of V. viviparus decreases, while in the case of 100 mg/l it increases abruptly, in comparison to the norm. The trematode infection intensifies these processes.

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PubMedDate not supplied

[Contribution to the study of Trematodes in Amphibians from the Cameroon (author's transl)].

Some 800 Amphibians representing 88 species were dissected for parasitic Trematodes of the digestive tract, the lungs and the bladder. 37 species of Anurans (244 specimens) harboured Trematodes. Nine species already found in Africa were observed. A new species, Haematoloechus ocellati n. sp. parasite of the lungs, is described. We propose the transfer of the species Haplometroides eburnense Maeder, 1969 into the genus Plagitura Holl, 1928. A large number of Anurans were examined for the first time in order to study Helminthes. This work brings in the new elements in the biogeography of african Trematodes Amphibians and increases the number of hosts for already mentioned species.

Amphibians↗

PubMedDate not supplied

[The effect of the trematode invasion and accumulation of heavy metals onto the pond snail (Mollusca: Gastropoda: Lymnaeidae)].

The cumulating of heavy metals (Cu, Cd, Pb, Zn) by the pond snail Lymnaea stagnalis from river and pond populations in a norm and under the trematode infection was examined. The copper and cadmium were accumulated by all specimens, mainly in the mantle and leg, in less content--in the hepatopancreas, and in the least content--in the shell and haemolymph. The lead was accumulated most intensively by the river specimens in the shell and mantle, while in the pond specimens it was accumulated in the mantle and leg. The greatest content of zink was found in the mantle, leg, and hepatopancreas. According to the ratio of cumulation the heavy metals by the river and pond populations the following series of ions were obtained respectively: Pb > Zn > Cu > Cd and Zn > Pb > Cu > Cd. The difference between uninfected specimens and one infected with trematodes was recorded in the ratio of cumulated heavy metals, in the ratio of benthic biological accumulation, and also based on bending force between metals compared in pairs. An intensity of differences was directly proportional to the intensity of the trematode infection.

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PubMedDate not supplied

[Ecological significance of the dilation of the distal portion of the uterus of some trematodes].

Many trematodes parasitic in the oral cavity, pharynx or oesophagus of snakes and birds or in the cloaca of birds possess a sac-shaped dilation of the uterine distal portion or the organ itself is sac-shaped. Trematodes possessing such uterus lay periodically more or less portions of eggs. The time of egg laying depends on the frequency of some functions of the host's organs (food capture by the host, swallowing the food, defecation), which the trematodes inhabit.

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PubMedDate not supplied

[Life cycle of trematode Psilotrema acutilostris (Psilostomidae) from Primor'e region].

Brought description trematodes Psilotrema acutilostris Oschmarin, 1963 received as a result experimental studying a life cycle. Installed that in conditions of Primorye land a role of intermediate host trematodes execute snails of Parafossarulus spiridonovi and P. manjuricus. The most further development trematodes goes with formation adolescaria. Adult worms P. acutilostris were growing in the chicken.

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PubMedDate not supplied

[Land molluscs--intermediate hosts of trematodes of the family Microphallidae travassos, 1920].

Encysted metacercariae of Microphallus sp. were found in the land mollusks Bradybaena duplocincta and Jaminia potaniniana asiatica collected on the slopes of Tien-Shan. The above mollusks are first reported as intermediate hosts of microphallids. The meta cercariae found were fed to white mice, golden hamsters, chickens and nestlings of sparrows and starlings. Maritae developed only in white mice and golden hamsters. Mature trematodes containing 14 to 35 eggs in the uterus were found in the small intestine 66-90 hours after the infection. Small mammals are assumed to be the definitive hosts of these trematodes. The trematodes of Microphallus sp. are characterized by a short life cycle with one intermediate host, land mollusk.

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PubMed1991

Trematodes nervous system.

Three main themes are discussed: 1. Development of the nervous system in the ontogeny of digenetic trematodes; 2. Central and integumentary nervous elements in Cercaria echinata (Echinostomatidae), their evolution in metacercaria and adult; 3. Chaetotaxy and systematics. The structure of the nervous system in digenetic trematodes is based on the occurrence of various neurotransmitters in the nerve tissue. Two major trends in the evolution of the nervous system from cercaria to adult are discerned, one leading to definitive, small number of commissures, established early in the development of the cercaria, the other one leading to formation of great number of commissures completed in the adult. Structure of the nervous system in sporocystic and/or redial generations in various groups of trematodes is compared. Its primitiveness in relation to that of other generations is noted. The central nervous system of Cercaria echinata is pointed out by fixation in glioxylic acid and examination in green light fluorescence. The integumentary sensory elements observed in light microscope, SEM and transmission electron microscope reveal a large variety in structures; propositions are made about their functions. In the corresponding metacercaria, the anterior part of the central nervous system remains unchanged; meanwhile the posterior part increases; several integumentary sensory elements disappear and poorly developed structures, improve; in the adult, transformations are completed. In about 200 various species of cercariae, the sensory receptors are arranged in a conspicuous relation with the nervous system. The study of their number and position; the chaetotaxy is used in systematics and allows very accurate conclusions in specific or infraspecific identifications and in all high taxonomical levels: family, sub-order, super-order. In the same way, miracidial and redial chaetotaxy are used n taxonomy.

Animals↗

PubMed1987

Superoxide dismutase in trematodes. Isoenzymatic characterization and studies of inhibition by a series of benzimidazoles and by pyrimidines of recent syntheses.

A comparative study was carried out of superoxide dismutase (E.C.1.15.1.1) (SOD) and catalase activities in purified extracts of two trematodes: Fasciola hepatica and Dicrocoelium dendriticum. The superoxide dismutase activity was very similar to that measured in other eukaryotic cells. As no catalase activity was detected, the possibility that SOD in these trematodes might have the particular importance of removing superoxide radicals is discussed. The SOD isoenzymes of each species were analysed by polyacrylamide gel electrophoresis and the patterns revealed a quantitative difference in the number of isoenzyme bands: F. hepatica showed three, and D. dendriticum only two. Determinations were made of the in vitro inhibitory activities of four benzimidazoles and six synthesised pyrimidine derivatives on SOD from trematodes. The present results confirm that the percentage inhibitions of the pyrimidine derivatives are markedly superior to those produced by the benzimidazoles.

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PubMedDate not supplied

[Chromosomal apparatus of trematodes of the general Diplostomum and Tylodelphys (Strigeidida, Diplostomatidae) and its taxonomic significance].

The chromosomal apparatus of three species of trematodes of Diplostomum (D. spathaceum, D. indistinctum, D. mergi) and one species Tylodelphys (T. clavata) is described. It has been suggested that karyological investigations can be used for taxonomic purposes. The opinion has been expressed that the number of chromosomes in the karyotype of these trematodes plays no taxonomic role. Of great taxonomic significance are the size and morphology of chromosomes. Differences in karyotypes of trematodes belonging to different species and genera were revealed by these characters. The absence of close dependence between morphology of adult and specific peculiarities of karyotypes in species of the same genus enables in some cases the use of chromosomal apparatus as a most reliable criterion for a differentiation of close species.

Animals↗

PubMedDate not supplied

[Demonstration of life cycle with four obligatory hosts of the Hemiurid Trematodes].

Research on the transmission of Hemiurid Trematode Halipegus ovocaudatus in experimental and natural conditions demonstrates the following: --the miracidium grows into a sporocyst producing rediae in the Mollusc Planorbis planorbis; -- the cystophorous cercariae become mesocercariae in the hemocoele of Copepodes or finally Ostracodes when swallowed; -- the mesocercariae become matacercariae in the mesenteron of larval Odonates (Zygoptera and Anisoptera) when these larvae swallow the Crustacea; -- the metacercariae become become adults in the Amphibial Rana ridibundal perezi which feeds on dragonflies. The four hosts (Mollusc -- Crustacean -- Odonat -- Amphibian) are obligatory in the life cycle for it is impossible to infect the Insects directly with the cecariae or the frog (tadpoles as well as adults) with the mesocercariae. The different stages of the life cycle of H. oveocaudatus aredescribed and the mode of the transmission is compared with the other species of Halipegus and with the Trematodes in general. The adaptative value of the lengthening of the cycle is discussed from the point of view of the conquest of terrestrial hosts by the Hemiurid Trematodes.

Amphibians↗

PubMed1996

The probability of a marine gastropod being infected by a trematode.

Sentinel snails were employed to determine the likelihood of an estuarine snail becoming infected with a trematode under natural conditions. In summers of 1991 and 1993, Ilyanassa obsoleta (Mollusca: Gastropoda) (n = 1,400) were collected from a saltmarsh in Lewes, Delaware, where parasite prevalence was low, and screened for infections. Putatively uninfected snails were individually marked and released onto the nearby Cape Henlopen sandflat where prevalence of trematodes among native snails is very high (approximately 80%). Most sentinels were free in the field for 1-5 mo and 186 were ultimately recovered. The overall estimate of probability of infection is 1.6%. The snail lives for many years and this low probability of becoming infected indicates that high prevalence of trematodes in this host is brought about not by rapid colonization, but by slow accumulation over time.

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PubMed1998

Cercarial production of the trematode Rhipidocotyle fennica in clams kept in the field.

The numbers of cercariae that trematodes produce have been previously investigated in the laboratory but not in the field. I studied cercarial production of the bucephalid trematode Rhipidocotyle fennica in the freshwater unionid clam Anodonta piscinalis kept under natural conditions. Naturally infected clams (n=180) were collected and marked in early June 1996. Every 14 days, starting from the collection date and ending in October, these clams were taken to the laboratory where they were monitored for the emergence of trematode cercariae. Between monitoring dates, the clams were returned to the collection site. From a random subsample of infected clams (n=12), the number of cercariae produced was counted during every monitoring. Cercarial production started in late July. The proportion of infected clams releasing cercariae increased from late July to late August. The mean daily production also increased during that period from 140 to 10,400 cercariae, decreasing thereafter. The mean annual production was 290,000+/-26,000 (160,000-440,000) cercariae. Daily production in late August and early September was positively correlated with annual production. Two of the 12 clams appeared to be infected with both R. fennica and Rhipidocotyle campanula. The average annual productions of R. fennica and R. campanula cercariae in double infections were 181,000+/-58,000 and 73,000+/-29,000, respectively.

Analysis of Variance↗

PubMed1977

Quantitative studies on acetylcholinesterase in seven species of digenetic trematodes.

Quantitative estimation of absolute levels and in vitro release of acetylcholinesterase (AChE) in seven species of digenetic trematodes: Isoparorchis hypselobagri from the swim bladder of catfish, Wallago attu; Srivastavaia indica and Gastrothylax crumenifer from the rumen, and Gigantocotyle explanatum from the liver of the water buffalo, Bubalus bubalis; Fasciolopsis buski, Echinostoma malayanum from the small intestine and Gastrodiscoides hominis from the caecum of the pig, Sus scrofa revealed that the enzyme is present in remarkably high quantities in species which inhibit gastrointestinal tract compared with those that parasitize liver and swim bladder. The rate of in vitro release of AChE also varies with the species which supports the view that such differential secretion probably takes place in situ as well to counteract peristalsis and it is a biochemical adaptation on the part of these trematodes.

Acetylcholinesterase↗

PubMed1989

Echinostoma caproni in mice: shedding of antigens from the surface of an intestinal trematode.

The surface antigens, which induce a serum antibody response during infection of mice with the intestinal trematode Echinostoma caproni, were examined. It was demonstrated that antigens are shed from the surface of juvenile and 4-week old adult E. caproni during in vitro culture. SDS-PAGE and Western blot analysis of in vitro shed and detergent solubilized surface antigens indicated that the four major antigens released from the surface of adult parasites had molecular masses of approximately 26,000, 66,000, 75,000 and 88,000. A modified ELISA technique showed the in vitro turn-over rate of the surface antigens to be very high, with a half-life of 8-15 min in both juvenile and adult E. caproni trematodes. Transmission electron microscopy of the surface of adult parasites revealed a highly active secreting tegument which was densely packed with membrane-bound vesicles, reflecting the high rate of shedding of the surface antigens. An attempt to immunize mice with detergent solubilized adult surface antigens failed to induce resistance to infection with metacercariae of E. caproni.

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PubMed1994

Host-parasite associations on a coral reef: pomacentrid fishes and digenean trematodes.

A comprehensive survey of 39 sympatric species from the Pomacentridae from the southern Great Barrier Reef revealed 18 species of digenean trematodes. Individual species of trematodes infected between one and 24 species of pomacentrids. Overall, host specificity was low, indicating host switching during the evolution of associations among these hosts and their parasites. Factors which may have facilitated host switching are discussed.

Animals↗

PubMed1982

Preliminary studies of lipids of the trematodes Eurytrema pancreaticum, Calicophoron erschowi and the turbellarian Penecurva sibirica.

The amount of total lipids, phospholipids, neutral lipids and fatty acids was determined in cattle parasites, namely the trematodes Eurytrema pancreaticum, Calicophoron erschowi, and in the free-living turbellarian Penecurva sibirica. Neutral lipids of these flatworms contained sterols, sterol esters, triacylglycerols and free fatty acids. P. sibirica also contained diacylglycerols. Parasitic and free-living flatworms differed in phospholipid composition: the turbellarian did not contain phosphatidylserine, and the trematodes had practically no sphingomyelin or lysophosphatidyl choline. E. pancreaticum, C. erschowi and P. sibirica contained high levels of phosphatidylcholine and phosphatidylethanolamine as well as lysophosphatidylethanolamine and cardiolipin. The fatty acid composition of total lipid extracts of flatworms and of the pancreas and rumen of the host animals were determined. The fatty acid composition of the flatworm lipids reflected the fatty acid composition of the host tissue but was not identical to it.

Animals↗

PubMed2006

Immunology and pathology of intestinal trematodes in their definitive hosts.

This review examines the significant literature on the immunology and pathology of intestinal trematodes in their definitive hosts. We emphasize information on selected species in six families for which the literature on these topics is extensive. The families are Brachylaimidae, Diplostomidae, Echinostomatidae, Gymnophallidae, Heterophyidae, and Paramphistomidae. For most of these families, coverage is considered under the following headings: (i) background; (ii) pathology of the infection; (iii) immunology of the infection; (iv) immunodiagnosis; and (v) human infection. Some of these heading have been subdivided further, based on the literature available on a particular topic. Following this coverage, we include a final section on the important topical literature on selected trematodes in families other than the six mentioned above.

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