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PubMedDate not supplied

[Age-related characteristics of the infestation of populations of the littoral periwinkles Littorina obtusata and L. saxatilis by trematode parthenitae].

Analysis of the age structure of parthenitae of trematodes of sympatric populations of L. obtusata and L. saxatilis was conducted in 1983 for 6 localities in Kandalaksha Bay of the White Sea. 10 species of trematodes were found. The main populational differences in the level of infection are caused by Microphallus piriformes. Species with secondary dispersion in the life cycle are characterized by the increase in the extent of infection in populations with age. In Microphallidae species of "pygmaeus" group the age structure of infection depends on the overage infection of populations: the increase in the parasitic press leads to the maximum turning towards the young part of the snail's population. The establishment of the age structure of infection is considered to be one of the regulation mechanisms in parasite--host relations on the populational level.

Aging↗

PubMed1986

Morphological and histochemical studies on the development of testis and spermatogenesis in the ruminal trematode of sheep, Paramphistomum cervi (Digenea: Paramphistomatidae).

Morphological and histochemical changes accompanying testicular development and spermatogenesis have been described in the ruminal trematode Paramphistomum cervi during the course of its infection in sheep. Small testes of 4-week-old worms contain a few primordial germ cells. Spermatogonial cells appear first in 6-week-old worms and increase in number by the 10th week when the testes become large and follicular. Mature spermatozoa appear in the testes of 16-week-old worms. General pattern of spermatogenesis is the same as described for other trematodes, i.e. a single spermatogonium gives rise to 32 spermatozoa. Cytophore is formed at secondary spermatogonial stage. Various spermatogenic stages contain proteins, glycogen and phospholipids, however, the amount of phospholipids decreases as the maturation proceeds. The mature spermatozoa stain strongly with PAS. The enucleated residual mass contains HgBB-positive proteins and lipid granules. The morphological and cytochemical changes occurring during various spermatogenic stages have been correlated with corresponding histoenzymological changes in the cytoplasm. Frequency of spermatogenesis has been worked out which indicates that the transformation of secondary spermatogonia into spermatids is relatively fast as compared to transformation of primary spermatogonia into secondary spermatogonia and stages of spermateleosis.

Animals↗

PubMed1984

Changing patterns of some trematode infections in Asia.

In certain areas of Asia the pattern of trematode infections in both man and animals seems to have changed in the recent past. On Taiwan, for example, paragonimiasis, fasciolopsiasis and schistosomiasis were at one time highly endemic in certain locations, but in recent years these parasitoses have been difficult to find in definitive, intermediate as well as reservoir hosts. Education, industrialization, alterations in the ecology and the use of modern agricultural practices have contributed to the changes. Conversely, it appears that human clonorchiasis is increasing in Taiwan while in Hong Kong, the disease, once highly prevalent, seems to be decreasing due to control measures implemented in China; the source of infected fish for Hong Kong residents has been China. Furthermore, Clonorchis sinensis infections are more common in higher income groups of Hong Kong since imported fish are more expensive. Along the same line, metagonimiasis is more common among the more affluent sports fishermen in Japan who eat mountain-stream trout as "sashimi" soon after the catch. One of the most dramatic changes in the prevalence of a trematode disease has been in the Lindu Lake region of Central Sulawesi, Indonesia. Echinostomiasis lindoensis was highly endemic in the area and human infection was acquired by eating infected Corbicular sp. clams. The fish Tilapia mossambica was subsequently introduced into the lake and competed for food with the clam and ate the glochidial larval stages of the clam. The clams are no longer present in the lake and consequently, the parasitosis has disappeared.(ABSTRACT TRUNCATED AT 250 WORDS)

Asia↗

PubMedDate not supplied

[The structural characteristics of the nervous system in 2 species of trematodes from the Prosostomata group].

Topographic anatomy of the nervous systems of the trematodes Azygia lucii and Phyllodistomum angulatum was studied by the histochemical method of cholinesterase detection. The cholinergic part of the nervous system of A. lucii is represented by the brain, the ventral, dorsal and lateral longitudinal cords, by rather long complementary anterior branch of the ventral cord and by very short anterior branch of the dorsal cord. All cords are connected with numerous commissures. In the anterior region of the body, between the brain and the ventral sucker there are distributed 9 ring commissures. Behind the ventral sucker there has been revealed up to 18 commissures, 10 of which are ring ones. The regularity of the distribution of commissures is disturbed only in the region of the ventral sucker. The nervous system of such type can be regarded as a regular frequent orthogon. In Ph. angulatum has been revealed another type of the nervous system--an uneven orthogon. It is represented by the brain, 3 pairs of longitudinal nerve cords, small complementary anterior branches of ventral and dorsal cords, 5 ring commissure between the oral--and ventral suckers and one ventral commissure behind the ventral sucker. The origin of regular frequent orthogon in A. lucii and the irregular orthogon in Ph. angulatum is explained by certain morphological peculiarities of their structure; the body shape, musculature development and the reprodactive system localization. The morphological diversity being a characteristic for the trematode nervous system allows to relate them with Neorhabdocoela suborder Typhloplanoida.

Animals↗

PubMedDate not supplied

[Modification of the liver phospholipid status of cattle by Orientobilharzia turkestanica trematodes].

The paper gives the data on a trematode influence onto the phospholipid (PL) contents in the liver of cows. It is shown, that the decrease of PL basic fraction concentrations, i.e. phosphatidilcholin (PC) by 20% and phosphotidilethanolamin (PE) by 26%, during the period of infection is accompanied by the increase of respective lysoforms, namely, lysoPC by 240%, and lysoPE by 160%, and as well as minor forms, PL-diphosphotidilgleserol by 70%, sphingomielin by 47% and phosphatidilserin by 41%. It is suggested, that the infection of cow liver by trematodes determines such contents and principles of membrane structures, which decrease their functional activity and probably increase its permeability for ions, some metabolites and low molecular carbohydrates.

Animals↗

PubMed1976

Histochemical studies on the distribution of alkaline phosphatase, acid phosphatase, 5-nucleotidase and ATPase in various reproductive tissues of certain digenetic trematodes.

Out of other functions performed by vitellaria in digenetic trematodes, their role in the formation of shell globules and shell membrane of the capsule, as well as in the excretion of iron with the help of vitamin C is very important. The present histochemical work shows the localization of certain enzymes in different parts of the reproductive system of ten species of trematodes viz.: Neopronocephalus triangularis Mehra, 1932; Glossimetra orientalis Mehra, 1937; Orientodiscus lobatus Srivastava, 1938; Eumegacetes artemii Mehra, 1935; Ganeo tigrinus mehra et Negi, 1928; Encyclometra caudata Dollfus, 1928; Thapariella udaipurensis Gupta and Sharma, 1970; Paradistomoides indicum Narain et Das, 1929; Patagifer wesleyi Verma, 1936; Proalarioides tropidonotus Vidyarthi, 1937 and indicates their functional significance. The hydrolytic enzymes (alkaline phosphatase, acid phosphatase, 5-nucleotidase and ATPase) are suggestive of their involvement in the uptake of certain nutrients, glycogen and lipoprotein being very significant among others. The four enzymes could also be detected in testes, ovary, uterus, cirrus sac and egg shell. The possible functional significance of each enzyme has been discussed.

Acid Phosphatase↗

PubMed1977

The role of Chaetogaster limnaei in the dynamics of trematode transmission in natural populations of freshwater snails.

Chaetogaster limnaei, an oligochaete was always found infesting Bulinus (Phy.) globosus, B.(B.) forskalii and Lymnaea natalensis in Bo, Sierra Leone, living below the shell or embedded in the mucus of the foot. The worms had no preference for snails with trematode infection. The population was highest in the dry season when fewer snails were infected by trematodes. This is suggested to be a result of the protection the worms give to snails against invading miracidia.

Animals↗

PubMed1982

Trematode infections in Pirenella conica in three sites of a mangrove lagoon in Sinai.

Over a period of 11 months, eight samples of Pirenella conica were taken at each of three sites of a mangrove lagoon in Sinai. Infection with larval trematodes, especially of Heterophyidae, was highest at the site within the mangrove thicket with a breeding colony of reef herons, the supposed definitive hosts of the Heterophyidae. The lowest frequency of infection was recorded from a tide-pool on the broad sand-flats surrounding the lagoon, where there was a great variation in the abundance of snails and xiphidiocercariae were more common than heterophyid cercariae. Predation from fish or other molluscs did not appear to be an important factor at either of these two sites. In all three sites, double infections of Heterophyidae and trematodes with xiphidiocercariae as well as of Heterophyidae and Echinostomatidae occurred less frequently than theoretically expected, but there was no competitive exclusion between Echinostomatidae and xiphidiocercariae.

Animals↗

PubMedDate not supplied

Carbohydrate-binding plasma proteins from the gastropod Biomphalaria glabrata: strain specificity and the effects of trematode infection.

As lectins are believed to mediate non-self-recognition in molluscs, carbohydrate-binding proteins (CBP) from the circulating plasma of the gastropod Biomphalaria glabrata were harvested by affinity chromatography using six different monosaccharides as ligands. Pools of plasma were derived from B. glabrata of either the M line strain, which is susceptible to infection with the PR1 strain of the digenetic trematode Schistosoma mansoni, or from the 13-16-R1 strain, which is resistant to infection. For each strain, plasma was obtained from control snails and from snails exposed to infection 1 or 8 days previously with S. mansoni or the related digenean, Echinostoma paraensei, which is able to develop in either host strain. For control snails, only minor interstrain differences were noted. In M line snails exposed 8 days previously to either parasite, marked changes in CBP populations were observed. Only E. paraensei infections produced comparable alterations in 13-16-R1 snails. The most conspicuous changes noted were the increased production of 80-120 kDa CBP in both strains, 150-210 kDa in 13-16-R1 snails, and 190-210 kDa in M line snails. The results demonstrate 1) interstrain differences in CBP, particularly following exposure to trematodes; 2) that infection provokes increased production and diversity of CBP that bind with greater affinity to the columns; and 3) that snails of the same strain respond differently to the two parasites used.

Animals↗

PubMed1987

Trematode eggshells: Novel protein biopolymers.

In the past few years recombinant DNA technology has somewhat serendipitously shed new light on the formation of trematode eggshells, with the publication of the sequences of highly expressed female-specific genes encoding protein components of the schistosome eggshell and with the isolation of DOPA-rich proteins and one of the corresponding genes from Fasciola. These proteins and other structural polypeptides with repetitive structures were the subject of a recent meeting Bioengineering for Material Applications (sponsored by the Office of Naval Research in Bethesda, USA, June 1987). In this article, based on that meeting, John Cordingley explains how the structure of trematode eggshells appears to show features common to several other biopolymers.

Journal Article↗

PubMed2006

Genetic markers for the identification and characterization of Opisthorchis viverrini, a medically important food borne trematode in Southeast Asia.

The liver fluke, Opisthorchis viverrini, is one of the major food borne trematodes in Southeast Asia, where infection causes hepatobiliary disease and subsequent development of cholangiocarcinoma. In Thailand, O. viverrini is most prevalent in the northeast where there is marked regional variation in the rate of infection in humans at provincial, district and village levels. To date, the roles of genetic variation of O. viverrini on this observed variability in infection, transmission and associated disease are not known. We have applied multilocus enzyme electrophoresis (MEE), specifically allozyme electrophoresis, to isolates of O. viverrini from Thailand and Laos to establish genetic markers to examine its systematics and population structure. Forty-six enzymes commonly found useful for genetic characterisation in parasitic helminths were screened, and of these, 33 enzymes gave sufficient staining and resolution to act as potential genetic markers. Sixteen enzymes were monomorphic and 17 enzymes were polymorphic in the pools of worms examined. Whether they are indicative of different enzyme loci, heterozygosity or unique genotypes within the pools of worms examined remains to be determined. Preliminary investigations examining five individual worms at enzyme loci where pools of worms showed multiple bands have confirmed the diagnostic value of the enzyme loci established as well as providing evidence of potential population sub structuring and heterozygosity. For the first time, we have established at least 17 enzymes that provide the basis to undertake comprehensive genetic analyses of the systematics and population structure of O. viverrini, a medically important food borne trematode in Southeast Asia.

Animals↗

PubMed2004

Effects of diet and larval trematode parasitism on lutein and beta-carotene concentrations in planorbid snails as determined by quantitative high performance reversed phase thin layer chromatography.

High performance thin layer chromatography (HPTLC) was used to quantify the concentrations of beta-carotene and lutein in Biomphalaria glabrata and Helisoma trivolvis (Colorado and Pennsylvania strains) snails under various conditions. These conditions were: snails fed a lettuce (L) vs. a yolk (Y) diet; B. glabrata infected with Echinostoma caproni vs. uninfected snails; and H. trivolvis (PA) infected with Echinostoma trivolvis vs. uninfected snails. The pigments were extracted from the snail whole bodies and digestive gland-gonad complexes, separated by reversed phase HPTLC, and quantified by densitometric scanning with standard calibration curves. Snails on the L-diet showed significant increases (Student's t-test, P<0.05) in the concentrations of beta-carotene and lutein compared to snails on the Y-diet. Snails infected with echinostomes showed no significant differences (Student's t-test, P>0.05) in the concentrations of lutein and beta-carotene compared to the uninfected cohorts. Our results were compared with previous studies that analyzed beta-carotene and lutein in snails infected with larval trematodes. Variations in the results of our study compared with others reflect intrinsic differences in the larval trematode-snail systems used.

Animals↗

PubMed2006

Rediae of echinostomatid and heterophyid trematodes suppress phagocytosis of haemocytes in Littorina littorea (Gastropoda: Prosobranchia).

A modulation of the phagocytic activity of hemocytes from the common periwinkle Littorina littorea by secretory-excretory products (SEP) released by trematode rediae during axenic in vitro cultivation was studied. The SEP released by the parasites Himasthla elongata (Echinostomatidae) and Cryptocotyle lingua (Heterophyidae) were found to inhibit the phagocytosis of zymozan particles by periwinkle hemocytes. The specificity of SEP effects was assessed: SEP of Himasthla militaris and Cryptocotyle concavum, two trematodes belonging to the same genera but infecting another closely related prosobranch snail Hydrobia ulvae, were also shown to be able to suppress L. littorea hemocytes phagocytic activity. However, no decrease in phagocytosis rate was observed when SEP of H. elongata and C. lingua were applied to monolayers of hemocytes from the bivalve mollusc Mytilus edulis. SEP from H. elongata was fractionated; only those fractions containing proteins of molecular weight more than 50 kDa were shown to possess inhibitory activity. Different H. elongata SEP concentrations were tested in for their ability to suppress phagocytosis by L. littorea hemocytes. Even very low SEP concentrations were shown to retain their ability to decrease phagocytosis rate, the inhibitory effect being dose-dependent. Hemocytes derived from snails naturally infected with H. elongata were also found to have lower phagocytic ability as compared to healthy individuals.

Animals↗

PubMed2001

NO nerves in trematodes, too! NADPH-diaphorase activity in adult Fasciolopsis buski.

The free radical nitric oxide (NO) is a unique molecule with an avidity to react with other molecules and is known to function as a neuronal messenger. This nitrergic transmitter with diverse functions in signal transduction, being a gas, is not stored in synaptic vesicles but is generated in various neuronal cells by a family of nitric oxide synthases (NOSs). The NADPH-d histochemical reaction is regarded as a selective marker for NOS in the neuronal tissue. With histochemical detection of NADPH-d, the presence of NOS is demonstrated in the digenetic trematode, Fasciolopsis buski. Strong NADPH-d staining was observed in the neuronal cell bodies in the two cerebral ganglia, the brain commissure and the nerve fibers in the main nerve cords. NADPH-d staining was also detectable in the innervation of the pharynx, the cirrus sac and the ventral sucker besides being observable sporadically in the nerve tributaries in the general parenchyma. NO released by the whole worm kept in PBS at 37 degrees C could also be measured biochemically. The NOS activity was assayed in the whole worm homogenate and also in the tissue homogenate containing only the anterior pre-acetabular part of the parasite body. The presence of NOS in this digenean parasite confirms that a nitrergic innervation occurs in the trematode group also as in other groups of exclusively parasitic helminths and that NO represents an old signal molecule in evolutionary scale.

Animals↗

PubMed2003

Trematode fauna of prosobranch snails of the genus Semisulcospira in Lake Biwa and the connected drainage system.

The parasite fauna of prosobranch snails of the genus Semisulcospira was surveyed in Lake Biwa and the adjacent water system. One aspidogastrean and 28 digenetic trematode taxa were detected in 19209 snails consisting of 10 morphological species. There was no trematode species peculiar to members of the subgenus Biwamelania that is endemic to the Lake Biwa water system. However, one species, Notocotylus magniovatus, was found only in the non-endemic subgenus Semisulcospira. Of 23 digenean taxa detected in more than one host, 13 were distributed in both the lake and the tributaries. Seven of these had host taxa, more than 1% of which were infected with the parasite in both the lake and the tributaries, four had such hosts only in the tributaries, and two had no such hosts. Three species detected only in Lake Biwa were previously reported from other rivers in Japan. In the seven species detected only in the tributaries, two species had life cycles that could be maintained only in rivers. These results indicate that the core areas for the distribution of parasites of Semisulcospira are tributaries, and the lake is a sink for these species. These results contradict the expectation that the parasite fauna should be richer in the lake than in tributaries because the lake is a stable habitat over a geological time scale and has more divergent freshwater animals than the adjacent water system.

Animals↗

PubMed1977

Alkali denaturation of oxyhaemoglobins of some digenetic trematodes and their hosts.

Oxyhaemoglobins of six digenetic trematodes,--Srivastavaia indica, Gastrothylax crumenifer, Gigantocotyle explanatum, Fasciolopsis buski, Gastrodiscoides hominis, Isoparorchis hypselobagri, and of their 3 vertebrate hosts, Bubalus bubalis, Sus scrofa, Wallago attu, were subjected to alkali denaturation at a pH of 12.4. All oxyhaemoglobins from trematodes and their hosts differ from each other in the rate and extent of alkali denaturation which may be explained due to variations in the amino acid sequences of a particular haem protein in addition to other factors.

Alkalies↗

PubMed1985

5'-Nucleotidase activity and substrate affinity in digenetic trematodes.

5'-nucleotidases of eight species of digenetic trematodes were studied using five different substrates. All species showed the following preferential order of substrate affinity; AMP greater than CMP greater than GMP greater than TMP greater than UMP. It was observed that different species occupying similar habitats possessed closely related levels of enzyme activities. The function of 5'-nucleotidases in trematodes is also suggested.

5'-Nucleotidase↗

PubMed2005

Progenesis in digenean trematodes: a taxonomic and synthetic overview of species reproducing in their second intermediate hosts.

Precocious egg production, i.e. progenesis, has been documented for a number of species in scattered reports throughout the trematode literature. The last 2 extensive studies on the subject date from Buttner in the early 1950s (in French) and from Tang in the early 1980s (in Chinese). Overall, 43 species were then known for their ability to produce eggs at the metacercarial stage while still in the second intermediate host. Here, we update the list, and document the existence of progenesis in a total of 79 digenean trematode species, for which we provide information on the taxonomy of the hosts, the facultative or obligate character of progenesis, relevant references, as well as some other pertinent biological information. We then review the subject by asking 7 questions of fundamental evolutionary importance. These include: What favours progenetic development? What are the associated costs and benefits? How are progenetic eggs released from the host? While exposing the various opinions of previous authors, we attempt to give a synthetic overview and stress on the importance of the metacercarial cyst wall (whether it is present, and if so its thickness) in the evolution and the adoption of a progenetic life-cycle.

Animals↗