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PubMed1995

[Trematode parasites of Italian bats].

Data are presented on bat trematodes in Italy, whose previous list included only the following five species: Plagiorchis vespertilionis, Plagiorchis asper, Mesotretes peregrinus, Prosthodendrium chilostomum, Prosthodendrium longiforme. Between 1945 and 1981, 289 bats were examined belonging to 13 species. A total of twelve trematode species were identified, nine of which are recorded for the first time in Italy: Lecithodendrium linstowi, Lecithodendrium granulosum, Lecithodendrium rotundum, Prosthodendrium herardovae, Prosthodendrium hurkovaae, Prosthodendrium parvouterus, Pycnoporus heteroporus, Matovius rhinolophi, Parabascus lepidotus. For each parasite species, hosts, localities and number of specimens/host are reported. Special attention is devoted to P. vespertilionis with description of specimens remarkably different from the type form, to L. linstowi for peculiar specimens from Rhinolophus hipposideros, and to M. rhinolophi with additions to the original description especially concerning the vitelline glands' structure. Pycnoporus macrolaimus, identified in a collection of bat trematodes of the Institute of Parasitology of the University "La Sapienza" of Rome, is also recorded for the first time in Italy.

Animals↗

PubMed1997

[Nematode and trematode fauna of the muskrat (Ondatra zibethicus LINK, 1795) in Lower Saxony].

From January 1995 to December 1995, 991 muskrats were examined for the occurrence and the regional prevalence of nematodes and trematodes. The muskrats were trapped in all parts of Lower Saxony. 77.2% of the studied population were less than one year old, 22.8% were older. The male to female ratio was 54.5% to 45.5%. One genus of nematodes, Trichuris spp., was found in the colon in 1.9% of the animals in the south of the investigated area. A species differentiation was not possible, as exclusively female parasites had been found. Additionally, two genera of trematodes (Echinostoma spp. and Quinqueserialis quinqueserialis) belonging to two different families were detected in 2.5% of the muskrats. In the north of the investigated area the prevalence was significantly higher than in the south. As to the echinostomatides, no species-differentiation was made because, according to KANEV (1985), many echinostomatides have not been described correctly in the past. Some echinostomatides cannot be differentiated until today. There was no statistically significant correlation between parasite infections and sex of the animals. Concerning Echinostoma spp. and Quinqueserialis quinqueserialis, a highly significant correlation was found between the age of the muskrats and the trematode-infections. Young animals were infected more often than older animals, none of the younger animals was infected with Trichuris spp.

Animals↗

PubMed2000

Flukes without snails: advances in the in vitro cultivation of intramolluscan stages of trematodes.

In vitro cultivation of parasitic helminths, including the digenetic trematodes, has long been a valuable tool in medical and veterinary parasitology, permitting and/or facilitating the development of diagnostic reagents, chemotherapeutic agents, and vaccines and providing insights into naturally complex host-parasite interactions. In vitro cultivation of the intramolluscan stages of trematodes has been particularly challenging, given the ontogenic complexities involved in the production of multiple larval generations from germinal tissues through an asexual "budding" process. Recently, however, advanced larval development has been achieved by incorporating the Biomphalaria glabrata embryonic (Bge) cell line into cocultivation systems. Most notably, the entire intramolluscan cycle (from miracidium to cercaria) has been completed for the human blood fluke Schistosoma mansoni, while significant primary sporocyst development has been attained for several other digeneans including S. japonicum and Fascioloides magna. Here we review recent advances in the cultivation of several larval trematode species and discuss the potential use of this culture system for addressing fundamental questions of host-parasite compatibility.

Animals↗

PubMed1994

Serotonin and neuropeptide immunoreactivities in the intramolluscan stages of three marine trematode parasites.

Using an indirect immunofluorescence technique interfaced with confocal scanning laser microscopy, whole-mount preparations of three genera of marine trematode larvae, Cryptocotyle lingua, Cercaria emasculans and Himasthla leptosoma, were screened for 5-hydroxytryptamine (5-HT) and selected neuropeptide immunoreactivities (IRs). IRs for pancreatic polypeptide (PP), peptide YY (PYY) and FMRFamide were found in the central nervous systems of the three species of cercariae, immunostaining the paired ganglia and central commissure and the longitudinal nerve cords, with slight differences in both distribution and intensity of IRs being observed for the different antisera used. PP, PYY and FMRFamide IRs were evident in both central and peripheral components of the nervous system in the rediae of C. lingua. 5-HT IR was confined to the peripheral nervous systems of the cercariae of C. emasculans and the rediae of C. lingua, appearing in the form of a network of immunoreactive fibres and associated large cell bodies. A moderate substance P IR was observed in the nervous system of the cercariae of C. lingua. The patterns of immunostaining described were compared with those obtained using antiserum directed to the C-terminal decapeptide amide of neuropeptide F (NPF), a native parasitic peptide from the cestode Moniezia expansa. Results demonstrated that serotoninergic and peptidergic components were present in the nervous systems of all of the trematode larvae studied and that some, if not all, of the IR for PP, PYY and FMRFamide was due to the presence of a trematode NPF homologue.

Amino Acid Sequence↗

PubMed2006

Larval trematodes in freshwater molluscs from the Elbe to Danube rivers (Southeast Germany): before and today.

Studies on life cycles of trematodes have a long tradition in Germany; (Odening 1978) listed a total of 177 trematodes, which can potentially complete their life cycles in German inland waters. However, almost no recent data on the occurrence of larval stages in molluscs are available. Therefore, a survey of trematodes in Southeast Germany was carried out in 2004. A total of 31 species of ten families (29 species of cercariae, seven species of metacercariae, and five species found of both) were found in 311 (4.9%) molluscs of 15 species. The dominant cercariae were Plagiorchis elegans, Echinoparyphium aconiatum, Opisthioglyphe ranae, and Diplostomum pseudospathaceum. Echinoparyphium pseudorecurvatum is reported, for the first time, under its valid scientific name from Germany. In previous studies from the same region, 88 species of cercariae of 16 families were found in 19 species of molluscs (52 cercariae with valid names and 36 not identified to species level). It is proposed that there is still a very similar spectrum of the most common species of cercariae typical for Central Europe as found 20, but also 100-150 years ago.

Animals↗

PubMed1990

Immune mechanisms in trematode-snail interactions.

Digenetic trematodes, including several species of medical and veterinary significance, nearly all depend on molluscs (usually gastropods) as hosts for asexual reproduction. The molluscan internal defence system, although lacking many of the familiar features of the vertebrate immune system, may pose a substantial obstacle to digenean development. In this article, Wil van der Knaap and Eric Loker discuss the manner in which this system is mobilized to kill larval trematodes and the real and putative mechanisms of digenean evasion of molluscan immune responses. These two possible outcomes of trematode-snail associations make them intriguing model systems for exploring processes of parasite infectivity and host resistance.

Journal Article↗

PubMed2006

Specific inhibitors of mitogen-activated protein kinase and PI3-K pathways impair immune responses by hemocytes of trematode intermediate host snails.

To characterize molecular mechanisms regulating snail cellular immune responses, the contributions of mitogen-activated protein kinases (MAPKs) and phosphatidylinositol 3-kinase (PI3-K) were examined in hemocytes of the trematode intermediate host snails Biomphalaria glabrata and Lymnaea stagnalis. Simultaneous measurement of phagocytosis/encapsulation and H2O2 production by hemocytes in the presence or absence of specific signal transduction inhibitors was used to assess the role of extracellular-signal regulated kinases 1 and 2 (ERK1/2), p38, JNK and PI3-K. Hemocyte spreading was significantly reduced in a dose-dependent manner by the ERK inhibitor, PD098059, and by wortmannin, a potent PI3-K inhibitor. The JNK inhibitor, SP600125, and the p38 kinase inhibitor, SB203580, had no effect on hemocyte spreading. Sheep red blood cell phagocytosis was significantly impaired by PD098059, SP600125, and SB203580. Hydrogen peroxide production during phagocytosis was severely inhibited by PD098059. Additionally, PD098059, but not the other inhibitors, significantly impaired the cellular encapsulation of trematode larvae and H2O2 production during encapsulation. These results suggest that MAPK and PI3-K signal transduction pathways play a pivotal role in the immune responses of snail hemocytes. PI3-K and ERK appear to strongly regulate cell motility. ERK, JNK and p38 contribute to phagocytosis-mediated signal transduction. ERK also play a major role in oxidative burst activation and the encapsulation of trematode larvae by snail hemocytes.

Animals↗

PubMed2005

Population genetics of complex life-cycle parasites: an illustration with trematodes.

Accurate inferences on population genetics data require a sound underlying theoretical null model. Organisms alternating sexual and asexual reproduction during their life-cycle have been largely neglected in theoretical population genetic models, thus limiting the biological interpretation of population genetics parameters measured in natural populations. In this article, we derive the expectations of those parameters for the life-cycle of monoecious trematodes, a group comprising several important human and livestock parasites that obligatorily alternate sexual and asexual reproduction during their life-cycle. We model how migration rates between hosts, sexual and asexual mutation rates, adult selfing rate and the variance in reproductive success of parasites during the clonal phase affect the amount of neutral genetic diversity of the parasite (effective population size) and its apportionment within and between definitive hosts (using F-statistics). We demonstrate, in particular, that variance in reproductive success of clones, a parameter that has been completely overlooked in previous population genetics models, is very important in shaping the distribution of the genetic variability both within and among definitive hosts. Within definitive hosts, the parameter F(IS) (a measure of the deviation from random mating) is decreased by high variance in clonal reproductive success of larvae but increased by high adult self-fertilisation rates. Both clonal multiplication and selfing have similar effects on between-host genetic differentiation (F(ST)). Migration occurring before and after asexual reproduction can have different effects on the patterns of F(IS), depending on values of the other parameters such as the mutation rate. While the model applies to any hermaphroditic organism alternating sexual and clonal reproduction (e.g. many plants), the results are specifically discussed in the light of the limited population genetic data on monoecious trematodes available to date and their previous interpretation. We hope that our model will encourage more empirical population genetics studies on monoecious trematodes and other organisms with similar life-cycles.

Animals↗

PubMed2005

Molecular-genetic analyses reveal cryptic species of trematodes in the intertidal gastropod, Batillaria cumingi (Crosse).

Cryptic species of the digeneans, Cercaria batillariae (Heterophyidae) and an undescribed philophthalmid, were detected using polymerase chain reaction-based restriction fragment-length polymorphism methodology and sequence analyses. These digeneans were all collected from the same species of gastropod first intermediate host, Batillaria cumingi (=Batillaria attramentaria). The mitochondrial cytochrome oxidase subunit 1 gene (approximately 800bp) and nuclear internal transcribed spacer 1 gene (approximately 400bp) were used for species level discrimination. Restriction fragment-length polymorphism analyses of cytochrome oxidase subunit 1 gene showed that C. batillariae included 10 distinguishable fragment patterns, and the philophthalmid included five patterns. On the basis of subsequent sequence analyses, the restriction fragment length polymorphism patterns of C. batillariae were grouped into eight phylogenetically distinct lineages and those of the philophthalmid into three phylogenetically distinct lineages. There was no evidence of gene flow among the different lineages due to the lack of heterozygosity within the observed internal transcribed spacer 1 gene fragment patterns. This suggests that all of these lineages are different species. Most of these species were widespread, but some exhibited restricted geographic distributions. We discuss the implications of these findings for host specificity of these trematodes. These results demonstrate the utility of genetic analysis to distinguish species of morphologically similar trematodes. Hence, trematode species diversity may often be underestimated when species identifications are limited to morphological features.

Animals↗

PubMed1995

Structural and functional comparison of trematode haemoglobins.

Haemoglobins from three different species of trematodes (Gastrothylax crumenifer, Paramphistomum epiclitum and Isoparorchis hypselobagri) and their respective hosts were digested with papain. Peptides so produced were separated on 10-15% SDS-PAGGE. The probability of coincidence of the peptides was analysed statistically. Oxygen affinity curves of trematode haemoglobins were found to be a rectangular hyperbolic. The Hill coefficient values of all the trematode haemoglobins were found to be 1. The P50 values, at 25 degrees C in 0.2M phosphate buffer pH 7.4, ranged from 0.8 to 1.6 mmHg.

Animals↗

PubMed1997

Trematode myoglobins, functional molecules with a distal tyrosine.

The myoglobins of two trematodes, Paramphistomum epiclitum and Isoparorchis hypselobagri, were isolated to homogeneity. The native molecules are monomeric with Mr 16,000-17,000 and pI 6.5-7.5. In each species, at least four different globin isoforms occur. Primary structure was determined at the protein level. The globin chains contain 147 amino acid residues. Although major determinants of the globin fold are conserved, characteristic substitutions are present. A Tyr residue occurs at the helical positions B10 and E7 (distal position). This is confirmed by NMR measurements (Zhang, W., Rashid, K. A., Haque, M., Siddiqi, A. H., Vinogradov, S. N., Moens, L. & La Mar, G. N. (1997) J. Biol. Chem. 272, 3000-3006). A distal Tyr normally provokes oxidation of the iron atom and the inability to bind oxygen, whereas a Tyr-B10 is indicative for a high oxygen affinity. In contrast, trematode myoglobins are functional molecules with a high oxygen affinity. Molecular modeling predicts two possible positions for the aromatic ring of Tyr-E7: one being outside the heme pocket making it freely accessible to the ligand and one within the heme pocket potentially able to form a second hydrogen bond with the iron-bound oxygen. A hydrogen bond between Tyr-B10 and the bound oxygen as in the Ascaris hemoglobin is predicted as well. The predicted structure may explain the high oxygen affinity of the trematode myoglobins.

Amino Acid Sequence↗

PubMed2004

Equal partnership: two trematode species, not one, manipulate the burrowing behaviour of the New Zealand cockle, Austrovenus stutchburyi.

Metacercariae of the trematode Curtuteria australis (Echinostomatidae) accumulate in the foot of the New Zealand cockle Austrovenus stutchburyi, severely impairing the cockle's ability to burrow under the sediments. This results in increased predation by birds on cockles, and thus enhanced transmission rates of the parasite to its bird definitive hosts. This host manipulation by the trematode is costly: fish regularly crop the tip of the foot of cockles stranded on the sediment surface, killing any metacercariae they ingest. A second, previously undetected trematode species (characterized by 23 collar spines) co-existing with C. australis, has been found in the foot of cockles in the Otago Harbour, South Island, New Zealand. The relative abundance of the two species varies among localities, with the identity of the numerically dominant species also changing from one locality to the next. Both C. australis and the new species have a strong preference for encysting in the tip of the cockle's foot, where their impact on the burrowing ability of the host is greatest, and where they both face the risk of cropping by fish. Results indicate that these two species are ecological equivalents, and their combined numbers determine how the cockle population is affected.

Animals↗

PubMed2004

The effects of mating system and genetic variability on susceptibility to trematode parasites in a freshwater snail, Lymnaea stagnalis.

The amount and distribution of genetic variability in host populations can have significant effects on the outcome of host-parasite interactions. We studied the effect of mating system and genetic variability on susceptibility of Lymnaea stagnalis snails to trematode parasites. Mating system of snails from eight populations differing in the amount of genetic variability was manipulated, and self- and cross-fertilized offspring were exposed to naturally occurring trematode parasites in a controlled lake experiment. Susceptibility of snails varied between populations, but mating-system treatment did not have a significant effect. Heterozygosity of snails was negatively correlated with the probability of trematode infection, however, suggesting that parasitic diseases may pose a serious threat to populations lacking genetic variability.

Analysis of Variance↗

PubMed2007

Clonal diversity of the marine trematode Maritrema novaezealandensis within intermediate hosts: the molecular ecology of parasite life cycles.

We quantified the clonal diversity of the New Zealand marine trematode Maritrema novaezealandensis (n = 1250) within Zeacumantus subcarinatus snail (n = 25) and Macrophthalmus hirtipes crab (n = 25) intermediate hosts using four to six microsatellite loci, and investigated the potential biological and physical factors responsible for the observed genetic patterns. Individual snails harboured one to five trematode genotypes and 48% of snails were infected by multiple parasite genotypes. Overall, the number of parasite genotypes did not increase with snail size, but was highest in intermediate-sized snails. Significantly larger numbers of parasite genotypes were detected in crabs (relative to snails; P < 0.001), with 16-25 genotypes recovered from individual crabs. Although crabs are typically infected by small numbers of cercariae sourced from many snails, they are occasionally infected by large numbers of cercariae sourced from single snails. The latter cases explain the significant genetic differentiation of trematode populations detected among their crab hosts (F(ST) = 0.009, P < 0.001). Our results suggest that the timing of infection and/or intraspecific competition among parasite clones within snails determine(s) the diversity of parasite clones that snails harbour. The presence of a large number of infected snails and tidal mixing of cercariae prior to infection results in crabs potentially harbouring hundreds of parasite genotypes despite the crabs' territorial behaviour.

Animals↗

PubMed2001

An empirical model of the optimal timing of reproduction for female amphipods infected by trematodes.

Life-history theory predicts that hosts should reproduce when first infected by parasites if hosts are capable and if parasites have a lower cost on current than on future reproduction of hosts. We constructed an empirical model to explore fitness of females of the intertidal amphipod Corophium volutator that reproduced soon versus long after infection by the trematode Gynaecotyla adunca. For uninfected females, the optimal time to reproduce was at their maximum body length. However, for females infected by low or high intensities of trematode metacercariae, reproductive potential (realized fecundity) was highest for females that mated immediately after becoming infected. Even after removing a high cost of delaying reproduction for infected amphipods (high likelihood of depredation by sandpipers, which are final hosts of G. adunca), realized fecundity remained highest if reproduction occurred immediately following infection by trematodes. Results from our model support the view that early reproduction of female amphipods following infection by G. adunca is an adaptive life-history response to parasitism.

Adaptation, Physiological↗

PubMed1965

[Studies on the mineral contents of some trematodes]

The mineral contents of the adult Clonorchis sinensis from rabbits and human were measured, and its qualitative and semi-quantitative analyses were studied with 3.4 meter Ebert-Grating spectrograph, and its quantitative analyses were studied with Beckman DU spectrophotometer. The adult Clonorchis sinensis used in this study were divided into two groups, the first group was collected from the bile passage of the man (C. sinensis from man), the second group was collected from the bile passage of the rabbit(C. sinensis from rabbit). Simultaneously, spectrographic and photometric analyses were also performed on the adult worms of Paragonimus westermani. Furthermore, comparative spectrographic analyses of the trace elements were carried out on the C. sinensis from man, C. sinensis from rabbit, Fasciola hepatica, Eurytrema pancreaticum, and Paragonimus westermani, and the approximate contents of the trace elements of the above trematodes were compared with that of their host tissues and biles. The results obtained were as follows: 1. In the spectrographic analyses of C. sinensis from man, sodium, phosphorus, potassium, copper, calcium, aluminum, iron, and magnesium were detected predominantly, and zinc, titanium, silicone, lead, manganese, barium, cromium, molybdenum, and silver were detected as trace elements. 2. In the differences of level of the minerals in these two C. sinensis, copper level of C. sinensis from man was higher than that of C. sinensis from rabbit, while calcium level of the former worm was higher than that of the latter worm. The trace level of lead, molybdenum, and silver were acertained in the former, but latter were not detected. 3. The contents of the minerals showed the characteristic features in each trematodes: the mineral of flukes in each host were much more than that of the others; such as copper in C. sinensis from man, calcium in the C. sinensis from rabbit, and silicone in the P. westermani. The vanadium was detected in the F. hepatica, E. pancreaticum, and P. westermani, while the other flukes were not detected. 4. In the comparative spectrographic analyses of the trace elements among the trematodes and their host tissues and biles, the minerals which detected from flukes were also found in their tissues and biles of their host. But the mineral levels of C. sinensis from man, F. hepatica, E. pancreaticum, and P. westermani were higher than that of their host tissues and biles, except the C. sinensis from rabbit.

Journal Article↗

PubMedDate not supplied

[The organizational characteristics of the generative material and the the proliferative dynamics of trematode mother sporocysts].

Analysis of miracidia germinal material organization and proliferation dynamics of mother sporocysts enabled us to divide them into three well-defined groups. The first one includes species whose miracidia possess only differentiated (mature) generative cells and embryos of earlier stages of cleavage. In this case during parasite phase of development of maternal sporocysts the generative function is not performed. To the first group therefore trematode species with pedogenetic larvae could be attributed also. The next group embraces species whose miracidia as well as mature generated cells have some undifferentiated cells; thus the parasitic phase of mother sporocyst development acquires restricted proliferative capacity. The third group consists of species with higher trematodes dominating. They perform generative function exclusively at parasitic phase of mother sporocyst development. Representatives of more archaic and ancient species are the bases of the first two groups on the contrary. Such type of distribution can not occur occasionally and apparently reflects first steps of emergenes of parthenogenetic generations of trematodes.

Animals↗

PubMedDate not supplied

[The effect of ammonium nitrate on the residual nitrogen content in the hemolymph of the pulmonate snail Planorbarius purpura (Mollusca: Pulmonata: Bulinidae) normally and in trematode invasion].

The effect of the ammonium nitrate (concentrations 2000, 4000, 6000 mg/l) on the content of urea, urea nitrogen and residual nitrogen in the haemolymph of normal Planorbarius purpura and in trematode-infected individuals. It is shown, that stimulation of metabolic processes is more expressed in uninfected specimens, while the trematode-infected ones, the protective process is strained. When the toxin concentration reaches 6000 mg/l, the trematode infected specimens enter the phase of depression with 3.73% hyponitrogen level.

Animals↗