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PubMed1992

Reinvestigation of the ultrastructure of spermiogenesis and the spermatozoon of Hymenolepis nana (Cestoda, Cyclophyllidea), parasite of the small intestine of Rattus rattus.

Spermiogenesis in Hymenolepsis nana begins with the formation of a differentiation zone. This is limited at the front by arched membranes, is surrounded by cortical microtubules associated with 12 crested-like bodies, and contains a single centriole made up of doublets. The distal centriole gives rise to a flagellum that grows at the same pace as the cortical microtubules. Migration of the nucleus takes place after the formation of the flagellum. It is followed by the separation of the old spermatid from the residual cytoplasm. The mature H. nana spermatozoon is filiform and lacks mitochondria. The axoneme, of the 9 + "1" pattern of the Platyhelminthes, does not reach the extremities of the spermatozoon. The nucleus is electron dense and is in close contact with the axoneme around which it coils in a spiral making an angle of 10 degrees to 15 degrees with the spermatozoon axis. The cortical microtubules follow a 10 degrees to 15 degrees helicoidal path along almost their whole length, except at their posterior extremity, where they are parallel to the spermatozoon axis. H. nana is distinguished by the early development of 12 crested-like bodies of different lengths and by the existence of a single centriole in the differentiation zone. Such a high number of crested-like bodies had never previously been reported in a cestode.

Animals↗

PubMed1998

Sexual selection, parasites and bower height skew in a bower-building cichlid fish.

The good genes mechanism of sexual selection predicts that secondary sexual ornaments may reliably reveal a males resistance to parasites. We studied correlates of courtship and spawning success in a species of Copadichromis, a lekking cichlid fish from Lake Malawi, Africa, which builds sand bowers. We present the first evidence of a negative relationship between the structure of an extended phenotypic character (height skew of sand bowers) and male parasite load. Males that spawned had significantly fewer dilepipid cestodes in their livers than males that did not spawn, never before demonstrated in a lekking species of fish. Furthermore, males that spawned had significantly heavier gonads than 'unsuccessful males. We also found significant correlations between relative liver weight and some measures of reproductive success. This may indicate females are choosing to mate with males in better condition. Copyright 1998 The Association for the Study of Animal Behaviour

Journal Article↗

PubMed1998

Temporal prey distribution affects the competitive ability of parasitized sticklebacks.

Parasitized animals are often reported to have a reduced competitive ability in experimental studies designed to examine foraging success under a specific type of competitive interaction; however, since animals compete under a range of competition regimes in natural situations, and because success is likely to require different foraging skills under each, it is unclear whether infected animals should be equally poor competitors under all competitive scenarios. We studied the foraging success of three-spined sticklebacks, Gasterosteus aculeatus, infected with plerocercoids of a cestode, Schistocephalus solidus, in competition with uninfected conspecifics. When pairs of differentially infected sticklebacks were presented with sequentially introduced items, the numbers of available prey taken by infected and uninfected competitors did not differ significantly, although nonparasitized fish were more successful at taking items over which there was direct competition. In contrast, when prey items were presented simultaneously in a locally dense patch, nonparasitized fish ingested significantly more of the available food than their infected counterparts: an apparent consequence of their greater ability to take items in rapid succession. Our results show that the type of competition conditions generated as a result of specific prey distribution patterns plays a role in determining the relative foraging success of parasitized sticklebacks, and suggest that this may have consequences for the distribution of different infection classes in natural, heterogeneous environments. (c) 1998 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed1994

Grillotia erinaceus (Cestoda, Trypanorhyncha): localization of neuroactive substances in the plerocercoid, using confocal and electron-microscopic immunocytochemistry.

Indirect immunocytochemistry, in conjunction with confocal scanning laser microscopy and electron-microscopic immunogold labeling, has been used to localize neuropeptide and 5-hydroxytryptamine (5-HT) immunoreactivities (IRs) in the plerocercoid (scolex and surrounding blastocyst) of the trypanorhynch tapeworm, Grillotia erinaceus. Antisera directed to two native cestode neuropeptides, neuropeptide F and the FMRFamide-related peptide, GNFFRFamide, were used to demonstrate the presence of a well-developed and extensive peptide-immunoreactive nervous system of central and peripheral elements in the juvenile scolex. Neuronal connectivity exists between the scolex and the surrounding blastocyst, in which there is a rich innervation of varicose fibers displaying peptide IR. Ultrastructurally, gold labeling of the peptide IR was found exclusively over the contents of dense secretory vesicles in the axons and somatic cytoplasm of neurons. Double-labeling experiments demonstrated an apparent colocalization of peptide IR, although the results of antigen preadsorption procedures indicated substantial cross-reactivity of the two antisera. A separate and well-differentiated 5-HT-immunoreactive nervous system, with a similar anatomical arrangement as the peptide-immunoreactive nervous system, is present in both the scolex and blastocyst.

Animals↗

PubMed1996

Taenia saginata: vaccination against cysticercosis in cattle with recombinant oncosphere antigens.

Taenia saginata is a medically and economically important cestode parasite. Infection with the cysticercus larval stage in cattle causes economic loss in the beef meat industry. A practical vaccine to prevent infection with the parasite in cattle would be valuable and would assist in control of transmission of the parasite to humans, the obligate definitive host. Here we use recombinant DNA techniques to clone oncosphere antigens of T. saginata and use the recombinant antigens in vaccine trials in cattle. Vaccination with a combination of two antigens, designated TSA-9 and TSA-18, induced up to 99.8% protection against experimental challenge infection with T. saginata eggs. Operational characteristics of the vaccine will need to be defined, such as duration of immunity and protection of newborn calves. The vaccine has the potential to be used on a commercial scale for the control of bovine cysticercosis.

Amino Acid Sequence↗

PubMed1999

Hymenolepis diminuta: catalysis of transmembrane proton translocation by mitochondrial NADPH-->NAD transhydrogenase.

The mitochondrial, inner-membrane-associated, reversible NADPH-->NAD transhydrogenase of adult Hymenolepis diminuta physiologically couples matrix-localized, NADP-specific "malic" enzyme with NADH-dependent anaerobic electron transport. Employing submitochondrial particles (SMP) as the source of enzyme activity and both spectrophotometric and fluorometric assessments, the present study made evident that in its catalysis of transhydrogenation between NADPH and NAD, the cestode enzyme engages in the concomitant transmembrane translocation of protons. As assessed spectrophotometrically, the catalysis of NADPH-dependent NAD reduction by H. diminuta SMP was stimulated significantly by carbonyl cyanide 3-chlorophenylhydrazone (CCCP), carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP), as well as by the protonophoric anthelmintic, niclosamide. In addition, N,N'-dicyclohexylcarbodiimide (DCCD) markedly diminished SMP-catalyzed hydride ion transfer between NADPH and NAD. The catalysis by SMP of concomitant, transhydrogenase-mediated proton translocation was evaluated more directly via fluorometric assays using 8-anilino-1-napthalenesulfonic acid (ANS) as the probe. These latter evaluations revealed a transhydrogenase-dependent enhancement of ANS fluorescence in accord with an intravesicular accumulation of protons. ANS fluorescence was quenched rapidly when the assay system was supplemented with CCCP, FCCP, or niclosamide. Consistent with the helminth transhydrogenase acting as a proton pump, transhydrogenase-mediated enhanced fluorescence also was inhibited by DCCD. Considered collectively, these data indicated, apparently for the first time for any invertebrate system, that the transhydrogenase, in catalyzing the NADPH-->NAD reaction, acts in the translocation of protons from the matrix to the intermembrane space mitochondrial compartment.

Anilino Naphthalenesulfonates↗

PubMed2002

Single-strand conformation polymorphism-based analysis reveals genetic variation within Spirometra erinacei (Cestoda: Pseudophyllidea) from Australia.

This study examined genetic variability within Spirometra erinacei (Cestoda: Pseudophyllidea) from different host species and geographical origins in Australia using a polymerase chain reaction (PCR)-based mutation detection approach, followed by DNA sequencing. Part of the cytochrome c oxidase subunit 1 gene (p cox 1) was amplified by PCR, scanned for sequence variation by single-strand conformation polymorphism (SSCP), and representative samples from different host species were selected for DNA sequencing. While no variation in SSCP profiles was detected among S. erinacei samples from dog, fox, cat, tiger snake and python, they differed in profile from 5 specimens from the green tree frog (Litoria caerulea). This was supported by sequence data which demonstrated that p cox 1 sequences of samples from the latter host species differed at 8 of 393 (2%) nucleotide positions from those from the non-amphibian host. Using a nucleotide difference in the p cox 1 sequence, a PCR-linked restriction fragment length polymorphism (RFLP) could be employed to unequivocally delineate between samples from non-amphibian and amphibian hosts. These findings demonstrate the existence of at least two genotypes within S. erinacei, which may have important implications for studying the epidemiology, ecology and systematics of this cestode.

Animals↗

PubMed1992

Insect muscle actins differ distinctly from invertebrate and vertebrate cytoplasmic actins.

Invertebrate actins resemble vertebrate cytoplasmic actins, and the distinction between muscle and cytoplasmic actins in invertebrates is not well established as for vertebrate actins. However, Bombyx and Drosophila have actin genes specifically expressed in muscles. To investigate if the distinction between muscle and cytoplasmic actins evidenced by gene expression analysis is related to the sequence of corresponding genes, we compare the sequences of actin genes of these two insect species and of other Metazoa. We find that insect muscle actins form a family of related proteins characterized by about 10 muscle-specific amino acids. Insect muscle actins have clearly diverged from cytoplasmic actins and form a monophyletic group emerging from a cluster of closely related proteins including insect and vertebrate cytoplasmic actins and actins of mollusc, cestode, and nematode. We propose that muscle-specific actin genes have appeared independently at least twice during the evolution of animals: insect muscle actin genes have emerged from an ancestral cytoplasmic actin gene within the arthropod phylum, whereas vertebrate muscle actin genes evolved within the chordate lineage as previously described.

Actins↗

PubMed1981

Release of neurosecretory material by protrusions of bounding membranes extending through the axolemma, in Diphyllobothrium dendriticum (Cestoda).

The release of neurosecretory material was studied in the cestode tapeworm Diphyllobothrium dendriticum. In plerocercoid larvae cultivated in vitro the neurosecretory vesicles release their content by way of protrusions extending through the axolemma into the intercellular space. The released material is directed predominantly towards the muscles. No omega figures were detected. The significance of this new type of release is discussed.

Animals↗

PubMed1977

Mutagenicity studies with praziquantel, a new anthelmintic drug: tissue-, host-, and urine-mediated mutagenicity assays.

Praziquantel, a new anthelmintic drug with activity against all species of schistosomes pathogenic to man, and against a wide range of Cestodes, was tested for mutagenic potential. For the detection of both base substitutions and frameshift mutations, Salmonella typhimurium TA 100 and TA 98 were used as tester strains. Using the plate assay with and without added S-9, host-mediated assay and urine-mediated assay without and after incubation with beta-glucuronidase/arylsulfatase, no mutagenic activity could be detected.

Administration, Oral↗

PubMed1990

Immunocytochemical localization of histamine in flatworms.

Specific antibodies against histamine were used to demonstrate the occurrence and cellular distribution of histamine-like immunoreactivity in three species of flatworms (phylum Platyhelminthes). In the parasitic cestode Diphyllobothrium dendriticum, histamine-reactivity was found in neurons of the main nerve cords, and in cells lining the central and peripheral excretory ducts. In the free-living microturbellarian Microstomum lineare and in the planarian Polycelis nigra, histamine-immunoreactivity was restricted to cells and fibres of the nervous system. The occurrence of histamine or a related substance in the nervous system of flatworms, which represent primary bilateria, indicates the importance of this neuroactive substance in the animal kingdom.

Animals↗

PubMed1994

Immunocytochemical distribution of neuropeptide F (NPF) in the gastropod mollusc, Helix aspersa, and in several other invertebrates.

The distribution of neuropeptide F (NPF) immunoreactivity in the snail, Helix aspersa, has been demonstrated by immunocytochemistry using 2 region-specific antisera. One, designated NPF3, was raised against a synthetic N-terminal fragment of Helix aspersa NPF; the other, designated PP221, was raised against the C-terminal hexapeptide amide of mammalian pancreatic polypeptide (PP) but cross-reacts fully with the analogous C-terminal region of Helix aspersa NPF. The distribution of NPF immunoreactivity has also been compared with that of FMRFamide using alternate serial sections of Helix aspersa ganglia. Results showed that NPF immunoreactivity was abundant and widespread in the central and peripheral nervous systems and the pattern of immunostaining obtained using both region-specific antisera was similar. Likewise, immunocytochemistry of neural tissues of a congeneric species, Helix pomatia, and 2 prosobranch gastropods, Buccinum undatum and Littorina littorea, produced similar staining patterns with both antisera. However, in the cephalopod mollusc, Loligo vulgaris, and the cestode, Moniezia expansa, positive immunostaining was only obtained with the C-terminal PP antiserum. Immunostaining of alternate serial sections of Helix aspersa ganglia with NPF3, and an antiserum raised to FMRFamide, showed that while a few neurones were immunoreactive with one antiserum only, in the majority, both immunoreactivities were co-localised. NPF thus appears to be an important neuropeptide of widespread distribution in Helix aspersa and the differential immunocytochemical staining obtained using the 2 region-specific antisera would suggest a high degree of primary structural conservation within the gastropod molluscs, but lack of conservation of the N-terminal region of the peptide in other invertebrate groups.

Amino Acid Sequence↗

PubMed1975

The histochemistry and fine structure of the embryophore of Shipleya inermis (Cestoda).

The embryophore (inner capsule) of the tapeworm Shipleya inermis was studied with histochemistry and electron microscopy. It was found to be unique for the cestodes in that it has a laminated construction. During development lamina are added until there are 10 which are arranged in an irregular zig-zag pattern. The embryophore is positive to tests for acid and alkaline phosphatase, and the Hales test for acid mucopolysaccharides. Permeability of tapeworm egg coverings is discussed.

Acid Phosphatase↗

PubMed1977

[Helminth fauna of Syrian lambs].

A study of the helminth fauna of lambs in Syria was made on 40 gastrointestinal tubes and 500 lungs from animals slaughtered in the abattoir of Hama. The parasites isolated were 21 nematode species, 4 cestode species and 2 bladderworm species (Cysticercus tenuicollis and Echinococcus species). Nematodirus oiratianus, Moniezia benedeni and Neostrongylus linearis were found for the first time in lambs in Syria. A detailed description is given of morphologic characteristics of Nematodirus oiratianus.

Abattoirs↗

PubMed1987

Effects on the development of Dipylidium caninum and on the host reaction to this parasite in the adult flea (Ctenocephalides felis felis).

Temperature was found to be a major factor affecting the development of Dipylidium caninum and the presence of a host reaction of adult Ctenocephalides felis felis to D. caninum. Adult fleas reared at 30-32 degrees C contained fully developed metacestodes when they emerged from their cocoons. However at lower temperatures, D. caninum could not complete development until the flea hosts had spent some time on their mammalian hosts. It was the surface temperature of the mammals (31-36 degrees C) and not the fleas' blood meals which resulted in the metacestodes completing their development. This development of D. caninum was therefore independent of the flea development. At 20 degrees C, a larger and more prolonged host reaction was mounted than at higher temperatures. The larval flea diet had a small effect on the subsequent cestode development and the adult fleas' reaction to it.

Animals↗

PubMed1987

Absorption, distribution and excretion of the anthelmintic praziquantel (Droncit) in rainbow trout (Salmo gairdneri R.).

Prazquantel is an anthelmintic active against trematodes and cestodes. The absorption, distribution and excretion of the drug was studied in serum, muscles, liver, bile fluid and kidneys of rainbow trout at two temperatures, 12 degrees C and 18 degrees C, after a single oral dose of 500 mg/kg body wt. A bioassay, using cercaria larvae of the trematode Diplostomum spathaceum as the test organism, was employed to measure the drug levels in tissues of the fish. The cercariae were very sensitive to praziquantel; their mobility was significantly reduced within 20 min in a 0.01 micrograms/ml solution. Praziquantel was readily absorbed from the gastrointestinal tract of the fish. Absorption was more rapid at 18 degrees C than at 12 degrees C. Only in the liver, however, did the peak values reach significantly higher levels at the higher temperature. The peak values in different tissues (10.2-31.8 micrograms/g) were reached 4-16 h after administration of the drug. The elimination of the drug from the tissues was less dependent on temperature than absorption. By 32 h p.a., 67%-96% of the maximum amounts had been eliminated from the tissues. Praziquantel was excreted partly with bile fluid and partly as water-soluble metabolites through the kidneys.

Animals↗

PubMed1986

Gastro-intestinal helminths of donkeys in Burkina Faso.

Thirty adult donkeys from Burkina Faso were necropsied and their gastro-intestinal worm burdens counted and determined. The strongylids were the most abundant species with a prevalence of 100% for Strongylus vulgaris. Four species of Strongylus, two of Triodontophorus and six of the Cyathostominae were recovered. All of the animals were also infested with habronematid nematodes, but oxyurid and ascaridid nematodes were found in low numbers. In addition to the nematodes, the paramphistomid trematode Gastrodiscus aegyptiacus and the anoplocephalid cestode Anoplocephala magna occurred in varying numbers. Faecal egg-counts from 131 donkeys ranged between 100 and 9,200 for strongylid eggs.

Animals↗

PubMed1981

Effect of praziquantel on adult Echinococcus granulosus in vitro: scanning electron microscopy.

The effect of praziquantel in vitro at concentrations of 5, 50 and 500 ppm for 1 h resulted in the progressive breakdown of the tegument and in morphologic distortion of adult Echinococcus granulosus when compared to controls. Scanning electron microscopy of all specimens treated in the various concentrations of praziquantel showed loss of most, if not all of the rostellar hooks and changes in the structure of the suckers. Many of the tapeworms immediately detached from the host's gut upon being placed in the drug, and all treated cestodes exhibited contraction or swelling, particularly in the penultimate proglottid. Intense contraction was apparent in the worms exposed to the higher drug concentrations. Characteristic conical microtriches on the terminal proglottid, as observed in the control specimens, became fused and matted when exposed to 5 ppm of praziquantel. At a drug concentration of 50 ppm, the tegumental surface developed grooves or furrows between clumps of fused microtriches, while 500 ppm caused production of holes within the denuded tegument of the parasite. Ovoid bodies, presumed to be eggs, were observed on the outer surfaces and just below the tegument of tapeworms treated with concentrations of 50 ppm. These structures also appeared to adhere to the outer surfaces of specimens exposed to 500 ppm. In view of the foregoing, special care should be taken in handling and disposing of feces from infected or suspect dogs after praziquantel treatment, since the breakdown in the tegumental surface of E. granulosus presumably results in the release of potentially infective eggs.

Animals↗