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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↗
PubMed1987

Treatment of fish parasites. 2. Effects of praziquantel, niclosamide, levamisole-HCl, and metrifonate on monogenea (Gyrodactylus aculeati, Diplozoon paradoxum).

In research for successful treatment of fish parasitized by monogeneans, four substances (Praziquantel, Niclosamide, Levamisole-HCl, and Metrifonate) were tested in vivo against Gyrodactylus aculeati parasitizing the skin of sticklebacks (Gasterosteus aculeatus). Fish were incubated in water containing different solutions of the drugs. Praziquantel, Niclosamide and Levamisole-HCl were effective against Gyrodactylus aculeati. Praziquantel caused irreversible lesions in the parasite tegument (beginning with 1 microgram/ml and 90 min exposure). Niclosamide was effective in a narrow concentration range of 0.075-0.1 microgram/ml (90 min). Levamisole-HCl was effective in a concentration range of 20-50 micrograms/ml for 120 min. Like Praziquantel, Niclosamide and Levamisole-HCl led to damage of the parasite tegument. The opisthaptor region and the openings of the cephalic glands were most severely affected. Furthermore, the effects of Niclosamide, Levamisole-HCl and Metrifonate on Diplozoon paradoxum parasitizing the gills of chubs (Squalius cephalus) and breams (Abramis brama) were investigated. Levamisole-HCl (10 micrograms/ml) and Niclosamide (0.2 microgram/ml) were effective against Diplozoon paradoxum after an exposure of 90 min and 45 min in vitro. The parasites were severely affected along the midbody. Metrifonate caused a lysis of the tegument and a strong secretion of slime. It is suggested that chemotherapy against Gyrodactylus sp. may be accomplished with 10 mg Praziquantel/l for 3 h during storage in smaller tanks. Niclosamide (0.1 mg/l for 90 min), or Levamisole-HCl (50 mg/l for 120 min) may be used alternatively. Concentrations of Niclosamide and Levamisole-HCl have to be calculated with accuracy, since fish only tolerate a very narrow range of these drugs (Niclosamide: 0.1 mg/l for 120 min; Levamisole-HCl: 50 mg/l for 120 min).

Animals↗
PubMed1988

Fine structure and permeability of the metacercarial cyst wall of Clinostomum marginatum (Digenea).

Encysted metacercariae of Clinostomum marginatum (Digenea) were obtained from tissues of yellow perch, Perca flavescens. The outermost wall (host response) as seen under electron microscopy consisted of a single, fibrous tissue layer, 10-25 micron thick. The tissue contained flattened fibrocytes, small fat deposits, and vacuoles embedded between layers of collagen fibers. The cyst cavity was filled with small vesicles, crystals, and debris. No layer corresponding to the primary (parasite-produced) cyst wall secreted by most species of metacercariae was noted. To determine the permeability of the cyst wall, encysted worms were incubated under initial rate conditions with [3H] glucose, with and without the glucose transport inhibitors phlorizin and phloretin. After incubation, the worms were mechanically excysted, washed, and processed to determine glucose uptake rates. Vmax and Kt were greater than those obtained for worms excysted prior to incubation with substrate. Moreover, the presence of phlorizin or phloretin in the incubation medium had no effect on glucose uptake by encysted worms. Thus, the selective permeability of the cyst wall permits free diffusion of glucose to the cutaneous transport systems of the worm, while restricting the movements of phlorizin and phloretin.

Animals↗
PubMed1992

Neuropeptide F-immunoreactivity in the monogenean parasite Diclidophora merlangi.

The localisation and distribution of neuropeptide F (NPF)-immunoreactivity (IR) in the monogenean fish-gill parasite, Diclidophora merlangi, have been investigated by whole-mount immunocytochemistry interfaced with confocal scanning laser microscopy and, at the ultrastructural level, by indirect immunogold labeling. Using antisera directed to intact synthetic NPF (Moniezia expansa, residues 1-39) or to the C-terminal decapeptide (residues 30-39) of synthetic NPF (M. expansa), immunostaining was found throughout the central (CNS) and peripheral nervous systems (PNS), including the innervation of the reproductive system. Immunoreactivity was found to be more intense using the antiserum to the C-terminal decapeptide fragment of NPF. At the subcellular level, gold labeling of NPF-IR was found exclusively over the contents of dense-cored vesicles that occupied nerve axons of both the CNS and the PNS. The distribution pattern of immunostaining for NPF mirrored exactly that previously documented for the vertebrate pancreatic polypeptide (PP) family of peptides and for FMRFamide. This finding and the results of preabsorption experiments strongly suggest that NPF is the predominant native neuropeptide in D. merlangi and that it accounts for most of the immunostaining previously obtained with PP and FMRFamide antisera.

Animals↗
PubMed1991

Fine structure of spermatogenesis in polyopisthocotylid monogeneans (Protomicrocotyle ivoriensis, Gastrocotyle sp.).

The development of spermatozoa in the polyopisthocotylean fish-gill flukes Protomicrocotyle ivoriensis and Gastrocotyle sp. was investigated by light and transmission electron microscopy. In both species the spermatogonia were undifferentiated cells, the cytoplasm of which contained numerous free ribosomes, and successive mitoses gave rise to primary spermatocytes, which are clearly identified by the presence of synaptonemal complexes in their nuclei. As compared with that of the spermatogonia, the cytoplasm of the primary spermatocytes contained an increased number of ribosomes. Golgi complexes were frequently seen in the spermatocytes of P. ivoriensis but not in Gastrocotyle sp. In P. ivoriensis the secondary spermatocytes were separated by interspaces between the irregularly shaped cell surfaces. In both species a syncytial mass of spermatids developed, which gave rise to 64 spermatozoa. Cross sections of the mature spermatozoa of both species revealed the presence of numerous submembranous microtubules and two axonemes showing a pattern of 9 doublet peripheral microtubules plus a central one. In contrast to microtubules plus a central one. In contrast to P. ivoriensis, in Gastrocotyle sp. the axonemes originated from different places at the axis of the spermatozoon. With respect to the other results obtained, the spermiogenesis and the fine structure of spermatozoa of both species studied were similar to previous findings in other polyopisthocotyleans.

Animals↗