Rainbow trout leucocyte activity: influence on the ectoparasitic monogenean Gyrodactylus derjavini.
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The ectoparasitic monogenean Gyrodactylus derjavini from rainbow trout Oncorhynchus mykiss was exposed in vitro to macrophages isolated as peritoneal exudate cells or as pronephros cells from the host. Cells colonized the parasite especially in the mannose-rich regions in the cephalic ducts where ciliated structures were abundant. Opsonization with fresh serum, in contrast to heat-inactivated serum, enhanced colonization also on other body parts. The adverse effect of the activated macrophages towards G. derjavini was associated with a heat-labile component released from these cells to the culture medium. Analysis of substances released from the cells showed reactivity for a number of enzymes, complement factor C3, interleukin (Il-1) and reactive oxygen metabolites. Chemotaxis assays with pronephric leucocytes showed chemoattractants in G. derjavini, and the respiratory burst level of macrophages was slightly elevated due to parasite exposure. It is suggested that skin leucocytes contribute to an increased level of complement factors in the trout skin during the host response, whereby a hostile microenvironment for the parasites is created. In addition, the IL-1 production could affect mucous cell secretion and hyperplasia and add to the antiparasitic action of the epithelium. Likewise, reactive oxygen metabolites and various enzymes are likely to be involved in the skin response. (+info)
Identification of a novel eosinophil chemotactic cytokine (ECF-L) as a chitinase family protein.
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A novel eosinophil chemotactic cytokine (ECF-L) was purified from the culture supernatant of splenocytes of mice by a combination of anion-exchange chromatography, Procion red-agarose affinity chromatography, size exclusion high performance liquid chromatography (HPLC), and reverse phase HPLC. The NH(2)-terminal amino acid sequence was determined by direct protein sequencing. An ECF-L cDNA clone of 1,506 nucleotides was isolated from a cDNA library, and the nucleotide sequence predicted a mature protein of 397 amino acids. A recombinant ECF-L showed a level of eosinophil chemotactic activity comparable with that of natural ECF-L, and the activity was inhibited by a monoclonal antibody to ECF-L. ECF-L also attracted T lymphocytes and bone marrow polymorphonuclear leukocytes in vitro, whereas it caused selective extravasation of eosinophils in vivo. ECF-L mRNA was highly expressed in spleen, bone marrow, lung, and heart. A comprehensive GenBank data base search revealed that ECF-L is a chitinase family protein. ECF-L retains those amino acids highly conserved among chitinase family proteins, but Asp and Glu residues essential for the proton donation in hydrolysis were replaced by Asn and Gln, respectively. Although ECF-L contains a consensus CXC sequence near the NH(2) terminus akin to chemokine family proteins, the rest of ECF-L shows poor homology with chemokines. (+info)
Occurrence of Bothriocephalus acheilognathi in cyprinid fish from three lakes in the flood plain of the Yangtze River, China.
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Cyprinid fish, Hemiculter leucisculus, Cultrichthys erythropterus and Culter dabryi, were sampled from Liangzi, Honghu and Tangxun lakes in the flood plain of the Yangtze River. The cestode Bothriocephalus acheilognathi Yamaguti, 1934 was found in the 3 lakes, but C. erythropterus sampled from Liangzi lake was found uninfected due probably to the small sample size. Findings of the cestode in the 3 lakes represent the first record of the parasite in the flood plain of the Yangtze River, indicating that B. acheilognathi may be distributed much wider in China than previously recognized. (+info)
First report of the invasive eel pest Pseudodactylogyrus bini in North America and in wild American eels.
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We detected 2 species of monogenean gill worms, Pseudodactylogyrus bini (Kikuchi, 1929) Gusev, 1965 and P. anguillae (Yin & Sproston, 1948) Gusev, 1965 (Monopisthocotylea: Pseudodactylogyridae), on American eel Anguilla rostrata in 2 rivers in South Carolina, USA. One of these, P. anguillae, was reported 5 yr ago from Nova Scotia; as well as in South Carolina, we also discovered it in 2 localities in Chesapeake Bay. Differences in the morphologies of specimens of either species of worm from North America and northeastern Asia were negligible. Similarly, the level of variation in sequences in the ITS2 (internal transcribed spacers) region of ribosomal RNA was minor, and not consistent with geographical origin. These data indicate that these monogeneans invaded North America only recently, possibly in parallel with the nematode Anguillicola crassus (which is known to have been introduced with commercial imports of foreign eels). We map the current global occurrence of these monogeneans, and conclude that their dispersal from northeastern Asia was largely as a result of the eel trade, and has probably been secondarily augmented by longshore migration of infected eels, and possibly also by transport in ballast waters. With present technology, all eel stocks must still be collected from the wild; unless shipments are disinfected at quarantine, these and other eel pathogens (such as A. crassus) are likely to continue to colonise other regions of the world. (+info)
Treatment of Microcotyle sebastis infestation in cultured rockfish Sebastes schlegeli by oral administration of praziquantel in combination with cimetidine.
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The effect of cimetidine on the treatment efficacy of praziquantel against Microcotyle sebastis infestation in cultured rockfish Sebastes schlegeli was investigated. Juvenile rockfish were divided into 7 groups, and orally administered praziquantel alone (50, 100 and 200 mg kg(-1) body wt, BW) or in combination with cimetidine at a dose of 200 mg kg(-1) BW for each praziquantel dose. The fish in the control group were administered only saline. The results clearly showed that coadministration of cimetidine with praziquantel led to a significantly increased treatment efficacy of the latter drug, and consequently would lead to a lowering of the total dose of praziquantel, and a reduction in the administration times and costs for the treatment of M. sebastis infestation in cultured rockfish. (+info)
Effects of Schistocephalus solidus infection on brain monoaminergic activity in female three-spined sticklebacks Gasterosteus aculeatus.
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The three-spined stickleback Gasterosteus aculeatus is an intermediate host of the tapeworm Schistocephalus solidus. Changes in predator avoidance, foraging and shoaling behaviour have been reported in sticklebacks infested with S. solidus, but the mechanisms underlying parasite-induced behavioural changes are not understood. Monoamine neurotransmitters are involved in the control of behaviour and central monoaminergic systems are sensitive to various stressors. Thus, the behavioural effects of S. solidus infestation might be a reflection of changes in brain monoaminergic activity in the stickleback host. The concentrations of 5-hydroxytryptamine (5-HT), dopamine (DA), norepinephrine (NE) and their metabolites 5-hydroxy-indoleacetic acid (5-HIAA), homovanilic acid (HVA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) were measured in the telencephalons, hypothalami and brainstems of parasitized and non-parasitized female sticklebacks held in the laboratory. The ratios of 5-HIAA:5-HT were significantly elevated in both the hypothalami and brainstems of infected sticklebacks. The concentrations of 5-HT and NE were significantly reduced in the telencephalons of infected fish as compared with controls, but there was no elevation of metabolite concentrations. The results are consistent with chronic stress in infected fish, but may also reflect other alterations of neuroendocrine status resulting from parasite infection. (+info)
Common sculpin Cottus gobio as a natural paratenic host of Proteocephalus longicollis (Cestoda: Proteocephalidae), a parasite of salmonids, in Europe.
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Common sculpins Cottus gobio L. (Pisces: Cottidae), from the Mlynsky Brook near Ceske Zleby in the Sumava National Park, southwestern Bohemia, Czech Republic, were found to harbour in their intestines juvenile cestodes Proteocephalus longicollis (Zeder, 1800), a common parasite of holarctic salmonids, with a prevalence of 60% and intensity of 1 to 11 (mean 5) parasites per fish; undoubtedly, these prey fish serve as paratenic hosts. In this locality, the definitive host of P. longicollis is the brown trout Salmo trutta m. fario L., large specimens of which apparently acquire infection of this parasite by feeding on infected sculpins. C. gobio is the first known natural paratenic host of P. longicollis in Europe. (+info)
Indirect fitness consequences of mate choice in sticklebacks: offspring of brighter males grow slowly but resist parasitic infections.
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'Good genes' models of sexual selection suggest that elaborate male sexual ornaments have evolved as reliable signals of male quality because only males of high genetic viability are able to develop and maintain them. Females benefit from choosing such individuals if quality is heritable. A key prediction is that the offspring of males with elaborate mating displays will perform better than those of less elaborate males, but it has proved difficult to demonstrate such an effect independently of the effects of differences in parental investment. We tested for 'good genes' linked to male ornamentation in the three-spined stickleback Gasterosteus aculeatus using in vitro fertilization to generate maternal half-siblings, which were raised without parental care. Maternal half-siblings sired by brightly coloured males grew less quickly than half-siblings sired by dull males but were more resistant to a controlled disease challenge. Among the offspring that became infected, those with brighter fathers had higher white blood cell counts. This suggests that highly ornamented males confer disease resistance on their offspring. The association with reduced growth suggests a mechanism for the maintenance of heritable variation in both disease resistance and male sexual coloration. (+info)