TY - JOUR
T1 - Spironucleus species
T2 - Economically-important fish pathogens and enigmatic single-celled eukaryotes
AU - Williams, Catrin F.
AU - Lloyd, David
AU - Poynton, Sarah L.
AU - Jorgensen, Anders
AU - Millet, Coralie Om
AU - Cable, Joanne
PY - 2011
Y1 - 2011
N2 - Diplomonads are aerotolerant anaerobic, binucleate fagellates, which are commonly found in the intestinal tract of wild and farmed fsh. Of the diplomonad genera, Spironucleus, composed of opportunistic pathogens, poses the greatest threat to aquaculture. Immunocompromised hosts or fsh without acquired immunity are thought to be more susceptible to parasitism by these otherwise commensal agents. Accumulation of fagellates along the intestinal tract often leads to systemic Spironucleosis causing high mortality of both ornamental and food fsh in aquaculture. The life cycle of these piscine diplomonads is direct, consisting of a motile, parasitic trophozoite and a resilient encysted stage, which facilitates water-borne transmission. Confusion in the nomenclature, as well as numerous reassignments of taxa, hampers our understanding of host range and geographical distribution of fsh diplomonads. Accurate identifcation requires transmission electron microscopy to characterise intricate ultrastructural features. Additionally, sequencing of the small subunit ribosomal RNA gene allows identifcation of cryptic Spironucleus spp. In vitro culture provides a convenient source of fagellates for biochemical and physiological research, allowing the identifcation of novel parasite-specifc molecular pathways such as H2 production within Spironucleus sp. This provides insight into the pathogenicity of these organisms and offers potential new targets for chemotherapy. Restrictions on the administration of the current drug of choice, metronidazole, in aquacultural settings, as well as reported cases of drug resistance, means that control of Spironucleosis is especially diffcult. Allium sativum (garlic)-derived compounds have proven highly effective at inhibiting parasite growth in vitro, showing great potential as a novel alternative therapy in the treatment of Spironucleosis. Further characterisation of the biochemistry, pathogenicity and taxonomy of fsh diplomonads is required in order to fully appreciate the true impact and economic consequences of Spironucleus spp. in aquaculture.
AB - Diplomonads are aerotolerant anaerobic, binucleate fagellates, which are commonly found in the intestinal tract of wild and farmed fsh. Of the diplomonad genera, Spironucleus, composed of opportunistic pathogens, poses the greatest threat to aquaculture. Immunocompromised hosts or fsh without acquired immunity are thought to be more susceptible to parasitism by these otherwise commensal agents. Accumulation of fagellates along the intestinal tract often leads to systemic Spironucleosis causing high mortality of both ornamental and food fsh in aquaculture. The life cycle of these piscine diplomonads is direct, consisting of a motile, parasitic trophozoite and a resilient encysted stage, which facilitates water-borne transmission. Confusion in the nomenclature, as well as numerous reassignments of taxa, hampers our understanding of host range and geographical distribution of fsh diplomonads. Accurate identifcation requires transmission electron microscopy to characterise intricate ultrastructural features. Additionally, sequencing of the small subunit ribosomal RNA gene allows identifcation of cryptic Spironucleus spp. In vitro culture provides a convenient source of fagellates for biochemical and physiological research, allowing the identifcation of novel parasite-specifc molecular pathways such as H2 production within Spironucleus sp. This provides insight into the pathogenicity of these organisms and offers potential new targets for chemotherapy. Restrictions on the administration of the current drug of choice, metronidazole, in aquacultural settings, as well as reported cases of drug resistance, means that control of Spironucleosis is especially diffcult. Allium sativum (garlic)-derived compounds have proven highly effective at inhibiting parasite growth in vitro, showing great potential as a novel alternative therapy in the treatment of Spironucleosis. Further characterisation of the biochemistry, pathogenicity and taxonomy of fsh diplomonads is required in order to fully appreciate the true impact and economic consequences of Spironucleus spp. in aquaculture.
KW - Aquaculture
KW - Diplomonad
KW - Garlic
KW - Hexamita
KW - Hydrogenosomes
KW - Spironucleus
KW - Taxonomy
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U2 - 10.4172/2155-9546.S2-002
DO - 10.4172/2155-9546.S2-002
M3 - Article
AN - SCOPUS:84879464330
SN - 2155-9546
JO - Journal of Aquaculture Research and Development
JF - Journal of Aquaculture Research and Development
IS - SPEC. ISSUE 2
M1 - 002
ER -