Location: Warmwater Aquaculture Research UnitTitle: Morphology and Small-Subunit Ribosomal DNA Sequence of Henneguya Adiposa (Myxosporea) From Ictalurus punctatus (Siluriformes)) Author
Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2009
Publication Date: 10/12/2009
Citation: Griffin, M.H., Wise, D.J., Pote, L.M. 2009. Morphology and Small-Subunit Ribosomal DNA Sequence of Henneguya Adiposa (Myxosporea) From Ictalurus punctatus (Siluriformes). Journal of Parasitology. 95:1076-1085. Interpretive Summary: With its widespread use a cultured food fish, the channel catfish is one of the most widely distributed freshwater fish species in North America. As such, an in depth knowledge of its pathogens is of significant importance to fisheries biologists and fish health professionals. One such group of pathogens includes the primitive metazoans belonging to the Myxozoa, including representatives of Henneguya. Henneguya adiposa, described here, is a parasite that affects channel catfish. This paper complements previous descriptions of the parasite with new data on the spore stage and its effect on the host.
Technical Abstract: The original description of Henneguya adiposa, a myxozoan parasitizing channel catfish Ictalurus punctatus, is supplemented with new data on spore morphology, including photomicrographs and line drawings, as well as 18S small-subunit (SSU) ribosomal DNA (rDNA) sequence. Elongate, translucent, linear plasmodia were situated between the connective tissue bands of the adipose fin. The myxospore possessed an elongate, lanceolate spore body, flattened parallel to the suture line: 17.1 ± 1.6 mm (range 14.7–20.5) in length, 4.1 ± 0.3 mm (range 3.4–4.6) wide in valvular view, and 3.7 ± 0.3 mm (range 3.2–4.0) thick in sutural view. Polar capsules were pyriform and unequal in length, measuring 7.2 ± 0.6 mm (range 5.8–8.3) long and 1.3 ± 0.2 mm (range 0.9–1.9) wide, with at least 8 turns in the polar filament coil. The caudal appendages were 38.0 ± 6.2 mm (range 23.2–48.8) and split posteriorly. The total length of the spore was 55.6 ± 6.5 mm (range 40.7–65.8). Phylogenetic analysis of 18S SSU rDNA sequence data placed this isolate within the Myxobolidae, indicating a close relationship to a group of Henneguya species parasitizing channel catfish in the southeast United States.