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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetics, Physiology, and Health Research to Improve Catfish Production

Location: Warmwater Aquaculture Research Unit

Title: Molecular and morphological characterization of myxozoan actinospore types from a commercial catfish pond in the Mississippi Delta

Authors
item Rosser, Thomas -
item Griffin, Matt -
item Quiniou, Sylvie
item Greenway, Terry -
item Khoo, Lester -
item Wise, David -
item Pot, Linda -

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 30, 2014
Publication Date: N/A

Interpretive Summary: Myxozoan parasites are a major hindrance to catfish aquaculture. One strategy used to prevent losses attributed to parasitic organisms is to disrupt or break their life cycle. This work characterized the infective stages of six different myxozoan parasites present in catfish production systems and will help complete the life cycles of these previously unclassified parasites. This information will assist in the development of management strategies to prevent losses attributed to these parasites.

Technical Abstract: The actinospore diversity of infected Dero digitata was surveyed (May, 2011) from a channel catfish production pond in the Mississippi Delta region for the elucidation of unknown myxozoan life cycles. Only two myxozoan life cycles have been molecularly confirmed in channel catfish (Ictalurus punctatus), identifying the actinospore stage from an aquatic oligochaete (Dero digitata) and the myxospore stage from the catfish. In this study Dero digitata were isolated from oligochaetes that were collected from the bottom sediment of a channel catfish production pond. After a one-week daily examination of the 2,592 isolated D. digitata, a total of six genetically different actinospore types were observed. The representative actinospore types were classified as two aurantiactinomyxons, two helioactinomyxons, one raabeia, and one triactinomyxon. Overall infection prevalence in the isolated oligochaetes was 4.4%. Actinospores were photographed and measured for morphological characterization. Four actinospore-types, previously undescribed molecularly and morphologically, were identified and characterized. Phylogenetic analysis revealed the raabeia and one of the helioactinomyxons (type 1) actinospores were closely related to the group of myxozoans known to parasitize ictalurids from North America. To date, no myxospores have been linked to any of the sequenced actinospores reported in this survey. The morphological and molecular sequencing data generated on these actinospore stages will be used to confirm the myxospore counterpart of each of these actinospores for completion of life cycles in these closed production systems.

Last Modified: 10/21/2014
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