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Sequence analysis of the internal transcribed spacer (ITS) region reveals a novel clade of Ichthyophonus sp. from rainbow trout

Diseases of Aquatic Organisms

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Abstract

The mesomycetozoean parasite Ichthyophonus hoferi is most commonly associated with marine fish hosts but also occurs in some components of the freshwater rainbow trout Oncorhynchus mykiss aquaculture industry in Idaho, USA. It is not certain how the parasite was introduced into rainbow trout culture, but it might have been associated with the historical practice of feeding raw, ground common carp Cyprinus carpio that were caught by commercial fisherman. Here, we report a major genetic division between west coast freshwater and marine isolates of Ichthyophonus hoferi. Sequence differences were not detected in 2 regions of the highly conserved small subunit (18S) rDNA gene; however, nucleotide variation was seen in internal transcribed spacer loci (ITS1 and ITS2), both within and among the isolates. Intra-isolate variation ranged from 2.4 to 7.6 nucleotides over a region consisting of ~740 bp. Majority consensus sequences from marine/anadromous hosts differed in only 0 to 3 nucleotides (99.6 to 100% nucleotide identity), while those derived from freshwater rainbow trout had no nucleotide substitutions relative to each other. However, the consensus sequences between isolates from freshwater rainbow trout and those from marine/anadromous hosts differed in 13 to 16 nucleotides (97.8 to 98.2% nucleotide identity).

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Sequence analysis of the internal transcribed spacer (ITS) region reveals a novel clade of Ichthyophonus sp. from rainbow trout
Series title:
Diseases of Aquatic Organisms
Volume
89
Issue:
2
Year Published:
2010
Language:
English
Publisher:
Inter-Research Science Center
Contributing office(s):
Western Fisheries Research Center
Description:
5 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
179
Last page:
183
Number of Pages:
5
Country:
United States