Original Paper

Parasitology Research

, Volume 102, Issue 2, pp 219-228

Arrested development of the myxozoan parasite, Myxobolus cerebralis, in certain populations of mitochondrial 16S lineage III Tubifex tubifex

  • D. V. BaxaAffiliated withSchool of Veterinary Medicine, Department of Medicine and Epidemiology, University of California Email author 
  • , G. O. KelleyAffiliated withCalifornia Department of Fish and Game, Fish Health Laboratory
  • , K. S. MukkatiraAffiliated withCalifornia Department of Fish and Game, Fish Health Laboratory
  • , K. A. BeauchampAffiliated withUS Geological Survey, National Fish Health Research Laboratory, Leetown Science Center
  • , C. RasmussenAffiliated withWestern Fisheries Research Center, United States Geological Survey
  • , R. P. HedrickAffiliated withSchool of Veterinary Medicine, Department of Medicine and Epidemiology, University of California

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

Laboratory populations of Tubifex tubifex from mitochondrial (mt)16S ribosomal DNA (rDNA) lineage III were generated from single cocoons of adult worms releasing the triactinomyxon stages (TAMs) of the myxozoan parasite, Myxobolus cerebralis. Subsequent worm populations from these cocoons, referred to as clonal lines, were tested for susceptibility to infection with the myxospore stages of M. cerebralis. Development and release of TAMs occurred in five clonal lines, while four clonal lines showed immature parasitic forms that were not expelled from the worm (non-TAM producers). Oligochaetes from TAM- and non-TAM-producing clonal lines were confirmed as lineage III based on mt16S rDNA and internal transcribed spacer region 1 (ITS1) sequences, but these genes did not differentiate these phenotypes. In contrast, random amplified polymorphic DNA analyses of genomic DNA demonstrated unique banding patterns that distinguished the phenotypes. Cohabitation of parasite-exposed TAM- and non-TAM-producing phenotypes showed an overall decrease in expected TAM production compared to the same exposure dose of the TAM-producing phenotype without cohabitation. These studies suggest that differences in susceptibility to parasite infection can occur in genetically similar T. tubifex populations, and their coexistence may affect overall M. cerebralis production, a factor that may influence the severity of whirling disease in wild trout populations.