Geology topics
Publications and source records attributed to M.E. Markiw.
Trophozoites and other pre-spore stages of the myxosporidan Myxosoma cerebralis were taken from infected rainbow trout ( Salmo gairdneri ) and cultured in vitro. Cultures eventually yielded mature spores capable of discharging their polar capsules. This is the first report of culture of a myxosporidan.
Studies of the life cycle of Myxosoma cerebralis showed that development of infectivity did not occur endogenously but that the spore “aging” process required participation of an aquatic tubificid oligochaete. Data suggestive of such involvement were derived from trials in which spores were “aged” in an array of inert, sterilized, pasteurized, or natural aquatic substrates and from examination of aquatic soils from trout hatcheries in which whirling disease was epizootic. The role of the aquatic oligochaete was confirmed two ways. First, signs of whirling disease developed, and M. cerebralis spores were produced in young rainbow trout ( Salmo gairdneri ) that had been fed oligochaetes harvested from pond soil taken from two hatcheries where whirling disease was epizootic. Second, when containers of pasteurized soil were populated with four genera of oligochaetes– Aeolosoma, Dero, Stylaria , or Tubifex – from a biological supply house, or with tubificid worms from trout hatcheries free of whirling disease, and then seeded with M. cerebralis spores and “aged” for 4 months, whirling disease occurred only in trout held with Tubifex and with hatchery tubificids.
Serologic relatedness of the two life stages of the salmonid whirling disease parasite Myxosoma cerebralis Hofer, 1903 — myxosporean spores from fish cartilage and actinosporean triactinomyxon spores from aquatic tubificids — were investigated. When the direct fluorescent antibody technique was used, anti-triactinomyxon and anti- M. cerebralis rabbit sera conjugated with fluorescein isothiocyanate cross-reacted with the respective heterologous life stage. Both stages showed similar locations of specific fluorescence with conjugates of either homologous or heterologous serum. Thus, serology supports the relatedness of the myxosporean M. cerebralis and the actinosporean triactinomyxon stages.
Methylene blue staining (0.08 %) was used to determine efficiency of heat treatment in killing spores of Myxosoma cerebralis . Nearly all spores heated at 90°C for 10 min and 70°C for 100 min became stained giving presumptive evidence that they were killed.
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This paper provides the latest scientific and technical advances in the management of salmonid whirling disease caused by the myxosporean Myxobolus cerebralis (Syn. Myxosoma cerebralis). The complete life cycle of the parasite and the biology of the infective agent to fish, the actinosporean Triactinomyxon stage, are reviewed, and suggested procedures for detection, identification, and control of the disease are discussed. The paper offers sources of information and related reference materials of interest to fish culturists, fishery biologists, and students.
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No abstract available at this time
No abstract available at this time
For 80 years the infectivity of salmonid whirling disease has eluded discovery. New findings now show that this myxosporean disease of fish is initiated by what is regarded as an actinosporean produced in a tubificid oligochaete. Experimental results provide evidence that, instead of being considered as representatives of separate classes in the phylum Myxozoa, the myxosporean and actinosporean are alternating life forms of a single organism.
No abstract available at this time
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Eleven dye substances were tested for their ability to stain Myxosoma cerebralis and to be retained through either the pepsin-trypsin-dextrose or the plankton centrifuge method of releasing and concentrating spores. Silver nitrate proved to be the best; it produced a distinctive brown color that has been retained by spores through 2.5 yr of storage. The method has applications in histologic studies of whirling disease, in quantifying the efficiency of spore detection procedures, and in teaching.
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Rabbits were immunized with antigens extracted from mature spores or prespore stages of Myxosoma cerebralis , and the resulting antisera and their globulins were used in direct and indirect fluorescent antibody techniques. Both kinds of antisera reacted with homologous spores and with stages of the organism that precede spores. When tested for specificity against spores of 12 other myxosporidans the direct fluorescent antibody technique showed cross-reactivity with only one other and that was a species of Myxosoma . The indirect fluorescent antibody technique showed some reactions across generic lines. The antisera have application in studies of the parasite's life cycle and in diagnostics.
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