Geology topics
Publications and source records attributed to K. Wolf.
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.
No abstract available.
No abstract available.
After fry of rainbow trout, Salmo gairdneri Richardson, had been infected parenterally with Herpesvirus salmonis , moribund or freshly dead specimens were examined histopathologically. The virus produced a generalized infection, the first signs of which appeared after 2–3 weeks. Visceral and respiratory organs and the heart showed major pathological changes, and pancreatic syncytia were judged to be pathognomonic. Kidneys were prime targets for the virus and showed the highest levels of infectivity; lesser amounts of virus were present in the stomach, liver, and intestine. The virus did not spread by contact to produce clinical disease nor could disease or viral replication be induced by parenteral inoculation of yearling Oncorhynchus nerka (Walbaum).
No abstract available at this time
In laboratory research, the rainbow trout has become a counterpart to the white rat, because that fish is an adaptable species available in much of the developed world and stocks from egg through adult are available throughout the year. Moreover, many strains are recognized, and their propagation and laboratory maintenance are not particularly demanding. Also, knowledge of rainbow trout nutrition, husbandry, diseases, immune responses, toxicology, and carcinogenesis exceeds that of any other salmonid or coldwater teleost. The rainbow trout is the logical surrogate species in many studies of other salmonids.
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
No abstract available at this time
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