1991 Volume 26 Issue 3 Pages 133-138
We tried several transmission experiments of naturally infected actinosporeans in the tubificid oligochaete, Branchiura sowerbyi, to myxosporean-free goldfish, Carassius auratus.
Almost all actinosporean spores collected by squashing tubificids or filtering effluent from a container with tubificids were physically damaged and/or unclean, and all infection experiments using such spores failed. However, coexistence of uninfected goldfish with a stock of B. sowerbyi shedding spores of several actinosporeans in the same container resulted in infections with three species of myxosporeans : Zschokkella, Myxobolus, and Thelohanellus spores in 15-20% of goldfish after 2.5-4 months. We improved the collection method of actinosporeans; tubificids were individually placed in the cell-well plates with 24 2 ml-wells and waterborne actinosporeans were detected by inverted phase-contrast microscopy. Actinosporeans harvested by this method were intact and purely concentrated. Eventually, in goldfish kept with tubificids harbouring the actinosporean Raabeia sp. in the same tank for 3 weeks, and in goldfish exposed to Raabeia suspension for 1 hour, spores of an unidentified Myxobolus were found 3-4 months after the exposure. Unexposed goldfish and ones exposed to actinosporean-free tubificids were both negative for the infection.
We developed the collection method of actinosporeans, and confirmed that the actinosporean Raabeia infecting the oligochaete B. sowerbyi was transformed into Myxobolus in goldfish.
