Evaluation of malacosporean life cycles through transmission studies

S. Tops, Dolores Baxa, T. S. McDowell, Ronald Hedrick, B. Okamura

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Myxozoans, belonging to the recently described Class Malacosporea, parasitise freshwater bryozoans during at least part of their life cycle, but no complete malacosporean life cycle is known to date. One of the 2 described malacosporeans is Tetracapsuloides bryosalmonae, the causative agent of salmonid proliferative kidney disease. The other is Buddenbrockia plumatellae, so far only found in freshwater bryozoans. Our investigations evaluated malacosporean life cycles, focusing on transmission from fish to bryozoan and from bryozoan to bryozoan. We exposed bryozoans to possible infection from: stages of T. bryosalmonae in fish kidney and released in fish urine; spores of T. bryosalmonae that had developed in bryozoan hosts; and spores and sac stages of B. plumatellae that had developed in bryozoans. Infections were never observed by microscopic examination of post-exposure, cultured bryozoans and none were detected by PCR after culture. Our consistent negative results are compelling: trials incorporated a broad range of parasite stages and potential hosts, and failure of transmission across trials cannot be ascribed to low spore concentrations or immature infective stages. The absence of evidence for bryozoan to bryozoan transmissions for both malacosporeans strongly indicates that such transmission is precluded in malacosporean life cycles. Overall, our results imply that there may be another malacosporean host which remains unidentified, although transmission from fish to bryozoans requires further investigation. However, the highly clonal life history of freshwater bryozoans is likely to allow both long-term persistence and spread of infection within bryozoan populations, precluding the requirement for regular transmission from an alternate host.

Original languageEnglish (US)
Pages (from-to)109-121
Number of pages13
JournalDiseases of Aquatic Organisms
Volume60
Issue number2
DOIs
StatePublished - Aug 9 2004

Fingerprint

bryozoan
Bryozoa
life cycle (organisms)
life cycle
spore
spores
fish
infection
salmonid
kidney diseases
evaluation
urine
parasite
life history
persistence
immatures
kidneys
parasites

Keywords

  • Freshwater bryozoans
  • Life cycles
  • Malacosporea
  • Myxozoa
  • Potential hosts
  • Proliferative kidney disease
  • Transmission

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science

Cite this

Evaluation of malacosporean life cycles through transmission studies. / Tops, S.; Baxa, Dolores; McDowell, T. S.; Hedrick, Ronald; Okamura, B.

In: Diseases of Aquatic Organisms, Vol. 60, No. 2, 09.08.2004, p. 109-121.

Research output: Contribution to journalArticle

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