Sequential development of Buddenbrockia plumatellae (Myxozoa: Malacosporea) within Plumatella repens (Bryozoa: Phylactolaemata)

Abstract

Colonies of the freshwater bryozoan Plumatella repens collected from a river in the UK were found to be infected with the myxozoan parasite Buddenbrockia plumatellae following laboratory maintenance. Optimisation of the bryozoan diet allowed maintenance of infected colonies for 90 d, permitting observation by light and electron microscopy of the sequential parasitic developmental cycle. Parasite stages were associated with host peritoneum, identifying the primary developmental phase. The association of B. plumatellae cells with peritoneal basal lamina and morphological similarities between parasite and host suggested that the parasite remodelled host tissue. Progressive expansion and elongation of individual parasites led to the release of freely floating vermiform stages within the host coelomic cavities. Within these 'worms', intraluminal masses developed, resulting in the formation of spores. Upon maturation, the 'worms' ruptured, releasing many spores within the host that were subsequently discharged. Although parasitism led to increased bryozoan fragmentation and lowered statoblast production, some colonies did survive, resulting in repeated waves of infection. Long-term laboratory maintenance of infected bryozoan colonies could provide a means of maintaining B. plumatellae for study until the full life cycle is ascertained.KEY WORDS: Myxozoa · Malacosporea · Bryozoa · Buddenbrockia plumatellae · Development · Remodel Resale or republication not permitted without written consent of the publisherDis Aquat Org 73: [159][160][161][162][163][164][165][166][167][168][169] 2006 focused on the development of B. plumatellae in populations of P. fungosa, Hyalinella punctata Hancock and Fredericella sultana Blumenbach (Canning et al. 2002). However, some details of the developmental cycle within bryozoans remained to be revealed; in particular, the presence of stages preceding coelozoic 'worm' development. Despite contrasting morphologies, molecular evidence led to a proposed synonymy of B. plumatellae and T. bryozoides (Monteiro et al. 2002), with the former name assuming historical precedence.The aim of the present study was to examine developmental stages of Buddenbrockia plumatellae within individual specimens of Plumatella repens. Repeated examination by light microscopy allowed the first description of prolonged sequential development in living hosts. Ultrastructural analysis of infected bryozoan tissue gave further insights into the morphological characteristics of the interaction between this unusual myxozoan parasite and host. MATERIALS AND METHODS Collection and observation of bryozoan colonies.In June 2002, floating branches and areas of plastic sheeting were collected from various locations in the River Avon, Wiltshire, UK (51°00' 09'' N, 1°44' 41'' W). These were examined grossly using a ×10 hand lens for bryozoans. Bryozoan colonies were transported in aerated plastic containers to the laboratory in Stirling, where they were attached to Petri dishes and maintained at 21°C on a diet of alga...

Transmission Biology of the Myxozoa

“…Morris et al (2002) documented ornamented spores with a mean diameter of 19.0 µm in the bryozoan Plumatella repens infected with worm-like malacosporean stages. The spores observed by McGurk et al (2006a), also released by a worm-shaped malacosporean in P. repens, were spherical and 17.7 µm in diameter. …”

Sacculogenesis and sporogony of Tetracapsuloides bryosalmonae (Myxozoa: Malacosporea) within the bryozoan host Fredericella sultana (Bryozoa: Phylactolaemata)

“…In addition, the mural cells of B. plumatellae also possessed sporoplasmosomes, (referred to as haplosporosomes by the authors) (Canning et al 1996) indicating that the formation of the B. plumatellae sacs is similar to that of T. bryosalmonae involving the aggregation and assimilation of presaccular parasites. Although presaccular stages have yet to be specifically identified for the sac stage of B. plumatellae, the vermiform developmental phase of this species has been associated with numerous small cells that circulate freely within the coelomic current (McGurk et al 2006b).…”

“…Intriguingly, B. plumatellae has two developmental sequences for sacculogenesis in different bryozoan hosts. In Cristatella mucedo, this parasite forms rounded sacs, while in a range of other bryozoan hosts, it forms motile vermiform stages (Canning et al 1996(Canning et al , 2002Tops et al 2005;McGurk et al 2006b). No correlating vermiform stage has been reported for T. bryosalmonae but its sac stage of development within the bryozoan host is similar to that of B. plumatellae infecting C. mucedo.…”

Early development of the myxozoan Buddenbrockia plumatellae in the bryozoans Hyalinella punctata and Plumatella fungosa, with comments on taxonomy and systematics of the Myxozoa

“…Data have been published on presaccular stages and sacculogenesis of T. bryosalmonae in Fredericella sultana (Blumenbach) (McGurk et al 2006b, Morris and Adams 2006. Similar stages have been described for the sac-like B. allmani in the body wall and body cavity of Lophopus crystallinus (Pallas) (Canning et al 2007) and two studies have addressed some aspects of the early development of worm-like B. plu-matellae in the body wall (basal lamina) of Plumatella repens (Linnaeus) (McGurk et al 2006a, Morris andAdams 2007b). The studies of B. plumatellae dealt with pre-sac cells and sac formation by enclosure of inner cells within a single cell-layered wall and included elongation of sacs to form vermiform stages.…”