Plastic parasites: Extreme dimorphism creates a taxonomic conundrum in the phylum Microsporidia

Stentiford, Grant D.; Bateman, Kelly S.; Feist, Stephen W.; Chambers, E.; Stone, David M.

doi:10.1016/j.ijpara.2012.11.010

Cited by 59 publications

(54 citation statements)

References 32 publications

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“…Few other morphological characters appear to be useful, and these characters are generally comparable to other reported but undescribed species in the genus (Shields & Wood 1991, Kiryu et al 2009, Ryazanova & Eliseikina 2010. Spores of A. metacarcini had hair-like villous projections that have previously been observed in other Ameson species (Vivarès & Sprague 1979, Vivarès & Azevedo 1988, Kiryu et al 2009, Ryazanova & Eliseikina 2010, Stentiford et al 2013b). Vivarès & Azevedo (1988) used the projections on the spore to separate the genera Ameson from Perezi within the family Pereziidae (see also Canning & Vávra 2000).…”

Section: Discussionsupporting

confidence: 63%

“…Those authors observed A. pulvis having 2 spore morphologies based on their location within host tissues and state of infection. The needle-like spores, similar to N. canceri from M. metacarcini, occurred early in infections and primarily in cardiac muscles, whereas the ovoid Ameson-like spores, with pronounced surface projections, occurred later in infections and primarily in skeletal muscles (Stentiford et al 2013b). In histological assessments of in fected M. metacarcini muscles, heart, gill, and hepa topancreas tissues we did not observe elongated needle-like spores resembling N. canceri in either early or advanced infections.…”

Section: Discussioncontrasting

confidence: 49%

“…Binucleate (diplokaryotic) meronts showed remarkable similarity to stages observed in A. atlanticum infecting Cancer pagurus, A. pulvis in fecting C. maenas, and A. michaelis infecting C. sapidus (Weidner 1970, Vivarès & Sprague 1979, Vivarès & Azevedo 1988, Sprague 1965, Stentiford et al 2013b. Meronts underwent vacuolation, thickening of the parasite spore wall, and a decrease in the nuclear:cytoplasm ratio as they progressed to become the chain-forming quadranucleate sporonts that are characteristic of the genus.…”

Section: Discussionmentioning

confidence: 88%

“…The inclusion of N. canceri within a clade containing species of Ameson, at least based upon SSU rRNA sequences, is surprising as it has a di plokaryotic lineage and produces elongated, needle-like spores, and would seem to be at odds with conventional taxonomy using morphological features. However, Stentiford et al (2013b) recently observed morphological plasticity in a microsporidian (presumed to be A. pulvis) infecting the marine crab C. maenas. Those authors observed A. pulvis having 2 spore morphologies based on their location within host tissues and state of infection.…”

Section: Discussionmentioning

confidence: 99%

“…However, in a subsequent study, 3 of 1134 M. metacarcini infected with microsporidia were found to harbor a microsporidian with ovoid spores morphologically dissimilar to N. canceri (Childers et al 1996). Recent studies combining ecological, morphological, and molecular data have demonstrated significant plasticity in morphological features within certain taxa (Vossbrinck & Debrunner-Vossbrinck 2005, Stentiford et al 2010, 2013b. Indeed, some genera of microsporidians change their spore characteristics with temperature, switching between free spores and octospores within a sporo phorous vesicle depending on environmental temperature (e.g.…”

Section: Discussionmentioning

confidence: 99%

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Ameson metacarcini sp. nov. (Microsporidia) infecting the muscles of Dungeness crabs Metacarcinus magister from British Columbia, Canada

Small

Meyer²,

Stentiford³

et al. 2014

Dis. Aquat. Org.

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The Dungeness crab Metacarcinus magister supports a large and valuable fishery along the west coast of North America. Since 1998, Dungeness crabs exhibiting pink-to orangecolored joints and opaque white musculature have been sporadically observed in low prevalence from the Fraser River delta of British Columbia, Canada. We provide histological, ultrastructural, and molecular evidence that this condition is caused by a new microsporidian parasite. Crabs displaying gross symptoms were confirmed to have heavy infections of ovoid-shaped microsporidian spores (~1.8 × 1.4 µm in size) within muscle bundles of the skeletal musculature. The parasite apparently infected the outer periphery of each muscle bundle, and then proliferated into the muscle fibres near the centre of each infected bundle. Light infections were observed in heart tissues, and occasionally spores were observed within the fixed phagocytes lining the blood vessels of the hepatopancreas. Transmission electron microscopy (TEM) revealed multiple life stages of a monokaryotic microsporidian parasite within the sarcoplasm of muscle fibres. Molecular analysis of partial small subunit rRNA sequence data from the new species revealed an affinity to Ameson, a genus of Microsporidia infecting marine crustaceans. Based on morphological and molecular data, the new species is distinct from Nadelspora canceri, a related microsporidian that also infects the muscles of this host. At present, little is known about the distribution, seasonality, and transmission of A. metacarcini in M. magister.

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