Observations on the electron-dense bodies of the PKX parasite, agent of proliferative kidney disease in salmonids

Morris, David J.; Adams, Alexandra; Richards, R. H.

doi:10.3354/dao039201

Cited by 16 publications

(33 citation statements)

References 12 publications

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“…24 & 25 in Hine & Wesney 1992), and similar dense MVBs occur in the cytoplasm and are involved in haplosporogenesis in Haplosporidium nelsoni (Perkins 1968(Perkins , 1979. Although vegetative stages of the myxozoan parasite PKX also form bodies resembling haplosporosomes from the trans-Golgi face, and these bodies are seen in MVBs, the latter are formed when the bodies are engulfed by cup-like structures (Morris et al 2000), which were not observed here.…”

Section: Discussionmentioning

confidence: 43%

“…In the haplosporidian Haplosporidium nelsoni, haplosporosomes align along the plasma membrane with an invagination in the internal membrane orientated at 90°to the surface (Scro & Ford 1990), and they disappear in the early stages of sporulation (Perkins 1968), supporting the interpretation that they may be involved in spore wall formation. The similar sporoplasmosomes of PKX, unlike the sporoplasmosomes of other myxozoans (Anderson et al 1999), have a lucent bar-like invagination and also orientate along the plasma membrane (Morris et al 2000). However, the PKX organism, Tetracapsula bryosalmonae, also has haplosporosomes (Canning et al 2000) which do not orientate along the plasma membrane, suggesting that they have an alternative function.…”

Section: Discussionmentioning

confidence: 99%

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Ultrastructure of a haplosporidian containing Rickettsiae, associated with mortalities among cultured paua Haliotis iris

Hine¹,

Wakefield²,

Diggles³

et al. 2002

Dis. Aquat. Org.

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Uninucleate and multinucleate stages of a protozoan parasite are described from cultured abalone Haliotis iris Martyn, 1784 in New Zealand. The parasite is identified as a haplosporidian by the occurrence of multinucleate plasmodia, mitochondria with tubular cristae, lipid droplets, anastomosing endoplasmic reticulum (aER), multivesicular bodies (MVBs), haplosporogenesis by the production of haplosporosome-like bodies from nuclear membrane-bound Golgi, and their maturation to haplosporosomes. Coated pits occurred in the plasma membrane and coated vesicles were scattered in the cytoplasm, particularly in association with the Golgi face away from the nucleus, and aER. It is concluded that the outward face of the Golgi may be the trans face, and that aER is the trans-Golgi network. Coated pits and bristle-coated vesicles are reported from a haplosporidian for the first time. The vesicles in the MVBs resembled the cores and inner membranes of haplosporosomes, without the outer layer. The possible inter-relationships of these features are discussed. The abalone parasite differs from previously described haplosporidians in the apparent absence of a persistent mitotic spindle, and the presence of intracytoplasmic coccoid to rod-shaped bacteria resembling Rickettsiales-like prokaryotes. Phylogenetic analysis of the 16S rRNA gene sequence of the Rickettsiales-like prokaryotes indicated that these organisms belong to the Rickettsia cluster. The prokaryotes have a high (7%) sequence divergence from known Rickettsieae, with Rickettsia sp. and R. massiliae being the closest relatives. The lack of non-molecular evidence prevents us from proposing a new rickettsial genus at this time.

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Section: Discussionmentioning

confidence: 43%

Section: Discussionmentioning

confidence: 99%

Ultrastructure of a haplosporidian containing Rickettsiae, associated with mortalities among cultured paua Haliotis iris

Hine¹,

Wakefield²,

Diggles³

et al. 2002

Dis. Aquat. Org.

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“…These appear to be fundamental differences, but they may not be. Haplosporosomes occur in haplosporidians (Haplosporidium, Minchinia, Bonamia, Urosporidium), paramyxeans (Paramyxa, Marteilia, Marteilioides), and the vegetative stages of myxozoans (Morris et al 2000). The latter are multicellular organisms, now regarded as cnidarians, and paramyxeans appear multicellular during sporulation.…”

Section: Parasite Taxonomic Affinitiesmentioning

confidence: 99%

Ultrastructure of Mikrocytos mackini, the cause of Denman Island disease in oysters Crassostrea spp. and Ostrea spp. in British Columbia, Canada

Hine¹,

Bower²,

Meyer³

et al. 2001

Dis. Aquat. Org.

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“…However, they are ultrastructurally and developmentally very different, casting doubt on the phylogeny based on 1 gene sequence. Haplosporosomes also occur in the vegetative stages of some myxozoans (Morris et al 2000), which are bilaterians (Okamura et al 2002) not protists. Therefore, haplosporosomes are not by themselves of phylogenetic significance.…”

Section: Introductionmentioning

confidence: 99%

Haemolymph parasite of the shore crab Carcinus maenas: pathology, ultrastructure and observations on crustacean haplosporidians

Stentiford¹,

Feist²,

Bateman³

et al. 2004

Dis. Aquat. Org.

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A protozoan parasite with some features of haplosporidians is described from the European shore crab Carcinus maenas. The parasite establishes a systemic infection through the haemal sinuses and connective tissues. Intracellular stages of the parasite were found within reserve inclusion, connective tissue, and muscle cells, while free forms were present in all haemal spaces. A uninucleate stage appeared to develop to a multinucleate plasmodial stage following multiple mitotic divisions of the nucleus. Histopathology also indicated that nuclear division may occur to form multinucleate plasmodia, in connective tissue, reserve inclusion and muscle cells, the multinucleate plasmodium being enclosed in the host-cell plasma membrane. It appears that the multinucleate plasmodium may then undergo internal cleavages which result in plasmodial fragmentation to form many uninucleate stages. Both stages, but particularly the uninucleate stage, contained cytoplasmic, large, ovoid, dense vesicles (DVs), some of which contained an internal membrane separating the medulla from the cortex, as in haplosporosomes. Golgi-like cisternae, closely associated with the nuclear membrane, formed DVs and haplosporosome-like bodies (HLBs), superficially resembling viruses. Infrequently, HLBs may condense to form haplosporosomes. The DVs, as in spores of some Haplosporidium spp. and paramyxeans, may give rise to, and are homologous with, haplosporosomes. Other features, such as the presence of an intranuclear mitotic spindle, lipid droplets, and attachment of DVs and haplosporosomes to the nuclear membrane, indicate that the C. maenas parasite is a haplosporidian. A similar organism reported from the haemolymph of spot prawns Pandalus spp., and haplosporidians reported from prawns Penaeus vannamei and crabs Callinectes sapidus may belong to this group. It is concluded that the well-characterised haplosporidians of molluscs and some other invertebrates may not be characteristic of the whole phylum, and that morphologically and developmentally similar organisms may also be haplosporidians, whether they have haplosporosomes or not.

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Observations on the electron-dense bodies of the PKX parasite, agent of proliferative kidney disease in salmonids

Cited by 16 publications

References 12 publications

Ultrastructure of a haplosporidian containing Rickettsiae, associated with mortalities among cultured paua Haliotis iris

Ultrastructure of a haplosporidian containing Rickettsiae, associated with mortalities among cultured paua Haliotis iris

Ultrastructure of Mikrocytos mackini, the cause of Denman Island disease in oysters Crassostrea spp. and Ostrea spp. in British Columbia, Canada

Haemolymph parasite of the shore crab Carcinus maenas: pathology, ultrastructure and observations on crustacean haplosporidians

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