Two myxosporean species, Zschokkella pleomorpha Lom et Dyková, 1995 (Zp) and Ortholinea fluviatilis Lom et Dyková, 1995 (Of) from the kidney of Tetraodon fluviatilis were studied by transmission electron microscope. Coelozoic sporogonie plasmodia of both species use pseudopodia-like projections for attachment to the epithelial cells of renal tubules. These projections either attach to host microvilli forming an interface reminiscent of septate junction (Zp) or are embedded into the epithelial cell surface (Of) or are inserted into gaps between epithelial cells (Zp, Of). Zp produces spores only by direct division of generative cells while in Of pansporoblasts prevail over direct division of generative cells. Sporogonie plasmodia of Zp greatly differ in size and in the variety of cytoplasmic constituents. A special feature in capsulogenesis is a transient envelope encasing the capsular primordium; there are fine fibres on the surface of the nascent filament spaced at 11 nm. In Of, vegetative nuclei of the plasmodium adhere to generative cells in a way reminding of sporoplasmic plasmodium of actinospores. In Of plasmodia, several unusual cytoplasmic structures were observed (membrane bound bodies with fuzzy radial contents or with a central dense inclusion, and endoplasmic reticulum cistemae forming a scalloped network). Of may also form intracellular coelozoic sporogonie plasmodia in the epithelial cells of renal tubules; these stages do not seem to constitute an important part of the life cycle.
A new species of amphizoic amoeba, Nuclearia pattersoni sp. n., isolated from gills of Rutilus rutilus L. is described. It is characterised by elongate flattened trophozoites of irregular shape. The longer dimension of their bodies is 13.2 (11.0-15.7) µm. Filopodia radiating mostly from the poles are 2 to 2.5 times longer than the body. The diameter of less frequently observed spherical trophozoites is 8.2-10.8 µm; their filopodia radiate to all directions. Cyst-like stages have shorter pseudopodia that arise from one pole only. The surface of locomotive forms from agar plate cultures has a thin amorphous glycocalyx, while most cells are covered by two layers of extracellular matrix. Mitochondria have flattened cristae, dictyosomes are located in the perinuclear zone. A conspicuous ultrastructural feature of the morphologically similar N. simplex, perinuclear striated band, is not present. Light microscopic and ultrastructural data are completed with the sequence of SSU rRNA gene and phylogenetic analysis including sequences of related taxa. The bacterial endosymbiont found in N. pattersoni type strain RR2G2 is assigned to the genus Rickettsia.
New strains of non-vannellid flattened amoebae isolated from fish, an invertebrate and the marine environment were studied together with Flabellula citata Schaeffer, 1926 selected by morphology as a reference strain. The study revealed a paucity of features distinguishing individual strains at the generic level, but clearly evidenced mutual phylogenetic relationships within the assemblage of strains as well as their affiliation to the Leptomyxida. In this study, the SSU rDNA dataset of leptomyxids was expanded and a new branching pattern was presented within this lineage of Amoebozoa. Sequences of three newly introduced strains clustered in close relationship with the type strain of F. citata, the type species of the genus. Three strains, including one resembling Flamella sp., were positioned within a sister-group containing Paraflabellula spp. Results of phylogenetic analysis confirmed doubts of previous authors regarding generic assignment of several Rhizamoeba and Ripidomyxa strains.
The small subunit ribosomal RNA gene (SSU rDNA) of two freshwater and one marine species of the genus Chloromyxum Mingazzini, 1890 were sequenced. The SSU rDNA trees obtained show the phylogenetic position of the marine species Chloromyxum leydigi Mingazzini, 1890 to be at the base of the freshwater clade, being well supported by a high bootstrap value. Chloromyxum cyprini Fujita, 1927 is closely related to Chloromyxum truttae Léger, 1906 and they represent a sister branch to raabeia sp., Myxidium sp. and Myxidium truttae Léger, 1930. Chloromyxum legeri Tourraine, 1931 is in a position ancestral to Myxidium lieberkuehni Bütschli, 1882 and Sphaerospora oncorhynchi Kent, Whitaker et Margolis, 1993. Three newly sequenced species of the genus Chloromyxum represent three separate lineages within the myxosporean tree and do not support the monophyly of this genus.
Four strains of non-encysting amoebae were isolated from organs of freshwater fishes and characterized using light and electron microscope. Morphology of three clonal strains was consistent with amoebae which had already been described from water habitats. Two strains, one isolated from kidney tissue of common goldfish, Carassius auratus (Linnaeus, 1758), and the second one from brain of chub, Leuciscus cephalus Linnaeus, 1758, were identified with Vannella platypodia (Gläser, 1912) Page, 1976. Both strains were identical, except for the length of glycostyles. The strain isolated from the liver of perch, Perea fluviatilis (Linnaeus, 1758), was assigned to the genus Vexillifera Schaeffer, 1926 as Vexillifera expectata sp. n. The taxonomic position of the fourth non-encysting strain could not be safely established, although it shares some trophic cell structures with protostelids (Protostelia, Eumycetozoea). We present its detailed description here also to demonstrate that amoeba stages of this type of organisms are capable to infect fishes.
In South Bohemia, Czech Republic, 178 shrews, including 98 common shrews, Sorex araneus L., 70 pygmy shrews, Sorex minutus L., and 10 lesser white-toothed shrews, Crocidura suaveolens (Pallas), were examined for Soricimyxum fegati Prunescu, Prunescu, Pucek et Lom, 2007 infections, using squash preparations of unfixed tissues, histological sections and molecular methods. The infection was found in 51 (52%) S. araneus, 14 (20%) S. minutus and 1 (10%) C. suaveolens. The records of the latter two species extend host range of S. fegati. Lesions associated with S. fegati infections in the liver, the organ of specific localisation of the parasite, were found to be induced by proliferative stages migrating toward lumina of bile ducts. In other organs of these three host species, xenoma-like formations (XLFs) were found that severely injured blood vessels. XLFs contained presporogonic stages of S. fegati, whose species identity was evidenced using molecular methods.