Archigregarines are a key group for understanding the early evolution of Apicomplexa. Here we report morphological, ultrastructural, and molecular phylogenetic evidence from two archigregarine species: Selenidium pygospionis sp. n. and S. pherusae sp. n. They exhibited typical features of archigregarines. Additionally, an axial row of vacuoles of a presumably nutrient distribution system was revealed in S. pygospionis. Intracellular stages of S. pygospionis found in the host intestinal epithelium may point to the initial intracellular localization in the course of parasite development. Available archigregarine SSU (18S) rDNA sequences formed four major lineages fitting the taxonomical affiliations of their hosts, but not the morphological or biological features used for the taxonomical revision by Levine (1971). Consequently, the genus Selenidioides Levine, 1971 should be abolished. The branching order of these lineages was unresolved; topology tests rejected neither para- nor monophyly of archigregarines. We provided phylogenies based on LSU (28S) rDNA and near-complete ribosomal operon (concatenated SSU, 5.8S, LSU rDNAs) sequences including S. pygospionis sequences. Although being preliminary, they nevertheless revealed the monophyly of gregarines previously challenged by many molecular phylogenetic studies. Despite their molecular-phylogenetic heterogeneity, archigregarines exhibit an extremely conservative plesiomorphic structure; their ultrastructural key features appear to be symplesiomorphies rather than synapomorphies.

• MeSH
• Apicomplexa klasifikace   genetika   izolace a purifikace   ultrastruktura   MeSH
• elektronová mikroskopie MeSH
• fylogeneze * MeSH
• lokomoce MeSH
• mikroskopie MeSH
• Polychaeta parazitologie   MeSH
• protozoální DNA chemie   genetika   MeSH
• ribozomální DNA chemie   genetika   MeSH
• RNA ribozomální 18S genetika   MeSH
• RNA ribozomální 28S genetika   MeSH
• RNA ribozomální 5.8S genetika   MeSH
• sekvenční analýza DNA MeSH
• shluková analýza MeSH
• vodní organismy klasifikace   genetika   izolace a purifikace   ultrastruktura   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Urosporids (Apicomplexa: Urosporidae) are eugregarines that parasitise marine invertebrates, such as annelids, molluscs, nemerteans and echinoderms, inhabiting their coelom and intestine. Urosporids exhibit considerable morphological plasticity, which correlates with their different modes of motility and variations in structure of their cortical zone, according to the localisation within the host. The gregarines Urospora ovalis and U. travisiae from the marine polychaete Travisia forbesii were investigated with an emphasis on their general morphology and phylogenetic position. Solitary ovoid trophozoites and syzygies of U. ovalis were located free in the host coelom and showed metabolic activity, a non-progressive movement with periodic changes of the cell shape. Solitary trophozoites of U. travisiae, attached to the host tissue or free floating in the coelom, were V-shaped. Detached trophozoites demonstrated gliding motility, a progressive movement without observable cell body changes. In both gregarines, the cortex formed numerous epicytic folds, but superfolds appeared exclusively on the surface of U. ovalis during metabolic activity. SSU rDNA sequences obtained from U. ovalis and U. travisiae revealed that they belong to the Lecudinoidea clade; however, they are not affiliated with other coelomic urosporids (Pterospora spp. and Lithocystis spp.), but surprisingly with intestinal lecudinids (Difficilina spp.) parasitising nemerteans.

• MeSH
• Apicomplexa klasifikace   cytologie   genetika   izolace a purifikace   MeSH
• fylogeneze MeSH
• lokomoce MeSH
• mikroskopie MeSH
• Polychaeta parazitologie   MeSH
• protozoální DNA chemie   genetika   MeSH
• ribozomální DNA chemie   genetika   MeSH
• RNA ribozomální 18S genetika   MeSH
• sekvenční analýza DNA MeSH
• shluková analýza MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

This study focused on the attachment strategy, cell structure and the host-parasite interactions of the protococcidian Eleutheroschizon duboscqi, parasitising the polychaete Scoloplos armiger. The attached trophozoites and gamonts of E. duboscqi were detected at different development stages. The parasite develops epicellularly, covered by a host cell-derived, two-membrane parasitophorous sac forming a caudal tipped appendage. Staining with Evans blue suggests that this tail is protein-rich, supported by the presence of a fibrous substance in this area. Despite the ultrastructural evidence for long filaments in the tail, it stained only weakly for F-actin, while spectrin seemed to accumulate in this area. The attachment apparatus consists of lobes arranged in one (trophozoites) or two (gamonts) circles, crowned by a ring of filamentous fascicles. During trophozoite maturation, the internal space between the parasitophorous sac and parasite turns translucent, the parasite trilaminar pellicle seems to reorganise and is covered by a dense fibrous glycocalyx. The parasite surface is organised in broad folds with grooves in between. Micropores are situated at the bottom of the grooves. A layer of filaments organised in bands, underlying the folds and ending above the attachment fascicles, was detected just beneath the pellicle. Confocal microscopy, along with the application of cytoskeletal drugs (jasplakinolide, cytochalasin D, oryzalin) confirmed the presence of actin and tubulin polymerised forms in both the parasitophorous sac and the parasite, while myosin labelling was restricted to the sac. Despite positive tubulin labelling, no microtubules were detected in mature stages. The attachment strategy of E. duboscqi shares features with that of cryptosporidia and gregarines, i.e. the parasite itself conspicuously resembles an epicellularly located gregarine, while the parasitophorous sac develops in a similar manner to that in cryptosporidia. This study provides a re-evaluation of epicellular development in other apicomplexans and directly compares their niche with that of E. duboscqi.

• MeSH
• aktiny ultrastruktura   MeSH
• Apicomplexa klasifikace   fyziologie   ultrastruktura   MeSH
• interakce hostitele a parazita MeSH
• Polychaeta parazitologie   MeSH
• protozoální proteiny ultrastruktura   MeSH
• trofozoiti fyziologie   MeSH
• tubulin ultrastruktura   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

A myxosporean producing actinospores of the tetractinomyxon type in Hydroides norvegicus Gunnerus (Serpulidae) in Denmark was identified as a member of the family Parvicapsulidae based on small-subunit ribosomal DNA (SSU rDNA) sequences. Myxosporean samples from various Danish and Norwegian marine fishes were examined with primers that detect the novel myxosporean. Sprattus sprattus (Linnaeus) and Clupea harengus Linnaeus (Teleostei, Clupeidae) were found to be infected. The sequences of this parvicapsulid from these hosts were consistently slightly different (0.8% divergence), but both these genotypes were found in H. norvegicus. Disporic trophozoites and minute spores of a novel myxosporean type were observed in the renal tubules of some of the hosts found infected through PCR. The spores appear most similar to those of species of Gadimyxa Køie, Karlsbakk et Nylund, 2007, but are much smaller. The actinospores of the tetractinomyxon type from H. norvegicus have been described previously. In GenBank, the SSU rDNA sequences of Parvicapsulidae gen. sp. show highest identity (82%) with Parvicapsula minibicornis Kent, Whitaker et Dawe, 1997 infecting salmonids (Oncorhynchus spp.) in fresh water in the western North America. A phylogenetic analysis places P. minibicornis and Parvicapsulidae gen. sp. in a sister clade to the other parvicapsulids (Parvicapsula spp. and Gadimyxa spp.).

• MeSH
• fylogeneze MeSH
• genotyp MeSH
• hostitelská specificita MeSH
• ledviny parazitologie   MeSH
• molekulární sekvence - údaje MeSH
• Myxozoa klasifikace   genetika   růst a vývoj   izolace a purifikace   MeSH
• nemoci ryb parazitologie   MeSH
• parazitární nemoci u zvířat parazitologie   MeSH
• Polychaeta parazitologie   MeSH
• polymerázová řetězová reakce veterinární   MeSH
• ribozomální DNA chemie   genetika   MeSH
• ryby MeSH
• sekvence nukleotidů MeSH
• sekvenční analýza DNA veterinární   MeSH
• sladká voda parazitologie   MeSH
• spory ultrastruktura   MeSH
• stadia vývoje MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Dánsko MeSH
• Norsko MeSH

Abstract: In a study of the benthic polychaete fauna of the southern Gulf of Mexico and the Caribbean Sea, several specimens of the terebellid polychaete Scionides reticulata (Ehlers) were found to host endoparasitic copepods that represent an undescribed species of the rare cyclopoid genus Entobius Dogiel, 1948. The new species, E. scionides sp. n., can be distinguished from its congeners by a combination of characters including a genital region without constrictions, three-segmented antennules, a reduced antenna with a blunt terminal process, reduced ornamentation of endopods of legs 1-4 and its relatively small size (2.3-2.7 mm). It is the smallest species of the genus. Comments on immature females are also provided, but males of this species remain unknown. It has a high prevalence (53%) in populations of the terebellid S. reticulata in the southern Gulf of Mexico, but it is absent from the Caribbean. This is the first occurrence of this copepod genus in the Americas. The finding of the new species of Entobius in S. reticulata confirms the strict specificity of most members of the genus and expands the host range of this copepod genus. A key for the identification of the species of Entobius is provided.

• MeSH
• Copepoda klasifikace   ultrastruktura   MeSH
• druhová specificita MeSH
• Polychaeta parazitologie   MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• karibský region MeSH
• Mexický záliv MeSH
• Mexiko MeSH

Sequencing of SSU rDNA showed that actinospores of the tetractinomyxon type, which develop in Chone infundibuliformis Kroyer (Annelida, Polychaeta, Sabellidae) from the northern Oresund, Denmark, are identical with Ceratomyxa auerbachi Kabata, 1962 (Myxozoa, Ceratomyxidae). This myxosporean was found in the gallbladder of the Atlantic herring Clupea harengus L. from the northern Oresund, Denmark, and from the Bergen area, western Norway. The pansporocysts and actinospores of C. auerbachi are described. This is the third elucidated two-host life cycle of a marine myxozoan, and the first involving a marine ceratomyxid.

• MeSH
• Eukaryota cytologie   fyziologie   izolace a purifikace   MeSH
• fylogeneze MeSH
• molekulární sekvence - údaje MeSH
• Polychaeta parazitologie   MeSH
• protozoální DNA genetika   chemie   MeSH
• ribozomální DNA genetika   chemie   MeSH
• RNA ribozomální 18S genetika   MeSH
• ryby parazitologie   MeSH
• sekvenční analýza DNA MeSH
• sekvenční homologie nukleových kyselin MeSH
• spory protozoální genetika   izolace a purifikace   MeSH
• žlučník patofyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Geografické názvy
• Dánsko MeSH
• Norsko MeSH

Nereis diversicolor O.F. Müller and N. succinea Frey et Leuckart (Polychaeta, Nereidae) living in brackish shallow areas in Denmark are naturally infected with tetractinomyxon actinospores. Infected Nereis spp. were experimentally fed to various potential fish hosts, and the actinosporean stages developed into myxosporean stages of Ellipsomyxa gobii Køie, 2003 (Ceratomyxidae) in the gallbladder of the common goby Pomatoschistus microps (Krøyer) (Gobiidae). The European eel Anguilla anguilla (L.), three-spined stickleback Gasterosteus aculeatus L., small sand eel Ammodytes tobianus L., flounder Platichthys flesus (L.), European plaice Pleuronectes platessa L. and common sole Solea solea (L.) did not become experimentally infected. In Danish shallow brackish areas P. microps is naturally infected with E. gobii, in some areas with a prevalence >90%. We compared small subunit ribosomal DNA sequences of the actinosporean with E. gobii from P. microps. Sequences were identical, which further verifies that both forms belong to the same organism. This is the first myxozoan two-host life cycle in the marine environment.

• MeSH
• Eukaryota genetika   růst a vývoj   fyziologie   ultrastruktura   MeSH
• interferenční mikroskopie MeSH
• mikroskopie fázově kontrastní MeSH
• Perciformes parazitologie   MeSH
• Polychaeta parazitologie   MeSH
• polymerázová řetězová reakce MeSH
• protozoální DNA chemie   genetika   MeSH
• RNA ribozomální chemie   genetika   MeSH
• sekvenční analýza DNA MeSH
• stadia vývoje MeSH
• žlučník parazitologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Dánsko MeSH