Dispersal and invasive stages of Urospora eugregarines (Apicomplexa) from brown bodies of a polychaete host.

Urosporid eugregarines (Apicomplexa: Urosporidae) are unicellular eukaryotic parasites inhabiting the coelom or the intestine of marine invertebrates such as annelids, molluscs, nemerteans, and echinoderms. Despite the availability of published morphological and phylogenetical analyses of coelomic gregarines, their long-term survival in the host body cavity and dispersal routes into the marine environment remain unclear. Here, we focus on Urospora gametocysts and oocysts with sporozoites, which were found viable inside the so-called brown bodies floating in the body cavity of the polychaete Travisia forbesii.

Evidence from the resurrected family Polyrhabdinidae Kamm, 1922 (Apicomplexa: Gregarinomorpha) supports the epimerite, an attachment organelle, as a major eugregarine innovation.

Background: Gregarines are a major group of apicomplexan parasites of invertebrates. The gregarine classification is largely incomplete because it relies primarily on light microscopy, while electron microscopy and molecular data in the group are fragmentary and often do not overlap. A key characteristic in gregarine taxonomy is the structure and function of their attachment organelles (AOs).

Eudiplozoon nipponicum: morphofunctional adaptations of diplozoid monogeneans for confronting their host.

Background: Monogeneans, in general, show a range of unique adaptations to a parasitic lifestyle, making this group enormously diverse. Due to their unique biological properties, diplozoid monogeneans represent an attractive model group for various investigations on diverse biological interactions. However, despite numerous studies, there are still gaps in our knowledge of diplozoid biology and morphofunctional adaptations.

Evolutionary relationships of Metchnikovella dogieli Paskerova et al., 2016 (Microsporidia: Metchnikovellidae) revealed by multigene phylogenetic analysis.

The species Metchnikovella dogieli (Paskerova et al. Protistology 10:148-157, 2016) belongs to one of the early diverging microsporidian groups, the metchnikovellids (Microsporidia: Metchnikovellidae). In relation to typical ('core') microsporidia, this group is considered primitive.

Motility and cytoskeletal organisation in the archigregarine Selenidium pygospionis (Apicomplexa): observations on native and experimentally affected parasites.

Representatives of Apicomplexa perform various kinds of movements that are linked to the different stages of their life cycle. Ancestral apicomplexan lineages, including gregarines, represent organisms suitable for research into the evolution and diversification of motility within the group. The vermiform trophozoites and gamonts of the archigregarine Selenidium pygospionis perform a very active type of bending motility.

Fine structure and Molecular Phylogenetic Position of Two Marine Gregarines, Selenidium pygospionis sp. n. and S. pherusae sp. n., with Notes on the Phylogeny of Archigregarinida (Apicomplexa).

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.

Effect of jasplakinolide and cytochalasin D on cortical elements involved in the gliding motility of the eugregarine Gregarina garnhami (Apicomplexa).

Since apicomplexans represent exclusively parasitic unicellular organisms with medical and economic impacts, the principles of their motility have been studied intensively. By contrast, the movement in apicomplexan basal groups, such as gregarines, remains to be elucidated. The present study focuses on Gregarina garnhami parasitising the digestive tract of the locust Schistocerca gregaria, and investigates the involvement of cytoskeletal elements (the ectoplasmic network and myonemes) and the secretion of mucosubstances during eugregarine gliding motility.

First Ultrastructural and Molecular Phylogenetic Evidence from the Blastogregarines, an Early Branching Lineage of Plesiomorphic Apicomplexa.

Blastogregarines are poorly studied parasites of polychaetes superficially resembling gregarines, but lacking syzygy and gametocyst stages in the life cycle. Furthermore, their permanent multinuclearity and gametogenesis by means of budding considerably distinguish them from other parasitic Apicomplexa such as coccidians and hematozoans. The affiliation of blastogregarines has been uncertain: different authors considered them highly modified gregarines, an intermediate apicomplexan lineage between gregarines and coccidians, or an isolated group of eukaryotes altogether.

Motility in blastogregarines (Apicomplexa): Native and drug-induced organisation of Siedleckia nematoides cytoskeletal elements.

Recent studies on motility of Apicomplexa concur with the so-called glideosome concept applied for apicomplexan zoites, describing a unique mechanism of substrate-dependent gliding motility facilitated by a conserved form of actomyosin motor and subpellicular microtubules. In contrast, the gregarines and blastogregarines exhibit different modes and mechanisms of motility, correlating with diverse modifications of their cortex. This study focuses on the motility and cytoskeleton of the blastogregarine Siedleckia nematoides Caullery et Mesnil, 1898 parasitising the polychaete Scoloplos cf.

Structures related to attachment and motility in the marine eugregarine Cephaloidophora cf. communis (Apicomplexa).

Gregarines represent a highly diversified group of ancestral apicomplexans, with various modes of locomotion and host-parasite interactions. The eugregarine parasite of the barnacle Balanus balanus, Cephaloidophora cf. communis, exhibits interesting organisation of its attachment apparatus along with unique motility modes.

Protococcidian Eleutheroschizon duboscqi, an Unusual Apicomplexan Interconnecting Gregarines and Cryptosporidia.

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.