The Spraguea Parasitism in Anglerfishes of the Genus Lophius.

PURPOSE: To follow the development of the microsporidian Spraguea americanus within the nervous tissue of Lophius. An attempt to determine when and how the infection begins. METHODS: Acquiring different age groups of Lophius and recovering the infected sites, particularly the supramedullary neuron fibers and preparing them for microscopy. RESULTS: The youngest juvenile Lophius recovered were 140 mm long with established infections. These infections consisted of meronts and sporoblasts but no spores. The evidence indicates these infections began a month or so earlier. CONCLUSIONS: Early stages of S. americanus development occur only in juvenile Lophius and not present in older fish. The prediction is infections of all Spraguea species begin early in the life of benthic juvenile Lophius. The high incidence of infection among these fish is an indicator that the location where the infection begins is likely rich in infective spores.

Microsporidia Have a Peculiar Outer Membrane with Exterior Cytoplasmic Proteins.

PURPOSE: Most eukaryotic cells have a plasma membrane with glycoproteins on the outer leaflet and cytoplasmic proteins on the inner leaflet. However, the microsporidians examined have a peculiar outer membrane with cytoplasmic proteins on the surface. His study was to determine if this is true and identify the presence of key cytoplasmic proteins on the exterior of the sporoplasm and spore stages. METHODS: Specific probes including GFP-labeled genes, antibodies, and electron microscopy were applied to studies on the sporoplasm and spore stages of different microsporidian species. RESULTS: Cytoplasmic membrane proteins cadherin, intermediate filaments, dynactin p150Glued and tubulin were identified on the outer leaflet of the exterior membrane of the sporoplasm or spore stages of Spraguea americanus, Anncaliia algerae, Ameson michaelis and Thelohania sp. CONCLUSION: The invasive sporoplasm stage of microsporidians acquires an outer membrane from a cytoplasmic organelle and it has been shown that the outside surface of this membrane bears cytoplasmic proteins. This membrane retains these cytoplasmic proteins even on the spore stage. For an intracellular parasite that locates directly within the cytoplasm of a host cell, the presence of these cytoplasmic proteins on the surface of the parasite appears to have a significant effect on the host's response.

Microsporidia Can Acquire Lamin-like Intermediate Filaments and Cell Adhesion Catenin-cadherin Complexes from the Host (?).

On their spore surfaces, Microsporidia often develop a canopy of filaments with characteristics of intermediate filaments (IF), as we demonstrated in previous studies on Thelohania sp., Ameson michaelis, and Spraguea lophii. Genomic studies indicate that among invertebrates, lamins that may localize in the cytoplasm or nucleus, are the only known IF type. These IFs can bind to the substrate containing cell adhesion molecules (CAMs) cadherins, associated with ß and γ catenins. The objects of this study were to determine whether microsporidia have CAMs with the attached IFs on their envelopes and to find out if these proteins are provided by the host. An examination was made for localization of lamins and CAMs on the spores of the mentioned above species and Anncaliia algerae, plus in the host animals. Then, we determined whether the spores of A. michaelis and A. algerae could bind vertebrate nuclear lamin onto the spore surface. We also tested transgenic Drosophila melanogaster stocks bearing cadherin-GFP to see whether developing A. algerae parasites in these hosts could acquire host CAMs. The tests were positive for all these experiments. We hypothesize that microsporidia are able to acquire host lamin IFs and cell adhesion catenin-cadherin complexes from the host.

Development of Anncaliia algerae (Microsporidia) in Drosophila melanogaster.

Representatives of the genus Anncaliia are known as natural parasites of dipteran and coleopteran insects, amphipod crustaceans, but also humans, primarily with immunodeficiency. Anncaliia algerae-caused fatal myositis is considered as an emergent infectious disease in humans. A. (=Nosema, Brachiola) algerae, the best studied species of the genus, demonstrates the broadest among microsporidia range of natural and experimental hosts, but it has never been propagated in Drosophila. We present ultrastructural analysis of development of A. algerae in visceral muscles and adipocytes of Drosophila melanogaster 2 wk after per oral experimental infection. We observed typical to Anncaliia spp. features of ultrastructure and cell pathology including spore morphology, characteristic extensions of the plasma membrane, and presence of "ridges" and appendages of tubular material at proliferative stages. Anncaliia algerae development in D. melanogaster was particularly similar to one of A. algerae and A.(Brachiola) vesicularum in humans with acute myositis. Given D. melanogaster is currently the most established genetic model, with a fully sequenced genome and easily available transgenic forms and genomic markers, a novel host-parasite system might provide new genetic tools to investigate host-pathogen interactions of A. algerae, as well to test antimicrosporidia drugs.

Role of the posterior vacuole in Spraguea lophii (Microsporidia) spore hatching.

Microsporidia constitute a large group of obligate intracellular protozoan parasites that inject themselves into host cells via the extrusion apparatus of the infective spore stage. Although the injection process is poorly understood, its energy source is thought to reside in the posterior vacuole that swells significantly during spore firing. Here we report the presence and localisation of the key peroxisomal enzymes catalase and acyl-CoA oxidase (ACOX) within the posterior vacuole of Spraguea lophii (Doflein, 1898) spores. Western blot analyses show that these enzymes discharge out of the spore and end up in the medium external to the extruded sporoplasms. The presence of a catalase enzyme system in the Microsporidia was first made evident by the detection of significant levels of molecular oxygen in the medium containing discharging spores in the presence of hydrogen peroxide. Catalase was visualised in inactive, activated, and discharged spores using alkaline diaminobenzidine (DAB) on glutaraldehyde-fixed cells. The position of these enzymes within the extrusion apparatus before and during spore discharge support the Lom and Vávra model that postulates discharge occurs by an eversion process. In addition to these enzymes, spores of S. lophii contain another characteristic peroxisomal component, the very long chain fatty acid (VLCFA) nervonic acid. A sizeable decrease in nervonic acid levels occurs during and after spore discharge. These data indicate that nervonic acid is discharged from the spore into the external medium during firing along with the catalase and ACOX enzymes.