Phagocytosis of Nosema grylli (Microsporida, Nosematidae) Spores in Vivo and in Vitro

Infection of Drosophila melanogaster by Tubulinosema kingi: Stage-specific susceptibility and within-host proliferation

“…As haemocyte upregulation may occur following tissue damage (Ramet et al, 2002;Evans et al, 2003), which can result from microsporidian infection (Hoch et al, 2004), the upregulation we observed may be a response to tissue damage rather than a real immune response. Microsporidia are capable germinating within phagocytic vaculoes (David and Weiser, 1994;Nassonova et al, 2001) and Hoch et al (2004) and Kurtz et al (2000) have argued that immune upregulation could benefit rather than harm the pathogen. Haemocytes usually phagocytose extracellular pathogens such as most bacteria and more work is needed to show whether they can mount an immune response against intracellular parasites.…”

EXPERIMENTAL EVOLUTION SHOWSDROSOPHILA MELANOGASTERRESISTANCE TO A MICROSPORIDIAN PATHOGEN HAS FITNESS COSTS

“…Similar cellular immune response has been reported from other insect‐microsporidia systems (Hoch et al 2004) although precisely how haemocytes attack Microsporidia is unclear. Although phagocytosis of microsporidian spores by insect haemocytes has been observed, by the time spores are produced the infection is already well established (Laigo and Paschke 1966; Nassonova et al 2001; Hoch et al 2004). Similarly, although melanization of infected tissue involving the phenol‐oxidase cascade has been recorded its efficacy is not certain (Hoch et al 2004).…”

Establishment of the new genus Paranosema based on the ultrastructure and molecular phylogeny of the type species Paranosema grylli Gen. Nov., Comb. Nov. (Sokolova, Selezniov, Dolgikh, Issi 1994), from the cricket Gryllus bimaculatus Deg

“…(A) Cross-section through a spore, fixed by the reduced osmium method: thick electron-lucid endospore (En), undulating multi-layered exospore (Ex), and filamentous structures scattered outside the parasite cell (arrows), are visible; the posterior end of the spore contains an electron-dense body (asterisk); (B) cross-section through a spore fixed by the osmium impregnation method, which resulted in negative contrast of the membranes: the polaroplast reveals two parts-the anterior portion (PP1) consisting of tightly arranged membranes, and the posterior portion (PP2) containing loosely arranged membranes, filament coils are arranged in two rows; (C) oblique section through the polar filament coils (arrow); (D,E) sections through the anterior portion of a mature spore showing a polar disk (PD) in the manubrial region of the polar filament, a polar cap (PC), and a polar sac (arrow); (F) section through a spore in the process of germinating, showing the diplokaryon (DK) and a small portion of the discharging sporoplasm, polar tube (PT) has been just fired; note that there is no membrane around the discharged tube, but the membranes of the cisternae in which the polar filament was packed (arrows), remain inside the spore after discharge; (G) extruded sporoplasm fixed 4-10 min after stimulation of polar tube extrusion; (H) an empty spore envelope after firing: arrows indicate the membranes that previously enclosed the polar filament. haemocytes, and in the pericardial cells (cricket haemopoetic organ; Nassonova et al, 2001;Sokolova et al, 2000). Throughout the N. grylli life cycle abundant morphological evidence of intimate interactions between host and parasite cells was observed.…”