Ultrastructure of the life-cycle stages of Goussia janae (Apicomplexa, Eimeriidae), with X-ray microanalysis of accompanying precipitates

The ultrastructural features of the life-cycle stages of Goussia janae from the intestinal epithelium of the dace Leuciscus leuciscus and chub L. cephalus are described. All merogonial, gamogonial, and early sporogonial stages were localized in the microvillar region in an intracellular and extracytoplasmic position, covered by closely apposed enterocyte and parasitophorous vacuole membranes. Two types of location in the host cell were observed: (i) a more frequent "monopodial" type with a single zone of attachment to the host-cell cytoplasm, and (ii) a "spider-like" type with several isolated zones of attachment. Merozoites were formed by either ecto- or endo-merogony. Microgamonts produced elongated biflagellate microgametes at their periphery. The oocyst wall, produced exclusively by the parasite, was formed at the end of the intracellular phase of the life cycle. Exogenous sporulation resulted in the formation of elongated sporocysts with a thin sporocyst wall bearing a longitudinal suture accompanied by a narrow membranaceous veil. In the cytoplasm and cytoplasmic and parasitophorous vacuoles of the parasite, fine, dense precipitates were present. X-ray microanalysis of these precipitates from osmicated and non-osmicated samples revealed high levels of Ca and P, indicating the possible presence of hydroxyapatite.

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Eimeria canadensis (Protozoa, Sporozoea): ultrastructure of the host–parasite interface during development of first-generation schizonts in vitro

Canadian Journal of Zoology ◽

10.1139/z80-278 ◽

1980 ◽

Vol 58 (11) ◽

pp. 2018-2025 ◽

Cited By ~ 1

Author(s):

Bodo E. G. Mueller

Keyword(s):

Host Cell ◽

Parasitophorous Vacuole ◽

Eimeria Species ◽

Outer Zone ◽

Ultrastructural Observation ◽

Cell Cytoplasm ◽

Cell Organelles ◽

Host Cell Cytoplasm ◽

Host Parasite

Eimeria canadensis sporozoites were inoculated into monolayer cultures of Madin–Darby bovine kidney and primary bovine embryonic kidney cells. Sporozoites retained their shape for at least 9 days. At that time, the nucleus was enlarged and contained a prominent nucleolus, and amylopectin granules were no longer apparent. The width of the parasitophorous vacuole (pv) between host cell cytoplasm and parasite pellicle widened during transformation of sporozoites into multinucleate schizonts. Areas of altered host cell cytoplasm immediately adjacent to the pv membrane increased in size and became confluent, resulting in the formation of two distinct layers of cytoplasm. The outer zone contained the host cell nucleus, mitochondria, Golgi stacks, and ER, whereas the inner layer appeared granular and was void of all cell organelles except structures resembling ribosomes. Microfilaments were abundant at the border between inner and outer zone. In the most advanced stages observed, host cell organelles persisted only in the perinuclear region. The remaining, attenuated cytoplasm resembled the former inner zone.The novel ultrastructural observation of a bilayered cytoplasm of cells harbouring E. canadensis schizonts is compared with light microscope reports of similar effects caused by other Eimeria species of ruminants and with electron microscope findings of altered intestinal and abomasal cells of sheep harbouring "globidial" schizonts.

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The Toxoplasma gondii rhoptry protein ROP 2 is inserted into the parasitophorous vacuole membrane, surrounding the intracellular parasite, and is exposed to the host cell cytoplasm.

The Journal of Cell Biology ◽

10.1083/jcb.127.4.947 ◽

1994 ◽

Vol 127 (4) ◽

pp. 947-961 ◽

Cited By ~ 151

Author(s):

C J Beckers ◽

J F Dubremetz ◽

O Mercereau-Puijalon ◽

K A Joiner

Keyword(s):

Toxoplasma Gondii ◽

Host Cell ◽

Direct Evidence ◽

Parasitophorous Vacuole ◽

Velocity Sedimentation ◽

Parasitophorous Vacuole Membrane ◽

Cell Cytoplasm ◽

Vacuole Membrane ◽

Specific Antibodies ◽

Host Cell Cytoplasm

The origin of the vacuole membrane surrounding the intracellular protozoan parasite Toxoplasma gondii is not known. Although unique secretory organelles, the rhoptries, discharge during invasion of the host cell and may contribute to the formation of this parasitophorous vacuole membrane (PVM), no direct evidence for this hypothesis exists. Using a novel approach we have determined that parasite-encoded proteins are present in the PVM, exposed to the host cell cytoplasm. In infected cells incubated with streptolysin-O or low concentrations of digitonin, the host cell plasma membrane was selectively permeabilized without significantly affecting the integrity of the PVM. Antisera prepared against whole parasites or a parasite fraction enriched in rhoptries and dense granules reacted with the PVM in these permeabilized cells, indicating that parasite-encoded antigens were exposed on the cytoplasmic side of the PVM. Parasite antigens responsible for this staining of the PVM were identified by fractionating total parasite proteins by SDS-PAGE and velocity sedimentation, and then affinity purifying "fraction-specific" antibodies from the crude antisera. Proteins responsible for the PVM-staining, identified with fraction-specific antibodies, cofractionated with known rhoptry proteins. The gene encoding one of the rhoptry proteins, ROP 2, was cloned and sequenced, predicting and integral membrane protein. Antibodies specific for ROP 2 reacted with the intact PVM. These results provide the first direct evidence that rhoptry contents participate in the formation of the PVM of T. gondii and suggest a possible role of ROP 2 in parasite-host cell interactions.

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Paromomycin and Geneticin Inhibit IntracellularCryptosporidium parvum without Trafficking through the Host Cell Cytoplasm: Implications for Drug Delivery

Infection and Immunity ◽

10.1128/iai.66.8.3874-3883.1998 ◽

1998 ◽

Vol 66 (8) ◽

pp. 3874-3883 ◽

Cited By ~ 44

Author(s):

Jeffrey K. Griffiths ◽

Ramaswamy Balakrishnan ◽

Giovanni Widmer ◽

Saul Tzipori

Keyword(s):

Host Cell ◽

Parasitophorous Vacuole ◽

Parasite Development ◽

Cell Cytoplasm ◽

Bacterial Killing ◽

Host Cell Cytoplasm ◽

Intracellular Parasites ◽

Mdbk Cells ◽

Major Route

ABSTRACT Cryptosporidium parvum, which causes intractable diarrhea and lethal wasting in people with AIDS, occupies an unusual intracellular but extracytoplasmic niche. No reliable therapy for cryptosporidiosis exists, though the aminoglycoside paromomycin is somewhat effective. We report that paromomycin and the related compound geneticin manifest their major in vitro anti-C. parvumactivity against intracellular parasites via a mechanism that does not require drug trafficking through the host cell cytoplasm. We used both normal and transformed aminoglycoside-resistant Caco-2 or MDBK cells in these studies. Timed-exposure experiments demonstrated that these drugs inhibit intracellular but not extracellular parasites. Apical but not basolateral exposure of infected cells to these drugs led to very significant parasite inhibition, indicating an apical topological restriction of action. We estimated intracytoplasmic concentrations of paromomycin, using an intracellular bacterial killing assay, and found that C. parvum infection did not lead to increased paromomycin concentrations compared to those in uninfected cells. Global [3H]paromomycin uptake by Caco-2 cells was ∼200-fold higher than the estimated intracytoplasmic paromomycin concentration, suggestive of host cell vesicular uptake and concentration (as has been reported with other cell lines). However, preinfection exposure of Caco-2 cells to paromomycin did not result in subsequent inhibition of parasite development, indicating that if exogenous paromomycin enters the infected host cell vesicular compartment, it does not effectively communicate with the parasite. Thus, the apical membranes overlying the parasite and parasitophorous vacuole may be the unsuspected major route of entry for paromomycin and may be of importance in the design and discovery of novel drug therapies for the otherwise untreatable C. parvum.

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Faculty Opinions recommendation of The Mycobacterium tuberculosis phagosome in human macrophages is isolated from the host cell cytoplasm.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1009414.126157 ◽

2002 ◽

Author(s):

Sergio Grinstein

Keyword(s):

Mycobacterium Tuberculosis ◽

Host Cell ◽

Cell Cytoplasm ◽

Human Macrophages ◽

Host Cell Cytoplasm

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The RhopH complex is transferred to the host cell cytoplasm following red blood cell invasion by Plasmodium falciparum

Molecular and Biochemical Parasitology ◽

10.1016/j.molbiopara.2008.04.002 ◽

2008 ◽

Vol 160 (2) ◽

pp. 81-89 ◽

Cited By ~ 48

Author(s):

Laetitia Vincensini ◽

Gamou Fall ◽

Laurence Berry ◽

Thierry Blisnick ◽

Catherine Braun Breton

Keyword(s):

Plasmodium Falciparum ◽

Blood Cell ◽

Host Cell ◽

Cell Invasion ◽

Red Blood Cell ◽

Cell Cytoplasm ◽

Host Cell Cytoplasm

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Brefeldin A inhibits transport of the glycophorin-binding protein from Plasmodium falciparum into the host erythrocyte

Biochemical Journal ◽

10.1042/bj3000821 ◽

1994 ◽

Vol 300 (3) ◽

pp. 821-826 ◽

Cited By ~ 55

Author(s):

J Benting ◽

D Mattei ◽

K Lingelbach

Keyword(s):

Plasmodium Falciparum ◽

Golgi Apparatus ◽

Host Cell ◽

Protein Secretion ◽

Secretory Pathway ◽

Binding Protein ◽

Brefeldin A ◽

Cell Cytoplasm ◽

Parasite Cell ◽

Host Cell Cytoplasm

Plasmodium falciparum, a protozoan parasite of the human erythrocyte, causes the most severe form of malaria. During its intraerythrocytic development, the parasite synthesizes proteins which are exported into the host cell. The compartments involved in the secretory pathway of P. falciparum are still poorly characterized. A Golgi apparatus has not been identified, owing to the lack of specific protein markers and Golgi-specific post-translational modifications in the parasite. The fungal metabolite brefeldin A (BFA) is known to inhibit protein secretion in higher eukaryotes by disrupting the integrity of the Golgi apparatus. We have used the parasite-encoded glycophorin-binding protein (GBP), a soluble protein found in the host cell cytoplasm, as a marker to investigate the effects of BFA on protein secretion in the intracellular parasite. In the presence of BFA, GBP was not transported into the erythrocyte, but remained inside the parasite cell. The effect caused by BFA was reversible, and the protein could be chased into the host cell cytoplasm within 30 min. Transport of GBP from the BFA-sensitive site into the host cell did not require protein synthesis. Similar observations were made when infected erythrocytes were incubated at 15 degrees C. Incubation at 20 degrees C resulted in a reduction rather than a complete block of protein export. The relevance of our findings to the identification of compartments involved in protein secretion from the parasite cell is discussed.

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