Are rhoptries in Apicomplexan parasites secretory granules or secretory lysosomal granules?

Ngô, Huân M.; Yang, Mei; Joiner, Keith A.

doi:10.1111/j.1365-2958.2004.04056.x

Cited by 64 publications

(22 citation statements)

References 56 publications

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“…There is some evidence that rhoptry proteins after leaving the Golgi complex are first accumulated in an intermediate compartment, a type of immature rhoptry which is a acidic organelle, with a pH of 3.5 to 5.5 whereas the mature organelle has a pH of 5.0 to 7.0 as determined using the DAMP technique [108][109]. Based on this fact and the involvement of both secretory and endocytic pathways in the rhoptry formation it has been considered that this organelle is equivalent to a lysosome [108,110]. A novel Na + /H + exchanger, designated as TgNEH2, was localized in the rhoptry of T. gondii [111].…”

Section: The Rhoptriesmentioning

confidence: 98%

An Introduction to the Structural Organization of Parasitic Protozoa

Souza¹

2008

CPD

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As eukaryotic cells, protozoa present a classical structural organization where most of the structures and organelles typical of mammalian cells are found. However, even for usual organelles these organisms present structural diversity. In addition, some of the protozoa structures, such as the mitochondria, peroxisomes and even the Golgi complex, are not observed. On the other hand, new organelles such as the hydrogenosomes, mitosomes, Apicoplast, kinetoplast, glycosomes (specialized peroxisomes), rhoptries, micronemes and dense granules, are characteristic features of some protozoa. Also, several unusual cytoskeletal structures, some of them made of yet uncharacterized proteins, are seen in these eukaryotic microorganisms. Further characterization of these structures indicates that they contain special enzymes involved in distinct metabolic pathways making them potential targets for the development of new anti parasite drugs.

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Section: The Rhoptriesmentioning

confidence: 98%

An Introduction to the Structural Organization of Parasitic Protozoa

Souza¹

2008

CPD

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“…This general idea is not new, with the first proposition almost a decade ago [47] that rhoptries are directly homologous to secretory lysosomes. A significant body of evidence, however, has now accumulated from diverse studies from morphology to trafficking to proteomics.…”

Section: Rhoptries and Micronemes: Divergent Endolysosomal Homologues?mentioning

confidence: 99%

Cryptic organelle homology in apicomplexan parasites: insights from evolutionary cell biology

Klinger

Nisbet

Ouologuem

et al. 2013

Current Opinion in Microbiology

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The economic and clinical significance of apicomplexan parasites drives interest in their many evolutionary novelties. Distinctive intracellular organelles play key roles in parasite motility, invasion, metabolism, and replication, and understanding their relationship with the organelles of better-studied eukaryotic systems suggests potential targets for therapeutic intervention. Recent work has demonstrated divergent aspects of canonical eukaryotic components in the apicomplexa, including Golgi bodies and mitochondria. The apicoplast is a relict plastid of secondary endosymbiotic origin, harboring metabolic pathways distinct from those of host species. The inner membrane complex is derived from the cortical alveoli defining the superphylum Alveolata, but in apicomplexans functions in parasite motility and replication. Micronemes and rhoptries are associated with establishment of the intracellular niche, and define the apical complex for which the phylum is named. Morphological, cell biological and molecular evidence strongly suggest that these organelles are derived from the endocytic pathway.

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“…Rhoptries are considered related to vesicular exosomes (Ngô et al, 2004), which are membrane-limited vesicles extruded by some cells when multivesicular bodies fuse with the plasma membrane (Fevrier and Raposo, 2004). Similarly, the vesicles observed in the vicinity of the necks of bradyzoites' rhoptries could be formed during the exocytosis of rhoptry content.…”

Section: Discussionmentioning

confidence: 99%

New details on the fine structure of the rhoptry of Toxoplasma gondii

Lemgruber

Lupetti

Souza

et al. 2010

Microscopy Res & Technique

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Rhoptries are organelles that have important, complex roles in Apicomplexa biology. During Toxoplasma gondii infection, these organelles take part in several essential and complex processes that include host cell entry and parasite development. Using different electron microscopy techniques, we characterized the fine morphology of the rhoptries of two of the most important life stages of T. gondii: the tachyzoite and the bradyzoite forms. The observed tachyzoite and bradyzoite rhoptries had delimited regions characterized by a dark and electron-dense neck, an amorphous and less electron-dense bulb, and a region of intermediate electron density, which connects the bulb to the neck. Metal replicas of frozen-fractured tachyzoites showed intramembranous particles of different densities and sizes on the fractured faces of rhoptry membranes. Both in tachyzoites and bradyzoites, the intramembranous particles were arranged in distinctive parallel arrays that decorated most part of these organelles. Tubulo-vesicular subcompartments and free particles within the rhoptry lumen were observed on freeze-fractured replicas. Cryo-fixed, deep-etched samples showed several pore-like structures localized in the bulb portion. No obvious evidence was found of a possible connection between rhoptries and micronemes.

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Are rhoptries in Apicomplexan parasites secretory granules or secretory lysosomal granules?

Cited by 64 publications

References 56 publications

An Introduction to the Structural Organization of Parasitic Protozoa

An Introduction to the Structural Organization of Parasitic Protozoa

Cryptic organelle homology in apicomplexan parasites: insights from evolutionary cell biology

New details on the fine structure of the rhoptry of Toxoplasma gondii

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