Opportunistic Amebae

John, David T.

doi:10.1002/9780470688618.taw0176

Cited by 6 publications

(7 citation statements)

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“…John (2005) reported that Naegleria can excyst in a relatively short time. Indeed, in our study excystation began 5 min after incubation in fresh NNE plates containing a lawn of heat‐inactivated E. aerogenes (data not shown).…”

Section: Discussionmentioning

confidence: 99%

Ultrastructural Study of the Encystation and Excystation Processes in Naegleria sp.

Chávez‐Munguía¹,

Omaña‐Molina²,

Castañón³

et al. 2009

J Eukaryotic Microbiology

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ABSTRACT. An important aspect of the biology of Naegleria sp. is the differentiation processes that occur during encystation and excystation. We studied these using both fluorescence and transmission electron microscopy techniques. In the initial stages of encystation, the cisternae of the endoplasmic reticulum became densely filled with a fibrillar material. Vesicles with a similar content that appeared to be derived from the cisternae were also observed in close contact with the plasma membrane. As encystation progressed, the fibrillar material became localized on the surface of the amoeba. An irregular compaction was observed in some areas of the cyst wall, which contained thin extensions of the cyst wall fibrillar material. Completely formed cysts had two to three ostioles, each sealed by an operculum. The operculum contained two areas in which a differential compaction of the fibrillar structure was observed. When excystation was induced, small dense granules (DGs), which were in close contact with fibrillar material were observed in the cyst cytoplasm and in the peritrophic space. During excystation, the more compact component of the operculum moves to enable the pseudopod of the emerging trophozoite to penetrate the ostiole. Vacuoles containing a fibrillar material, probably derived from the cyst wall, were observed in the cytoplasm of the pseudopodia. Our results provide a platform for further studies using biochemical markers to investigate the origin of the cyst wall as well as the role of DGs during excystation in Naegleria.

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Section: Discussionmentioning

confidence: 99%

Ultrastructural Study of the Encystation and Excystation Processes in Naegleria sp.

Chávez‐Munguía¹,

Omaña‐Molina²,

Castañón³

et al. 2009

J Eukaryotic Microbiology

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“…A MONG the free-living amoebas of the genus Naegleria, Naegleria fowleri is unique in that it is potentially pathogenic. Under certain conditions, this ameba produces a rapidly fatal primary amoebic meningoencephalitis in humans, often killing previously healthy young males exposed to warm recreational waters (John 2005;Yoder et al 2010).…”

mentioning

confidence: 99%

Naegleria fowleri: Enolase is Expressed During Cyst Differentiation

Chávez‐Munguía¹,

Segovia-Gamboa²,

Salazar‐Villatoro³

et al. 2011

Journal of Eukaryotic Microbiology

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Cysts of Naegleria fowleri present an external single-layered cyst wall. To date, little information exists on the biochemical components of this cyst wall. Knowledge of the cyst wall composition is important to understand its resistance capacity under adverse environmental conditions. We have used of a monoclonal antibody (B4F2 mAb) that specifically recognizes enolase in the cyst wall of Entamoeba invadens. By Western blot assays this antibody recognized in soluble extracts of N. fowleri cysts a 48-kDa protein with similar molecular weight to the enolase reported in E. invadens cysts. Immunofluorescence with the B4F2 mAb revealed positive cytoplasmic vesicles in encysting amebas, as well as a positive reaction at the cell wall of mature cysts. Immunoelectron microscopy using the same monoclonal antibody confirmed the presence of enolase in the cell wall of N. fowleri cysts and in cytoplasmic vesicular structures. In addition, the B4F2 mAb had a clear inhibitory effect on encystation of N. fowleri.

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“…This is a case of primary amoebic meningoencephalitis, an extremely rare and sporadic central nervous system (CNS) infection caused by N. fowleri , commonly referred to as brain eating amoeba. 1 Fresh water bodies are identified as the habitat of this pathogen. 2 There are three morphological forms for this organism such as amoeboid, flagellate and cyst; of these, amoebae are the invading forms.…”

Section: Discussionmentioning

confidence: 99%