Acanthamoeba castellanii cysts: new ultrastructural findings

Chávez‐Munguía, Bibiana; Salazar‐Villatoro, Lizbeth; Lagunes-Guillén, Anel; Omaña‐Molina, Maritza; Espinosa‐Cantellano, Martha; Martı́nez-Palomo, Adolfo

doi:10.1007/s00436-012-3261-7

Cited by 12 publications

(18 citation statements)

References 26 publications

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“…Similarly, Kaushal and Shukla () reported that excystment of A. culbertsoni could take up to 48 h. The morphological and ultrastructural changes occurring during the excystment of V. vermiformis were very different than the ones observed for Acanthamoeba and Naegleria (Chavez‐Munguia et al. , , ). No ostioles were observed in V. vermiformis cysts on the contrary to Acanthamoeba and Naegleria (Chavez‐Munguia et al.…”

Section: Discussionmentioning

confidence: 92%

“…No ostioles were observed in V. vermiformis cysts on the contrary to Acanthamoeba and Naegleria (Chavez‐Munguia et al. , , ). Trophozoites differentiate into the cyst wall and large vacuoles were produced, likely in the aim to digest the cyst wall before to exit.…”

Section: Discussionmentioning

confidence: 99%

“…Morphological and ultrastructural changes that occur during encystment and excystment processes have been well documented on FLA belonging the genus Acanthamoeba and Naegleria (Bowers and Korn ; Chavez‐Munguia et al. , , ). On the contrary, only few studies on encystment of V. vermiformis are available to date (Dykova et al.…”

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confidence: 95%

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Morphological Study of the Encystment and Excystment of Vermamoeba vermiformis Revealed Original Traits

Fouque

Yéfimova

Trouilhé

et al. 2014

J Eukaryotic Microbiology

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Free-living amoebae are ubiquitous protozoa commonly found in water. Among them, Acanthamoeba and Vermamoeba (formerly Hartmannella) are the most represented genera. In case of stress, such as nutrient deprivation or osmotic stress, these amoebae initiate a differentiation process, named encystment. It leads to the cyst form, which is a resistant form enabling amoebae to survive in harsh conditions and resist disinfection treatments. Encystment has been thoroughly described in Acanthamoeba but poorly in Vermamoeba. Our study was aimed to follow the encystment/excystment processes by microscopic observations. We show that encystment is quite rapid, as mature cysts were obtained in 9 h, and that cyst wall is composed of two layers. A video shows that a locomotive form is likely involved in clustering cysts together during encystment. As for Acanthamoeba, autophagy is likely active during this process. Specific vesicles, possibly involved in ribophagy, were observed within the cytoplasm. Remarkably, mitochondria rearranged around the nucleus within the cyst, suggesting high needs in energy. Unlike Acanthamoeba and Naegleria, no ostioles were observed in the cyst wall suggesting that excystment is original. During excystment, large vesicles, likely filled with hydrolases, were found in close proximity to cyst wall and digest it. Trophozoite moves inside its cyst wall before exiting during excystment. In conclusion, Vermamoeba encystment/excystment displays original trends as compare to Acanthamoeba.

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

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Morphological Study of the Encystment and Excystment of Vermamoeba vermiformis Revealed Original Traits

Fouque

Yéfimova

Trouilhé

et al. 2014

J Eukaryotic Microbiology

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“…Under unfavorable conditions, amoebae form cysts, which are resistant to environmental stress and metabolically inactive14. During encystation, A. castellanii retracts its pseudopodia and becomes rounded1516. In order to verify that rounded-infected cells were not encysted, A. castellanii were stained with Calcofluor White to reveal cellulose in the cell wall of mature cysts17.…”

Section: Resultsmentioning

confidence: 99%

Legionella pneumophila prevents proliferation of its natural host Acanthamoeba castellanii

Mengue¹,

Régnacq²,

Aucher³

et al. 2016

Sci Rep

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Legionella pneumophila is a ubiquitous, pathogenic, Gram-negative bacterium responsible for legionellosis. Like many other amoeba-resistant microorganisms, L. pneumophila resists host clearance and multiplies inside the cell. Through its Dot/Icm type IV secretion system, the bacterium injects more than three hundred effectors that modulate host cell physiology in order to promote its own intracellular replication. Here we report that L. pneumophila prevents proliferation of its natural host Acanthamoeba castellanii. Infected amoebae could not undergo DNA replication and no cell division was observed. The Dot/Icm secretion system was necessary for L. pneumophila to prevent the eukaryotic proliferation. The absence of proliferation was associated with altered amoebal morphology and with a decrease of mRNA transcript levels of CDC2b, a putative regulator of the A. castellanii cell cycle. Complementation of CDC28-deficient Saccharomyces cerevisiae by the CDC2b cDNA was sufficient to restore proliferation of CDC28-deficient S. cerevisiae and suggests for the first time that CDC2b from A. castellanii could be functional and a bona fide cyclin-dependent kinase. Hence, our results reveal that L. pneumophila impairs proliferation of A. castellanii and this effect could involve the cell cycle protein CDC2b.

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“…In this context, we recently demonstrated that V. cholerae survives predation by Acanthamoeba castellanii , a free-living amoebal species 25 . This amoeba is frequently encountered in aquatic reservoirs and follows a bi-phasic lifecycle: the motile trophozoite form, which grazes on bacterial prey, and the double-walled resistant cyst stage, which forms under harsh conditions 26 . We previously showed that V. cholerae interacts with A. castellanii through the evolution of two distinct phenotypes.…”

Section: Introductionmentioning

confidence: 99%

Molecular insights into Vibrio cholerae’s intra-amoebal host-pathogen interactions

et al. 2018

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Vibrio cholerae, which causes the diarrheal disease cholera, is a species of bacteria commonly found in aquatic habitats. Within such environments, the bacterium must defend itself against predatory protozoan grazers. Amoebae are prominent grazers, with Acanthamoeba castellanii being one of the best-studied aquatic amoebae. We previously showed that V. cholerae resists digestion by A. castellanii and establishes a replication niche within the host’s osmoregulatory organelle. In this study, we decipher the molecular mechanisms involved in the maintenance of V. cholerae’s intra-amoebal replication niche and its ultimate escape from the succumbed host. We demonstrate that minor virulence features important for disease in mammals, such as extracellular enzymes and flagellum-based motility, have a key role in the replication and transmission of V. cholerae in its aqueous environment. This work, therefore, describes new mechanisms that provide the pathogen with a fitness advantage in its primary habitat, which may have contributed to the emergence of these minor virulence factors in the species V. cholerae.

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Acanthamoeba castellanii cysts: new ultrastructural findings

Cited by 12 publications

References 26 publications

Morphological Study of the Encystment and Excystment of Vermamoeba vermiformis Revealed Original Traits

Morphological Study of the Encystment and Excystment of Vermamoeba vermiformis Revealed Original Traits

Legionella pneumophila prevents proliferation of its natural host Acanthamoeba castellanii

Molecular insights into Vibrio cholerae’s intra-amoebal host-pathogen interactions

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