Induction of Encystment in <i>Acanthamoeba palestinensis.</i> Factors Influencing Cyst Formation

Lasman, M.; Shafran, A.

doi:10.1111/j.1550-7408.1978.tb04173.x

Cited by 10 publications

(4 citation statements)

References 12 publications

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“…Excystment of cysts to trophozoites was induced by adding fresh rich culture medium and was checked up to day 5. Cell density was determined by counting the cells in a Bürker chamber using the eosin exclusion test (Lasman and Shafran 1978). Cells were also stained for microscopic observations with Congo Red (40 μ g ml −1 ) for 30 min at 37°C, owing to its specific binding to cellulose, which is the principal component of the endocyst (Connell et al.…”

Section: Methodsmentioning

confidence: 99%

Photosensitized inactivation of Acanthamoeba palestinensis in the cystic stage

et al. 2006

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Aims: To develop alternative approaches for medical and environmental control of pathogenic Acanthamoeba spp. by means of photodynamic treatment with a tetracationic Zn(II)‐phthalocyanine (RLP068). Methods and Results: Incubation of cyst cultures with RLP068 for 1 h caused an accumulation of readily detectable concentrations of the phthalocyanine, even at doses as low as 0·5 μmol l−1. RLP068 exhibited no dark toxicity towards cysts up to 5 μmol l−1 concentration. A decrease of c. 50% in cyst survival in comparison with controls was measured upon incubation of the cysts with 0·5 μmol l−1 RLP068, followed by exposure to light (600–700 nm) for 20 min at a fluence rate of 50 mW cm−2 (60 J cm−2). After incubation with 3 and 5 μmol l−1 RLP068 and irradiation, the cysts lost their excystment ability as early as day 5 and up to day 10, and were clearly damaged when observed under an interference contrast microscope. Conclusions: These data indicate the promising use of RLP068 in phototreatment of diseases caused by pathogenic amoebae and in initial disinfection of wastewaters. Significance and Impact of the Study: Rapid and extensive photodamage may be induced in the highly resistant cystic stages by means of 600‐ to 700‐nm light sources.

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Section: Methodsmentioning

confidence: 99%

Photosensitized inactivation of Acanthamoeba palestinensis in the cystic stage

et al. 2006

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“…Cell density was determined by counting the cells in a Bűrker chamber using the eosin exclusion test (Lasman and Shafran 1978). Sodium dodecyl sulfate (SDS) was obtained from Merck (Darmstadt, Germany).…”

Section: Methodsmentioning

confidence: 99%

“…The dishes were incubated at 30°C for 24 h in order to evaluate the survival of the treated cells. The effect on cell survival of RLP068 alone and RLP068 in combination with light was evaluated by the eosin exclusion test (Lasman and Shafran 1978). All cells were counted, and the resulting values were expressed as percentages of cell numbers in control samples, and were calculated as the average of three independent experiments performed in duplicate.…”

Section: Methodsmentioning

confidence: 99%

Mechanisms involved in the photosensitized inactivation ofAcanthamoeba palestinensistrophozoites

Ferro

Guidolin

Tognon

et al. 2009

Journal of Applied Microbiology

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Aims: To advance our understanding of the mechanisms involved in the RLP068 phthalocyanine‐photosensitized inactivation of Acanthamoeba palestinensis trophozoites through a precise identification of the targets of the photoprocess in both the cytosolic and mitochondrial compartments. Methods and Results: We followed the activities of selected marker enzymes as well as we performed fluorescence and transmission electron microscopy investigations of the alterations induced by the photoprocess in the fine structure of subcellular compartments. RLP068 is preferentially located in the contractile vacuole: the fluorescence in that site is particularly evident in the unirradiated cells and becomes more diffused after irradiation. Electron microscopic analysis of photosensitized A. palestinensis cells clearly shows that the swelling of trophozoites and the appearance of vacuoles spread throughout the cytoplasm after phototreatment. The activity of a typical cytoplasmic enzyme, such as lactate dehydrogenase, underwent a 35% decrease as a consequence of the photoprocess, reflecting the photodamage induced by migrating phthalocyanine molecules in their micro‐environment. Conclusions: The presence of multiple targets for the phthalocyanine‐photosensitized process is of utmost importance because this pattern of cell damage makes it unlikely that photoresistant A. palestinensis strains are gradually selected or mutagenic phenomena are developed as a consequence of the photoinduced damage. Significance and Impact of the Study: Photosensitization via phthalocyanines appears to represent an efficient and safe approach for achieving a close control of the population of a potentially pathogenic protozoan such as A. palestinensis, opening new perspectives for the disinfection of microbiologically polluted waters.

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“…These amoebae are also known to play host to bacteria such as Legionella (Rowbotham 1980), and then to act as reservoirs and vehicles of infection in humans (WinieckaKrusnell and Linder 2001). Acanthamoeba can survive periods of dehydration, starvation, or other unfavorable situations by forming a cellulose-containing cyst (Lasman and Shafran 1978;Aksozek et al 2002). These cysts can remain viable for about 8-24 months on agar slopes; however, cyst survival was found to be sporadic and so is an unreliable method of storage (Biddick et al 1984).…”

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confidence: 99%

Long-term, low-maintenance storage of Acanthamoeba strains

Lorenzo‐Morales

Maciver

2006

Parasitol Res

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A simple, low cost method is described for the long-term storage of the potential human pathogen Acanthamoeba. Amoebae are placed in dried, sterile clay pellets within which they form cysts that remain viable and pure for at least 5 years. This method compares favorably with other storage methods and requires no specialist equipment. We have demonstrated that amoeba stored by this method retain both their pathogenic potential and their small subunit ribosomal DNA sequence type.

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Induction of Encystment in Acanthamoeba palestinensis. Factors Influencing Cyst Formation

Cited by 10 publications

References 12 publications

Photosensitized inactivation of Acanthamoeba palestinensis in the cystic stage

Photosensitized inactivation of Acanthamoeba palestinensis in the cystic stage

Mechanisms involved in the photosensitized inactivation ofAcanthamoeba palestinensistrophozoites

Long-term, low-maintenance storage of Acanthamoeba strains

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