Molecular Aspects of the Cell Cycle and Encystment of Acanthamoeba

Byers, Thomas J.; Kim, Byeong G.; King, Louis E.; Hugo, Eric R.

doi:10.1093/clind/13.supplement_5.s373

Cited by 64 publications

(55 citation statements)

References 67 publications

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“…In the ciliates Colpoda inflata (Benitez and Gutiérrez, 1997) and Sterkiella histriomuscorum (Tourancheau et al, 1999), mRNAs were found in resting cysts. Several fungal species produce dormant spores containing stored mRNA (Camonis et al, 1982) and, in Acanthamoeba, Byers et al (1991) managed to isolate mRNA from resting cysts that was capable of actin translation in vitro. Gutiérrez et al (2001) described transcripts encoding, among others, a heat-shock protein (Hsp70) in cryptobiotic stages of C. inflata and Colpoda nova.…”

Section: Discussionmentioning

confidence: 99%

Stress gene (hsp70) sequences and quantitative expression inMilnesium tardigradum(Tardigrada) during active and cryptobiotic stages

Schill

Steinbrück²,

Köhler

2004

Journal of Experimental Biology

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SUMMARY The eutardigrade Milnesium tardigradum can undergo cryptobiosis,i.e. entry into a reversible ametabolic stage induced by dehydration, cooling and, probably, osmotic and anoxic stress. For the first time in tardigrades,we described partial sequences of three heat-shock protein (hsp70family) genes and examined gene expression on the way from an active to a cryptobiotic and back to an active stage again. Results showed different patterns of gene expression in the hsp70 isoforms. All three isoforms seem to be true heat-shock proteins since transcription could be clearly enhanced by temperature elevation. Isoform 1 and, at a lower level, isoform 3 do not seem to have a specific function for cryptobiosis. By contrast,transcription of isoform 2 is significantly induced in the transitional stage between the active and the cryptobiotic stage, resulting in a comparatively high mRNA copy number also during cryptobiosis. This pattern of induction implies that isoform 2 is the most relevant hsp70 gene for M. tardigradum individuals entering the cryptobiotic stage.

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Section: Discussionmentioning

confidence: 99%

Stress gene (hsp70) sequences and quantitative expression inMilnesium tardigradum(Tardigrada) during active and cryptobiotic stages

Schill

Steinbrück²,

Köhler

2004

Journal of Experimental Biology

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“…Byers et al 70 showed that this action is weak and reversible. This is different from its effect on exponential phase cultures (see cancer chemotherapy section) when it acted as an inhibitor of ODC and the cultures remained as trophozoites.…”

Section: Steric Biguanidesmentioning

confidence: 99%

Acanthamoeba keratitis update—incidence, molecular epidemiology and new drugs for treatment

Seal

2003

Eye

175

135

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“…During the first stage, the vegetative trophozoite form is feeding and replicating. The second stage develops not only under unfavorable environmental conditions, such as nutrient starvation, heat, cold, and desiccation, but also in the presence of elevated concentration of various chemical compounds, with the trophozoites differentiating into cysts (13,40). During the encystment phase, amoebae become round and form two distinct layers: the endocyst, containing cellulose, and the ectocyst, containing various polysaccharides and proteins (27,34).…”

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Resistance of Acanthamoeba Cysts to Disinfection Treatments Used in Health Care Settings

et al. 2010

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Free-living amoebae that belong to the genus Acanthamoeba are widespread in the environment, including water. They are responsible for human infections and can host pathogenic microorganisms. Under unfavorable conditions, they form cysts with high levels of resistance to disinfection methods, thus potentially representing a threat to public health. In the present study we evaluated the efficacies of various biocides against trophozoites and cysts of several Acanthamoeba strains. We demonstrated that disinfectant efficacy varied depending on the strains tested, with environmental strains demonstrating greater resistance than collection strains. Trophozoites were inactivated by all treatments except those using glutaraldehyde as an active compound: for these treatments, we observed resistance even after 30 min exposure. Cysts resisted many treatments, including certain conditions with glutaraldehyde and other biocides. Moist heat at 55°C was not efficient against cysts, whereas exposure at 65°C was. Several chemical formulations containing peracetic acid, hydrogen peroxide, or ortho-phthalaldehyde presented greater efficacy than glutaraldehyde, as did ethanol and sodium hypochlorite; however, some of these treatments required relatively long incubation times to achieve cyst inactivation. Amoebal cysts can be highly resistant to some high-level disinfectants, which has implications for clinical practice. These results highlight the need to consider the effective disinfection of protozoa in their vegetative and resistant forms due to their intrinsic resistance. This is important not only to prevent the transmission of protozoa themselves but also due to the risks associated with a range of microbial pathogens that are found to be associated intracellularly with these microorganisms.

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Molecular Aspects of the Cell Cycle and Encystment of Acanthamoeba

Cited by 64 publications

References 67 publications

Stress gene (hsp70) sequences and quantitative expression inMilnesium tardigradum(Tardigrada) during active and cryptobiotic stages

Stress gene (hsp70) sequences and quantitative expression inMilnesium tardigradum(Tardigrada) during active and cryptobiotic stages

Acanthamoeba keratitis update—incidence, molecular epidemiology and new drugs for treatment

Resistance of Acanthamoeba Cysts to Disinfection Treatments Used in Health Care Settings

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