Examinando por Autor "Jorge E. Araya"

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    Ítem
    Haloterrigena sp. Strain SGH1, a Bacterioruberin-Rich, Perchlorate-Tolerant Halophilic Archaeon Isolated From Halite Microbial Communities, Atacama Desert, Chile.
    (2020) Nataly Flores; Sebastian Hoyos; Mauricio Venegas; Alexandra Galetović; Lidia M. Zúñiga; Francisca Fábrega; Bernando Paredes; Camila Salazar-Ardiles; Claudia Vilo; Carmen Ascaso; Jacek Wierzchos; Virginia Souza-Egipsy; Jorge E. Araya; Ramon Alberto Batista-García; Benito Gómez-Silva
    An extreme halophilic archaeon, strain SGH1, is a novel microorganism isolated from endolithic microbial communities colonizing halites at Salar Grande, Atacama Desert, in northern Chile. Our study provides structural, biochemical, genomic, and physiological information on this new isolate living at the edge of the physical and chemical extremes at the Atacama Desert. SGH1 is a Gram-negative, red-pigmented, non-motile unicellular coccoid organism. Under the transmission electron microscope, strain SGH1 showed an abundant electro-dense material surrounding electron-lucent globular structures resembling gas vacuoles. Strain SGH1 showed a 16S rRNA gene sequence with a close phylogenetic relationship to the extreme halophilic archaea Haloterrigena turkmenica and Haloterrigena salina and has been denominated Haloterrigena sp. strain SGH1. Strain SGH1 grew at 20–40°C (optimum 37°C), at salinities between 15 and 30% (w/v) NaCl (optimum 25%) and growth was improved by addition of 50 mM KCl and 0.5% w/v casamino acids. Growth was severely restricted at salinities below 15% NaCl and cell lysis is avoided at a minimal 10% NaCl. Maximal concentrations of magnesium chloride and sodium or magnesium perchlorates that supported SGH1 growth were 0.5 and 0.15M, respectively. Haloterrigena sp. strain SGH1 accumulates bacterioruberin (BR), a C50 xanthophyll, as the major carotenoid. Total carotenoids in strain SGH1 amounted to nearly 400 μg BR per gram of dry biomass. Nearly 80% of total carotenoids accumulated as geometric isomers of BR: all-trans-BR (50%), 5-cis-BR (15%), 9-cis-BR (10%), 13-cis-BR (4%); other carotenoids were dehydrated derivatives of BR. Carotenogenesis in SGH1 was a reversible and salt-dependent process; transferring BR-rich cells grown in 25% (w/v) NaCl to 15% (w/v) NaCl medium resulted in depigmentation, and BR content was recovered after transference and growth of unpigmented cells to high salinity medium. Methanol extracts and purified BR isomers showed an 8–9-fold higher antioxidant activity than Trolox or β-carotene. Both, plasma membrane integrity and mitochondrial membrane potential measurements under acute 18-h assays showed that purified BR isomers were non-toxic to cultured human THP-1 cells.
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    Ítem
    Observational cross-sectional study of Trichomonas tenax in patients with periodontal disease attending a Chilean university dental clinic
    (2019) Casandra Bracamonte-Wolf; Patricio R. Orrego; Christian Muñoz; Daniel Herrera; Joel Bravo; Jorge Gonzalez; Héctor Varela; Alejandro Catalán; Jorge E. Araya
    Background: The oral flagellated protozoan Trichomonas tenax has been associated with patients with periodontal disease. However, no recent studies have been conducted on the prevalence of T. tenax in Chile. The aim of this study was to determine the presence of T. tenax in patients with periodontal disease, admitted to the Dental Clinic of the University of Antofagasta, Chile, through Polymerase Chain Reaction (PCR) amplification of the beta-tubulin gene. Methods: An observational, cross-sectional study was conducted on 50 patients diagnosed with periodontal disease, 20 of them with gingivitis and 30 with periodontitis. T. tenax was identified by PCR amplification of the beta-tubulin gene. Associations between the protozoan and periodontal disease or the presence of risk factors to establish T. tenax infection were determined using the chi-square test and binary logistic regression analysis. Results: T. tenax was present in 28 out of 50 (56%) of patients with periodontal disease, and was more prevalent when associated with periodontitis (21 out of 30; 70%) than dental plaque-induced gingivitis (7 out of 20; 35%). Non-statistically-significant associations were observed between the presence of T. tenax and age, gender, smoking habit or diabetes. Statistically significant associations were observed between the presence of T. tenax and periodontal disease, and between T. tenax and the Periodontal Screening and Recording (PSR) index. Conclusion: T. tenax showed a high presence in patients with progressive states of periodontal diseases. Consequently, T. tenax detection is strongly recommended in patients with periodontal disease diagnosis and with a PSR index greater than 3.