Browsing by Author "Soto Liebe, Katia"

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    Covid-19 and city: Towards an integrated model of housing, microbiology, environment and urbanism
    (2021) Encinas Pino, Felipe; Soto Liebe, Katia; Aguirre Nuñez, Carlos;; González, Bernardo; Bustamante Gómez, Waldo; Schueftan, Alejandra; Ugalde, Juan; Blondel, Carlos; Truffello Robledo, Ricardo; Araya, Paz; Freed Huici, Carmen Marcela; CEDEUS (Chile)
    As of May 2020, the global health crisis caused by the SARS-CoV-2 virus moves its epicentre to Latin America, with cities showing high rates of poverty, segregation, and overcrowding. Current advances in microbiology make it possible to understand in depth the relationships between cities, COVID-19, and other microorganisms, but a conceptual framework to articulate them is lacking, especially in contexts where social determinants are so relevant. This article proposes an integrated approach to microbiology, housing, environment, and urbanism, based on a model of interactions and an empirical analysis applied to Santiago de Chile. It was possible to analyse how the propagation of COVID-19 in the city is enhanced by vulnerabilities of socio-spatial, residential and urban health, including an approach from the concept of energy poverty. At the same time, it was possible to verify how the variables associated with these vulnerabilities allowed to explain the incidence rate per 100 000 inhabitants through the different communes of Santiago de Chile. Among these, the level of housing overcrowding, the number of households with heads of household in precarious employment, and travel to the central business district stand out. Finally, the need for microbiological sampling to improve housing conditions, neighbourhoods, and cities propose a new research agenda for this Urban Microbiome" multidisciplinary team, contributing to overcoming the vulnerabilities identified in this research.
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    Reassessment of the toxin profile of Cylindrospermopsis raciborskii T3 and function of putative sulfotransferases in synthesis of sulfated and sulfonated PSP toxins
    (PERGAMON-ELSEVIER SCIENCE LTD, 2010) Soto Liebe, Katia; Murillo, Alejandro A.; Krock, Bernd; Stucken, Karina; Fuentes Valdes, Juan J.; Trefault, Nicole; Cembella, Allan; Vasquez, Monica
    The toxigenic freshwater cyanobacterium Cylindrospermopsis raciborskii T3 has been used as a model to study and elucidate the biosynthetic pathway of tetrahydropurine neurotoxins associated with paralytic shellfish poisoning (PSP). There are nevertheless several inconsistencies and contradictions in the toxin profile of this strain as published by different research groups, and claimed to include carbamoyl (SIX, NEO, GTX2/3), decarbamoyl (dcSTX), and N-sulfocarbamoyl (C1/2, 81) derivatives. Our analysis of the complete genome of another PSP toxin-producing cyanobacterium, Raphidiopsis brookii D9, which is closely related to C. raciborskii T3, resolved many issues regarding the correlation between biosynthetic pathways, corresponding genes and the T3 toxin profile. The putative sxt gene cluster in R. brookii D9 has a high synteny with the T3 sxt cluster, with 100% nucleotide identity among the shared genes. We also compared the PSP toxin profile of the strains by liquid chromatography coupled to mass spectrometry (LC-MS/MS). In contrast to published reports, our reassessment of the PSP toxin profile of T3 confirmed production of only SIX, NEO and dcNEO. We gained significant insights via correlation between specific sxt genes and their role in PSP toxin synthesis in both D9 and T3 strains. In particular, analysis of sulfotransferase functions for SxtN (N-sulfotransferase) and SxtSUL (O-sulfotransferase) enzymes allowed us to propose an extension of the PSP toxin biosynthetic pathway from SIX to the production of the derivatives GTX2/3. C1/2 and B1. This is a significantly revised view of the genetic mechanisms underlying synthesis of sulfated and sulfonated STX analogues in toxigenic cyanobacteria. (C) 2010 Elsevier Ltd. All rights reserved.