Search

A partir de mayo de 2020, la crisis sanitaria global causada por el virus SARS-CoV-2 traslada su epicentro hacia Latinoamérica, con foco en ciudades que presentan altos índices de pobreza, segregación y hacinamiento. Los avances en microbiología posibilitan comprender en profundidad las relaciones entre ciudad, COVID-19 y otros microorganismos, pero falta establecer un marco conceptual que las articule, especialmente en contextos donde las determinantes sociales son tan relevantes. Este artículo tiene como objetivo el proponer una aproximación integrada de microbiología, vivienda, ambiente y urbanismo, a partir de un modelo de interacciones y un análisis empírico para Santiago de Chile. En base a esto, se pudo analizar cómo el proceso de propagación en la ciudad se ve potenciada por vulnerabilidades de índole socio espacial, sanitaria intradomiciliaria y urbana, más una aproximación desde el concepto de pobreza energética. Al mismo tiempo, se pudo comprobar como las variables asociadas a estas vulnerabilidades permitían explicar la tasa de incidencia de casos confirmados por cada 100 000 habitantes a través de las distintas comunas en el área metropolitana de Santiago de Chile. Dentro de éstas, destacan el nivel de hacinamiento de las viviendas, la cantidad de hogares con jefes/as de hogar en trabajo precario y los viajes hacia el distrito central de negocios de la ciudad. Finalmente, se establece la necesidad de proponer una agenda de investigación para este nuevo equipo multidisciplinario de “Microbioma Urbano” en relación con la necesidad de realización de muestreos microbiológicos que permitan mejorar las condiciones de viviendas, barrios y ciudades, aportando en la superación de las vulnerabilidades identificadas en este estudio. A partir de maig de 2020, la crisi sanitària global causada pel virus SARS-CoV-2 trasllada el seu epicentre cap a Llatinoamèrica, amb focus en ciutats que presenten alts índexs de pobresa, segregació i amuntegament. Els avenços en microbiologia permeten entendre en profunditat les relacions entre ciutat, COVID-19 i altres microorganismes, però cal establir un marc conceptual que les articuli, especialment en contextos on les determinants socials són tan rellevants. Aquest article té com a objectiu el proposar una aproximació integrada de microbiologia, habitatge, ambient i urbanisme, a partir d'un model d'interaccions i una anàlisi empírica per a Santiago de Xile. En base a això, es va poder analitzar com el procés de propagació a la ciutat es veu potenciada per vulnerabilitats d'índole soci espacial, sanitària intra-domiciliaria i urbana, més una aproximació des del concepte de pobresa energètica. Al mateix temps, es va poder comprovar com les variables associades a aquestes vulnerabilitats permetien explicar la taxa d'incidència de casos confirmats per cada 100 000 habitants a través de les diferents comunes a l'àrea metropolitana de Santiago de Xile. Dins d'aquestes, destaquen el nivell d'amuntegament dels habitatges, la quantitat de llars amb caps de la llar en treball precari i els viatges cap al districte central de negocis de la ciutat. Finalment, s'estableix la necessitat de proposar una agenda de recerca per a aquest nou equip multidisciplinari de "Microbioma Urbà" en relació amb la necessitat de realització de mostrejos microbiològiques que permetin millorar les condicions d'habitatges, barris i ciutats, aportant en la superació de les vulnerabilitats identificades en aquest estudi. 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.

The composition of the vaginal microbiome, including both the presence of pathogens involved in sexually transmitted infections (STI) as well as commensal microbiota, has been shown to have important associations for a woman’s reproductive and general health. Currently, healthcare providers cannot offer comprehensive vaginal microbiome screening, but are limited to the detection of individual pathogens, such as high-risk human papillomavirus (hrHPV), the predominant cause of cervical cancer. There is no single test on the market that combines HPV, STI, and microbiome screening. Here, we describe a novel inclusive women’s health assay that combines self-sampling with sequencing-based HPV detection and genotyping, vaginal microbiome analysis, and STI-associated pathogen detection. The assay includes genotyping and detection of 14 hrHPV types, 5 low-risk HPV types (lrHPV), as well as the relative abundance of 32 bacterial taxa of clinical importance, includingLactobacillus,Sneathia,Gardnerella, and 4 pathogens involved in STI, with high sensitivity, specificity, and reproducibility. For each of these taxa, healthy ranges were determined in a group of 50 self-reported healthy women. The hrHPV portion of the test was evaluated against the Digene High-Risk HPV HC2 DNA test with vaginal samples obtained from 185 women. Results were concordant for 181/185 of the samples (overall agreement of 97.83%, Cohen’s kappa = 0.93), with sensitivity and specificity values of 94.74% and 98.64%, respectively. Two discrepancies were caused by the Digene assay’s known cross-reactivity with low-risk HPV types, while two additional samples were found to contain hrHPV not detected by Digene. This novel assay could be used to complement conventional cervical cancer screening, because its self-sampling format can expand access among women who would otherwise not participate, and because of its additional information about the composition of the vaginal microbiome and the presence of pathogens.

Aims: To optimize a protocol for the extraction and an in-depth analysis of the soluble protein fraction of two nonaxenic toxin-producing cyanobacteria Cylindrospermopsis raciborskii (hepatotoxin-producing), and Raphidiopsis sp. (neurotoxin-producing), using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Methods and Results: The soluble protein fractions from strains of C. raciborskii and Raphidiosis sp. with different toxicity phenotypes were analysed by 2D-PAGE. Specific protocols were optimized specifically for each strain. Between 500 and 700 sharp protein spots were distinguished in a single 4–7 pH range 2D-PAGE for each cyanobacterium. Comparison of the protein maps of C. raciborskii CS-505 (a cylindrospermopsin-producing strain) and Raphidiopsis sp. D9 (saxitoxin-producing strain) against the nontoxic C. raciborskii strain CS-509 revealed many unique proteins in each protein map. We confirmed that the resolved proteins were cyanobacterial by identifying three randomly chosen protein spots from a Raphidiopsis sp. strain D9 2D-PAGE, using high-performance liquid chromatography (HPLC) tandem mass spectrometry (MS). Conclusions: The 2D-PAGE conditions presented here provide a robust protocol for proteomic studies in two CYN- and STX-producing model organisms, C. raciborskii and Raphidiopsis sp. Significance and Impact of the Study: We present the first protocols for proteomic analyses of Cylindrospermopsis raciborskii and Raphidiopsis sp.

Cell division in bacteria has been studied mostly in Escherichia coli and Bacillus subtilis, model organisms for Gram-negative and Gram-positive bacteria, respectively. However, cell division in filamentous cyanobacteria is poorly understood. Here, we identified a novel protein, named CyDiv (Cyanobacterial Division), encoded by the all2320 gene in Anabaena sp. PCC 7120. We show that CyDiv plays a key role during cell division. CyDiv has been previously described only as an exclusive and conserved hypothetical protein in filamentous cyanobacteria. Using polyclonal antibodies against CyDiv, we showed that it localizes at different positions depending on cell division timing: poles, septum, in both daughter cells, but also in only one of the daughter cells. The partial deletion of CyDiv gene generates partial defects in cell division, including severe membrane instability and anomalous septum localization during late division. The inability to complete knock out CyDiv strains suggests that it is an essential gene. In silico structural protein analyses and our experimental results suggest that CyDiv is an FtsB/DivIC-like protein, and could therefore, be part of an essential late divisome complex in Anabaena sp. PCC 7120.

Paralytic shellfish poisoning (PSP) toxins are a group of naturally occurring neurotoxic alkaloids produced among several genera of primarily freshwater cyanobacteria and marine dinoflagellates. Although saxitoxin (STX) and analogs are all potent Na(+) channel blockers in vertebrate cells, the functional role of these compounds for the toxigenic microorganisms is unknown. Based upon the known importance of monovalent cations (such as sodium) in the maintenance of cellular homeostasis and ion channel function, we examined the effect of high extracellular concentrations of these ions on growth, cellular integrity, toxin production and release to the external medium in the filamentous freshwater cyanobacterium, Raphidiopsis brookii D9; a gonyautoxins (GTX2/3) and STX producing toxigenic strain. We observed a toxin export in response to high (17 mM) NaCl and KCl concentrations in the growth medium that was not primarily related to osmotic stress effects, compared to the osmolyte mannitol. Addition of exogenous PSP toxins with the same compositional profile as the one produced by R. brookii D9 was able to partially mitigate this effect of high Na⁺ (17 mM). The PSP toxin biosynthetic gene cluster (sxt) in D9 has two genes (sxtF and sxtM) that encode for a MATE (multidrug and toxic compound extrusion) transporter. This protein family, represented by NorM in the bacterium Vibrio parahaemolyticus, confers resistance to multiple cationic toxic agents through Na⁺/drug antiporters. Conserved domains for Na⁺ and drug recognition have been described in NorM. For the D9 sxt cluster, the Na⁺ recognition domain is conserved in both SxtF and SxtM, but the drug recognition domain differs between them. These results suggest that PSP toxins are exported directly in response to the presence of monovalent cations (Na⁺, K⁺) at least at elevated concentrations. Thus, the presence of both genes in the sxt cluster from strain D9 can be explained as a selective recognition mechanism by the SxtF/M transporters for GTX2/3 and STX. We propose that these toxins in cyanobacteria could act extracellularly as a protective mechanism to ensure homeostasis against extreme salt variation in the environment.

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 (STX, NEO, GTX2/3), decarbamoyl (dcSTX), and N-sulfocarbamoyl (C1/2, B1) 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 STX, 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 STX 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.

Cyanobacterial morphology is diverse, ranging from unicellular spheres or rods to multicellular structures such as colonies and filaments. Multicellular species represent an evolutionary strategy to differentiate and compartmentalize certain metabolic functions for reproduction and nitrogen (N(2)) fixation into specialized cell types (e.g. akinetes, heterocysts and diazocytes). Only a few filamentous, differentiated cyanobacterial species, with genome sizes over 5 Mb, have been sequenced. We sequenced the genomes of two strains of closely related filamentous cyanobacterial species to yield further insights into the molecular basis of the traits of N(2) fixation, filament formation and cell differentiation. Cylindrospermopsis raciborskii CS-505 is a cylindrospermopsin-producing strain from Australia, whereas Raphidiopsis brookii D9 from Brazil synthesizes neurotoxins associated with paralytic shellfish poisoning (PSP). Despite their different morphology, toxin composition and disjunct geographical distribution, these strains form a monophyletic group. With genome sizes of approximately 3.9 (CS-505) and 3.2 (D9) Mb, these are the smallest genomes described for free-living filamentous cyanobacteria. We observed remarkable gene order conservation (synteny) between these genomes despite the difference in repetitive element content, which accounts for most of the genome size difference between them. We show here that the strains share a specific set of 2539 genes with >90% average nucleotide identity. The fact that the CS-505 and D9 genomes are small and streamlined compared to those of other filamentous cyanobacterial species and the lack of the ability for heterocyst formation in strain D9 allowed us to define a core set of genes responsible for each trait in filamentous species. We presume that in strain D9 the ability to form proper heterocysts was secondarily lost together with N(2) fixation capacity. Further comparisons to all available cyanobacterial genomes covering almost the entire evolutionary branch revealed a common minimal gene set for each of these cyanobacterial traits.

This is the first report of planktonic choanoflagellates from the Chilean coast, relating their abundance with that of bacteria and viruses. Surface water samples were taken off Antofagasta, Montemar, and Puerto Montt and samples from ballast tanks were also analyzed. The choanoflagellates were identified following morphological type descriptions. Viruses and bacteria were stained with SYBR Green and choanoflagellates, bacteria, and viruses were counted simulta - neously using red autofluorescence for the former and green fluorescence for the latter two. Six species of Acanthoecidae were observed for the first time in Chilean waters: Calliacantha multispina (0.3·10 3 L -1 ), Acanthocorbis apoda, Stepha- noeca diplocostata (2.0·10 3 L -1 ), Crinolina isefiordensis , Parvicorbicula superpositus, and Pleurasiga minima (5.0·10 3 L -1 ). The concentrations of bacteria (1.1·10 6 -4.5·10 6 ) and viral-like particles (VLPs) (7.9·10 6 -21·10 6 ) agreed with those typically found in marine coastal waters. In addition, Acanthocorbis asymmetrica was found in ballast waters, where its high concentration (20·10 3 L -1 ) likely resulted from the particular physical and biological environment therein.