Redox gradient shapes the abundance and diversity of mercury-methylating microorganisms along the water column of the Black Sea.

In the global context of seawater deoxygenation triggered by climate change and anthropogenic activities, changes in redox gradients impacting biogeochemical transformations of pollutants, such as mercury, become more likely. Being the largest anoxic basin worldwide, with high concentrations of the potent neurotoxic methylmercury (MeHg), the Black Sea is an ideal natural laboratory to provide new insights about the link between dissolved oxygen concentration and hgcAB gene-carrying (hgc+) microorganisms involved in the formation of MeHg. We combined geochemical and microbial approaches to assess the effect of vertical redox gradients on abundance, diversity, and metabolic potential of hgc+ microorganisms in the Black Sea water column. The abundance of hgcA genes [congruently estimated by quantitative PCR (qPCR) and metagenomics] correlated with MeHg concentration, both maximal in the upper part of the anoxic water. Besides the predominant Desulfobacterales, hgc+ microorganisms belonged to a unique assemblage of diverse-previously underappreciated-anaerobic fermenters from Anaerolineales, Phycisphaerae (characteristic of the anoxic and sulfidic zone), Kiritimatiellales, and Bacteroidales (characteristic of the suboxic zone). The metabolic versatility of Desulfobacterota differed from strict sulfate reduction in the anoxic water to reduction of various electron acceptors in the suboxic water. Linking microbial activity and contaminant concentration in environmental studies is rare due to the complexity of biological pathways. In this study, we disentangle the role of oxygen in shaping the distribution of Hg-methylating microorganisms consistently with MeHg concentration, and we highlight their taxonomic and metabolic niche partitioning across redox gradients, improving the prediction of the response of marine communities to the expansion of oxygen-deficient zones. IMPORTANCE Methylmercury (MeHg) is a neurotoxin detected at high concentrations in certain marine ecosystems, posing a threat to human health. MeHg production is mainly mediated by hgcAB gene-carrying (hgc+) microorganisms. Oxygen is one of the main factors controlling Hg methylation; however, its effect on the diversity and ecology of hgc+ microorganisms remains unknown. Under the current context of seawater deoxygenation, mercury cycling is expected to be disturbed. Here, we show the strong effect of oxygen gradients on the distribution of potential Hg methylators. In addition, we show for the first time the significant contribution of a unique assemblage of potential fermenters from Anaerolineales, Phycisphaerae, and Kiritimatiellales to Hg methylation, stratified in different redox niches along the Black Sea gradient. Our results considerably expand the known taxonomic diversity and ecological niches prone to the formation of MeHg and contribute to better apprehend the consequences of oxygen depletion in seawater.

Detecting anal human papillomavirus infection in men who have sex with men living with HIV: implications of assay variability.

BACKGROUND: Incidence of anal cancer (AC) caused by persistent human papillomavirus (HPV) infection has risen in the last years in men who have sex with men (MSM) living with HIV. There is consensus that this population should be screened for anal precancerous lesions, but the role of HPV DNA testing in AC screening programmes is still under debate. OBJECTIVES: This study employed two molecular test to detect anal HPV DNA and compared assay performance and prognostic value for the diagnosis of histology proven high-grade intraepithelial anal lesions. METHODS: MSM living with HIV attended their regular check-up visits consisting of detection of anal HPV infection, anal cytology, digital anorectal examination and high resolution anoscopy. HPV DNA was detected using Hybrid Capture 2 High-Risk test (HC2, total assay) and LINEAR ARRAY HPV Genotyping Test (LA, type-specific assay) RESULTS: Among 274 participant, prevalence of HPV DNA was 48.5% by HC2 and 89.4% by LA. HPV16 (30.6%) and HPV6 (19.6%) were the most common genotypes identified. Prevalence of multiple HPV infections was 56.2%. Agreement between HPV DNA assays was 75.2% (κ=0.51; 95% CI 0.42 to 0.60). Total HPV detection demonstrated high sensitivity (90%; 95% CI 68.3 to 98.8) and moderate specificity (58.4%; 95% CI 50.2 to 66.3), while type-specific HPV16/18 genotyping provided an increase in specificity and showed the highest area under the curve (0.81; 95% CI 0.74 to 0.89) and Youden's index (0.63). CONCLUSIONS: Both methodologies identified a high prevalence of anal HPV infection and multiple HPV infections in MSM living with HIV, showing a moderate overall agreement between them. Either total HPV detection or type-specific HPV16/18 detection together with a threshold ≥atypical squamous cells of undetermined significance for abnormal cytology showed an acceptable diagnostic accuracy.

Variability in codon usage in Coronaviruses is mainly driven by mutational bias and selective constraints on CpG dinucleotide

The Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the third virus within the Orthocoronavirinae causing an emergent infectious disease in humans, the ongoing coronavirus disease 2019 pandemic (COVID-19). Due to the high zoonotic potential of these viruses, it is critical to unravel their evolutionary history of host species shift, adaptation and emergence. Only such knowledge can guide virus discovery, surveillance and research efforts to identify viruses posing a pandemic risk in humans. We present a comprehensive analysis of the composition and codon usage bias of the 82 Orthocoronavirinae members, infecting 47 different avian and mammalian hosts. Our results clearly establish that synonymous codon usage varies widely among viruses and is only weakly dependent on the type of host they infect. Instead, we identify mutational bias towards AT-enrichment and selection against CpG dinucleotides as the main factors responsible of the codon usage bias variation. Further insight on the mutational equilibrium within Orthocoronavirinae revealed that most coronavirus genomes are close to their neutral equilibrium, the exception is the three recently-infecting human coronaviruses, which lie further away from the mutational equilibrium than their endemic human coronavirus counterparts. Finally, our results suggest that while replicating in humans SARS-CoV-2 is slowly becoming AT-richer, likely until attaining a new mutational equilibrium.

Propiedades antimicrobianas del cobre en tapones nasales de acetato de polivinilo y silicona. Un modelo in vitro de adherencia y supervivencia / Antimicrobial properties of copper in polyvinyl acetate and silicone nasal packs. An in vitro model of bacterial adhesion and survival

Introducción: Los tapones nasales más utilizados son los compuestos por acetato de polivinilo y silicona, existiendo complicaciones asociadas a su uso, como la cacosmia y el síndrome de shock tóxico, producido por S.aureus, con alta mortalidad. El cobre ha demostrado tener propiedades antimicrobianas en materiales biomédicos. Objetivo: Evaluar las propiedades antimicrobianas del cobre en tapones nasales modificados con cobre, frente a bacterias de la mucosa nasal. Diseño: Estudio Experimental. Materiales y Métodos: Se usó un sistema experimental in vitro utilizando tapones de acetato de polivinilo y silicona con láminas de cobre y sin cobre, que se cultivaron en un medio con cepas de S.aureus meticilino-sensible (SAMS) y S.aureus meticilino-resistente (SAMR). Resultados: Se observó una reducción en el porcentaje de sobrevida bacteriana en los distintos tapones nasales con cobre, respecto a aquellos sin cobre, tanto para los medios inoculados con SAMS y SAMR, los cuales fluctuaron entre un 61% y un 66% para tapones de acetato de polivinilo y entre un 78% y 86% para aquellos tapones siliconados. Conclusión: Se sugiere la incorporación de cobre en tapones nasales, abriéndose un amplio campo de investigación sobre el uso de tapones con cobre y la disminución de complicaciones infecciosas asociadas.

Background: Nasal packs are mostly made of polyvinyl acetate and silicone, being complications associated to their use such as cacosmia and toxic shock syndrome, produced by S. aureus, with high mortality rates. Copper has proven antimicrobial properties in biomedical materials. Objetive: The purpose of this study is to evaluate the antimicrobial properties of copper in a modified prototype of nasal packs with cooper, against bacteria of the nasal mucosa. Desing: Experimental Study. Methods: An in vitro model was used with polyvinyl acetate and silicone nasal packs with and without copper, that were were grown in a medium with strains of methicillinsensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA). Results: There was a significant reduction of bacterial survival percentages in all modified nasal packs with copper, for both the culture medium inoculated with MSSA and MRSA, which ranged between 61% and 66% for the modified polyvinyl acetate nasal packs and between 78% and 86% for the modified silicone nasal packs. Conclusion: we suggest the incorporation of copper in the use of nasal packing, generating a wide investigating field about the use of copper in nasal packs and the decrease of infectious complications.