Insights on metal pollution of a Patagonia watershed: A case study in the lower course of the Negro river, Argentina.

This study evaluated the occurrence and distribution of largely known pollutants (Ag, Cd, Cu, Cr, Hg, Ni, Pb, Pd, and Zn), as well as emerging ones (Li, and V) in the water dissolved fraction, suspended particulate matter, and surface sediments from the lower course of the Negro River, Argentina. There are scarce preceding data on inorganic pollution in the entire watershed and, in the case of the emerging pollutants, there are almost no studies performed worldwide. Sampling was conducted in 2019 at six sampling sites, three of them mostly river dominated and the rest under marine domain. The samples were subjected to an acid digestion in a microwave digester, and analyzed using an Inductively Coupled Plasma Atomic Emission Spectrometer. Results: revealed that Cu, Li, V, and Zn were always on the top four of the highest average metal concentrations in water and sediment fractions. The pollution assessment indicated that the watershed might be exposed to anthropogenic pollution, as over 60% of Cu and Zn, and over 85% of Hg in water dissolved samples from the marine dominated sites were above the maximum recommended values from guidelines. The multivariate analyses characterized the watershed into two clusters, with metals in the sediment fraction mainly contributing to the uppermost sites. Indeed, sedimentary Cu and Zn background enrichment indices pointed out a moderate pollution of the river dominated sites. This study highlights the relevance of an integrative approach in metal pollution evaluation, as the results denoted a progressive deterioration of the watershed, affecting the water quality of the lower course of the Negro River and its adjacent coastal zone. Overall, these results contribute to a more complete evaluation of the potential to fulfill the Sustainable Development Goals, with implications for future treatment strategies to enhance the environmental quality of the area.

Assessing threats, regulations, and strategies to abate plastic pollution in LAC beaches during COVID-19 pandemic.

Plastic use and production have dramatically increased globally over the past 65 years with the improvement of life quality by the daily use of plastic products. Still, around 50% of the plastic produced is disposable products that generate substantial waste. Several reports pointed out the adverse effects of plastic litter in coastal environments in recent years, emphasizing single-use plastics (SUP). In this manner, Latin America and the Caribbean (LAC) coastal environments are highly vulnerable due to wastewater treatment facilities scarcity and poor plastic waste management strategies. Since COVID-19 pandemic, the single-use plastic waste/person rate is expected to rise due to the use of personal protective equipment and SUP as health care measures. Based on literature research and the review of plastic waste regulations, this paper will assess the main COVID-19 plastic pollution threats and LAC beaches' regulations to suggest possible measures to abate this problem. The main findings suggest that unifying the ongoing fragmented and overlapped policies is key to abate plastic pollution, including plastic industry regulations and circular economies. In addition, increasing public risk perception about plastic pollution is critical to reducing plastic waste generation. Research advances in the adverse effects of plastic debris could improve the public's perception of plastic pollution risk, pushing forward global marine plastic governance.

Characterization of Mycobacterium chelonae-Like Strains by Comparative Genomics.

Isolates of the Mycobacterium chelonae-M. abscessus complex are subdivided into four clusters (CHI to CHIV) in the INNO-LiPA® Mycobacterium spp DNA strip assay. A considerable phenotypic variability was observed among isolates of the CHII cluster. In this study, we examined the diversity of 26 CHII cluster isolates by phenotypic analysis, drug susceptibility testing, whole genome sequencing and single-gene analysis. Pairwise genome comparisons were performed using several approaches, including average nucleotide identity (ANI) and genome-to-genome distance (GGD) among others. Based on ANI and GGD the isolates were identified as M. chelonae (14 isolates), M. franklinii (2 isolates) and M. salmoniphium (1 isolate). The remaining 9 isolates were subdivided into three novel putative genomospecies. Phenotypic analyses including drug susceptibility testing, as well as whole genome comparison by TETRA and delta differences, were not helpful in separating the groups revealed by ANI and GGD. The analysis of standard four conserved genomic regions showed that rpoB alone and the concatenated sequences clearly distinguished the taxonomic groups delimited by whole genome analyses. In conclusion, the CHII INNO-LiPa is not a homogeneous cluster; on the contrary, it is composed of closely related different species belonging to the M. chelonae-M. abscessus complex and also several unidentified isolates. The detection of these isolates, putatively novel species, indicates a wider inner variability than the presently known in this complex.

Detection of a Putative TetR-Like Gene Related to Mycobacterium bovis BCG Growth in Cholesterol Using a gfp-Transposon Mutagenesis System.

In vitro transposition is a powerful genetic tool for identifying mycobacterial virulence genes and studying virulence factors in relation to the host. Transposon shuttle mutagenesis is a method for constructing stable insertions in the genome of different microorganisms including mycobacteria. Using an IS1096 derivative, we have constructed the Tngfp, a transposon containing a promoterless green fluorescent protein (gfp) gene. This transposon was able to transpose randomly in Mycobacterium bovis BCG. Bacteria with a single copy of the gfp gene per chromosome from an M. bovis BCG::Tngfp library were analyzed and cells exhibiting high levels of fluorescence were detected by flow cytometry. Application of this approach allowed for the selection of a mutant, BCG_2177c::Tngfp (BCG-Tn), on the basis of high level of long-standing fluorescence at stationary phase. This BCG-Tn mutant showed some particular phenotypic features compared to the wild type strain, mainly during stationary phase, when cholesterol was used as a sole carbon source, thus supporting the relationships of the targeted gene with the regulation of cholesterol metabolism in this bacteria. This approach showed that Tngfp is a potentially useful tool for studying the involvement of the targeted loci in metabolic pathways of mycobacteria.

HspX knock-out in Mycobacterium tuberculosis leads to shorter antibiotic treatment and lower relapse rate in a mouse model--a potential novel therapeutic target.

Effective global tuberculosis control is hindered by the need for prolonged chemotherapy which leads to poor patient compliance. Therefore novel drug targets that shorten the duration of chemotherapy and reduce disease relapse rates are highly desirable. We have previously shown that HspX, an alpha-crystallin-like protein, is associated with growth suppression of Mycobacterium tuberculosis in mouse models. We determined to evaluate hspX as a novel target for controlling M. tuberculosis growth in combination with traditional antibiotic therapy in the Cornell mouse model. The hspX deletion mutant (ΔhspX) was used as a model of potential hspX inhibition. Normal BALB/c mice were infected with ΔhspX or the wild type (WT) strain. Three weeks after infection, the mice were treated with rifampicin, isoniazid and pyrazinamide for 14 weeks followed by 8 weeks of hydrocortisone. The effect of chemotherapy was measured by organ bacterial counts and the relapse rate. Antibiotic treatment of mice infected with ΔhspX resulted in faster visceral clearance; organs were disease free 8 weeks post-treatment for ΔhspX infection compared to 14 weeks for the WT strain. Disease relapse rate was significantly lower in ΔhspX infection (60.7%) compared to WT infection (92.6%). HspX may be a promising therapeutic target in combination with traditional antibiotic therapy to shorten the length of treatment and reduce disease relapse.

Sewage pollution effects on mesozooplankton structure in a shallow temperate estuary.

The effects of a sewage effluent with no treatment on the mesozooplankton structure and the environmental quality were evaluated in the Bahía Blanca Estuary, during June to November 1995. The highest values of particulate organic matter, nutrients and specially phosphate, were observed in the effluent discharge zone. In addition, taxa richness, mesozooplankton abundance and Shannon diversity values were lower in the sewage discharge area compared with the less polluted area. Eurytemora americana and Acartia tonsa as well as larvae of Balanus glandula, Neohelice granulata and Spionidae were found in the discharge area with lower densities. These results highlight the importance of sewage effluent effects on mesozooplankton community providing background data to use in other monitoring programmes.