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Simple Summary: Mercury is one of the most common pollutants in agricultural and industrial areas; therefore, its study has become increasingly important. This element is often quantified using biomonitors, whose gradual response is representative of the entire community. This is especially important in areas where pollution is known or suspected, like the Mezquital Valley in central Mexico. Here, we aimed to determine the total mercury concentration in three species of small wild mammals that differ in diet to identify possible exposure threats in their habitat. We took hair and liver samples from two bat species and one wild mouse species over the course of a year. We found no difference in mercury concentration among species, but liver mercury was significantly lower during the dry season. This supports previous studies that pointed to wastewater as the main source of mercury exposure in this location. This is the first study to use small wild mammals as biomonitors in the Mezquital Valley, which is a critically contaminated site, as well as the first record of toxic metals in the protected bat species Leptonycteris yerbabuenae. Mercury (Hg) has been extensively studied due to its impact on the environment and health, but its effects on wild mammal populations are still poorly known. Therefore, the use of biomonitors has gained importance. Our objective was to report and compare, for the first time, the amount of mercury in small mammals belonging to three trophic guilds and to provide an initial toxicology perspective in the Mezquital Valley, a critically polluted area of Central Mexico. We quantified total Hg from the hair and liver of a nectarivorous bat (Leptonycteris yerbabuenae), an insectivorous bat (Corynorhinus townsendii) and a granivorous mouse (Peromyscus melanophrys) using atomic absorption spectrometry during the dry and rainy seasons. We compared the mercury concentrations between seasons, species and matrices. In all species, the average mercury content was higher in hair than liver, and there was no correlation between matrices. There was no difference in mercury content among species. Hg concentrations in the livers of P. melanophrys and C. townsendii were lower during the dry season than the rainy season, suggesting a seasonal decline in mercury availability. All of the values detected were below the neurotoxicity threshold reported in small mammals (10 ppm); however, we propose constant monitoring of Hg in their environment and confirm the utility of these species as biomonitors. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has caused several millions of deaths and forced the world population to a new normality. This study aims to analyze the air quality variation of several gaseous pollutants (CO, NO2, SO2, O3, PM10, and PM2.5) during the pre-lockdown, lockdown, and unlock period in the city of Monterrey using ground-based measurements. In this research, we proposed to use a control period of previous years to identify parameter variation due to local climate. The results showed a drastic decrease in measured contaminants during the lockdown period as follows: SO2 (−41.9%) > PM10 (−30.5%) > PM2.5 (−25.6%) > NO2 (−14.9%) > CO (−9.8%) compared to the control period (2017–2019). The O3 was the only air pollutant that showed an opposite trend, increasing during lockdown (+15%) and unlock (+2.2%), whereas CO (−16.6%) and NO2 (−30.6%) were further decreased. Moreover, using OMI/AURA satellite data, we detected a NO2 tropospheric column reduction by −1.9% during lockdown concerning the same period in the control interval. Moreover, we found a significant improvement in the Air Quality Index (AQI) due to the lockdown. Our findings indicate an association between air pollutants and economic activity and can be used in future strategies to improve urban air quality. [ABSTRACT FROM AUTHOR]

The present study was designed to detect the effect of heavy metals in two zones of the Metropolitan Area of Mexico City (MAMC), the Centro de Ciencias de la Atmósfera (CCA), and the Altzomoni station in the Iztaccíhuatl-Popocatépetl National Park. Taraxacum officinale was selected as the indicator organism of responses to atmospheric contamination by heavy metals. Determinations of heavy metals were performed, and total mRNA was extracted to quantify the expression of microRNA398 (miR398), superoxide dismutase 2 (CSD2), and the amounts of free radicals using the bromide of 3-(4,5-dimethylthiazole-2-ilo)-2,5-diphenyltetrazole (MTT) salts reduction assay. Results from the Altzomoni station showed high concentrations of five heavy metals, especially Aluminum, while three heavy metals were identified in the CCA-UNAM zone, most importantly, Vanadium, both in the dry season; miR398 expression presented subtle changes but was greater in the leaves from the stations with higher concentrations of heavy metals. Observations included a significant expression of CSD2, mainly in the dry season in both study zones, where levels were significant with respect to controls (p < 0.05). Reduced MTT was also higher in the dry season than in the rainy season (p < 0.05). In conclusion, the increase in heavy metals on the leaves of Taraxacum officinale induces increased expression of the CSD2 gene and reduced MTT; thus, they can be used as indicators for biomonitoring heavy metal concentrations. [ABSTRACT FROM AUTHOR]

Calypso (thiacloprid), Poncho (clothianidin), Gaucho (imidacloprid), and Jade (imidacloprid) are commercial neonicotinoid insecticides, a new class of agrochemicals in México. However, genotoxic and cytotoxic studies have not been performed. In the present study, human peripheral blood lymphocytes (PBL) were exposed in vitro to different concentrations of the four insecticides. The genotoxic and cytotoxic effects were evaluated using the alkaline comet and trypan blue dye exclusion assays. DNA damage was evaluated using two genotoxicity parameters: tail length and comet frequency. Exposure to 9.5 × 10-6 to 5.7 × 10-5 M Jade; 2.8×10-4 to 1.7×10-3MGaucho; 0.6×10-1 to 1.4×10-1MCalypso; 1.2×10-1 to 9.5×10-1MPoncho for 2 h induced a significant increase DNA damage with a concentration-dependent relationship. Jade was the most genotoxic of the four insecticides studied. Cytotoxicity was observed in cells exposed to 18 × 10-3 M Jade, 2.0 × 10-3M Gaucho, 2.0 × 10-1M Calypso, 1.07M Poncho, and cell death occurred at 30 × 10-3 M Jade, 3.3 × 10-3M Gaucho, 2.8 × 10-1M Calypso, and 1.42M Poncho. This study provides the first report of genotoxic and cytotoxic effects in PBL following in vitro exposure to commercial neonicotinoid insecticides. [ABSTRACT FROM AUTHOR]

Calypso (thiacloprid), Poncho (clothianidin), Gaucho (imidacloprid), and Jade (imidacloprid) are commercial neonicotinoid insecticides, a new class of agrochemicals in México. However, genotoxic and cytotoxic studies have not been performed. In the present study, human peripheral blood lymphocytes (PBL) were exposed in vitro to different concentrations of the four insecticides. The genotoxic and cytotoxic effects were evaluated using the alkaline comet and trypan blue dye exclusion assays. DNA damage was evaluated using two genotoxicity parameters: tail length and comet frequency. Exposure to 9.5 × 10(-6) to 5.7 × 10(-5) M Jade; 2.8 × 10(-4) to 1.7 × 10(-3) M Gaucho; 0.6 × 10(-1) to 1.4 × 10(-1) M Calypso; 1.2 × 10(-1) to 9.5 × 10(-1) M Poncho for 2 h induced a significant increase DNA damage with a concentration-dependent relationship. Jade was the most genotoxic of the four insecticides studied. Cytotoxicity was observed in cells exposed to 18 × 10(-3) M Jade, 2.0 × 10(-3) M Gaucho, 2.0 × 10(-1) M Calypso, 1.07 M Poncho, and cell death occurred at 30 × 10(-3) M Jade, 3.3 × 10(-3) M Gaucho, 2.8 × 10(-1) M Calypso, and 1.42 M Poncho. This study provides the first report of genotoxic and cytotoxic effects in PBL following in vitro exposure to commercial neonicotinoid insecticides.