Evaluation of the cytotoxicity and genotoxicity of glufosinate-ammonium at technical and commercial grades in HepG2 cells.

Exposure to genotoxic agents is associated with the development of cancer and related diseases. For this reason, assessing the genotoxicity of chemical compounds is necessary. In this line, information about the genotoxic effect of glufosinate-ammonium (GLA) has been reported only for the technical grade. However, humans are frequently exposed to commercial formulations of pesticides. Commercial formulations are characterized by using inner agents that increase toxicity compared to pesticides in technical grade. This study aimed to determine the cytotoxic and genotoxic effects of GLA on HepG2 cells. MTT and comet assays were performed to evaluate cell viability and DNA damage, respectively. HepG2 cells were exposed for 24 h to different concentrations of GLA (at 0.01 µg/mL; 0.04 µg/mL; 0.1 µg/mL; 0.24 µg/mL; 0.52 µg/mL; 1.25 µg/mL; 2.62 µg/mL and 13.12 µg/mL) in commercial- (Finale Ultra®) or technical-grade (GLAT). The results indicated that only Finale Ultra® induced a reduction in cell viability at 13.12 µg/mL. Furthermore, exposure to Finale Ultra® or GLAT was associated with increased DNA damage at concentrations from 0.52-13.12- µg/mL. This study shows the genotoxic effect of GLA on HepG2 cells.

Limited oxygen conditions as an approach to scale-up and improve D and L-lactic acid production in mineral media and avocado seed hydrolysates with metabolically engineered Escherichia coli.

The effectiveness of micro-aeration on lactate (LA) production by metabolically engineered Escherichia coli was evaluated in 1 L bioreactors containing mineral media and glucose (70 g/L). Volumetric oxygen transfer coefficients (kLa) between 12.6 and 28.7 h-1 increased the specific growth rate (µ) and volumetric productivity (QLA) by 300 and 400%, respectively, without a significant decrease in lactate yield (YLA), when compared with non-aerated fermentations. A kLa of 12.6 h-1 was successfully used as a criterion to scale-up the production of L and D-lactate from 1 to 11 and 130 L. Approximately constant QLA and YLA values were obtained throughout the fermentation scale-up process. Furthermore, a D-lactogenic fermentation was carried out in 1 L bioreactors using avocado seed hydrolysate as a culture medium under the same kLa value, displaying high QLA and YLA.

Methamidophos induces cytotoxicity and oxidative stress in human peripheral blood mononuclear cells.

Previous studies have shown that organophosphate pesticide (OP) exposure is associated with oxidative stress. Methamidophos (MET) is an OP widely used in agriculture, which is regarded as a highly toxic pesticide and it is a potent inhibitor of acetylcholinesterase. The aim of this study was to evaluate whether MET can induce oxidative stress at low concentrations in primary cultures of human peripheral blood mononuclear cells (PBMCs). PBMCs from healthy individuals were exposed to MET (0-80 mg/L) for 0-72 h. We performed the MTT and neutral-red assays to assess the cytotoxicity. As indicators of oxidative stress, the levels of reactive oxygen species (ROS) were assessed using flow cytometry, and the malondialdehyde (MDA) and reduced glutathione (GSH) levels were determined. MET decreased the viability of PBMCs in a dose-dependent manner. At concentrations of 3, 10, or 20 mg/L for 24 h, MET increased the ROS production significantly compared with the vehicle control. Similarly, MET increased the levels of MDA at the same concentrations that increased ROS (10 and 20 mg/L); however, no changes in GSH levels were observed. These results suggest that MET increased the generation of oxidative stress in PBMCs. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 147-155, 2017.

Improving poly-3-hydroxybutyrate production in Escherichia coli by combining the increase in the NADPH pool and acetyl-CoA availability.

The biosynthesis of poly-3-hydroxybutyrate (P3HB), a biodegradable bio-plastic, requires acetyl-CoA as precursor and NADPH as cofactor. Escherichia coli has been used as a heterologous production model for P3HB, but metabolic pathway analysis shows a deficiency in maintaining high levels of NADPH and that the acetyl-CoA is mainly converted to acetic acid by native pathways. In this work the pool of NADPH was increased 1.7-fold in E. coli MG1655 through plasmid overexpression of the NADP(+)-dependent glyceraldehyde 3-phosphate dehydrogenase gene (gapN) from Streptococcus mutans (pTrcgapN). Additionally, by deleting the main acetate production pathway (ackA-pta), the acetic acid production was abolished, thus increasing the acetyl-CoA pool. The P3HB biosynthetic pathway was heterologously expressed in strain MG1655 Δack-pta/pTrcgapN, using an IPTG inducible vector with the P3HB operon from Azotobacter vinelandii (pPHB Av ). Cultures were performed in controlled fermentors using mineral medium with glucose as the carbon source. Accordingly, the mass yield of P3HB on glucose increased to 73 % of the maximum theoretical and was 30 % higher when compared to the progenitor strain (MG1655/pPHB Av ). In comparison with the wild type strain expressing pPHB Av , the specific accumulation of PHB (gPHB/gDCW) in MG1655 Δack-pta/pTrcgapN/pPHB Av increased twofold, indicating that as the availability of NADPH is raised and the production of acetate abolished, a P3HB intracellular accumulation of up to 84 % of the E. coli dry weight is attainable.

Effects of exposure to environmental pollutants on mitochondrial DNA copy number: a meta-analysis.

Exposure to environmental pollutants has been associated with alteration on relative levels of mitochondrial DNA copy number (mtDNAcn). However, the results obtained from epidemiological studies are inconsistent. This meta-analysis aimed to evaluate whether environmental pollutant exposure can modify the relative levels of mtDNAcn in humans. We performed a literature search using PubMed, Scopus, and Web of Science databases. We selected and reviewed original articles performed in humans that analyzed the relationship between environmental pollutant exposure and the relative levels of mtDNAcn; the selection of the included studies was based on inclusion and exclusion criteria. Only twenty-two studies fulfilled our inclusion criteria. A total of 6011 study participants were included in this systematic review and meta-analysis. We grouped the included studies into four main categories according to the type of environmental pollutant: (1) heavy metals, (2) polycyclic aromatic hydrocarbons (PAHs), (3) particulate matter (PM), and (4) cigarette smoking. Inconclusive results were observed in all categories; the pooled analysis shows a marginal increase of relative levels of mtDNAcn in response to environmental pollutant exposure. The trial sequential analysis and rate confidence in body evidence showed the need to perform new studies. Therefore, a large-scale cohort and mechanistic studies in this area are required to probe the possible use of relative levels of mtDNAcn as biomarkers linked to environmental pollution exposure.

Bacterial Diversity and Population Dynamics During the Fermentation of Palm Wine From Guerrero Mexico.

Palm wine is obtained by fermentation of palm tree sap. In the Pacific coast of Mexico, palm wine is called Tuba and it is consumed as a traditional fermented beverage. Tuba has empirical applications such as an auxiliary in gastrointestinal diseases and a good source of nutrients. In the present study, a next-generation sequencing of the V3-V4 regions of the 16S rRNA gene was employed to analyze bacterial diversity and population dynamics during the fermentation process of Tuba, both in laboratory controlled conditions and in commercial samples from local vendors. Taxonomic identification showed that Fructobacillus was the main genus in all the samples, following by Leuconostoc, Gluconacetobacter, Sphingomonas, and Vibrio. Alpha diversity analysis demonstrated variability between all the samples. Beta diversity clustered the bacterial population according to the collection origin of the sample. Metabolic functional profile inference showed that the members of the bacterial communities may present the vitamin, antibiotic and antioxidant biosynthesis genes. Additionally, we further investigated the correlation between the predominant genera and some composition parameters of this beverage. This study provides the basis of the bacterial community composition and functionality of the fermented beverage.

Genotypes of Common Polymorphisms in the PON1 Gene Associated with Paraoxonase Activity as Cardiovascular Risk Factor.

BACKGROUND: Paraoxonase-1(PON1) exhibits hydrolytic activity and prevents the oxidation of high and low-density lipoproteins. Polymorphisms in the PON1 gene have been associated with variations in paraoxonase activity and with the risk of coronary artery disease (CAD). AIM OF THE STUDY: This study analyzed the association between the frequencies of genotypes of the L55 M and Q192 R SNPs in the PON1 gene with the PON1 activity and with CAD risk factors. METHODS: Women, determined by body composition, biochemical markers, and arylesterase (AREase) and paraoxonase (CMPase) activities were studied. Genotyping of L55 M and Q192 R polymorphisms was performed by TaqMan. Seventeen studies were used in the meta-analysis. RESULTS: A significant decrease in PON1 activity in carrying the LM/MM and QQ genotypes is identified, correlations are found between the AREase activity with glucose, cholesterol and atherogenic risk index. Carriers of the LM or MM genotype were related with obesity (OR = 1.6; p = 0.039), and the MQ haplotype has an effect on the decrease in AREase (ß = â€’22.4; p <0.001) and CMPase (ß = â€’3.8; p <0.001). In addition, a lower proportion of Native American admixture was observed in women with LM or MM genotype, while it was higher for the European proportion compared with the LL genotype (p <0.001). CONCLUSIONS: The LL-L55 M and QR-Q192 R genotypes are identified as the most frequently in the different states or cities of the country, and genotypic proportions are different, probably depending on the genetic structure of the populations. The association that is reported more frequently in the different studies is with enzymatic activity.

Source apportionment of lead in the blood of women of reproductive age living near tailings in Taxco, Guerrero, Mexico: An isotopic study.

The concentration and isotopic composition of lead in the blood of forty seven women of reproductive age (15-45y) exposed to multiple sources in two rural communities of the mining region of Taxco, Guerrero in southern Mexico were determined in order to identify specific contributing sources and their apportionment and to trace probable ingestion pathways. Our data indicate that >36% of the studied women have blood lead concentrations above 10µgdL-1 and up to 87% above 5µgdL-1. Tailings contain between 2128 and 5988mgkg-1 of lead and represent the most conspicuous source in the area. Lead contents in indoor dust are largely variable (21.7-987mgkg-1) but only 15% of samples are above the Mexican Regulatory Guideline for urban soils (400mgkg-1). By contrast, 85% of glazed containers (range: 0.026-68.6mgkg-1) used for cooking and food storage are above the maximum 2mgL-1 of soluble lead established in the Mexican Guideline. The isotopic composition indicates that lead in the blood of 95% of the studied women can be modeled in terms of a mixing system between local ores (and derivatives), glazed pottery and Morelos bedrock, end-members, with the two former being largely the most important contributors. Only one sample shows influence of indoor paints. Indoor dust is dominated by ores and derivatives but some samples show evidence of contribution from a less radiogenic source very likely represented by interior paints. This study supports the application of lead isotopic ratios to identify potential sources and their apportionment in humans exposed to multiple sources of lead from both, natural and anthropogenic origin.

Maternal C677T MTHFR polymorphism and environmental factors are associated with cleft lip and palate in a Mexican population.

INTRODUCTION: Nonsyndromic cleft lip and cleft palate (CL/P) is associated with environmental, nutritional, and genetic factors. Maternal polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene have been associated with CL/P. OBJECTIVES: To determine the relationship between the risk of having a child with CL/P and maternal C677T and A1298C MTHFR polymorphisms, the intake of folate supplements, and exposure to environmental factors during the first trimester of pregnancy, a case-control study of Mexican mothers (88 case mothers and 116 control mothers) was conducted. METHODS: A questionnaire was used to assess exposure to environmental factors. The C677T and A1298C polymorphisms were identified by polymerase chain reaction with restriction fragment length polymorphism. RESULTS: Mothers with the 677CT or 677TT genotype had a higher risk of having a child with CL/P than mothers with the 677CC genotype (odds ratio [OR], 2.4; 95% confidence interval [CI], 1.1-5.7). An increased risk of having a child with CL/P was associated with the lack of folate supplementation during the first trimester of pregnancy (OR, 3.8; 95% CI, 1.9-7.6), and this risk was greater in the mothers with the 677TT or 677CT genotype than mothers who reported taking folate supplements and had the 677CC genotype (OR, 11.2; 95% CI, 3.3-37.5). Pesticide exposure was associated with CL/P. There was no significant association between either the A1298C variant or tobacco exposure and the risk of CL/P. CONCLUSION: These results suggest that gene-environment interactions play an important role in the development of CL/P.

Specific ethanol production rate in ethanologenic Escherichia coli strain KO11 Is limited by pyruvate decarboxylase.

Modification of ethanol productivity and yield, using mineral medium supplemented with glucose or xylose as carbon sources, was studied in ethanologenic Escherichia coli KO11 by increasing the activity of five key carbon metabolism enzymes. KO11 efficiently converted glucose or xylose to ethanol with a yield close to 100% of the theoretical maximum when growing in rich medium. However, when KO11 ferments glucose or xylose in mineral medium, the ethanol yields decreased to only 70 and 60%, respectively. An increase in GALP(Ec) (permease of galactose-glucose-xylose) or PGK(Ec) (phosphoglycerate kinase) activities did not change xylose or glucose and ethanol flux. However, when PDC(Zm) (pyruvate decarboxylase from Zymomonas mobilis) activity was increased 7-fold, the yields of ethanol from glucose or xylose were increased to 85 and 75%, respectively, and organic acid formation rates were reduced. Furthermore, as a response to a reduction in acetate and ATP yield, and a limited PDC(Zm) activity, an increase in PFK(Ec) (phosphofructokinase) or PYK(Bs) (pyruvate kinase from Bacillus stearothermophilus) activity drastically reduced glucose or xylose consumption and ethanol formation flux. This experimental metabolic control analysis showed that ethanol flux in KO11 is negatively controlled by phosphofructokinase and pyruvate kinase, and positively influenced by the PDC(Zm) activity level.