Koo et al., 2018
Koo, Dal-Hoe, Molin, William T, Saski, Christopher A, Jiang, Jiming, Putta, Karthik, Jugulam, Mithila, Friebe, Bernd, & Gill, Bikram S, “Extrachromosomal circular DNA-based amplification and transmission of herbicide resistance in crop weed Amaranthus palmeri,” Proceedings of the National Academy of Sciences of the United States of America, 2018, 115(13), 3332-3337. DOI: 10.1073/pnas.1719354115.
ABSTRACT:
Gene amplification has been observed in many bacteria and eukaryotes as a response to various selective pressures, such as antibiotics, cytotoxic drugs, pesticides, herbicides, and other stressful environmental conditions. An increase in gene copy number is often found as extrachromosomal elements that usually contain autonomously replicating extrachromosomal circular DNA molecules (eccDNAs). Amaranthus palmeri, a crop weed, can develop herbicide resistance to glyphosate [N-(phosphonomethyl) glycine] by amplification of the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene, the molecular target of glyphosate. However, biological questions regarding the source of the amplified EPSPS, the nature of the amplified DNA structures, and mechanisms responsible for maintaining this gene amplification in cells and their inheritance remain unknown. Here, we report that amplified EPSPS copies in glyphosate-resistant (GR) A. palmeri are present in the form of eccDNAs with various conformations. The eccDNAs are transmitted during cell division in mitosis and meiosis to the soma and germ cells and the progeny by an as yet unknown mechanism of tethering to mitotic and meiotic chromosomes. We propose that eccDNAs are one of the components of McClintock’s postulated innate systems [McClintock B (1978) Stadler Genetics Symposium] that can rapidly produce soma variation, amplify EPSPS genes in the sporophyte that are transmitted to germ cells, and modulate rapid glyphosate resistance through genome plasticity and adaptive evolution. FULL TEXT
Kongtip et al., 2017
Kongtip, Pornpimol, Nankongnab, Noppanun, Phupancharoensuk, Ratanavadee, Palarach, Chonlada, Sujirarat, Dusit, Sangprasert, Supha, Sermsuk, Malasod, Sawattrakool, Namthip, & Woskie, Susan Renee, “Glyphosate and Paraquat in Maternal and Fetal Serums in Thai Women,” Journal of Agromedicine, 2017, 22(3), 282-289. DOI: 10.1080/1059924x.2017.1319315.
ABSTRACT:
OBJECTIVES: This longitudinal study measured the glyphosate and paraquat concentrations found in maternal and umbilical cord serum in 82 pregnant women who gave birth in three provinces of Thailand.
METHODS: Through questionnaires and biological samples collected at childbirth, factors such as personal characteristics, family members occupation, agricultural activities, and herbicide use in agricultural work were evaluated as predictors of glyphosate and paraquat levels in the pregnant women. Statistical analysis used univariate and binary multiple logistic regression, where the outcome was the probability of exposure to paraquat or glyphosate above the limit of detection associated with occupation and household factors.
RESULTS: The glyphosate concentrations in the pregnant women’s serum at childbirth (median: 17.5, range: 0.2-189.1 ng/mL) were significantly higher (P < .007) than those in the umbilical cord serum (median: 0.2, range: 0.2-94.9 ng/mL). However, the paraquat concentrations in the serum of the pregnant women at childbirth (83% </=limit of detection [LOD], with maximum of 58.3 ng/mL) were similar to those in the umbilical cord serum (80% <LOD, with maximum of 47.6 ng/mL). Women with glyphosate levels >LOD in serum at childbirth were 11.9 times more likely to report work as an agriculturist (P < .001), 3.7 times more likely to live near agricultural areas (P = .006), and 5.9 times more likely to have a family member who worked in agriculture (P < .001). The only factors affecting paraquat exposures in pregnant women at childbirth were reporting the agricultural activity of digging in farm soil and working in the agricultural fields in the third trimester of pregnancy.
CONCLUSIONS: These results show that pregnant women who work in agriculture or live in families that work in agriculture have higher exposures to the herbicides glyphosate and paraquat. The potential for long-term health impacts of these prenatal exposures to children should be evaluated, and greater regulation of the sale and use of herbicides should be considered in Thailand. FULL TEXT
Klarich et al., 2017
Klarich, Kathryn L., Pflug, Nicholas C., DeWald, Eden M., Hladik, Michelle L., Kolpin, Dana W., Cwiertny, David M., & LeFevre, Gregory H., “Occurrence of Neonicotinoid Insecticides in Finished Drinking Water and Fate during Drinking Water Treatment,” Environmental Science & Technology Letters, 2017, 4(5), 168-173. DOI: 10.1021/acs.estlett.7b00081.
ABSTRACT:
Neonicotinoid insecticides are widespread in surface waters across the agriculturally intensive Midwestern United States. We report for the first time the presence of three neonicotinoids in finished drinking water and demonstrate their general persistence during conventional water treatment. Periodic tap water grab samples were collected at the University of Iowa over 7 weeks in 2016 (May−July) after maize/soy planting. Clothianidin, imidacloprid, and thiamethoxam were ubiquitously detected in finished water samples at concentrations ranging from 0.24 to 57.3 ng/L. Samples collected along the University of Iowa treatment train indicate no apparent removal of clothianidin or imidacloprid, with modest thiamethoxam removal (∼50%). In contrast, the concentrations of all neonicotinoids were substantially lower in the Iowa City treatment facility finished water using granular activated carbon (GAC) filtration. Batch experiments investigated potential losses. Thiamethoxam losses are due to base-catalyzed hydrolysis under high-pH conditions during lime softening. GAC rapidly and nearly completely removed all three neonicotinoids. Clothianidin is susceptible to reaction with free chlorine and may undergo at least partial transformation during chlorination. Our work provides new insights into the persistence of neonicotinoids and their potential for transformation during water treatment and distribution, while also identifying GAC as a potentially effective management tool for decreasing neonicotinoid concentrations in finished drinking water.
Kasuba et al., 2018
Kasuba, Vilena, Milic, Mirta, Rozgaj, Ruzica, Kopjar, Nevenka, Mladinic, Marin, Zunec, Suzana, Vrdoljak, Ana Lucic, Pavicic, Ivan, Cermak, Ana Marija Marjanovic, Pizent, Alica, Lovakovic, Blanka Tariba, & Zeljezic, Davor, “Effects of low doses of glyphosate on DNA damage, cell proliferation and oxidative stress in the HepG2 cell line,” Environmental Science and Pollution Research, 2017, 24(23), 19267-19281. DOI: 10.1007/s11356-017-9438-y.
ABSTRACT:
We studied the toxic effects of glyphosate in vitro on HepG2 cells exposed for 4 and 24 h to low glyphosate concentrations likely to be encountered in occupational and residential exposures [the acceptable daily intake (ADI; 0.5 μg/mL), residential exposure level (REL; 2.91 μg/mL) and occupational exposure level (OEL; 3.5 μg/mL)]. The assessments were performed using biomarkers of oxidative stress, CCK-8 colorimetric assay for cell proliferation, alkaline comet assay and cytokinesis-block micronucleus (CBMN) cytome assay. The results obtained indicated effects on cell proliferation, both at 4 and 24 h. The levels of primary DNA damage after 4-h exposure were lower in treated vs. control samples, but were not significantly changed after 24 h. Using the CBMN assay, we found a significantly higher number of MN and nuclear buds at ADI and REL after 4 h and a lower number of MN after 24 h. The obtained results revealed significant oxidative damage. Four-hour exposure resulted in significant decrease at ADI [lipid peroxidation and glutathione peroxidase (GSH-Px)] and OEL [lipid peroxidation and level of total antioxidant capacity (TAC)], and 24-h exposure in significant decrease at OEL (TAC and GSH-Px). No significant effects were observed for the level of reactive oxygen species (ROS) and glutathione (GSH) for both treatment, and for 24 h for lipid peroxidation. Taken together, the elevated levels of cytogenetic damage found by the CBMN assay and the mechanisms of primary DNA damage should be further clarified, considering that the comet assay results indicate possible cross-linking or DNA adduct formation.
Jiang et al., 2018
Jiang, X., Zhang, N., Yin, L., Zhang, W. L., Han, F., Liu, W. B., Chen, H. Q., Cao, J., & Liu, J. Y., “A commercial Roundup(R) formulation induced male germ cell apoptosis by promoting the expression of XAF1 in adult mice.,” Toxicology Letters, 2018, 296, 163-172, DOI: 10.1016/j.toxlet.2018.06.1067.
ABSTRACT:
Roundup(R) is extensively used for weed control worldwide. Residues of this compound may lead to side effects of the male reproductive system. However, the toxic effects and mechanisms of Roundup(R) of male germ cells remain unclear. We aimed to investigate the apoptosis-inducing effects of Roundup(R) on mouse male germ cells and explore the role of a novel tumor suppressor XAF1 (X-linked inhibitor of apoptosis-associated factor 1) involved in this process. We demonstrated that Roundup(R) can impair spermatogenesis, decrease sperm motility and concentration, and increase the sperm deformity rate in mice. In addition, excessive apoptosis of germ cells accompanied by the overexpression of XAF1 occurred after Roundup(R) exposure both in vitro and in vivo. Furthermore, the low expression of XIAP (X-linked inhibitor of apoptosis) induced by Roundup(R) was inversely correlated with XAF1. Moreover, the knockdown of XAF1 attenuated germ cell apoptosis, improved XIAP expression and inhibited the activation of its downstream target proteins, caspase-3 and PARP, after Roundup(R) exposure. Taken together, our data indicated that XAF1 plays an important role in Roundup(R)-induced male germ cell apoptosis. The present study suggested that Roundup(R) exposure has potential negative implications on male reproductive health in mammals.
Hong et al., 2018
Hong, Y., Yang, X., Huang, Y., Yan, G., & Cheng, Y., “Assessment of the oxidative and genotoxic effects of the glyphosate-based herbicide Roundup on the freshwater shrimp, Macrobrachium nipponensis,” Chemosphere, 2018, 210, 896-906. DOI: 10.1016/j.chemosphere.2018.07.069.
ABSTRACT:
In the present study, an acute toxic test was performed to assess the oxidative stress and genotoxic effects of the herbicide on the freshwater shrimp Macrobrachium nipponensis. The results showed that the 48-h and 96-h LC50 values of Roundup to M. nipponensis were 57.684mg/L and 11.237mg/L, respectively. For further investigation, the shrimps were exposed to sublethal concentrations of 0.35, 0.70, 1.40, 2.80 and 5.60mg/L for 96h. A significant decrease in total haemocytes count (THC) was observed at concentration of 5.60mg/L throughout the experiment. The level of superoxide dismutase (SOD), catalase (CAT) and total antioxidant capacity (T-AOC) in all the treatments decreased in a dose- and time-dependent manner except for the concentration group of 0.35mg/L. The malondialdehyde (MDA), hydrogen peroxide (H2O2) and protein carbonyl in serum increased significantly at concentrations of 2.80mg/L and 5.60mg/L. A significant decrease in acetylcholinesterase (AChE) activity was observed at each concentration (P0.05). In addition, the micronucleus (MN) frequency of haemocytes significantly increased (P0.05) at concentrations of 1.40, 2.80 and 5.60mg/L, whereas the comet ratio and %DNA in the tails exhibited a clear time- and dose-dependent response during the exposure. The analysis of the integrated biomarker response (IBR) showed the induction of oxidative stress biomarkers and the inhibition of antioxidants, and this dose-dependent relation suggests the sensitivity and availability of all the biomarkers. These results revealed that Roundup had a prominent toxic effect on M. nipponensis based on the antioxidative response inhibition and genotoxicity.
Henner and Backhaus, 2019
Hollert, Henner, & Backhaus, Thomas, “Some food for thought: a short comment on Charles Benbrook´s paper ‘How did the US EPA and IARC reach diametrically opposed conclusions on the genotoxicity of glyphosate-based herbicides?’ and its implications,” Environmental Sciences Europe, 2019, 31(1). DOI: 10.1186/s12302-019-0187-z.
ABSTRACT:
Not available. FULL TEXT
Hmielowski, 2019
Hmielowski, Tracy, “Glyphosate and Phosphate Interactions in soils,” CSA News, 2019, 64(1), DOI: 10.2134/csa2019.64.0103.
SUMMARY:
• Phosphate and glyphosate interact “competitively” when both are present in the soil.
• The application of inorganic P fertilizers after glyphosate has been applied was shown to mobilize glyphosate.
• Management strategies should consider the potential for glyphosate mobilization to reduce impacts on crops and glyphosate runoff to nearby water sources.
With both phosphorus and glyphosate being applied to agricultural fields across the globe, the chemicals are commonly present together. Phosphorus is applied as inorganic forms of P (PO₄³¯) and taken up through the plant roots. Glyphosate is absorbed through foliage, and while it readily adsorbs to soil, it has been found to degrade rapidly. The two chemicals have a competitive interaction, given the similarity between the PO₄³¯and the phosphonomethyl function group of glyphosate. This means that inorganic P fertilizers can potentially displace glyphosate, and vice versa, on the surface of soil particles. FULL TEXT
Hicks et al., 2018
Hicks, Helen L., Comont, David, Coutts, Shaun R., Crook, Laura, Hull, Richard, Norris, Ken, Neve, Paul, Childs, Dylan Z., & Freckleton, Robert P., “The factors driving evolved herbicide resistance at a national scale,” Nature Ecology & Evolution, 2018, 2(3), 529-536. DOI: 10.1038/s41559-018-0470-1.
ABSTRACT:
Repeated use of xenobiotic chemicals has selected for the rapid evolution of resistance, threatening health and food security at a global scale. Strategies for preventing the evolution of resistance include cycling and mixtures of chemicals and diversification of management. We currently lack large-scale studies that evaluate the efficacy of these different strategies for minimizing the evolution of resistance. Here we use a national-scale data set of occurrence of the weed Alopecurus myosuroides (black-grass) in the United Kingdom to address this. Weed densities are correlated with assays of evolved resistance, supporting the hypothesis that resistance is driving weed abundance at a national scale. Resistance was correlated with the frequency of historical herbicide applications, suggesting that evolution of resistance is primarily driven by intensity of exposure to herbicides, but was unrelated directly to other cultural techniques. We find that populations resistant to one herbicide are likely to show resistance to multiple herbicide classes. Finally, we show that the economic costs of evolved resistance are considerable: loss of control through resistance can double the economic costs of weeds. This research highlights the importance of managing threats to food production and healthcare systems using an evolutionarily informed approach in a proactive not reactive manner.
Hertz-Picciotto et al., 2018
Hertz-Picciotto, Irva, Sass, Jennifer B., Engel, Stephanie, Bennett, Deborah H., Bradman, Asa, Eskenazi, Brenda, Lanphear, Bruce, & Whyatt, Robin, “Organophosphate exposures during pregnancy and child neurodevelopment: Recommendations for essential policy reforms,” PLOS Medicine, 2018, 15(10). DOI: 10.1371/journal.pmed.1002671.
SUMMARY POINTS:
• Widespread use of organophosphate (OP) pesticides to control insects has resulted in ubiquitous human exposures.
• High exposures to OP pesticides are responsible for poisonings and deaths, particularly in developing countries.
• Compelling evidence indicates that prenatal exposure at low levels is putting children at risk for cognitive and behavioral deficits and for neurodevelopmental disorders.
To protect children worldwide, we recommend the following:
• Governments phase out chlorpyrifos and other OP pesticides, monitor watersheds and other sources of human exposures, promote use of integrated pest management (IPM) through incentives and training in agroecology, and implement mandatory surveillance of pesticide-related illness.
• Health professions implement curricula on the hazards from OP pesticides in nursing and medical schools and in continuing medical education courses and educate their patients and the public about these hazards.
• Agricultural entities accelerate the development of nontoxic approaches to pest control through IPM and ensure the safety of workers through training and provision of protective equipment when toxic chemicals are to be used. FULL TEXT