- Email: [email protected]
Double strand breaks and DNA repair protein induction by pesticides
Abstracts / Toxicology Letters 259S (2016) S73–S247
PP23.14 The exposure to methamidophos induced genotoxic damage on HepG2 cells S.P. Cotino-Najera, M. Ramirez-Vargas, V. Antonio-Vejar, M. Olea-Flores, M.E. Moreno-Godinez Laboratory of Toxicology and Environmental Health, Autonomous University of Guerrero, Chilpancingo, Guerrero, Mexico Introduction: The classical mechanism of toxicity associated with organophosphorus pesticides (OP) is the inhibition of acetylcholinesterase activity leading to neurotoxic effects. However, genotoxic effects could be an important mechanism through which OP exert their toxicity effects. Methamidophos (MET) is an OP widely used in the south of Mexico in agriculture. It is unknown whether MET induces DNA damage at concentrations of biological relevance. Objective: The present investigation was focused in the determination of the genotoxic damage of MET using HepG2 cells as a test model based on the fact that liver is the main organ implicated on the metabolism of pesticides. Materials and methods: HepG2 cells were exposed to MET (0–500 mg/L) for 48 h, this exposure was not cytotoxic from the HepG2 cells, comet assays were performed to determine the genotoxic damage by exposure to MET, the olive tail moment (OTM) was measured. Results: Results from MTT assays indicated that MET at concentrations of 10, 20, 50, 350 or 500 mg/L does not change the cell viability of HepG2 at 48 h of exposure. The comet assay resulted in a significant increase of OTM at concentrations of 10, 20, or 50 mg/L, however; only the exposure to 500 mg/L was statics significant (p < 0.05) in exposed HepG2 cells to MET, versus controls at 48 h. Conclusions: These results suggest that biological relevant concentrations of MET are capable of inducing genotoxic effects in HepG2 cells. Financial support: This study was partially supported by the Pesticide Toxicology Network (Conacyt-Mexico #253789/271775). http://dx.doi.org/10.1016/j.toxlet.2016.07.531 PP23.15 Double strand breaks and DNA repair protein induction by pesticides K. Suárez-Larios, R.D. Montero-Montoya Department of Genomic Medicine and Environmental Toxicology. Institute of Biomedical Research, Universidad Nacional Autónoma de México, Ciudad de México, Mexico Introduction: Several studies have found an association between the exposure to pesticides with chronic pathologies including neurological and reproductive effects or developmental problems and cancer. In the last years, these compounds have been proposed as leukemogenic agents, probably by producing reciprocal translocations. However, this idea has not been explored yet, having thus an information gap. Objective: The aim of this study is to generate knowledge about the role of some pesticides and their metabolites in the formation of reciprocal translocations. We evaluated two steps that lead to the formation of this type of damage: the production of double strand breaks (DSB) in DNA and their subsequent recombination repair, either via HR or NHEJ.
S221
Materials and Methods: We selected eight pesticides and metabolites. DSB were evaluated as foci of phosphorylated histone H2AX by immunofluorescence microscopy in lymphocytes treated during 1.5 h with four concentrations of each pesticide or metabolite. Repair proteins, phosphorylated Ku80 (NHEJ) or Rad51 (HR) were identified by Western blot in mononuclear cells treated with the pesticides that induced significant DSB. Results: We found a significant increase in foci with permetrin, glyphosate, paraoxon, pentaclorophenol and endosulfan lactone, the latter in a dose dependent manner, being the last three the metabolites of parathion, lindane and endosulfan. All these compounds induced a significant increase in phosphorylated Ku80 or Rad51 in at least one dose. Conclusions: Pesticides are capable of producing DSB’s in lymphocytes and, consequently, induce the phosphorylation and/or induction of proteins associated to repair mechanisms of this type of damage. Financial support: PAEP, 2016. Coordinación de Estudios de Posgrado, UNAM and Children Environmental Health Network (Conacyt-251229/271626). http://dx.doi.org/10.1016/j.toxlet.2016.07.532 PP23.16 Methamidophos and parathion degradation kinetic in Ataulfo and Manila mango during the ripening period F.D. Jaimes-Rendón 1 , H. Sotelo-Arroyo 1 , M.E. Moreno Godínez 2 , D. Návez González 3 , G. Huerta-Beristain 1 1
Laboratorio de Biotecnología, Facultad de Ciencias Químico Biológicas. Universidad Autónoma de Guerrero, Chilpancingo, Guerrero, Mexico 2 Laboratorio de Toxicología y Salud Ambiental, Facultad de Ciencias Químico Biológicas, Universidad Autónoma de Guerrero, Chilpancingo, Guerrero, Mexico 3 Laboratorio de Toxicología Ambiental, Unidad de Investigación Especializada en Microbiología, Universidad Autónoma de Guerrero, Chilpancingo, Guerrero, Mexico Organophosphate pesticides (OPs), organic compounds derived from phosphorus, are used worldwide in industry and agriculture to improve the quality and quantity of food. Mexico is the fifth producer of Mango worldwide and Guerrero state is the main Mexican producer. To avoid mango production loss due to pests, many OPs are commonly used on crops. This study evaluated the degradation kinetics of OPs (methamidophos and parathion) in mango fruit, specifically in Manila and Ataulfo mango. Manila or Ataulfo mango samples were collected from Tecpan de Galeana, Guerrero, Mexico during the ripening season once per week, for 11 weeks. Samples were used to determine levels of organophosphate pesticides including methamidophos, parathion, diazinon, methyl parathion and malathion. OPs extracion and purification were performed by the dispersion of solid phase matrix method, whereas OPs pesticides quantification was performed by gas chromatography (GC) coupled to an electron capture detector (ECD). The data show that methamidophos was present in both Manila and Ataulfo mango with no degradation but a slight increase in methamidophos concentration in week 7. On the other hand, parathion in both Manila and Ataulfo mango was first degraded from week 1 to week 7, and then accumulated in the fruit during last period corresponding to last stage of mango ripening. Further, most samples were found above the MRLs established by FAO and EPA for methamidophos and parathion. We conclude that while methamidophos trends to accumulate during the ripening period in both varieties
PP23.14 The exposure to methamidophos induced genotoxic damage on HepG2 cells S.P. Cotino-Najera, M. Ramirez-Vargas, V. Antonio-Vejar, M. Olea-Flores, M.E. Moreno-Godinez Laboratory of Toxicology and Environmental Health, Autonomous University of Guerrero, Chilpancingo, Guerrero, Mexico Introduction: The classical mechanism of toxicity associated with organophosphorus pesticides (OP) is the inhibition of acetylcholinesterase activity leading to neurotoxic effects. However, genotoxic effects could be an important mechanism through which OP exert their toxicity effects. Methamidophos (MET) is an OP widely used in the south of Mexico in agriculture. It is unknown whether MET induces DNA damage at concentrations of biological relevance. Objective: The present investigation was focused in the determination of the genotoxic damage of MET using HepG2 cells as a test model based on the fact that liver is the main organ implicated on the metabolism of pesticides. Materials and methods: HepG2 cells were exposed to MET (0–500 mg/L) for 48 h, this exposure was not cytotoxic from the HepG2 cells, comet assays were performed to determine the genotoxic damage by exposure to MET, the olive tail moment (OTM) was measured. Results: Results from MTT assays indicated that MET at concentrations of 10, 20, 50, 350 or 500 mg/L does not change the cell viability of HepG2 at 48 h of exposure. The comet assay resulted in a significant increase of OTM at concentrations of 10, 20, or 50 mg/L, however; only the exposure to 500 mg/L was statics significant (p < 0.05) in exposed HepG2 cells to MET, versus controls at 48 h. Conclusions: These results suggest that biological relevant concentrations of MET are capable of inducing genotoxic effects in HepG2 cells. Financial support: This study was partially supported by the Pesticide Toxicology Network (Conacyt-Mexico #253789/271775). http://dx.doi.org/10.1016/j.toxlet.2016.07.531 PP23.15 Double strand breaks and DNA repair protein induction by pesticides K. Suárez-Larios, R.D. Montero-Montoya Department of Genomic Medicine and Environmental Toxicology. Institute of Biomedical Research, Universidad Nacional Autónoma de México, Ciudad de México, Mexico Introduction: Several studies have found an association between the exposure to pesticides with chronic pathologies including neurological and reproductive effects or developmental problems and cancer. In the last years, these compounds have been proposed as leukemogenic agents, probably by producing reciprocal translocations. However, this idea has not been explored yet, having thus an information gap. Objective: The aim of this study is to generate knowledge about the role of some pesticides and their metabolites in the formation of reciprocal translocations. We evaluated two steps that lead to the formation of this type of damage: the production of double strand breaks (DSB) in DNA and their subsequent recombination repair, either via HR or NHEJ.
S221
Materials and Methods: We selected eight pesticides and metabolites. DSB were evaluated as foci of phosphorylated histone H2AX by immunofluorescence microscopy in lymphocytes treated during 1.5 h with four concentrations of each pesticide or metabolite. Repair proteins, phosphorylated Ku80 (NHEJ) or Rad51 (HR) were identified by Western blot in mononuclear cells treated with the pesticides that induced significant DSB. Results: We found a significant increase in foci with permetrin, glyphosate, paraoxon, pentaclorophenol and endosulfan lactone, the latter in a dose dependent manner, being the last three the metabolites of parathion, lindane and endosulfan. All these compounds induced a significant increase in phosphorylated Ku80 or Rad51 in at least one dose. Conclusions: Pesticides are capable of producing DSB’s in lymphocytes and, consequently, induce the phosphorylation and/or induction of proteins associated to repair mechanisms of this type of damage. Financial support: PAEP, 2016. Coordinación de Estudios de Posgrado, UNAM and Children Environmental Health Network (Conacyt-251229/271626). http://dx.doi.org/10.1016/j.toxlet.2016.07.532 PP23.16 Methamidophos and parathion degradation kinetic in Ataulfo and Manila mango during the ripening period F.D. Jaimes-Rendón 1 , H. Sotelo-Arroyo 1 , M.E. Moreno Godínez 2 , D. Návez González 3 , G. Huerta-Beristain 1 1
Laboratorio de Biotecnología, Facultad de Ciencias Químico Biológicas. Universidad Autónoma de Guerrero, Chilpancingo, Guerrero, Mexico 2 Laboratorio de Toxicología y Salud Ambiental, Facultad de Ciencias Químico Biológicas, Universidad Autónoma de Guerrero, Chilpancingo, Guerrero, Mexico 3 Laboratorio de Toxicología Ambiental, Unidad de Investigación Especializada en Microbiología, Universidad Autónoma de Guerrero, Chilpancingo, Guerrero, Mexico Organophosphate pesticides (OPs), organic compounds derived from phosphorus, are used worldwide in industry and agriculture to improve the quality and quantity of food. Mexico is the fifth producer of Mango worldwide and Guerrero state is the main Mexican producer. To avoid mango production loss due to pests, many OPs are commonly used on crops. This study evaluated the degradation kinetics of OPs (methamidophos and parathion) in mango fruit, specifically in Manila and Ataulfo mango. Manila or Ataulfo mango samples were collected from Tecpan de Galeana, Guerrero, Mexico during the ripening season once per week, for 11 weeks. Samples were used to determine levels of organophosphate pesticides including methamidophos, parathion, diazinon, methyl parathion and malathion. OPs extracion and purification were performed by the dispersion of solid phase matrix method, whereas OPs pesticides quantification was performed by gas chromatography (GC) coupled to an electron capture detector (ECD). The data show that methamidophos was present in both Manila and Ataulfo mango with no degradation but a slight increase in methamidophos concentration in week 7. On the other hand, parathion in both Manila and Ataulfo mango was first degraded from week 1 to week 7, and then accumulated in the fruit during last period corresponding to last stage of mango ripening. Further, most samples were found above the MRLs established by FAO and EPA for methamidophos and parathion. We conclude that while methamidophos trends to accumulate during the ripening period in both varieties