Cytostatic and genotoxic effect of temephos in human lymphocytes and HepG2 cells.

Temephos is an organophosphorus pesticide that is used in control campaigns against Aedes aegypti mosquitoes, which transmit dengue. In spite of the widespread use of temephos, few studies have examined its genotoxic potential. The aim of this study was to evaluate the cytotoxic, cytostatic and genotoxic effects of temephos in human lymphocytes and hepatoma cells (HepG2). The cytotoxicity was evaluated with simultaneous staining (FDA/EtBr). The cytostatic and genotoxic effects were evaluated using comet assays and the micronucleus technique. We found that temephos was not cytotoxic in either lymphocytes or HepG2 cells. Regarding the cytostatic effect in human lymphocytes, temephos (10 µM) caused a significant decrease in the percentage of binucleated cells and in the nuclear division index as well as an increase in the apoptotic cell frequency, which was not the case for HepG2 cells. The comet assay showed that temephos increased the DNA damage levels in human lymphocytes, but it did not increase the MN frequency. In contrast, in HepG2 cells, temephos increased the tail length, tail moment and MN frequency in HepG2 cells compared to control cells. In conclusion, temephos causes stable DNA damage in HepG2 cells but not in human lymphocytes. These findings suggest the importance of temephos biotransformation in its genotoxic effect.

Evaluation of pollution in Camichin estuary (Mexico): pro-oxidant and antioxidant response in oyster (Crassostrea corteziensis).

The physiological system of molluscs, particularly pro-oxidant and antioxidant mechanisms, could be altered by pollutants and induce disturbance on health status and productive parameters of aquatic organisms, such as oyster. Therefore, the aim of this study was to evaluate the chemical contamination in water (total metals and polycyclic aromatic hydrocarbons) and oxidative stress parameters in oysters (Crassostrea corteziensis) in Camichin estuary, located in Mexican Tropical Pacific. The results obtained showed the presence of arsenic, lead and zinc, as well as naphthalene, pyrene and benzo[a]pyrene in concentrations relatively higher than criteria established by local and international guidelines. Regarding the biomarkers of oxidative stress response (H2O2 and O2 concentration, catalase activity, lipid peroxidation, and hydroperoxide concentration), differences between oyster from estuary and control group were significant. These results indicate that these pollutants could be related with oxidative stress detected in oyster.

Organophosphate pesticides increase the expression of alpha glutathione S-transferase in HepG2 cells.

Chlorpyrifos and methyl parathion are among the most widely used insecticides in the world. Human populations are constantly exposed to low doses of both due to their extensive use and presence in food and drinking water. Glutathione S-transferase (GST) catalyzes the conjugation of glutathione on electrophilic substrates and is an important line of defense in the protection of cellular components from reactive species. GST alpha1 (GSTA1) is the predominant isoform of GST expressed in the human liver; thus, determining the effect of insecticides on GSTA1 transcription is very important. In the present study, we analyzed the effects of methyl parathion and chlorpyrifos on GSTA1 gene expression in HepG2 cells using real time PCR, and activity and immunoreactive protein assays. The results demonstrated that exposure to methyl parathion and chlorpyrifos increased the level of GSTA1 mRNA, GSTA1 immunoreactive protein and GST activity relative to a control. These results demonstrated that these insecticides can increase the expression of GSTA1. In conclusion, HepG2 cell cultures treated with methyl parathion and chlorpyrifos could be a useful model for studying the function of GSTA1 and its role in the metabolism of xenobiotics in the liver.

Phytoremediatory effect and growth of two species of Ocimum in endosulfan polluted soil.

Endosulfan is a hazardous organochlorine pesticide banned or restricted in several countries. However, it has been found in the environment and in animal samples. To study a potential way to bioremediate soils contaminated with this pesticide, two plant species of the genus Ocimum were studied: Ocimum basilicum L. and Ocimum minimum L., since they are economically feasible and well adapted to the climatic conditions of the Nayarit zone (Mexican pacific coast). Young plants were transplanted into soil experimentally polluted with endosulfan. Growth of both species was not affected by endosulfan, the plants grew, flourished, and produced seeds; 30 days later, endosulfan concentration was lower in the soil with O. basilicum than in the soil without plants. On day 90, no differences in endosulfan concentrations were found between soil with or without O. minimum. At day 1, plants in the polluted soil showed lipoperoxidation, as measured by thiobarbituric acid-reactive species (TBARS). Interestingly, a higher TBARS value was observed at day 3 in transplanted plants as compared to non-transplanted plants. In conclusion, both species can endure endosulfan pollution (as high as 1 g kg(-1)) in soils. O. basilicum seems to be an adequate candidate for bioremediation of soils polluted with endosulfan.

Acetylcholinesterase and metallothionein in oysters (Crassostrea corteziensis) from a subtropical Mexican Pacific estuary.

Substantial efforts have been devoted to developing and applying biomarkers for ecological risk assessment. Bivalve mollusks, such as mussels and oysters, are commonly used in environmental monitoring programs because of their wide geographical distribution, great sensitivity to environmental pollutants, and ability to accumulate anthropogenically derived chemicals at a high rate. Acetylcholinesterase (AChE) activity and metallothionein (MT's) content are representative specific biomarkers that indicate the presence of anticholinesterasic compounds (like organophosphorus and carbamate pesticides) and metals, respectively. The aim of this study was to evaluate AChE activity and MT's content in Crassostrea corteziensis from Boca de Camichín estuary. The results obtained here showed that AChE activity was 65% lower in oysters from Boca de Camichín than in control organisms. In contrast, MT's content in collected organisms was not statistically different from that in control organisms. AChE activity and MT's content in oysters could be used as early biomarkers of effects and exposure to pesticides and heavy metals, respectively, in aquatic environments.

Immunologic parameters evaluations in Nile tilapia (Oreochromis niloticus) exposed to sublethal concentrations of diazinon.

Fish resistance to microorganisms depends basically on the immune response. Although there are several studies on the diazinon mammalian immunotoxicity, in the case of fish there are only few. The aim of present study was to evaluate the effect of diazinon on immunological parameters (relative spleen weight, splenocytes count, lysozyme activity, respiratory burst and IgM concentration) in Nile tilapia. Diazinon at sublethal concentrations (0.39 and 0.78 mg/L) did not alter RSW, splenocytes count or lysozyme activity. However, at the highest concentration tested (1.96 mg/L) diazinon significantly increased respiratory burst and IgM concentration. In summary, diazinon (and perhaps other pesticides) could alter immunological response and induce oxidative stress.

Effect of sub-lethal concentrations of endosulfan on phagocytic and hematological parameters in Nile tilapia (Oreochromis niloticus).

The effect of endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin-3-oxide), an organochlorine pesticide, was evaluated on phagocytic (phagocytic index and percentage of active cells) and hematological parameters in Nile tilapia. Experimental data showed that an acute exposure to endosulfan (4.0 and 7.0 microg/L) induces a significant decrease in the phagocytic index and the percentage of active cells in peripherical blood of Nile tilapia. However, hemoglobin concentration (Hb), hematocrit (Hto), red blood cell count (RBC), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) were not significantly altered in fish exposed to endosulfan compared with control group.

Effect of Chlorpyrifos on the Hematology and Phagocytic Activity of Nile Tilapia Cells (Oreochromis niloticus).

Chlorpyrifos is an organophosphorous insecticide widely used in agriculture and domestic activities. However, little is known about the effect of this pesticide on the immune system of fish and other alterations of its physiological system. The aims of the present study were the evaluation of the LC(50) (lethal concentration(50)) and the potential toxicity of this substance on Nile tilapia (Oreochromis nilotucus), as well as its effect on some hematological values and phagocytic functions of this fish. Results obtained showed that chlorpyrifos does not have any effect on the following parameters: number of red blood cells, hemoglobin, hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC). However, the phagocytic index and the percentage of phagocytic active cells were significantly affected, which could indicate that phagocytic parameters from Nile tilapia are more sensitive than hematological ones to assess the effect of acute intoxication with chlorpyrifos.