In vitro induction of sister chromatid exchanges and chromosomal aberrations in peripheral lymphocytes of the oyster toadfish and American eel

Dimethoate induces genotoxicity as a result of oxidative stress: in vivo and in vitro studies

Dimethoate ([O,O-dimethyl S-(N-methylcarbamoylmethyl) phosphorodithioate]) is an organophosphate insecticide and acaricide widely used for agricultural purposes. Genotoxicity refers to the ability of a chemical agent interact directly to DNA or act indirectly leading to DNA damage by affecting spindle apparatus or enzymes involved in DNA replication, thereby causing mutations. Taking into consideration the importance of genotoxicity induced by dimethoate, the purpose of this manuscript was to provide a mini review regarding genotoxicity induced by dimethoate as a result of oxidative stress. The present study was conducted on studies available in MEDLINE, PUBMED, EMBASE, and Google scholar for all kind of articles (all publications published until May, 2020) using the following key words: dimethoate, omethoate, DNA damage, genetic damage, oxidative stress, genotoxicity, mutation, and mutagenicity. The results showed that many studies were published in the scientific literature; the approach was clearly demonstrated in multiple tissues and organs, but few papers were designed in humans. In summary, new studies within the field are important for better understanding the pathobiological events of genotoxicity on human cells, particularly to explain what cells and/or tissues are more sensitive to genotoxic insult induced by dimethoate.

Herbal medicine against genotoxicity of dimethoate, an insecticide, in mammalian somatic cells

In this study, the genotoxic effects of dimethoate (DIM) were investigated with the in vitro micronucleus test in human peripheral lymphocytes. The ethanol extracts of Rosa canina and Salvia lavandulifolia were used to remove possible genotoxic effects of these substances. For this purpose, different concentrations (0.5-1-2 μg/mL) of dimethoate, DIM + RC_eta and DIM + SL_eta (1:1 v/v) application groups were prepared and applied to the blood culture. The obtained data were compared with the negative control group that was prepared with dimethyl sulfoxide (DMSO) as solvent and a well-known genotoxic effects of ethyl methanesulfonate (EMS) as positive control group. It was observed in lymphocyte cells that the frequency of MN considerably increased depending on the increasing dose of DIM whereas the nuclear division index (NBI)decreased according to the control group, especially in the last concentration (2 μg/mL). But, as the MN frequency decreased, NBI values approached to control group with 2μg/mL DIM + RC_eta and 2μg/mL DIM + SL_eta according to DIM application group (P < 0.05). Additionally, RC_eta and SL_eta were analyzed by gas chromotography-mass spectrometry (GC-MS).

Protective Effects of Quercetin against Dimethoate-Induced Cytotoxicity and Genotoxicity in Allium sativum Test

The present investigation was directed to study the possible protective activity of quercetin-a natural antioxidant against dimethoate-induced cyto- and genotoxicity in meristematic cells of Allium sativum. So far there is no report on the biological properties of quercetin in plant test systems. Chromosome breaks, multipolar anaphase, stick chromosome, and mitotic activity were undertaken in the current study as markers of cyto- and genotoxicity. Untreated control, quercetin controls (@ 5, 10 and 20 μg/mL for 3 h), and dimethoate exposed groups (@ 100 and 200 μg/mL for 3 h) were maintained. For protection against cytogenotoxicity, the root tip cells treated with dimethoate at 100 and 200 μg/mL for 3 h and quercetin treatment at 5, 10, and 20 μg/mL for 16 h, prior to dimethoate treatment, were undertaken. Quercetin was found to be neither cytotoxic nor genotoxic in Allium sativum control at these doses. A significant increase (P < 0.05) in chromosomal aberrations was noted in dimethoate treated Allium. Pretreatment of Allium sativum with quercetin significantly (P < 0.05) reduced dimethoate-induced genotoxicity and cytotoxicity in meristematic cells, and these effects were dose dependent. In conclusion, quercetin has a protective role in the abatement of dimethoate-induced cyto- and genotoxicity in the meristematic cells of Allium sativum that resides, at least in part, on its antioxidant effects.

Genotoxicity associated with oxidative damage in the liver and kidney of mice exposed to dimethoate subchronic intoxication

BACKGROUND AND AIMS

Because of the widespread use of pesticides for domestic and industrial applications, the evaluation of their toxic effects is of major concern to public health. The aim of the present study was to investigate the propensity of dimethoate (DM), an organophosphorus pesticide, to cause oxidative damage in the liver and kidney of mice and its associated genotoxic effect.

METHODS

DM was administered intraperitoneally at doses of 1, 5, 10, 15, and 30 mg/kg body weight for 30 consecutive days in BALB/c mice. Oxidative stress was monitored in the kidney and liver by measuring malondialdehyde level, protein carbonyl concentration, and the catalase activity. The genotoxicity of DM was assessed by the comet assay in vivo.

RESULTS AND DISCUSSION

Our results indicated that DM inhibited acetylcholinesterase activities in the liver and kidney of treated mice. DM increased lipid peroxidation and protein carbonyl levels in the liver and kidney in a dose-dependent manner. Catalase activity was found to be significantly increased in the liver and kidney at doses higher than 5 mg/kg body weight.

CONCLUSIONS

Our study demonstrated that DM induced DNA damage in the liver and kidney of treated mice in a dose-dependent manner; this induction was associated to DM-induced oxidative stress. Further investigations are needed to prove the implication of oxidative stress in genotoxicity induced by DM.

Genotoxicity Evaluation of Dimethoate to Experimental Mice by Micronucleus, Chromosome Aberration Tests, and Comet Assay

Dimethoate (DM) is an organophosphate insecticide with numerous uses on field and agricultural crops and ornamentals. Data concerning DM-acute genotoxicity are controversial and knowledge on its delayed effect is limited. For this reason, we aimed to further explore DM genotoxicity resulting from subchronic intoxication of experimental mice. Thus, DM was administered to mice at doses ranging from 1 to 30 mg/kg body weight for a period of 30 consecutive days. There was a significant increase ( P < .05) in the frequency of micronucleated bone marrow cells following DM administration. Furthermore, the chromosome aberration assay revealed a significant increase in the percentage of chromosome abnormalities in a dose-dependent manner. Dimethoate was also found to induce significant DNA damage in mouse bone marrow cells as assessed by the comet assay. Altogether, our results showed that, after a subchronic exposure, DM was a genotoxic compound in experimental mice.

Effects of pesticides on human peripheral lymphocytes in vitro: induction of DNA damage

Because of the widespread use of pesticides for domestic and industrial applications the evaluation of their genotoxic effects is of major concern to public health. Although various experimental data have provided evidence that pesticides can possess genotoxic properties in animals and in in vitro test systems after acute and chronic exposure, the information on the genotoxic effects of some of pesticides is limited and inconsistent. In the present study, the genotoxic potential of commonly used pesticides (i.e., dimethoate and methyl parathion from the organophosphate class, propoxur and pirimicarb from carbamates, and cypermethrin and permethrin from pyrethroids) have been evaluated. The genotoxic effects of these substances were examined using the single cell gel electrophoresis (comet) assay in freshly isolated human peripheral lymphocytes. The cells were incubated with 10, 50, 100 and 200 microg/ml concentrations of the test substances for 0.5 h at 37 degrees C and DNA damage was compared with that obtained in lymphocytes from the same donor not treated with substances. Hydrogen peroxide, 100 microM, was used as a positive control. Within the concentration ranges studied, no significant cytotoxic effects were observed. Dimethoate and methyl parathion at 100 and 200 microg/ml; propoxur at 50, 100 and 200 microg/ml, and pirimicarb, cypermethrin and permethrin at 200 microg/ml significantly increased DNA damage in human lymphocytes.

In vitro cytogenetic testing of an organoselenium compound and its sulfur analogue in cultured rat bone marrow cells

Background

Selenium (Se) is a non-metal element, occurring in varying degrees in the environment and it has been found to be a component of several enzymes. Different selenium compounds have been associated with carcinogenicity, toxicity, modification of metal toxicity and prevention of cancer. Organoselenium compounds had substantially greater bioavailability and less toxicity than that of inorganic selenium. From a chemical point of view, Se resembles sulfur (S) in many of its properties, thus, Se and S may be considered to be isosteric. The ability of a synthetic organoselenium compound; cyclopenta-dienyldicarbonyl ironselenoterephthalic acid (CSe) and its sulfur analogue (CS) in the range of 10^-8 to 10^-5 M, to induce sister-chormatid exchanges (SCE) and alter cell division expressed as mitotic index (MI) as well as cell survival has been investigated.

Methods

Rat bone marrow cells were cultured in the presence of CSe and CS in the range of 10^-8 to 10^-5 M with a total exposure time of 4, 16 or 28 h at 37°C. Fluorescence-plus-Giemsa (FPG) technique was used to visualize chromosomes for SCE analysis and MI determination. Trypan blue exclusion technique was used to determine cell viability.

Results

At the three exposure times, cell survival progressively decreased with increasing concentration, but the effect of either chemical was not significant (ANOVA; P < 0.05) as compared to the negative control. Significant reductions in MI were calculated at the highest concentration (10^-5 M) when either chemical was applied for 16 or 28 h. Furthermore, the mean SCE increased with longer exposure times and, in general, CSe had slightly greater effect on cell survival and caused higher frequencies of SCE than CS. The exception was the 10^-8 M treatment. However, both CSe and CS failed to induce 2-fold SCE as that of the negative control and therefore they are not considered as mutagens.

Conclusion

Both CSe and CS in the range of 10^-8 to 10^-5 M could not double the SCE rate of the negative control and therefore not considered as mutagens at these experimental conditions.

DNA integrity and total oxyradical scavenging capacity in the Mediterranean mussel, Mytilus galloprovincialis: a field study in a highly eutrophicated coastal lagoon

In Mediterranean coastal lagoons, the combination of human impact and wide variability of natural environmental factors can lead to upsets in ecosystem homeostasis resulting in biodiversity decline. Oxidative damage has been causally linked to various kinds of environmental stress, both natural and artificial, the result being impairment of cellular functions. DNA damage and the efficiency of antioxidant defences in Mytilus galloprovincialis from the highly eutrophicated Orbetello Lagoon (Tuscany, Italy) were investigated, respectively by the single cell gel electrophoresis (or Comet test) and the total oxyradical scavenging capacity assay. Results showed significantly higher levels of DNA damage in mussels collected from the inner parts of the lagoon compared to specimens from more external sites. Specimens with the lower genetic integrity also exhibited a reduced efficiency in neutralizing three potent cellular oxidizing species, namely peroxyl radicals (ROO*), hydroxyl radicals (*OH) and peroxynitrite (HOONO), suggesting the involvement of reactive oxygen species in mediating the genetic damage. The analyzed biological parameters also showed a seasonal variability with a minimum of both DNA integrity and antioxidant scavenging efficiency during the warm months and an opposite trend in winter. The potential of analyzed techniques is discussed for the assessment of both anthropogenic and natural disturbance.

Sister-chromatid exchanges in human lymphocytes induced by dimethoate, omethoate, deltamethrin, benomyl and their mixture

Dimethoate and omethoate, two common organophosphorus insecticides, induced a dose-related increase in the frequency of sister-chromatid exchanges (SCEs) in human lymphocytes in vitro (P of the regression lines less than 0.01). Two other common pesticides, the pyrethroid insecticide deltamethrin and the systemic fungicide benomyl, induced a modest increase in SCEs which bordered on statistical significance (P = 0.053 and 0.055, respectively). Mixtures of the four pesticides at total concentrations of 41.5 and 83 micrograms/ml (composed of 43% dimethoate, 43% omethoate, 12% deltamethrin and 1.2% benomyl) induced a dose-dependent increase in SCEs (P less than 0.01). The effects of these mixtures of pesticides were variable using lymphocytes from different individuals, although these differences did not attain statistical significance. Moreover, low concentrations of the four pesticides that did not increase SCEs significantly when tested alone, were positive for SCE induction when tested as a mixture. The experiments show that sub-threshold doses of pesticides may increase SCEs when present in a mixture.

Genotoxic, carcinogenic, and teratogenic hazards in the marine environment, with special reference to the Mediterranean Sea

Genotoxic, carcinogenic, and teratogenic hazards arising out of pollution in the marine environment are discussed in this article, with special reference to the situation in the Mediterranean area. A number of chemical compounds or complex mixtures relevant to marine pollution, either natural or of anthropogenic origin, are tentatively listed, along with protective factors which may play a counteracting role in the same environment. Harmful substances tend to undergo interactions and transformations in seawater, sediments, and marine biota, due to physical, chemical, microbial, or light-mediated mechanisms. Bioaccumulation phenomena in marine organisms may result from food-chain biomagnification processes or from concentration of pollutants by filter feeders. A variety of sources can account for marine pollution by genotoxic, carcinogenic, and teratogenic compounds, but there is a relative paucity of analytical data concerning the Mediterranean. Metabolic transformations of xenobiotics occur in all marine organisms, the biochemical mechanisms in fish being comparable to those which have been extensively investigated in mammals. Induction of metabolic pathways, and especially of the mixed-function oxygenase system, represents the earliest warning signal of exposure to pollutants. Occurrence of neoplastic diseases is documented by experimental and field studies in marine vertebrates as well as in invertebrates. The association with local pollution phenomena has been recognized in several studies, but other etiopathogenetic factors may be also involved, and in some cases tumors have been reported to be unrelated to chemical pollution. Genotoxic agents have been detected by means of suitable techniques in seawater, sediments, and marine organisms. Several studies have investigated the presence of carcinogen-DNA adducts, DNA damage and repair processes, and cytogenetic alterations, such as chromosomal aberrations, sister-chromatid exchanges, and micronuclei, in tissues of marine organisms. However, monitoring of these end-points under field conditions encounters some limitations and problems. Even more fragmentary is the information on teratogenic effects in marine organisms, although interesting test systems have been set up. On the whole, a quite extensive database on all these toxicological issues is already available in the literature, but further studies are warranted for an adequate assessment of genotoxic, carcinogenic, and teratogenic hazards, and possibly counteracting factors in the marine environment, and specifically in the Mediterranean Sea.

Induction of sister-chromatid exchanges and chromosomal aberrations in hematopoietic tissue of a marine fish following in vivo exposure to genotoxic carcinogens

The development of procedures to assess genetic damage in fish exposed in situ to point sources of aquatic pollution can be expected to contribute to the evaluation of the role of genotoxic contaminants in epizootic neoplasia in fish populations. To this end methods have been developed for assessing the in vivo induction of chromosomal aberrations (CAs) and sister-chromatid exchanges (SCEs) in tissues of a marine teleost, the oyster toadfish, which may be applicable to other species. An alternative to the solid tissue and squash techniques for metaphase preparation permits the resolution of more than 100 SCEs/metaphase in toadfish kidney cells, which have moderately large chromosomes (0.122 pg DNA/chromosome). The bleeding of toadfish which have been injected with 5-bromodeoxyuridine (BrdUrd) and the subsequent use of hematopoietic tissue (kidney) for cytogenetic analysis was shown to increase the metaphase yield and provide a more predictable production of second-division metaphases required for SCE analysis. With these methods linear dose-dependent increases in chromatid-type exchange CAs and SCEs were obtained with i.p. exposure to ethyl methanesulfonate (EMS) and cyclophosphamide (CP). The doses required to double the observed control SCE frequencies (least effective doses) were 170 mg/kg for EMS and 7.4 mg/kg for CP. which are comparable to those reported for rodent bone marrow assays. A BrdUrd-sensitive site for chromatid breakage was observed on a pair of apparently homologous acrocentric chromosomes for the toadfish.