IN VIVO SISTER CHROMATID EXCHANGES: A TEST SYSTEM MONITORING ENVIRONMENTAL GENOTOXICITY.

An in vivo sister chromatid exchange (SCE) assay system for monitoring environmental genotoxicity, using bone marrow cells has been developed, tested and applied to groups of inbred and wild mice under various environmental conditions. The best results were obtained with nine, serial, intraperitoneal injections of 5-bromo-2\u27-deoxyuridine (BUdR) (40 (mu)g/g of body weight) and 5-fluorodeoxyuridine (FUdR) (2 (mu)g/g of b.w.) and then with 5 (mu)g/g of b.w. of colchicine, given on the 27th hour following the first injections of BUdR/FUdR. The mice were sacrificed 3 hours later. With the above injection schedule, male mice of C3H/HeJ and C57BL/6J maintained in the laboratory gave a mean (+OR-) SEM baseline SCE value of 3.42 (+OR-) 0.07 and 3.62 (+OR-) 0.08 respectively. The female mice of the same strains gave higher numbers of SCEs/cell. Males obtained from natural populations in southwestern Ontario had a higher mean SCE value (6.02 (+OR-) 0.16) as did the inbred males maintained in outdoor enclosures (5.08 (+OR-) 0.22). Wild mice maintained in the laboratory for a period of six months or more, gave SCE values similar to those of the control mice (3.46 (+OR-) 0.12). The SCE values in wild caught mice and in enclosure maintained inbreds were inversely proportional (r = -0.49) to the distance between the sites where the animals were either collected or maintained and the nearest major industrial centres. Based on the differences in SCE values between laboratory maintained mice and wild mice as well as laboratory maintained and inbred mice housed at various outdoor sites together with the geographic patterns in SCE levels, it is suggested that the in vivo SCE analysis in bone marrow cells using the bromodeoxyuridine substitution method, has the potential of being an early warning surveillance system for the general levels of environmental genotoxic agents.Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1983 .N393. Source: Dissertation Abstracts International, Volume: 44-03, Section: B, page: 0679. Thesis (Ph.D.)--University of Windsor (Canada), 1983

Tradescantia bioassays as monitoring systems for environmental mutagenesis: a review.

Since the early studies on the genetic effects of chemical and physical agents, species and clones of Tradescantia have been used as experimental subjects, by virtue of a series of favorable genetic characteristics. Bearing just six pairs (2n = 12) of large, easily observable chromosomes, cells from almost every part of the plant, from the root tips to the developing pollen tube, yield excellent material for cytogenetic studies. As a consequence of the intensive use of Tradescantia in genetic studies, a series of genetic characteristics have been found that offer opportunities for the detection of agents affecting the stability of the genome. At least five such characteristics have been selected as endpoints for the establishment of assays to evaluate mutagenesis. Three of these, root-tip mitosis, pollen-tube, and microspore mitosis are essentially chromosome aberration assays, wherein one observes and evaluates the visible damage in the chromosomes. A fourth, the stamen-hair mutation assay (Trad-SHM), is a point mutation mitotic assay based on the expression of a recessive gene for flower color in heterozygous plants. The fifth assay is a cytogenetic test based on the formation of micronuclei (Trad-MCN) that result from chromosome breakage in the meiotic pollen mother cells. This article examines the characteristics and fundamentals of the Trad-MCN and the Trad-SHM assays and reviews the results obtained to date with these systems in the assessment of environmental mutagenesis

Comparison between the Comet Assay and Fast Micromethod® for Measuring DNA Damage in HeLa Cells

The sensitivity and precision of the single cell gel electrophoresis (Comet) assay and Fast Micromethod® for DNA damage determinations in human HeLa cell line were compared. The first assay allows analysis of DNA breaks in individual cells while the second is a rapid and convenient procedure for DNA breaks determination in cell suspensions on single microplates. Both assays detect DNA strand breaks, alkali-labile sites and transient breaks occurring at sites of ongoing repair and might be applied for the assessment of surface water genotoxic potential as well as for clinical use. DNA damage in HeLa cells was induced by different doses of γ-rays generated by Cs137 (8 to 500 cGy), UV-C light (10 to 1000 J m-2) and by different concentrations of 4-nitroquinoline-V-oxide (0.026-2.6 μmol dm-3). Gamma rays induced a dose-depended response with the average Comet tail moment values from 7 mm for the negative control to 291 mm for 200 cGy, from 6.1 to 192 mm for 500 J m-2 of UV-C light and from 7.1 to 238 mm for 1.0 μmol dm-3 of 4-nitro-quinoline-N-oxide. The Fast Micromethod® strand scission factor varied from 0.010 for negative control to 0.701 for 500 cGy, from 0.019 to 1.196 for 1000 J m-2 and from 0.003 to 0.810 for 0.5 μmol dm-3 of 4-nitroquinoline-IV-oxide. Sensitivity was the same for both methods and in the case of 4-nitroquinoline-IV-oxide even better precision (lower variation coefficient) was achieved with the Fast Micromethod®. Since the time required for multiple analysis by the Fast Micromethod® is short (2 hours or less), its use in measuring DNA breakage in cells can be recommended for environmental genotoxicity monitoring

Use of the Comet Assay to Evaluate Pesticide Toxicity on Non-Target Microalgae

Aquatic environments are often contaminated with numerous organic and inorganic compounds. More than 90% of the applied load of pesticides is dispersed in the environment, reaching non-target species of these aquatic systems. Several of these compounds are reported to be capable of interacting with the DNA of living cells and therefore cause genotoxic effects. The assessment of genotoxic potential in surface water is one of the main tasks of environmental monitoring for the control of pollution. Alkaline single-cell gel electrophoresis, also known as the comet assay, is a valuable technique which allows detection of DNA damage at single-cell level and provides a unique opportunity to investigate intercellular differences. The potential genotoxicity of herbicides on non-target freshwater microalgae using the comet assay was studied. Taking into account the results obtained, comet assay provides a sensitive and rapid system for measuring primary DNA damage in microalgae which could be an important aspect of environmental genotoxicity monitoring in surface waters

Comparison of the sensitivity of different toxicity test endpoints in a microalga exposed to the herbicide paraquat

[Abstract]The use of herbicides constitutes the principal method of weed control but the introduction of these compounds into the aquatic environment can provoke severe consequences for non-target organisms such as microalgae. Toxic effects of these pollutants on microalgae are generally evaluated using phytotoxicity tests based on growth inhibition, a population-based parameter. However, physiological cellular endpoints could allow early detection of cell stress and elucidate underlying toxicity mechanisms. Effects of the herbicide paraquat on the freshwater microalga Chlamydomonas moewusii were studied to evaluate growth rate and cellular parameters such as cellular viability and metabolic activity assayed by flow cytometry and DNA damage assayed by the comet assay. Sensitivity of growth and parameters assayed by flow cytometry were similar, showing a significant effect in cultures exposed to a paraquat concentration of 0.1 µM or higher, although in cultures exposed during 48 h to 0.05 µM, a significant stimulation of cellular fluorescein fluorescence was observed, related to cellular metabolic activity. After only 24 h of herbicide exposure significant DNA damage was observed in microalgal cells exposed to all paraquat concentrations assayed, with a 23.67% of comets in cultures exposed to 0.05 µM, revealing the genotoxicity of this herbicide. Taking into account the results obtained, comet assay provides a sensitive and rapid system for measuring primary DNA damage in Chlamydomonas moewusii, which could be an important aspect of environmental genotoxicity monitoring in surface waters.Ministerio de Educación y Ciencia; CGL 2004/02037 BOSGalicia.Consellería de Innovación, Industria e Comercio; PGIDIT05PXIC10303P

Can human biomonitoring studies contribute to improve public health decisions?

Abstract publicado em: J Clin Toxicol 2017, 7:3 (suppl)., 66. Doi: 10.4172/2161-0495-C1-025-005: Disponível em: https://www.omicsonline.org/conference-proceedings/2161-0495-C1-025-005.pdfStatement of the Problem: Our previous work has shown the presence of the hazardous chemicals within a complex mixture of contaminants (e.g., metals, pesticides, polycyclic aromatic hydrocarbons) trapped in sediments of a Portuguese estuary. In that case-study, an epidemiological survey confirmed the exposure of the local population mainly through food chain, suggesting the need of a biomonitoring study that includes the quantification of contaminants in biological fluids as well as biomarkers of early biological effects (e.g., biochemical, genetic and omics-based endpoints) in the target population. Recognizing the knowledge gap between exposure to hazardous substances and health outcomes, not only in Portuguese population, but also throughout Europe, the project European Human Biomonitoring Initiative (HBM4EU) has just started, with the overarching goal of generating knowledge towards the safe management of chemicals. Methodology & Theoretical Orientation: Human biomonitoring will be used to understand the human exposure to chemicals and resulting health impacts. The first steps rely on harmonizing procedures for human biomonitoring across countries, to provide policy makers with comparable data on human internal exposure to chemicals and mixtures of chemicals at EU level. Then, linking data on internal exposure with the hazardous chemicals, will allow to aggregate external exposure and identifying exposure pathways and upstream sources. Conclusion & Significance: By generating scientific evidence on the causal links between human exposure to chemicals and negative health outcomes, an evidence-base will be established to allow the use of human biomonitoring in chemical risk assessment methodologies to data. The risk management and communication with stakeholders and policy makers will ensure that results are applied in the design of new regulations for chemicals and for supporting public health protection policies.HBM4EU project, Grant agreement No: 733032info:eu-repo/semantics/publishedVersio