Genotoxicity evaluation of environmental pollutants using analysis of nucleolar alterations

Abstract

Nucleolar alterations resulting from the action of either chemical or physical agents can serve as important genotoxicity biomarkers. In this study, the efficiency of AgNOR banding technique to identify the presence of nucleoli in micronucleus and assess nucleolar alterations in aberrant cells of Allium cepa was evaluated. Seeds of this plant were exposed to both water samples from a river that receives untreated urban effluent and to the trifluralin herbicide (0.84 mg/L concentration), both analyzed in two different seasons (summer and winter seasons). Samples induced significant frequencies of chromosomal and nuclear aberrations and micronuclei, as observed in cells submitted to conventional chromosomal staining. The herbicide caused a significant increase in the number of nucleoli and micronuclei, interpreted as due to the elimination of excessive nucleolar material resulting from polyploidization. The use of the AgNOR technique enabled the identification of both the presence of the nucleolus in some micronuclei and the nucleolar organizer region (NOR) behavior of aberrant cells. The NOR-banding technique showed to be an efficient tool for studying the genotoxic effects caused by a xenobiotics and a complex environmental sample.

Assessment of the cytotoxic, genotoxic and mutagenic effects of the commercial black dye in Allium cepa cells before and after bacterial biodegradation treatment

“…Chromosomal staining techniques have been successfully applied to chromosomal analyses in plants (Tuna et al, 2004) and may provide information about the DNA composition and its arrangement along chromosomes, enabling a more detailed analysis of the structural organization of chromosomes (Kim et al, 2002). Staining with silver nitrate has been used to identify the number of nucleoli and possible active sites of NOR in different plant species (Carvalho and Guerra, 2002;Ventura-Camargo et al, 2011;Mazzeo and Marin-Morales, 2015). The positions of NORs helps researchers gain a better understanding of the chromosomal alterations that were established in each karyotype (Mazzeo and Marin-Morales, 2015).…”

“…Staining with silver nitrate has been used to identify the number of nucleoli and possible active sites of NOR in different plant species (Carvalho and Guerra, 2002;Ventura-Camargo et al, 2011;Mazzeo and Marin-Morales, 2015). The positions of NORs helps researchers gain a better understanding of the chromosomal alterations that were established in each karyotype (Mazzeo and Marin-Morales, 2015). Thus, in cases in which chromosomal aberrations are induced by genotoxic agents, this technique may provide particular sensitivity by easily diagnosing the probable sites of action of these agents and determining the cell aberrations they caused.…”

Efficacy of Avena Sativa L. And Trifolium Alexandrinum L. Test System for Detecting the Genotoxic and Phytotoxic Potential of Water Pollution

“…SM samples were taken in a period with almost no precipitation (0 mm); they are the most contaminated, likely due to low precipitation in this dry season which suggests a higher concentration of pollutants in the water of river. The increase in temperature, as observed in summer, promotes water evaporation and can elevate the dissolution of substances in water, including some metals (Delpla et al, 2009;Mazzeo and Marin-Morales, 2015). However, much precipitation occurred in the winter seasons (72.14 mm in January and 90.93 mm in February 2015.)…”

Genotoxic Biomarkers in Fishes of the Chapada Das Mesas National Park, Brazil

“…The genetic material of eukaryotic cells of fish species can also be altered by exposure to dissolved chemicals in the water, resulting in the formation of micronuclei, which can be used as biomarkers to assess the degree of contamination in the environment [14]. The micronuclei are derived from chromosomal fragments resulting from breaks that are not incorporated into the main nucleus of the daughter cells after mitosis due to damage introduced into the parental cells [15].…”