Alkaline Comet Assay as a Potential Tool in the Assessment of DNA Integrity in Freshwater Zooplankton Affected by Pollutants from Water Treatment Facility

Abstract

In this pilot study, we evaluated the usefulness of the alkaline comet assay as a biomonitoring tool at the level of plankton communities affected by varying water quality. Zooplankton was collected in autumn 2007 and spring 2008 in two shallow lakes, one being predominantly polluted with aluminium compounds as result of water treatment process (Lake Njivice; 45°10′ N, 14°30′ E) and the other unpolluted (Lake Ponikve; 45°05′ N, 14°30′ E) used as control. Water and sediment chemistry parameters were assessed at both lake sampling sites. The results indicated that the main pollutant in both matrices was aluminium, whose concentrations exceeded the value of 0.15 mg/L −1 legally accepted for drinking water by Croatian water quality regulations. Plankton composition of the investigated lakes showed that only a few species are dominant and appear at both sites. Cladocerans are represented by Daphnia magna Straus 1820, and copepods by the calanoid Eudiaptomus padanus etruscus (Losito 1901), the cyclopoid Cyclops sp. and dipterans by larvae of Chaoborus flavicans (Meigen 1830). Other species were determined only occasionally and with low abundance. As observed, the comet assay had adequate sensitivity to detect the differences in levels of DNA damage among the dominant zooplankton taxa. Zooplanktons collected in Lake Njivice show a lower degree of DNA integrity compared with animals from the reference lake (Lake Ponikve). Inter-species variability in DNA damage was observed, indicating different genome susceptibility to the same genotoxic pollutants present in the aquatic environment. Furthermore, in the polluted Lake Njivice, seasonal differences in the levels of DNA damage within particular species of zooplankton were also noted. Calanoida, Daphnia and Chaoborus mainly had higher values of all three comet parameters in autumn 2007 than in spring 2008. Feeding modes strongly influenced the level of DNA damage in zooplankton species studied. We assume that the mechanisms of DNA damage and genotoxicity, as Water Air Soil Pollut (

Impact of Genotoxic Contaminants on DNA Integrity of Copepod from Freshwater Bodies in Chennai, Tamil Nadu, India

“…This result was confirmed with Plankton as an Indicator of heavy Metal Pollution in a Freshwater Reservoir [6]. In previous study the Comet assay has been used to investigate the levels of DNA damage in marine and freshwater copepods exposed to different water borne pollutants [6,26]. According to Kumarave et al [27] DNA damage was minimal to moderate (<40%) in Chembarambakkam species and minimal to high (<86%) from species and the results suggested that the Retteri and Velacheri lake are contaminated with different types of genotoxicants.…”

“…The comet assay study indicated the potential of Cr, when present in excess concentrations induce DNA damage in the cells of copepod organisms. This result was confirmed with Plankton as an Indicator of heavy Metal Pollution in a Freshwater Reservoir [6]. In previous study the Comet assay has been used to investigate the levels of DNA damage in marine and freshwater copepods exposed to different water borne pollutants [6,26].…”

“…Known that copepod is a biomarker against genotoxic contaminants because they act as primary consumers in freshwater ecosystems and it is vulnerable to various environmental contaminants by uptake from the dissolved phase as well as from food sources [15] only a few studies have been carried out on impact of genotoxic contaminants in freshwater zooplankton [6]. The present study provides preliminary data of DNA integrity in Freshwater copepods (M. aspericornis) that are affected by varying water quality parameter particularly heavy metal.…”

“…Genetic approaches suggest powerful tools to investigate the modern status of populations, deduce the history of population changes and expecting future population direction [6] on living organisms, which have a response to genotoxicants, DNA damage due to genotoxicants experience in aquatic environment, can be used as a biological indicators or biomarkers [7]. They suggest the opportunity of genotoxicant assessment into aquatic environment and currently using them to evaluate ecosystem or organism health is a popular concept [8].…”

“…Cell suspensions were immediately processed for the alkaline comet assay. The comet assay was performed according to [6] with slight modification. All preparatory steps were performed under dim light to avoid additional DNA damage.…”