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MutY is a glycosylase known for its role in DNA base excision repair (BER). It is critically important in the prevention of DNA mutations derived from 7,8-dihydro-8-oxoguanine (8-oxoG), which are the major lesions resulting from guanine oxidation. MutY has been described as a DNA repair enzyme in the GO system responsible for removing adenine residues misincorporated in 8-oxoG:A mispairs, avoiding G:C to T:A mutations. Further studies have shown that this enzyme binds to other mispairs, interacts with several enzymes, avoids different transversions/transitions in DNA, and is involved in different repair pathways. Additional activities have been reported for MutY, such as the repair of replication errors in newly synthesized DNA strands through its glycosylase activity. Moreover, MutY is a highly conserved enzyme present in several prokaryotic and eukaryotic organisms. MutY defects are associated with a hereditary colorectal cancer syndrome termed MUTYH-associated polyposis (MAP). Here, we have reviewed the roles of MutY in the repair of mispaired bases in DNA as well as its activities beyond the GO system., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The Guaíba Basin is a source of drinking water for Porto Alegre (RS, Brazil). The water from this basin receives industrial, urban, and rural waste from many sources. The mussel species Limnoperna fortunei was chosen based on population data, distribution, and sensitivity. Previous tests with comet assay and micronuclei frequency in this freshwater mussel have shown to be successful in biomonitoring studies. The aim of this study was to evaluate the genotoxic contamination of the Guaíba Lake Hydrographic Region, through the determination of damage by the micronuclei and comet assays in L. fortunei (golden mussel). Nine sampling sites were evaluated in three different seasons: five sites in the mouths of the main rivers that flow into Guaíba lake; one site at the mouth of a stream; one major site of sewage discharge; two sites at Guaíba lake, near a sewage discharge; and the control site in a preservation area. DNA damage was detected by the single cell gel assay, as well as the frequency of micronuclei in hemocytes of mussels exposed under laboratory conditions for 7 days to water and sediment samples. Significant results were found in different seasons in almost all sampling sites (P<0.05, ANOVA Dunnet's test). Most of the positive results were found in samples affected mainly by urban effluents. It was possible to observe that there was a weak relation between mutagenic and genotoxic responses and mussels inorganic elements contents. Seasonal variation was observed at different sampling sites, but always indicating a huge contamination near urban sewage discharge. These results are consistent with previous studies, allowing us to infer that urban contamination is the biggest problem in this region. It is also possible to infer that L. fortunei is a good sentinel organism for the Guaíba Basin.

The development of methodologies for biomonitoring freshwater ecosystems is of particular relevance in view of the serious problem of aquatic environmental pollution. The mussel species Limnoperna fortunei (golden mussel) was chosen to be tested as a biomonitor organism based on its population data and distribution. L. fortunei individuals were exposed to UV radiation in vitro, and in vivo to pentachlorophenol (PCP) and copper sulphate (CuSO(4)), with the aim of standardizing comet assay and micronucleus test methodologies and evaluating the potential of this organism as a biomonitor. Haemolymph cells immobilized in agarose on slides exposed to UV radiation showed a dose-response relationship with maximum damage at 4.2 J/m(2). For the chemical tests, individuals were exposed for 2h for the comet assay and 24 and 48 h for the micronucleus test. A dose-response relationship was observed for both chemicals. 3x10(-5) M CuSO(4) induced high genotoxicity, also producing some toxicity after 48 h of exposure. PCP induced maximum damage in both assays at 150 μg/L. Individuals exposed to PCP showed 100% repair 2 h after the exposure period, as assessed by the comet assay. Exposure to an environmental sample over 7 days confirmed the mussel sensitivity to water contaminants, detected both by the comet assay and the micronucleus test. The results allow us to suggest the golden mussel as a potential biomonitor organism.