Julio Alejandro Navoni

Ecotoxicological water assessment of an estuarine river from the Brazilian Northeast, potentially affected by industrial wastewater discharge.

Water pollution generated by industrial effluents discharge is a threat to the maintenance of aquatic ecosystems and human development. The Jundiai River estuarine, located in Northeast Brazil, receives an industrial pretreated effluent load from the city of Macaíba/RN/Brazil. The present study aimed to assess the water quality of this water reservoir through i) physicochemical characterization, ii) quantification of metal concentration and iii) by an ecotoxicological assessment carried out using Mysidopsis juniae and Pomacea lineata. The study was performed throughout the period comprising May to September 2014. Physicochemical variables such as chloride, total solids and electrical conductivity presented values in the waste discharge point, significantly different with those located out of the waste releasing point. Apart from that, metal concentration showed variable behavior throughout the monitored period. Levels of Al, Fe, Cu, Cd, Cr, Ni, Pb and Ag were over the considered guidelines. Both natural and anthropogenic sources seem to be involved in the resulting environmental scenario. A reduction in the fecundity rate (using Mysidopsis juniae) along with an increase in mortality rate (in both species) was observed ratifying the presence of toxic substances in this water reservoir. Moreover, a correlation analysis stated an association of the aforementioned toxicological effects with the delivery of industrial waste products. The ecotoxicological assessment performed highlighted the presence of toxic substance/s in water from the Jundiai River. Especially as a consequence of industrial activity, a fact that might threaten the bioma and, therefore, the human health of the population settled in the studied region.

Water mutagenic potential assessment on a semiarid aquatic ecosystem under influence of heavy metals and natural radioactivity using micronuclei test

The contamination of water bodies by heavy metals and ionizing radiation is a critical environmental issue, which can affect water quality and, thus, human health. This study aimed to evaluate the water quality of the Boqueirão de Parelhas Dam in the Brazilian semiarid region. A 1-year study (2013–2014) was performed through the assessment of physicochemical parameters, heavy metal content, and radioactivity along with the mutagenicity potential of water using micronuclei test in Orechromis niloticus (in vivo) and the cytokinesis-block micronucleus (CBMN) assay in human lymphocytes (in vitro). A deterioration of water organoleptics characteristics by the presence of high levels of sulfate and total solids was observed. High concentrations of aluminum, nickel, silver, and lead along with the alpha particle content were higher than the limits suggested by the World Health Organization and Brazilian legislation for drinking water. An increase in the frequency of micronuclei and nuclear abnormalities was observed in both experimental models. The results obtained confirmed the mutagenic potential present in water samples. This study highlights that geogenic agents affect water quality becoming a human health concern to be taken into account due to the relevance that this water reservoir has in the region.

Validation of Comet assay in Oregon-R and Wild type strains of Drosophila melanogaster exposed to a natural radioactive environment in Brazilian semiarid region

Natural radiation of geological origin is a common phenomenon in Brazil, a country where radioactive agents such as uranium may be often found. As an unstable atom, uranium undergoes radioactive decay with the generation of a series of decay by-products, including radon, which may be highly genotoxic and trigger several pathological processes, among which cancer. Because it is a gas, radon may move freely between cracks and gaps in the ground, seeping upwards into the buildings and in the environment. In this study, two Drosophila melanogaster Meigen (Diptera, Drosophilidae) strains called Oregon-R and Wild (collected in a non-radioactive environment) were exposed to atmospheric radiation in the Lajes Pintadas city, in the semiarid zone of northeastern Brazil. After six days of environmental exposure, the organisms presented genetic damage significantly higher than that of the negative control group. The genotoxic effects observed reinforce the findings of other studies carried out in the same region, which warn about the environmental risks related to natural radioactivity occurrence. The results also validate the use of the Comet assay in hemocytes of D. melanogaster as a sensitive test to detect genotoxicity caused by natural radiation, and the use of a recently collected D. melanogaster strain in the environmental of radon.

The use of bacterial bioremediation of metals in aquatic environments in the twenty-first century: a systematic review

Metal pollution is a current environmental issue as a consequence of unregulated anthropic activiy. A wide range of bioremediation strategies have been successfully implemented to recover contaminated areas. Among them, bacterial bioremediation stands out as a promising tool to confront these types of concerns. This study aimed to compare and discuss worldwide scientific evolution of bacterial potential for metal bioremediation in aquatic ecosystems. The study consisted of a systematic review, elaborated through a conceptual hypothesis model, during the period from 2000 to 2016, using PubMed, MEDLINE, and SciELO databases as data resources. The countries with the largest number of reports included in this work were India and the USA. Industrial wastewater discharge was the main subject associated to metal contamination/pollution and where bacterial bioremediations have mostly been applied. Biosorption is the main bioremediation mechanism described. Bacterial adaptation to metal presence was discussed in all the selected studies, and chromium was the most researched bioremedied substrate. Gram-negative Pseudomonas aeruginosas and the Gram-positive Bacillus subtilis bacteria were microorganisms with the greatest applicability for metal bioremediation. Most reports involved the study of genes and/or proteins related to metal metabolism and/or resistence, and Chromobacterium violaceum was the most studied. The present work shows the relevance of metal bacterial bioremediation through the high number of studies aimed at understanding the microbiological mechanisms involved. Moreover, the developed processes applied in removal and/or reducing the resulting environmental metal contaminant/pollutant load have become a current and increasingly biotechnological issue for recovering impacted areas.

Mutagenic potential assessment associated with human exposure to natural radioactivity

Lucrécia city, known to harbor a high cancer rate, is located in a semiarid region characterized by the presence of mineral reservoirs, facing a high exposure to metal and natural radioactivity. The present study aimed to assess the environmental scenario at a semiarid region located in Northeastern Brazil. Metal concentration, alpha and beta radiation, and cyanobacteria content in tap water along with indoor radon and gamma emitters (U, K and Th) concentrations were measured. In addition, mutagenic and nuclear instability effects were assessed using buccal micronucleus cytome assay. The study included five samplings corresponding to a period between 2007 and 2009. Drinking water from Lucrécia city presented levels of Mn, Ni and Cr along with cyanobacteria in concentrations one to four times higher than regulatory guidelines considered. Furthermore, high levels of all the tested radionuclides were found. A high percentage of the houses included in this study presented indoor radon concentrations over 100 Bq m-3. The mean annual effective dose from Lucrécia houses was six times higher than observed in a control region. The levels of exposure in most of the Lucrécia houses were classified as middle to high. A significant mutagenic effect, represented as an increase of micronuclei (MN) frequency and nuclear abnormalities as nuclear buds (NB), binucleated cells (BN), and pyknotic cells (PYC) were found. The results obtained highlight the role of high background radioactivity on the observed mutagenic effect and could help to explain the exacerbated cancer rate reported in this locality.

Effect of Hecogenin on DNA instability

Hecogenin is a sapogenin found in Agave species in high quantities and is responsible for the many therapeutic effects of these medicinal plants. In addition, this compound is also widely used in the pharmaceutical industry as a precursor for the synthesis of steroidal hormones and anti-inflammatory drugs. Despite Hecogenin being widely used, little is known about its toxicological properties. Therefore, the present study aimed to investigate the cytotoxic, genotoxic and mutagenic effects of Hecogenin on HepG2 cells. Cytotoxicity was analyzed using the MTT test. Then, genotoxic and mutagenic potentials were assessed by comet assay and cytokinesis-block micronucleus assay, respectively. Cytotoxic effect was observed only when cells were exposed to concentrations of Hecogenin equal or higher than 100 μM. Although a lower concentration of Hecogenin caused DNA damage, a reduction on nuclear mutagenic markers in HepG2 cells was observed. The results indicated that Hecogenin treatment generated DNA damage, but in fact it would be repaired, avoiding dissemination of the damage throughout the cell division. Further studies need to be performed to confirm the observed protective effect of Hecogenin against genomic instability.

Diosgenin induces genotoxic and mutagenic effects on HepG2 cells

Yam roots and other plants from Dioscorea genus have cultural, nutritional and economic importance to tropical and subtropical regions and have a great amount of diosgenin in its composition. In the present study the cytotoxic, genotoxic and mutagenic potential of diosgenin on HepG2 cells was investigated. Cytotoxicity was assessed using MTT and clonogenic assay. Genotoxic and mutagenic effects were performed using single cell gel electrophoresis and cytokinesis-block micronucleus assay, respectively. A reduction on cell viability was observed due to diosgenin treatment at concentrations higher than 30u202fμM. A genotoxic effect was shown by comet assay and CBMN. Besides, an increase in micronucleus frequency along with a significant cytostatic effect were observed. Diosgenin elicited DNA damage on HepG2 cells which could not be efficiently repaired contributing to the mutagenic effect observed. Those results suggest that diosgenin deleterious effect could take place through genetic instability, fact that affects the normal cell cycle, leading to cells death.