Silvia Regina Batistuzzo de Medeiros

The complete genome sequence of Chromobacterium violaceum reveals remarkable and exploitable bacterial adaptability

Chromobacterium violaceum is one of millions of species of free-living microorganisms that populate the soil and water in the extant areas of tropical biodiversity around the world. Its complete genome sequence reveals (i) extensive alternative pathways for energy generation, (ii) ≈500 ORFs for transport-related proteins, (iii) complex and extensive systems for stress adaptation and motility, and (iv) widespread utilization of quorum sensing for control of inducible systems, all of which underpin the versatility and adaptability of the organism. The genome also contains extensive but incomplete arrays of ORFs coding for proteins associated with mammalian pathogenicity, possibly involved in the occasional but often fatal cases of human C. violaceum infection. There is, in addition, a series of previously unknown but important enzymes and secondary metabolites including paraquat-inducible proteins, drug and heavy-metal-resistance proteins, multiple chitinases, and proteins for the detoxification of xenobiotics that may have biotechnological applications.

Cytotoxic and genotoxic potential of surface water from the Pitimbu river, northeastern/RN Brazil

In this study, the onion (Allium cepa) root test was used to evaluate the genotoxicity of the Pitimbu River (Natal city, Brazil) surface water. The water was collected at five sampling sites along the river and one sample was obtained after the treatment (flocculation, chlorination and pH correction) of the river water for human consumption. All raw river water samples increased the frequency of chromosomal abnormalities and/or micronuclei and two of the water samples produced alterations in the mitotic index of the root cells. Two of the water samples also altered root growth and two produced morphological modifications in the A. cepa roots. Water collected from a site near an industrial area was the most consistently toxic and genotoxic of the samples. Although the water chlorinated for human consumption was not genotoxic, the data indicate that surface water from the Pitimbu River contains toxic and genotoxic compounds that potentially may impact this aquatic ecosystem.

Genotoxicity and composition of particulate matter from biomass burning in the eastern Brazilian Amazon region

In the present study Tradescantia pallida micronucleus (Trad-MCN) bioassay was used to assess the genotoxicity of particulate matter with a mass median aerodynamic diameter less than 10 μm (PM₁₀) in Tangara da Serra (MT), a Brazilian Amazon region that suffers the impact of biomass burning. The levels of PM (coarse and fine size fractions) and black carbon (BC) collected were also measured. Furthermore, the alkanes and polycyclic aromatic hydrocarbons (PAHs) were identified and quantified in the samples taken during the burning period by gas chromatography with flame ionization detection (GC-FID). The PM and BC results for both fractions indicate a strong correlation (p < 0.001). The analysis of alkanes indicates an anthropic influence. Retene was the most abundant PAH found, an indicator of biomass burning, and 12 other PAHs considered to be potentially mutagenic and/or carcinogenic were identified in this sample. The Trad-MCN bioassay showed a significant increase in micronucleus frequency during the period of most intense burning, possibly related to the mutagenic PAHs that were found in such extracts. This study demonstrated that Trad-MCN was sensitive and efficient in evaluating the genotoxicity of organic compounds from biomass burning. It further emphasizes the importance of performing chemical analysis, because changes in chemical composition generally have a negative effect on many living organisms. This bioassay (ex situ), using T. pallida with chemical analysis, is thus recommended for characterizing the genotoxicity of air pollution.

Micronucleus frequency in children exposed to biomass burning in the Brazilian Legal Amazon region: a control case study

BackgroundThe Amazon represents an area of 61% of Brazilian territory and is undergoing major changes resulting from disorderly economic development, especially the advance of agribusiness. Composition of the atmosphere is controlled by several natural and anthropogenic processes, and emission from biomass burning is one with the major impact on human health. The aim of this study was to evaluate genotoxic potential of air pollutants generated by biomass burning through micronucleus assay in exfoliated buccal cells of schoolchildren in the Brazilian Amazon region.MethodsThe study was conducted during the dry seasons in two regions of the Brazilian Amazon. The assay was carried out on buccal epithelial cells of 574 schoolchildren between 6-16 years old.ResultsThe results show a significant difference between micronucleus frequencies in children exposed to biomass burning compared to those in a control area.ConclusionsThe present study demonstrated that in situ biomonitoring using a sensitive and low cost assay (buccal micronucleus assay) may be an important tool for monitoring air quality in remote regions. It is difficult to attribute the increase in micronuclei frequency observed in our study to any specific toxic element integrated in the particulate matters. However, the contribution of the present study lies in the evidence that increased exposure to fine particulate matter generates an increased micronuclei frequency in oral epithelial cells of schoolchildren.

Effect of titanium surface modified by plasma energy source on genotoxic response in vitro

Titanium (Ti) is currently the most widely used material for the manufacture of orthopedic and dental implants. Changes in the surface of commercial pure Ti (cp Ti) can determine the functional response of cells, and is therefore a critical factor for the success of the implant. However, the genotoxicity of titanium surfaces has been poorly studied. Thus, the purpose of this study was to evaluate the genotoxic potential of a new titanium surface developed by plasma treatment using argon-ion bombardment and compare it with an untreated titanium surface. Accordingly, comet assay, analysis of chromosomal aberrations (CAs), and Cytokinesis Block Micronucleus (CBMN) assay were carried out, using CHO-K1 (Chinese hamster ovary) cells grown on both titanium surfaces. Our results show that the untreated titanium surface caused a significant increase in % tail moment, in the number of cells with CAs, tetraploidy, micronucleus frequency, and other nuclear alterations when compared with the negative control and with the plasma-treated titanium surface. This difference may be attributed to increased surface roughness and changes in titanium oxide layer thickness.

Genetic damage of organic matter in the Brazilian Amazon: A comparative study between intense and moderate biomass burning

BACKGROUND The biomass burning that occurs in the Amazon region has an adverse effect on environmental and human health. However, in this region, there are limited studies linking atmospheric pollution and genetic damage. OBJECTIVE We conducted a comparative study during intense and moderate biomass burning periods focusing on the genetic damage and physicochemical analyses of the particulate matter (PM). METHOD PM and black carbon (BC) were determined; organic compounds were identified and quantified using gas chromatography with flame ionization detection, the cyto-genotoxicity test was performed using two bioassays: cytokinesis-block micronucleus (CBMN) in A549 cells and Tradescantia pallida micronucleus (Trad-MCN) assay. RESULTS The PM10 concentrations were lower than the World Health Organization air quality standard for 24h. The n-alkanes analyses indicate anthropogenic and biogenic influences during intense and moderate biomass burning periods, respectively. Retene was identified as the most abundant polycyclic aromatic hydrocarbon during both sampling periods. Carcinogenic and mutagenic compounds were identified. The genotoxic analysis through CBMN and Trad-MCN tests showed that the frequency MCN from the intense burning period is significantly higher compared to moderate burning period. CONCLUSIONS This is the first study using human alveolar cells to show the genotoxic effects of organic PM from biomass burning samples collected in Amazon region. The genotoxicity of PM can be associated with the presence of several mutagenic and carcinogenic compounds, mainly benzo[a]pyrene. These findings have potential implications for the development of pollution abatement strategies and can minimize negative impact on health.

High-risk human papillomavirus (HPV) is not associated with p53 and bcl-2 expression in oral squamous cell carcinomas.

OBJECTIVE To determine the frequency and type of human papillomavirus (HPV) in oral squamous cell carcinomas (OSCC), as well as to identify a possible association between HPV infection and the expression pattern of p53 and bcl-2, and identify whether the oral HPV infection is a characteristic finding in our sample. METHODS We performed polymerase chain reaction and dot blot hybridization for the detection of HPV DNA in paraffin sections as well as immunohistochemical analysis of p53 and bcl-2 in our sample. RESULTS Twenty-six cases (29.5%) were positive for the virus by PCR. Dot blot hybridization identified HPV 18 in 21 (80.8%) cases, HPV 16 in one (3.8%) case and a combination of the two types in the four (15.4%) remaining cases. No other type of HPV was detected in the sample. Immunohistochemistry showed p53 in 26 (60.4%) cases and bcl-2 in 17 (39.5%) ones. No significant association was observed between the presence of HPV and the expression of the proteins studied (p=0.988 and p=0.748, respectively). CONCLUSIONS Although this investigation have detected only 29.5% of HR-HPV DNA in OSCC, it is possible that this virus contribute to the development of some case of this tumor. Furthermore, it seems that the immunohistochemical expression of p53 and bcl-2 and the presence of HPV DNA are independent events in OSCC.

Genotoxic analysis in aquatic environment under influence of cyanobacteria, metal and radioactivity

The micronucleus (MN) and nuclear abnormality (NA) tests were employed to evaluate the genotoxic potential of the Lucrecia dam (RN, Brazil) located in a semi-arid region and influenced by crop irrigation and irregular rainfall. The analyses of these water samples demonstrated the presence of several cyanobacteria as well as metals and radioactivity. The Nile Tilapia (Oreochromis niloticus) was used for micronucleus and nuclear abnormality assays and analysis of metal concentrations in gills and liver samples. Genotoxic assays in source water fish showed a significant increase in the frequency of nuclear damage (MN and NA) in relation to the negative control group. In conclusion, the results obtained with water surface and biological samples from the Lucrecia dam suggest that this important water resource contains a number of chemical and microbiological pollutants with genotoxic potential and that these substances may be compromising the species inhabiting this ecosystem. Particular care must be taken to prevent further degradation of this water supply. Capsule: A battery of assay was successfully applied to assess the water quality of Lucrecia dam from a Northeastern region of Brazil.

Cashew nut roasting: chemical characterization of particulate matter and genotocixity analysis.

BACKGROUND Particulate matter (PM) is potentially harmful to health and related to genotoxic events, an increase in the number of hospitalizations and mortality from respiratory and cardiovascular diseases. The present study conducted the first characterization of elemental composition and polycyclic aromatic hydrocarbon (PAH) analysis of PM, as well as the biomonitoring of genotoxic activity associated to artisanal cashew nut roasting, an important economic and social activity worldwide. METHODS The levels of PM2.5 and black carbon were also measured by gravimetric analysis and light reflectance. The elemental composition was determined using X-ray fluorescence spectrometry and PAH analysis was carried out by gas chromatography-mass spectrometry. Genotoxic activity was measured by the Tradescantia pallida micronucleus bioassay (Trad-MCN). Other biomarkers of DNA damage, such as nucleoplasmic bridges and nuclear fragments, were also quantified. RESULTS The mean amount of PM2.5 accumulated in the filters (January 2124.2 µg/m(3); May 1022.2 µg/m(3); September 1291.9 µg/m(3)), black carbon (January 363.6 µg/m(3); May 70 µg/m(3); September 69.4 µg/m(3)) and concentrations of Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br and Pb were significantly higher than the non-exposed area. Biomass burning tracers K, Cl, and S were the major inorganic compounds found. Benzo[k]fluoranthene, indene[1,2,3-c,d]pyrene, benzo[ghi]perylene, phenanthrene and benzo[b]fluoranthene were the most abundant PAHs. Mean benzo[a]pyrene-equivalent carcinogenic power values showed a significant cancer risk. The Trad-MCN bioassay revealed an increase in micronucleus frequency, 2-7 times higher than the negative control and significantly higher in all the months analyzed, possibly related to the mutagenic PAHs found. CONCLUSIONS This study demonstrated that artisanal cashew nut roasting is a serious occupational problem, with harmful effects on workers׳ health. Those involved in this activity are exposed to higher PM2.5 concentrations and to 12 PAHs considered potentially mutagenic and/or carcinogenic. The Trad-MCN with T. pallida was sensitive and efficient in evaluating the genotoxicity of the components and other nuclear alterations may be used as effective biomarkers of DNA damage.

Genotoxic potential generated by biomass burning in the Brazilian Legal Amazon by Tradescantia micronucleus bioassay: a toxicity assessment study.

BackgroundThe Brazilian Amazon has suffered impacts from non-sustainable economic development, especially owing to the expansion of agricultural commodities into forest areas. The Tangará da Serra region, located in the southern of the Legal Amazon, is characterized by non-mechanized sugar cane production. In addition, it lies on the dispersion path of the pollution plume generated by biomass burning. The aim of this study was to assess the genotoxic potential of the atmosphere in the Tangará da Serra region, using Tradescantia pallida as in situ bioindicator.MethodsThe study was conducted during the dry and rainy seasons, where the plants were exposed to two types of exposure, active and passive.ResultsThe results showed that in all the sampling seasons, irrespective of exposure type, there was an increase in micronucleus frequency, compared to control and that it was statistically significant in the dry season. A strong and significant relationship was also observed between the increase in micronucleus incidence and the rise in fine particulate matter, and hospital morbidity from respiratory diseases in children.ConclusionsBased on the results, we demonstrated that pollutants generated by biomass burning in the Brazilian Amazon can induce genetic damage in test plants that was more prominent during dry season, and correlated with the level of particulates and elevated respiratory morbidity.