Glutathione S-transferase gene polymorphism,cigarette smoking and DNA damage

Several factors such as smoking habits, diet, occupational, and environmental exposure to chemical carcinogens influence the overall level of DNA damage. In 69 healthy adult volunteers’ polymorphisms of glutathione S-transferase (GST), an enzyme which participates in the metabolism of a broad range of carcinogens and endogenous compounds were determined. The level of DNA damage was assessed by comet assay and classified according to GSTT1/M1 genotype and smoking habits. GSTM1 null genotype was recognized in 48% of studied subjects and GSTT1 null genotype in only two cases (3%). In subjects carrying GSTT1/M1 alleles a significantly lower degree of DNA damage, determined as % DNA in the comet's tail, than in null individuals was noted. However, the results obtained did not indicate that in studied subjects an elevated endogenous level of DNA damage may be significantly related to smoking habits.     

Assessment of the in vivo genotoxicity of a new formulation of Bacillus thuringiensis var israelensis SH-14

Biological control agents have become a useful alternative for the reduction of the use of chemical insecticides. LABIOFAM (Cuba) is developing a new formulation of a biolarvicide that possesses as active biological agent Bacillus thuringiensis var israelensis serotype H14. In order to evaluate the genotoxicity of this new formulation, an in vivo battery test was used: micronucleus (MN), chromosome aberrations (CAs), and sperm morphology (SM) assays. A dose of 6.45?×?10⁸ spores was administered per animal via oral administration. Bone marrow cells were collected 24?h after a two day treatment for the MN assay, and 24?h after a unique treatment for the CA assay, using cyclophosphamide as the positive control. Sperm cells were collected at 5 weeks from the first of five administrations for the SM test, using acrylamide as positive control. Bacillus thuringiensis var israelensis serotype H14 failed to show either a significative increase of micronucleated polychromatic erythrocytes, chromosomal aberrations, or sperm abnormalities. Acute oral administration of a high dose of Bacillus thuringiensis var israelensis serotype H14 did not produce mutagenic effects in bone marrow or sperm cells.     

Mitigation of glyphosate-based herbicide toxicity in maize (Zea mays L.) seedlings by ascorbic acid

Abstract

The toxicity of glyphosate at 3.6?mg L^?1 to maize seedlings raised from un-treated seeds and the effectiveness of seed pretreatment by soaking in 0.25?mmol L^?1 ascorbic acid (AsA) solution for mitigation of toxicity were evaluated in hydroponic culture. Glyphosate dramatically reduced the growth of roots and photosynthetic pigments in the leaves but increased protein content in the leaves. Superoxide dismutase activity and AsA concentration in the roots were increased, and guaiacol peroxidase (GPOX) activity was unaffected. Pretreatment with AsA improved the dry mass of the roots and shoots, increased the protein content in roots and leaves, and significantly decreased the activity of GPOX in roots. The positive effect of AsA treatment was not associated with more efficient functioning of the antioxidative system.     

Trends in precipitation chemistry in Alaska, 1980–1998

Nineteen years (1980–1998) of precipitation chemistry data from a site in Alaska are examined for trends using a least squares general linear model. The annual concentrations of SO^2– ₄ show a significant decreasing trend at 0.001 level and the annual change in concentration is —0.012mg 1^–1 yr^–1. The annual concentrations of NO ^– ₃ show an increasing tendency non‐significant. The annual base cation concentrations show a clear significant decreasing trend at 0.001 level and the decrease is —0.009mg 1^–1 yr^–1. Ca²⁺ concentrations exhibit a significant decreasing trend at 0.001 level and the annual change of concentration is —0.003 mg 1^–1 yr^–1. Mg²⁺ and Na⁺ concentrations show a significant decreasing trend at 0.01 level and the annual change is —0.001 mg1^–1 yr^–1 for Mg²⁺ and —0.004 mg1^–1 yr^–1 for Na⁺. K⁺ concentrations are characterised by a decreasing trend, significant at 0.05 level. K⁺ concentrations have decreased —0.002mg1^–1 yr^–1. The strongest rates of concentration decline for base cations, Ca²⁺, Mg²⁺, K⁺ and Na⁺ occurred in fall and winter season. The annual values of pH show a decreasing trend non‐significant. The values of pH oscillate between 5.1 and 5.6 during the period considered.     

Analysis of the ph in Europe during the period 1986–1997

The annual averages (1986–1997) of pH are analysed for the most important European Monitoring and Evaluation Programme stations in Europe. The first objective is to discover the different temporal patterns and trends for the pH. To do this, a cluster analysis is developed. The trends are analysed by linear regression for the annual averages. In general, the pH shows an increasing trend significant at 0.05 level and the annual change ranging from +0.01 to +0.05 pH‐units per year for the different clusters obtained. The second objective is to examine the spatial variability of pH in precipitation through the use of principal component analysis. Six statistically significant modes of variability are obtained for the pH which represent the 84.5% of the total variance.     

An approach to simulate wind fields around an urban environment for wind energy application

This work proposes an approach to simulate wind flow fields around an urban environment with the aim of evaluating the potential impact of buildings on the general wind patterns and power production using the current generation of commercial wind turbines. The simulation process was performed with the aid of accessible computational tools that can potentially render the proposed procedure applicable in other cases of interest. The roughness of the urban environment was defined as the association of roughness map, topography, and an alternative process for obtaining the volumetry of buildings. A case study was conducted in a region located at the district of Boa Viagem (Recife-PE) for assessing the applicability of the approach. Scenarios were designed in order to simulate wind flow patterns and pre-identify sites that have suitable wind energy potential for electric power production by investigating the combination of wind speed magnitude and turbulence intensity. From the results obtained, it was possible to identify zones of potential wind sources that are not detected in classical wind atlas probably due to the influence of the built environment on local wind flow patterns.     

Multidimensional trade-offs in species responses to disturbance: implications for diversity in a subtropical forest

Species employ diverse strategies to cope with natural disturbance, but the importance of these strategies for maintaining tree species diversity in forests has been debated. Mechanisms that have the potential to promote tree species coexistence in the context of repeated disturbance include life history trade-offs in colonization and competitive ability or in species' ability to survive at low resource conditions and exploit the temporary resource-rich conditions often generated in the wake of disturbance (successional niche). Quantifying these trade-offs requires long-term forest monitoring and modeling. We developed a hierarchical Bayes model to investigate the strategies tree species employ to withstand and recover from hurricane disturbance and the life history trade-offs that may facilitate species coexistence in forests subject to repeated hurricane disturbance. Unlike previous approaches, our model accommodates temporal variation in process error and observations from multiple sources. We parameterized the model using growth and mortality data from four censuses of a 16-ha plot taken every five years (1990-2005), together with damage data collected after two hurricanes and annual seed production data (1992-2005). Species' susceptibilities to hurricane damage as reflected by changes in diameter growth and fecundity immediately following a storm were weak, highly variable, and unpredictable using traditional life history groupings. The lower crowding conditions (e.g., high light) generated in the wake of storms, however, led to greater gains in growth and fecundity for pioneer and secondary-forest species than for shade-tolerant species, in accordance with expectation of life history. We found moderate trade-offs between survival in high crowding conditions, a metric of competitive ability, and long-distance colonization. We also uncovered a strong trade-off between mean species fecundity in low crowding conditions, a metric of recovery potential, and competitive ability. Trade-offs in competitive and colonization ability, in addition to successional niche processes, are likely to contribute to species persistence in these hurricane-impacted forests. The strategies species employ to cope with hurricane damage depend on the degree to which species rely on sprouting, repair of adult damage, changes in demographic rates in response to enhanced resource availability after storms, or long-distance dispersal as recovery mechanisms.     

Bioavailability, ecotoxicity, and geological characteristics of trace lead in sediments from two sites on Negro River, Uruguay, South America

Bioassays of two sites along the Rio Negro in Uruguay indicate ecotoxicity, which could be attributable to trace concentrations of lead in river sediments. Monthly samples at two sites at Baygorria and Bonete locations were analyzed for both particle size and lead. Lead was determined by atomic spectrometry in river water and sediment and particle size by sieving and sedimentation. Data showed that Baygorria's sediments have greater percentage of clay than Bonete's (20.4 and 5.8%, respectively). Lead was measurable in Baygorria's sediments, meanwhile in Bonete's, it was always below the detection limit. In water samples, lead was below detection limit at both sites. Bioassays using sub-lethal growth and survival test with Hyalella curvispina amphipod, screening with bioluminescent bacteria Photobacterium leiognathi, and acute toxicity bioassay with Pimephales promelas fish indicated toxicity at Baygorria, with much less effect at Bonete. Even though no lethal effects could be demonstrated, higher sub-lethal toxicity was found in samples from Baygorria site, showing a possible concentration of the contaminant in the clay fraction.