GEOTRACES IC1 (BATS) contamination-prone trace element isotopes Cd, Fe, Pb, Zn, Cu, and Mo intercalibration

International audienceWe report data on the isotopic composition of cadmium, copper, iron, lead, zinc, and molybdenum at the GEOTRACES IC1 BATS Atlantic intercalibration station. In general, the between lab and within-lab precisions are adequate to resolve global gradients and vertical gradients at this station for Cd, Fe, Pb, and Zn. Cd and Zn isotopes show clear variations in the upper water column and more subtle variations in the deep water; these variations are attributable, in part, to progressive mass fractionation of isotopes by Rayleigh distillation from biogenic uptake and/or adsorption. Fe isotope variability is attributed to heavier crustal dust and hydrothermal sources and light Fe from reducing sediments. Pb isotope variability results from temporal changes in anthropogenic source isotopic compositions and the relative contributions of U.S. and European Pb sources. Cu and Mo isotope variability is more subtle and close to analytical precision. Although the present situation is adequate for proceeding with GEOTRACES, it should be possible to improve the within-lab and between-lab precisions for some of these properties

Thioredoxin 1 in prostate tissue is associated with gleason score, erythrocyte antioxidant enzyme activity, and dietary antioxidants

Background. Prostate cancer is the most common noncutaneous cancer and second leading cause of cancer-related mortality in men in the US. Growing evidence suggests that oxidative stress is involved in prostate cancer. Methods. In this study, thioredoxin 1 (Trx 1), an enzyme and subcellular indicator of redox status, was measured in prostate biopsy tissue from 55 men from the North Carolina-Louisiana Prostate Cancer Project. A pathologist blindly scored levels of Trx 1. The association between Trx 1 and the Gleason score, erythrocyte antioxidant enzyme activity, and dietary antioxidant intake was determined using Fisher's exact test. Results. Trx 1 levels in benign prostate tissue in men with incident prostate cancer were positively associated with the Gleason score (P=0.01) and inversely associated with dietary antioxidant intake (P=0.03). In prostate cancer tissue, Trx 1 levels were associated with erythrocyte glutathione peroxidase activity (P=0.01). No association was found for other erythrocyte enzymes. Greater Gleason score of malignant tissue corresponds to a greater difference in Trx 1 levels between malignant and benign tissue (P=0.04). Conclusion. These results suggest that the redox status of prostate tissue is associated with prostate cancer grade and both endogenous and exogenous antioxidants

Percepção ambiental dos produtores e qualidade do solo em propriedades orgânicas e convencionais.

O sistema orgânico de produção deve resultar na utilização mais racional dos recursos naturais, sobretudo do solo. Os produtores orgânicos devem adotar práticas conservacionistas, além de atender a outros princípios deste sistema de produção. Neste trabalho foram avaliadas as práticas de manejo e conservação do solo adotadas por produtores orgânicos e convencionais nas regiões dos municípios de Socorro (Serra da Mantiqueira e Mogiana) e Ibiúna, situados no Estado de São Paulo. O objetivo dessa pesquisa foi verificar o grau de adoção de práticas conservacionistas pelos produtores e avaliar a qualidade do solo na agricultura orgânica e convencional. Foi elaborado e aplicado um questionário, com visitas locais para verificação das práticas conservacionistas e ocorrência de erosão, em 30 propriedades. Os resultados foram expressos em índices indicadores de diversidade de uso do solo, atitude conservacionista, percepção de erosão e do impacto sobre os recursos hídricos. Foram também realizadas análises de atributos químicos, físicos e biológicos indicadores da qualidade do solo. Concluiu-se que os produtores orgânicos têm maior percepção quanto à atitude conservacionista e nas propriedades orgânicas há maior diversidade de cultivos, embora não haja maior diversidade geral de uso do solo. A produção orgânica de alface, em Ibiúna proporcionou maior atividade biológica no solo e maior colonização por fungos micorrízicos arbusculares. O sistema orgânico possui maiores teores de matéria orgânica e menores de potássio e não houve diferença entre os atributos físicos do solo dos sistemas orgânico e convencional

Communication and mutual resource exchange in north Florida hermit crabs

The patterns of shell exchange in three species of hermit crabs which overlap in distribution and shell use were observed in the laboratory. Crabs showed no tendency to initiate more exchanges with conspecifics as compared with nonconspecific individuals and there were no specific size dominance effects. Lack of common communicatory patterns between Clibararius vittatus and Pagurus pollicaris was correlated with minimal actual exchange, while Pagurus impressus exchanged with both species and executed patterns in common with both. The pattern of shell exchanges and preferences indicated that, in some cases, both individuals may gain in interspecific exchanges.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46904/1/265_2004_Article_BF00569198.pd

Efeito Do Sistema De Plantio E Doses Do Nicosulfuron Sobre A Atividade Microbiana Do Solo

This study aimed to evaluate the effect of atrazine + nicosulfuron on soil microbial activity, under the conventional and no-tillage systems. The experiment was carried out in an area of maize-brachiaria intercropping, where atrazine + nicosulfuron were applied at (1,500 + 10 and 1,500 + 30 g h -1) with a weed-handed area being maintained without prior cultivation and another area without weed control. At flowering, soil samples were collected to determine the rate of CO 2 unfastening, microbial biomass carbon (MBC) and metabolic quotient (qCO 2) using the relation between accumulated CO 2 and MBC. The rate of CO 2 unfastening was lower only in plots without weed control. MBC was higher in the no-tillage system, being negatively affected due to the absence of vegetation. Lower MBC was observed in the weed-handed areas, probably due to the absence of straw. Under no-tillage system conditions, no difference was observed between the soil treatments with herbicide application and those without weed control. It can be concluded that the evaluated microbiological indicators were sensitive to the treatments, showing lower soil disturbance under no-tillage system conditions. However, in crop-livestock integration under the conventional system, the negative herbicide effect increase of nicosulfuron rate