Deposition of gold mining tailings in tropical soils: metal pollution and toxicity to earthworms

Journal of Soils and Sediments - This study consists of the evaluation of metals acute toxicity levels taking into consideration a hypothetic scenario of dam breaking and land deposition of two...     

Constructive Approaches to Intellectual Property Complexity in Today＇s Agricultural Technology World

Essential to progress in plant biotechnology for deliverable applications, patent and patent application data must be transparent in order to determine where there is whitespace for innovation.     

Resistance to common bacterial blight in Phaseolus vulgaris L. recombinant inbred lines under natural infection of Xanthomonas axonopodis pv. phaseoli

Among the main causes of poor yield in common beans are fungal, viral and bacterial diseases. Common bacterial blight, caused by Xanthomonas axonopodis pv. phaseoli (Xap), is one of the major bacterial diseases leading to significant losses in Brazil. Chemical control is ineffective, therefore, the use of resistant varieties becomes an interesting alternative. The objective of the present work was to evaluate disease resistance under natural infection of the pathogen in 109 recombinant inbred lines (F₇) of P. vulgaris originated from the cross HAB-52 (susceptible — snapbean) × BAC-6 (resistant — common bean) in two different environments, as well as to calculate genetic parameters to assist in the selection of promising materials to be used in the CBB resistance breeding program. The data of the genetic parameters were compared to those calculated for the F₃ generation originated from the same cross. The heritability results for DI (disease index) and VI (variation index) in F₃ were 26.85% and 0.26, respectively, whereas in F₇ they were 91.77% and 1.36, respectively. These results demonstrate a potential to be explored for this advanced population, that in the future, along with other pathogen variability studies and tests in other environments, may provide more information regarding a more precise evaluation of promising genotypes to be used in common bean breeding programs aiming to obtain CBB resistant varieties. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of coupling media on velocity and attenuation of ultrasonic waves in Brazilian wood

Coupling media are necessary to ensure that transducers bond to wood specimens to minimize coupling losses and improve the accuracy of ultrasonic measurements. There are several types of coupling media available, and the optimal choice is not known. In this work, we analyzed the results of ultrasonic wave attenuation for 0.1-MHz longitudinal and transverse transducers with six different materials as coupling media in nine species of Brazilian wood with densities in the range 700–1170 kg/m³. Tests were performed using constant pressure on the transducer and with wave propagation in the longitudinal direction. For transverse transducers, the polarization was in the radial and tangential directions. The results were analyzed statistically and showed that, for attenuation in both longitudinal and transverse waves, the material used for coupling had significant effects, whereas the wood species had no effect. For longitudinal waves, the statistical evaluation showed that the coupling material performance was strongly dependent on the species of wood, but it was not possible to observe any tendency of behavior associated with specific anatomical properties.     

Influence of soil and host plant crop on the genetic diversity of Azospirillum amazonense isolates

The genetic structure of Azospirillum amazonense populations isolated from the rhizosphere soil and washed and surface-sterilised roots of rice, maize and sorghum plants, cropped simultaneously in two different soils (clay loam and sandy loam) was characterised. Genetic diversity was measured by restriction fragment length polymorphism of the amplified 16S–23S rDNA intergenic spacer region (RISA-RFLP) and cluster analysis. Four genetically distinct clusters of isolates were observed with 78% similarity, suggesting that the A. amazonense population was heterogeneous at the strain level regardless of the soil type or host plant. Analysis of molecular variance (AMOVA) demonstrated that the host plant had a highly significant selective effect on the genetic structure of this species, especially on those isolates intimately associated with them, but also to a lesser extent on isolates from the rhizosphere and washed roots. The soil type also had a highly significant selective effect on A. amazonense genetic diversity, especially for those isolates from the rhizosphere soil. The selective effect of the soil type combined with that of the host plant suggests that environmental factors, such as soil texture and composition of exudates provided by C₃ or C₄ plants, play major roles in the overall genetic structure of A. amazonense populations associated with these cereals.     

Interactions of Glomus clarum with Acetobacter diazotrophicus in infection of sweet potato (Ipomoea batatas), sugarcane (Saccharum spp.), and sweet sorghum (Sorghum vulgare)

Summary Spores of the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus clarum obtained from sweet potatoes grown in soil inoculated with this fungus and with an enrichment culture of Acetobacter diazotrophicus contained A. diazotrophicus and several other bacteria, including a diazotrophic Klebsiella sp. Inoculation of micropropagated sweet potatoes with G. clarum and A. diazotrophicus enhanced spore formation in soil compared to VAM inoculation alone. Plants inoculated with VAM spores containing the bacteria showed additional increases in the number of spores formed within roots. A. diazotrophicus infected aerial plant parts only when inoculated together with VAM or when present within VAM spores. Micropropagated sugarcane seedlings inoculated with the same VAM spores containing the diazotrophs also contained much higher numbers of A. diazotrophicus in aerial parts than seedlings inoculated in vitro with the bacteria alone. When grown in non-sterile soil, the sugarcane seedlings again showed the greatest infection of aerial parts after inoculation with VAM spores containing the diazotrophs. This treatment also increased VAM colonization and the numbers of spores formed within roots. Similar effects were observed in sweet sorghum except that the aerial plant parts were not infected by A. diazotrophicus.     

Brain catecholamines: relation to defense reaction evoked by acute brainstem transection in cat

The concentration of noradrenaline, but not serotonin, in the brainstem of cats is reduced 3 hours after the production of a defense reaction by supracollicular decerebration, even when movements and changes in blood pressure are abolished by transection of the spinal cord. After midcollicular decerebration, which does not elicit a defense reaction, noradrenaline concentrations do not change. The decrease in its concentration accompanying the defense reaction produtced by brain lesions probably reflects activity, in this behavior, of neturons containinig noradrenaline.