Laboratory measurements of biomarkers and individual performances in Chironomus xanthus to evaluate pesticide contamination of sediments in a river of southeastern Brazil

This study aimed at evaluating biomarkers, individual and population responses in the native Chironomus xanthus to assess the toxicity of pesticide-contaminated sediments from the Monjolinho River (Southeast Brazil). We measured cholinesterase (ChE) and glutathione S-transferase activities (GST), as biomarkers and survival, individual growth and adult emergence, as individual performances. There was no response of the ChE activity and a tendency to decreased GST activity in contaminated sites, but this was generally not statistically significant. Therefore, there was no association of the biomarker responses with exposure to sediment containing pesticides. In contrast, ash free dry mass was significantly increased and male emergence was decreased in C. xanthus exposed to the same sediments. In conclusion, the selected biomarkers were not sensitive and specific enough to detect and anticipate effects of pesticide contamination at the levels measured in the study area. Nevertheless, individual performances alterations pointed to potential pollution problems and possible ecological consequences. (C) 2010 Elsevier Inc. All rights reserved.

Suspension of apatite particles in a self-aerated Denver laboratory flotation cell

Effective solids suspension is a necessary precondition for particle collection, and solids suspension is largely dependent on the hydrodynamics of the flotation cell. This study attempted to correlate the status of the suspension of apatite particles of different sizes in a Denver laboratory flotation cell versus the impeller rotational speed (N) adopted to operate the machine. The latter variable (N) influences the impeller capacity to lift the particles from the bottom of the tank and also to disperse them throughout the volume of the vessel. Such an impeller capacity can be characterized by the critical impeller speed for the accomplishment of solids off-bottom suspension (N(z)) and also by the velocity of the radial water flow discharged by the impeller (U) divided by the particle terminal settling velocity (U(s)). This way, the status of the suspension of apatite particles inside the flotation cell can be characterized by one of three categories: ""segregation"" (N/N(2) < 0.60 and U(s)/U > 0.08); ""suspension"" (0.60 <= N/N(2) < 1 and 0.06 < U(s)/U < 0.10); and ""dragging"" (N/N(2) >= 1 and U(s)/U <= 0.03). The range of impeller rotational speed (N), which was able to suspend the finest particles (D(p) = 90,mu m), was unable to suspend the coarsest particles (D(P) = 254 mu m). Conversely, the high value of N (N > 1,300 rpm), which is adequate to suspend the coarsest particles, may promote the entrainment of the finest particles to the froth layer.

Registration of temporal sequences of coronal and sagittal MR images through respiratory patterns

This work discusses the determination of the breathing patterns in time sequence of images obtained from magnetic resonance (MR) and their use in the temporal registration of coronal and sagittal images. The registration is made without the use of any triggering information and any special gas to enhance the contrast. The temporal sequences of images are acquired in free breathing. The real movement of the lung has never been seen directly, as it is totally dependent on its surrounding muscles and collapses without them. The visualization of the lung in motion is an actual topic of research in medicine. The lung movement is not periodic and it is susceptible to variations in the degree of respiration. Compared to computerized tomography (CT), MR imaging involves longer acquisition times and it is preferable because it does not involve radiation. As coronal and sagittal sequences of images are orthogonal to each other, their intersection corresponds to a segment in the three-dimensional space. The registration is based on the analysis of this intersection segment. A time sequence of this intersection segment can be stacked, defining a two-dimension spatio-temporal (2DST) image. The algorithm proposed in this work can detect asynchronous movements of the internal lung structures and lung surrounding organs. It is assumed that the diaphragmatic movement is the principal movement and all the lung structures move almost synchronously. The synchronization is performed through a pattern named respiratory function. This pattern is obtained by processing a 2DST image. An interval Hough transform algorithm searches for synchronized movements with the respiratory function. A greedy active contour algorithm adjusts small discrepancies originated by asynchronous movements in the respiratory patterns. The output is a set of respiratory patterns. Finally, the composition of coronal and sagittal image pairs that are in the same breathing phase is realized by comparing of respiratory patterns originated from diaphragmatic and upper boundary surfaces. When available, the respiratory patterns associated to lung internal structures are also used. The results of the proposed method are compared with the pixel-by-pixel comparison method. The proposed method increases the number of registered pairs representing composed images and allows an easy check of the breathing phase. (C) 2010 Elsevier Ltd. All rights reserved.

Laboratory evaluation of recycled construction and demolition waste for pavements

The wide production of construction and demolition waste and its illegal deposition are serious current problems in Brazil. This research proposes to evaluate the feasibility of using aggregate from recycled construction and demolition waste (RCDW) in pavement applications. A laboratory program was conducted by geotechnical characterization, bearing capacity and repeated load triaxial tests. The results show that the composition and the compactive effort influence on the physical characteristics of the RCDW aggregate. The compaction process has promoted a partial crushing and breakage of RCDW particles, changing the grain-size distribution and increasing the percentage of cubic grains. This physical change contributes to a better densification of the RCDW aggregate and consequently an improvement in bearing capacity, resilient modulus and resistance to permanent deformation. The results have shown that the RCDW aggregate may be utilized as coarse base and sub-base layer for low-volume roads. (C) 2010 Elsevier Ltd. All rights reserved.

The Infection of Soybean Leaves by Phakopsora pachyrhizi during Conditions of Discontinuous Wetness

The ability of Phakopsora pachyrhizi to cause infection under conditions of discontinuous wetness was investigated. In in vitro experiments, droplets of a uredospore suspension were deposited onto the surface of polystyrene. After an initial wetting period of either 1, 2 or 4 h, the drops were dried for different time intervals and then the wetness was restored for 11, 10 or 8 h. Germination and appressorium formation were evaluated. In in vivo experiments, soybean plants were inoculated with a uredospore suspension. Leaf wetness was interrupted for 1, 3 or 6 h after initial wetting periods of 1, 2 or 4 h. Then, the wetting was re-established for 11, 10 or 8 h, respectively. Rust severity was evaluated 14 days after inoculation. The germination of the spores and the formation of the appressoria on the soybean leaves after different periods of wetness were also quantified in vivo by scanning electron microscopy. P. pachyrhizi showed a high infective capacity during short periods of time. An interruption of wetness after 1 h caused average reductions in germination from 56 to 75% and in appressorium formation from 84 to 96%. Rust severity was lower in all of the in vivo treatments with discontinuous wetness when compared to the control plants. Rust severity was zero when the interruption of wetness occurred 4 h after the initial wetting. Wetting interruptions after 1 and 2 h reduced the average rust severity by 83 and 77%, respectively. The germination of the uredospores on the soybean leaves occurred after 2 h of wetness, with a maximum germination appearing after 4 h of wetness. Wetness interruption affected mainly the spores that had initiated the germination.

Natural infection of Nicandra physaloides by Tomato severe rugose virus in Brazil

Nicandra physaloides, a common weed in South America, was found to be infected by an isolate of Tomato severe rugose virus (ToSRV), a bipartite begomovirus. The plants developed severe yellow rugose mosaic and were collected in So Paulo State, Brazil. This isolate of ToSRV was transmitted by Bemisia tabaci B biotype from infected plants of N. physaloides to healthy plants of N. physaloides and tomato in a glasshouse. This is the first report of natural infection of N. physaloides by ToSRV in Brazil.

Inheritance of resistance to Puccinia psidii G. Winter in a eucalyptus interspecific hybrid progeny evaluated under conditions of natural infection

Inheritance of resistance to Puccinia psidii G. Winter in a eucalyptus interspecific hybrid progeny evaluated under conditions of natural infection Rust caused by the fungus Puccinia psidii is currently the most important disease of eucalyptus. It is widely disseminated in Brazil, and causes serious damage in nurseries and plantation areas. The identification of resistant germplasm along with knowledge of the genetic basis of resistance heredity are the first requirements for the success of breeding programs aiming to develop resistant varieties. Earlier studies carried out under controlled conditions suggested a monogenic control as well as the participation of at least two genes promoting resistance to rust. The goal of this study was to evaluate the resistance to P. psidii under field conditions in fourteen progenies from controlled crosses and self-crosses among four hybrid clones of Eucalyptus grandis Hill ex Maiden x Eucalyptus urophylla ST Blake that contrast for resistance to the fungus. Results indicated that resistance could be explained by one locus with main effects and at least three different alleles. However, loci with minor effects may influence the resistance, since variation on severity classes was observed. Differences in segregation of resistance between reciprocal crosses were not observed, indicating absence of cytoplasmic effects.

Effect of acibenzolar-S-methyl and Saccharomyces cerevisiae on the activation of Eucalyptus defences against rust

Tree defence mechanisms against the fungus Puccinia psidii were examined by comparing the activities of defence-related enzymes (chitinase, peroxidase and phenylalanine ammonia-lyase) of two Eucalyptus grandis x E. urophylla (urograndis) hybrids, previously classified as either susceptible to rust (VR hybrid) or moderately resistant to rust (C0 hybrid). Furthermore, the potential of disease control by artificial activation of host defences using either acibenzolar-S-methyl (ASM) or Saccharomyces cerevisiae extract was also investigated. Greenhouse inoculation trials revealed that the C0 hybrid had lower disease severity than the VR hybrid but following foliar applications of either ASM or S. cerevisiae extract treatment, disease severity (evaluated at 15 days after inoculation) was reduced in both hybrids. This enhanced resistance was associated with the induction of a hypersensitive reaction which appeared to be effective in controlling rust in both clones. The activity of all enzymes differed between clones and inducer treatment. The role of the defence-related enzymes in imparting resistance to eucalypt hybrids against rust is discussed.

Infection of guava by Colletotrichum gloeosporioides and Colletotrichum acutatum under different temperatures and wetting periods

Anthracnose, caused by Colletotrichum gloeosporioides and C acutatum, is one of file main post-harvest diseases in guavas. This study aimed to determine the influence of environmental variables oil germination and appressorium formation of Colletotrichum gloeosporioides and C acutatum and infection of Kumagai guavas by these pathogens. The germination rate and the apressorium formation rate in vitro were determined under temperatures of 10, 15, 20, 25, 30, 35 and 40 degrees C, with wetting periods of 6, 12 and 24 hours, The infection of guavas was determined under temperatures of 15, 20, 25 and 30 degrees C and wetting period of 24 hours. There was no germination at 40 degrees C for either species. The germination and apressorium formation rate were rather high in the range of 15 to 30 degrees C for C. gloeosporioides, with a maximum at 25 degrees C. For the species C. acutatum, germination and apressorium formation rates were more sensitive to variations in temperature, with a maximum at 20 degrees C. The wetting periods tested somewhat influenced the germination of C. gloeosporioides, whereas in C acutatum the germination was significantly lower with 6 hours of wetting than 12 and 24 hours. The infection of guavas, for both fungal species, increased with the temperature, unlike conidium germination and apressorium formation. Incidences of 100% occurred with 30 degrees C, at 10 days after the inoculation.

Peach brown rot incidence related to pathogen infection at different stages of fruit development in an organic peach production system

Brown rot, caused by Monilinia fructicola, is the most widespread disease for organic peach production systems in Brazil. The objective of this study was to determine the favorable periods for latent infection by M. fructicola in organic systems. The field experiment was carried out during 2006, 2007 and 2008 using the cultivar Aurora. After thinning fruits were bagged using white paraffin bags, and the treatments were performed by removing the bags and exposing the fruit for four days to the natural infection during each of seven fruit stages from pit hardening to harvest. Throughout the entire growing season, the conidial density and the weather variables were measured and related to the disease incidence using multiple regression analyses. At the fourth day after harvest in each season, the cumulative disease incidence was assessed, and it ranged from 40 to 98%. The incidence of brown rot on fruit that were exposed during the embryo growing stage was lower than that of unbagged fruit throughout the entire season in 2006 and 2008. The relative humidity and the conidia density were significantly correlated to disease incidence. Based on our results, M. fructicola can infect peaches during any stage of fruit development, and control of the disease must be revised to account for organic peach production systems. (C) 2011 Elsevier Ltd. All rights reserved.

Acquired tolerance of tomato (Lycopersicon esculentum cv. Micro-Tom) plants to cadmium-induced stress

The effects of varying concentrations of cadmium (Cd) on the development of Lycopersicon esculentum cv. Micro-Tom (MT) plants were investigated after 40 days (vegetative growth) and 95 days (fruit production), corresponding to 20 days and 75 days of exposure to CdCl(2), respectively. Inhibition of growth was clearly observed in the leaves after 20 days and was greater after 75 days of growth in 1 mM CdCl(2), whereas the fruits exhibited reduced growth following the exposure to a concentration as low as 0.1 mM CdCl(2). Cd was shown to accumulate in the roots after 75 days of growth but was mainly translocated to the upper parts of the plants accumulating to high concentrations in the fruits. Lipid peroxidation was more pronounced in the roots even at 0.05 mM CdCl(2) after 75 days, whereas in leaves, there was a major increase after 20 days of exposure to 1 mM CdCl(2), but the fruit only exhibited a slight significant increase in lipid peroxidation in plants subjected to 1 mM CdCl(2) when compared with the control. Oxidative stress was also investigated by the analysis of four key antioxidant enzymes, which exhibited changes in response to the increasing concentrations of Cd tested. Catalase (EC 1.11.1.6) activity was shown to increase after 75 days of Cd treatment, but the major increases were observed at 0.1 and 0.2 mM CdCl(2), whereas guaiacol peroxidase (EC 1.11.1.7) did not vary significantly from the control in leaves and roots apart from specific changes at 0.5 and 1 mM CdCl(2). The other two enzymes tested, glutathione reductase (EC 1.6.4.2) and superoxide dismutase (SOD, EC 1.15.1.1), did not exhibit any significant changes in activity, apart from a slight decrease in SOD activity at concentrations above 0.2 mM CdCl(2). However, the most striking results were obtained when an extra treatment was used in which a set of plants was subjected to a stepwise increase in CdCl(2) from 0.05 to 1 mM, leading to tolerance of the Cd applied even at the final highest concentration of 1 mM. This apparent adaptation to the toxic effect of Cd was confirmed by biomass values being similar to the control, indicating a tolerance to Cd acquired by the MT plants.

mRNA profile of Nellore calves after primary infection with Haemonchus placei

Haemonchus parasites are responsible for many losses in animal production. However, few studies are available, especially of zebu cattle. In this study, we investigated mRNA differences of immune response genes in naive Nellore calves infected with Haemonchus placei, relating these differences to patterns of cellular infiltrate. Calves were infected with 15,000 H. placei 13 larvae and after 7 days lymph node and abomasum tissues were collected. IL-2, IL-4, IL-8, IL-12, IL-13, IFN-gamma, MCP-1, lysozyme, pepsinogen and TNF-alpha genes were evaluated by qPCR. Mast cells, eosinophils and globular leukocytes were counted by abomasum histology. In the infected group, IL-4, IL-13 and TNF-alpha were up-regulated in the abomasal lymph node. In the abomasum, IL-13 increased and TNF-alpha was down-regulated (p < 0.05). No differences were detected for mast cells and eosinophil counts in abomasal tissue (p > 0.05). We conclude that for this infection time, there was Th2 polarization but that cellular infiltrate in abomasal tissue takes longer to develop. (C) 2010 Elsevier B.V. All rights reserved.

Influence of light and leaf epicuticular wax layer on Phakopsora pachyrhizi infection in soybean

Influence of light and leaf epicuticular wax layer on Phakopsora pachyrhizi infection in soybean Asian rust, caused by the fungus Phakopsora pachyrhizi, is one of the most serious phytosanitary problems of soybean in Brazil, especially because no cultivars with satisfactory resistance levels as yet exist. The objective of this study was to evaluate the influence of luminosity and of leaf epicuticular wax on the infection of soybean by P. pachyrhizi. The adaxial and abaxial leaflet surfaces of the first trifoliate leaf from cultivar BRS 154, phenological stage V2, were inoculated with a suspension of 105 uredospores/mL. The plants were kept for 24 hours in a humid chamber at temperature of 23 degrees C, in light or dark conditions, using a factorial design. Subsequently, the plants were maintained for 14 days under a 12-hour photoperiod. The disease severity and density were evaluated. For in vitro experiments, in light or dark conditions, the evaluation was done in terms of uredospore germination and appressorium formation. The wax content of adaxial and abaxial leaflets was analyzed quantitatively using chloroform extraction and ultrastructurally using scanning electron microscope. Higher density and severity were observed when the adaxial surface was inoculated, with later incubation of the plants in the dark, with no significant interaction between these factors. Spore germination in the dark (40.7%) was statistically different from spore germination in the light (28.5%). The same effect was observed with appressorium formation, in the dark (24.7%) and in the light (12.8%). The quantity and the ultrastructural aspects of epicuticular wax content did not show differences between the adaxial and abaxial surfaces; nor did they show any effect on infection by Phakopsora pachyrhizi in the soybean cultivar studied.

Influence of soybean phenological stage and leaflets age on infection by Phakopsora pachyrhizi

Influence of soybean phenological stage and leaflets age on infection by Phakopsora pachyrhizi This work was conducted to study the influence of soybean growth stage and leaf age on the infection of Phakopsora pachyrhizi, the soybean rust pathogen. Soybean plants (cv. BRS 154 and BRS 258) at the V(3), R(1) and R(5) growth stages were inoculated with a 1 x 10(5) urediniospores per mL suspension. After a period of 24 hours in dew chambers, all plants were removed from the chambers and placed under greenhouse conditions for 20 days. Mean latent period (PLM) and disease severity were estimated. The susceptibility of trifoliate leaves to soybean rust was estimated on cv. BRS 154 at the growth stage R5. Pathogen inoculation was done at the first four trifoliate leaves. Fifteen days after inoculation, leaflets of each trefoil were evaluated for disease severity, lesion mean size and infection frequency. Plants` growth stage did not influence the PLM. Cultivars BRS 154 and BRS 258 presented PLM of 8 and 9 days, respectively. There was no difference in disease severity at the growth stages V(3) and R(1), but those values were higher than at the R(5) growth stage, 8 days after inoculation. The oldest trefoil showed the highest disease values.

Restoration of Pattern Recognition Receptor Costimulation to Treat Chromoblastomycosis, a Chronic Fungal Infection of the Skin

Chromoblastomycosis is a chronic skin infection caused by the fungus Fonsecaea pedrosoi. Exploring the reasons underlying the chronic nature of F. pedrosoi infection in a murine model of chromoblastomycosis, we find that chronicity develops due to a lack of pattern recognition receptor (PRR) costimulation. F. pedrosoi was recognized primarily by C-type lectin receptors (CLRs), but not by Toll-like receptors (TLRs), which resulted in the defective induction of proinflammatory cytokines. Inflammatory responses to F. pedrosoi could be reinstated by TLR costimulation, but also required the CLR Mincle and signaling via the Syk/CARD9 pathway. Importantly, exogenously administering TLR ligands helped clear F. pedrosoi infection in vivo. These results demonstrate how a failure in innate recognition can result in chronic infection, highlight the importance of coordinated PRR signaling, and provide proof of the principle that exogenously applied PRR agonists can be used therapeutically.