Participation of interleukin-5, interleukin-8 and leukotriene B4 in eosinophil accumulation in two different experimental models

There are several experimental models describing in vivo eosinophil (EO) migration, including ip injection of a large volume of saline (SAL) or Sephadex beads (SEP). The aim of this study was to investigate the mechanisms involved in the EO migration in these two models. Two consecutive injections of SAL given 48 hr apart, induced a selective recruitment of EO into peritoneal cavity of rats, which peaked 48 hr after the last injection. SEP, when injected ip, promoted EO accumulation in rats. The phenomenom was dose-related and peaked 48 hr after SEP injection. To investigate the mediators involved in this process we showed that BW A4C, MK 886 and dexamethasone (DXA) inhibited the EO migration induced by SAL and SEP. To investigate the source of the EO chemotactic factor we showed that mast cells, macrophages (MO), but not lymphocytes, incubated in vitro in presence of SAL released a factor which induced EO migration. With SEP, only mast cells release a factor that induced EO migration, which was inhibited by BW A4C, MK 886 and DXA. Furthermore, the chemotactic activity of SAL-stimulated mast cells was inhibited by antisera against IL-5 and IL-8 (interleukin). SAL-stimulated MO were only inhibited by anti-IL-8 antibodies as well SEP-stimulated mast cells. These results suggest that the EO migration induced by SAL may be dependent on resident mast cells and MO and mediated by LTB4, IL-5 and IL-8. SEP-induced EO migration was dependent on mast cells and may be mediated by LTB4 and IL-8. Furthermore, IL-5 and IL-8 induced EO migration, which was also dependent on resident cells and mediated by LTB4 . In conclusion, EO migration induced by SAL is dependent on mast cells and MO, whereas that induced by SEP is dependent on mast cells alone. Stimulated mast cells release LTB4, IL-5 and IL-8 while MO release LTB4 and IL-8. The IL-5 and IL-8 release by the SAL or SEP-stimulated resident cells may act in an autocrine fashion, thus potentiating LTB4 release.

Mechanisms of cell accumulation induced by Mycobacterium bovis BCG

Mycobacteria, specially Mycobacterium tuberculosis are among the micro-organisms that are increasing dramatically the number of infections with death, all over the world. A great number of animal experimental models have been proposed to investigate the mechanisms involved in the host response against these intracellular parasites. Studies of airway infection in guinea-pigs and rabbits, as well as, in mice intravenously infected with BCG have made an important contribution to our understanding of the virulence, pathogenesis and the immunology of mycobacterial infections. Although, there are few models to study the mechanisms of the initial inflammatory process induced by the first contact with the Mycobacteria, and the relevance of the acute generation of inflammatory mediators, cytokines and leukocyte infiltration to the development of the mycobacterial infection. In this work we reviewed our results obtained with a model of M. bovis BCG-induced pleurisy in mice, describing the mechanisms involved in the leukocyte influx induced by BCG at 24 hr. Different mechanisms appear to be related with the influx of neutrophils, eosinophils and mononuclear cells and distinct inflammatory mediators, cytokines and adhesion molecules are involved in the BCG-induced cell accumulation.

Comparison of two commercial formulations of Bacillus thuringiensis var. israelensis for the control of Anopheles aquasalis (Diptera: Culicidae) at three salt concentrations

Anopheles aquasalis larvae are salt water tolerant, preferring concentrations between 10 and 20 parts per thousand (ppt). The larvicidal efficacy of two formulations of Bacillus thuringiensis var. israelensis (Vectobac-12AS® and Bactivec®), was investigated against An. aquasalis at salinities of 0, 10, and 20 ppt. A probit analysis was used to calculate the lethal concentrations (LC50 and LC95) for each product at each salinity. The LC50 and LC95 were higher for Bactivec® than Vectobac-12AS®, and for Bactivec®, the LC50 and LC95 increased with salinity. Vectobac-12AS® should thus be preferred to Bactivec® for An. aquasalis control, especially in saline breeding habitats.

Total lipid and fatty acid accumulation during basidiospore formation in the ectomycorrhizal fungus Pisolithus sp.

The basidiospores of Pisolithus sp. contain large amounts of lipids, indicating provision for future germination in the host rhizosphere. However, the accumulation, composition, and mobilization of lipids during formation and germination of these spores are largely unknown. In this study, lipid storage and fatty acid composition during basidiosporogenesis were analyzed in fresh basidiocarps using bright-field microscopy and gas chromatography. Abundant lipid bodies are found in the hyphae, basidia, and basidiospores of fungal basidiocarps. This evidences a considerable C transport in the basidiocarp to meet the C demand during basidiospore formation. Fatty acid composition analysis revealed the presence of 24 compounds with chains of 9 to 18 C atoms, either saturated or insaturated, with one or two insaturations. The fatty acid composition and content varied according to the developmental stage of the peridioles. In free basidiospores, the predominant compounds were 16:0, 16:1w5c, 18:1w9c, and 18:2w6,9c/18:0ante, at concentrations of 76, 46, 192, and 51 µg g-1 dry matter, respectively. Our results indicate that oleic acid is the major constituent of lipid reserves in Pisolithus sp. basidiospores. Further studies are being conducted to determine the factors that induce lipid mobilization during spore germination.

Relationships between grain yield and accumulation of biomass, nitrogen and phosphorus in common bean cultivars

Shoot biomass is considered a relevant component for crop yield, but relationships between biological productivity and grain yield in legume crops are usually difficult to establish. Two field experiments were carried out to investigate the relationships between grain yield, biomass production and N and P accumulation at reproductive stages of common bean (Phaseolus vulgaris) cultivars. Nine and 18 cultivars were grown on 16 m² plots in 1998 and 1999, respectively, with four replications. Crop biomass was sampled at four growth stages (flowering R6, pod setting R7, beginning of pod filling R8, and mid-pod filling R8.5), grain yield was measured at maturity, and N and P concentrations were determined in plant tissues. In both years, bean cultivars differed in grain yield, in root mass at R6 and R7 stages, and in shoot mass at R6 and R8.5, whereas at R7 and R8 differences in shoot mass were significant in 1998 only. In both years, grain yield did not correlate with shoot mass at R6 and R7 and with root mass at R6. Grain yield correlated with shoot mass at R8 in 1999 but not in 1998, with shoot mass at R8.5 and with root mass at R7 in both years. Path coefficient analysis indicated that shoot mass at R8.5 had a direct effect on grain yield in both years, that root mass at R7 had a direct effect on grain yield in 1998, and that in 1999 the amounts of N and P in shoots at R8.5 had indirect effects on grain yield via shoot mass at R8.5. A combined analysis of both experiments revealed that biomass accumulation, N and P in shoots at R6 and R7 as well as root mass at R6 were similar in both years. In 1998 however bean accumulated more root mass at R7 and more biomass and N and P in shoots at R8 and R8.5, resulting in a 57 % higher grain yield in 1998. This indicates that grain yield of different common bean cultivars is not intrinsically associated with vegetative vigor at flowering and that mechanisms during pod filling can strongly influence the final crop yield. The establishment of a profuse root system during pod setting, associated with the continuous N and P acquisition during early pod filling, seems to be relevant for higher grain yields of common bean.

Dry matter production and nutrient accumulation after successive crops of lettuce, tomato, rice, and andropogongrass in a substrate with zeolite

Zeolites are hydrated crystalline aluminosilicate minerals of natural occurrence, structured in rigid third dimension net that can be used as slow release plant-nutrient source. The main objective of this study was to evaluate the effects of plant growth substrate under zeolite application, enriched with N, P and K, on dry matter yield and on nutrient contents in consecutive crops of lettuce, tomato, rice, and andropogon grass. The experiment was carried out in a greenhouse, with 3 kg pots with an inert substrate, evaluated in a randomized block design with three replications. Treatments consisted of four types of enrichment of concentrated natural zeolite: concentrated zeolite (Z) only, zeolite + KNO3 (ZNK), zeolite + K2HPO4 (ZPK) and zeolite + H3PO4 + apatite (ZP), and a control grown in substrate fertilized with a zeolite-free nutrient solution. Four levels of enriched zeolite were tested: 20, 40, 80, and 160 g/pot. Four successive crops were grown on the same substrate in each pot: lettuce, tomato, rice, and andropogon grass. Results indicated that N, P and K enriched zeolite was an adequate slow-release nutrient source for plants. The total dry matter production of above-ground biomass of four successive crops followed a descending order: ZP > ZPK > ZNK > Z.

Diversity and efficiency of bradyrhizobium strains isolated from soil samples collected from around sesbania virgata roots using cowpea as trap species

The genetic diversity of ten Bradyrhizobium strains was evaluated for tolerance to high temperatures, to different salinity levels and for the efficiency of symbiosis with cowpea plants (Vigna unguiculata (L.) Walp.). Eight of these strains were isolated from nodules that appeared on cowpea after inoculation with suspensions of soil sampled from around the root system of Sesbania virgata (wand riverhemp) in ecosystems of South Minas Gerais. The other two strains used in our analyses as references, were from the Amazon and are currently recommended as cowpea inoculants. Genetic diversity was analyzed by amplifying repetitive DNA elements with the BOX primer, revealing high genetic diversity with each strain presenting a unique band profile. Leonard jar assays showed that the strains UFLA 03-30 and UFLA 03-38 had the highest N2-fixing potentials in symbiosis with cowpea. These strains had more shoot and nodule dry matter, more shoot N accumulation, and a higher relative efficiency than the strains recommended as inoculants. All strains grew in media of pH levels ranging from 4.0 to 9.0. The strains with the highest N2-fixing efficiencies in symbiosis with cowpea were also tolerant to the greatest number of antibiotics. However, these strains also had the lowest tolerance to high salt concentrations. All strains, with the exceptions of UFLA 03-84 and UFLA 03-37, tolerated temperatures of up to 40 ºC. The genetic and phenotypic characteristics of the eight strains isolated from soils of the same region were highly variable, as well as their symbiotic efficiencies, despite their common origin. This variability highlights the importance of including these tests in the selection of cowpea inoculant strains.

Cadmium availability and accumulation by lettuce and rice

Among the toxic elements, Cd has received considerable attention in view of its association with a number of human health problems. The objectives of this study were to evaluate the Cd availability and accumulation in soil, transfer rate and toxicity in lettuce and rice plants grown in a Cd-contaminated Typic Hapludox. Two simultaneous greenhouse experiments with lettuce and rice test plants were conducted in a randomized complete block design with four replications. The treatments consisted of four Cd rates (CdCl2), 0.0; 1.3; 3.0 and 6.0 mg kg-1, based on the guidelines recommended by the Environmental Agency of the State of São Paulo, Brazil (Cetesb). Higher Cd rates increased extractable Cd (using Mehlich-3, Mehlich-1 and DTPA chemical extractants) and decreased lettuce and rice dry matter yields. However, no visual toxicity symptoms were observed in plants. Mehlich-1, Mehlich-3 and DTPA extractants were effective in predicting soil Cd availability as well as the Cd concentration and accumulation in plant parts. Cadmium concentration in rice remained below the threshold for human consumption established by Brazilian legislation. On the other hand, lettuce Cd concentration in edible parts exceeded the acceptable limit.

Phosphorus accumulation and pollution potential in a hapludult fertilized with pig manure

Successive applications of pig litter to the soil surface can increase the phosphorus (P) content and alter its adsorption, promoting P transfer to surface or subsurface waters. The purpose of this study was to evaluate P accumulation and the pollution potential of a soil after application of pig litter. In March 2010, eight years after the installation of an experiment in Braço do Norte, Santa Catarina, SC, Brazil, on a Typic Hapludult, soil was sampled (layers 0-2.5, 2.5-5, 5-10, 10-15, 15-20 and 20-30 cm) after the following fertilization treatments: no pig litter fertilization, pig slurry application and pig manure application. In this period, 694 and 1,890 kg P2O5 ha-1 were applied in the treatments with pig slurry and pig manure, respectively. The P content was determined, based on Mehlich-1, anion exchange resin (AER), 0.01 mol L-1 CaCl2 and total P in the samples. The adsorption isotherm parameters were also determined by the Langmuir and Koski-Vähälä & Hartikainem models in the layers 0-2.5 and 20-30 cm. The application of 1,890 kg P2O5 ha-1 in the form of pig manure led to P accumulation, as evidenced by Mehlich-1, down to a depth of 15 cm, by AER and 0.01 mol L-1 CaCl2 down to 20 cm and by total P to 30 cm. After application of 1,890 kg P2O5 ha-1 in the form of pig manure, the values of maximum P adsorption capacity were lowest in the deepest layer (20-30 cm), indicating the occupation of part of the adsorption sites of the particles. The application of swine manure to the soil over eight years increased the P quantity in the soil solution of the surface layer, indicating environmental contamination risk for surface and subsurface waters.

Nutrition, dry matter accumulation and partitioning and phosphorus use efficiency of potato grown at different phosphorus levels in nutrient solution

High rates of phosphate fertilizers are applied to potato (Solanum tuberosum L.), which may cause antagonistic interactions with other nutrients and limit crop yields when over-supplied. The purpose of this study was to evaluate the influence of phosphorus (P) levels in nutrient solution on P use efficiency, nutritional status and dry matter (DM) accumulation and partitioning of potato plants cv. Ágata. The experiment was carried out in a greenhouse, arranged in a completely randomized block design with four replications. Treatments consisted of seven P levels in nutrient solution (0, 2, 4, 8, 16, 31, and 48 mg L-1). Plants were harvested after 28 days of growth in nutrient solution, and separated in roots, stems and leaves for evaluations. The treatment effects were analyzed by regression analysis. Phosphorus levels of up to 8 mg L-1 increased the root and shoot DM accumulation, but drastically decreased the root/shoot ratio of potato cv. Ágata. Higher P availability increased P concentration, accumulation and absorption efficiency, but decreased P use efficiency. Higher P levels increased the N, P, Mg, Fe, and Mn concentrations in roots considerably and decreased K, S, Cu, and Zn concentrations. In shoot biomass, N, P, K, and Ca concentrations were significantly increased by P applied in solution, unlike Mg and Cu concentrations. Although higher P levels (> 8 mg L-1) in nutrient solution increased P concentration, accumulation and absorption efficiency, the DM accumulation and partitioning of potato cv. Ágata were not affected.

Forms and accumulation of copper and zinc in a sandy typic hapludalf soil after long-term application of pig slurry and deep litter

Successive applications of pig slurry and pig deep litter may lead to an accumulation of copper (Cu) and zinc (Zn) fractions in the soil profile. The objective of this study was to evaluate the Cu and Zn forms and accumulation in a Sandy Typic Hapludalf soil after long-term application of pig slurry and deep litter. In March 2010, eight years after initiating an experiment in Braço do Norte, Santa Catarina (SC), Brazil, on a Sandy Typic Hapludalf soil, soil samples were collected from the 0-2.5, 2.5-5.0, 5-10 and 10-15 cm layers in treatments consisting of no manure application (control) and with applications of pig slurry and deep litter at two levels: the single and double rate of N requirement for maize and black oat succession. The soil was dried, ground in an agate mortar and analyzed for Cu and Zn contents by 0.01 mol L-1 EDTA and chemically fractionated to determine Cu and Zn. The applications of Pig deep litter and slurry at doses equivalent to 90 kg ha-1 N increased the contents of available Cu and Zn in the surface soil layer, if the double of this dose was applied in pig deep litter or double this dose in pig slurry, Cu and Zn migrated to a depth of 15 cm. Copper is accumulated mainly in the organic and residual fractions, and zinc preferentially in the fraction linked to clay minerals, especially in the surface soil layers.

Accumulation of phosphorus fractions and contamination potential in vineyard soils in the southern region of the state of Santa Catarina, Brazil

In vineyards, if phosphate is applied both before planting and at intervals during growth without consideration of technical criteria, the soil P fractions may be increased and their proportions altered. This study was carried out to evaluate the accumulation of P fractions and the parameters of the adsorption isotherm in a sandy Typic Hapludalf soil in vineyards with a history of successive and excessive phosphate fertilization. In December 2010, two vineyards were selected, one 4 and the other 15 years old, in Urussanga, State of Santa Catarina (Brazil). Three trenches were dug in each area and soil was collected from the 0-5, 5-10 and 10-20 cm depth ranges. The soil samples were dried in a forced-air oven, sieved and subjected to chemical analyses, P chemical fractionation and P adsorption isotherms. Excessive phosphate fertilization, before and during cultivation, particularly in the older vineyard and, consequently, with a longer history of phosphate fertilization, increased the inorganic P concentrations to the depth of 20 cm, especially in labile fractions extracted by anion exchange resin and NaHCO3 in the non-labile fraction, as well as in the non-labile fraction extracted by 1.0 mol L-1 HCl. The application of phosphate fertilizers and the long cultivation period increased the P levels in the organic labile fraction extracted by 0.5 mol L-1 NaHCO3, and especially in the moderately labile fraction extracted by 0.1 and 0.5 mol L-1 NaOH. Phosphate fertilization of older vineyards, i.e., cultivated for 15 years, increased the amounts of P desorbed in water, indicating a risk of contamination of surface waters and groundwater. The phosphate fertilization before planting, without considering the results of soil analysis, and during cultivation, disregarding the results of soil analysis, leaf analysis and expected yield, led to a reduction in the maximum P adsorption capacity in the 0-5 cm layer of vineyard 2, indicating saturation of part of the reactive particle adsorption sites.

Manganese accumulation and its relation to "eucalyptus shoot blight in the Vale do Rio Doce"

Eucalyptus Shoot Blight in the Vale do Rio Doce (ESBVRD) is an anomaly that leads to reduced growth and, in more extreme cases, to death of eucalyptus plants. Initially diagnosed in plantations in the region of the Vale do Rio Doce, in the State of Minas Gerais, Brazil, this problem has also been found in plantations in other regions of the country and even in other countries. Although the symptoms of this anomaly are well-known, its causes are not yet understood. The aim of this study was to evaluate the cause-effect relationship between accumulation of manganese (Mn) in eucalyptus clones and ESBVRD. Characterization of the environment in areas of greater occurrence of this problem in regard to soil, climate and fluctuation of the water table was undertaken in eucalyptus plantations of the Celulose Nipo-brasileira S.A. (Cenibra) company in the region of the Vale do Rio Doce. Plant tissues were sampled in two situations. In the first situation, diagnosis occurred in the initial phase of the anomaly in clones with differentiated tolerance to the problem; in the second situation, diagnosis was made in a single clone, considered to be sensitive, in two time periods - in the phase with the strong presence of symptoms and in the recovery phase, in areas of occurrence and in areas of escape from the problem. The most ESBVRD-sensitive clone showed much higher (4.8 times higher) leaf Mn contents than more tolerant clones. In plants with the anomaly, Mn leaf contents were greater than 3,070 mg kg-1, much greater than the quantity found in those without the anomaly (734 mg kg-1). In the period in which the symptoms began to wane, there was a sharp decline in leaf Mn contents, from 2,194 to 847 mg kg-1. Manganese content in the above ground part and plant litter (44.4 g ha-1) in the area of occurrence of the anomaly was three times greater than that found in these same components (14.1 g ha-1) in the area of absence of the symptom. Based on the evidence found, such as the existence of environmental conditions favorable to high Mn availability to the plants in the areas of greatest incidence of ESBVRD, greater uptake of Mn in sensitive clones and in plants with symptoms, and a synchronism between the intensity of symptoms of ESBVRD and leaf Mn contents, it may be inferred that temporary excess of Mn in eucalyptus plants is closely related to ESBVRD.

Genotypic variability in seed accumulation of foliar-applied molybdenum to common bean

The genotypic variability in molybdenum (Mo) accumulation in common bean seeds has been demonstrated in cases in which soil is the main Mo source, but this variability is yet unknown when Mo is foliar-applied. Therefore, seed Mo concentrations (SMoCc) and seed Mo contents (SMoCt) of 12 genotypes were determined in four experiments in the Zona da Mata, Minas Gerais, Brazil, in which plants were sprayed with 600 g ha-1 Mo. For comparison, two additional experiments without external Mo were conducted. Without Mo application, the average SMoCc was undetectable or 2.83 µg g-1, without significant differences among genotypes. On average, with Mo applications, SMoCc ranged from 14.7 to 25.0 µg g-1 and SMoCt, from 3.94 to 6.84 µg. 'Majestoso' was among the genotypes with the highest SMoCc in the four experiments. However, the large-seeded 'Jalo MG-65' and 'Carnaval' generally had higher SMoCt than the small-seeded 'Majestoso'. 'Ouro Negro' and especially 'Valente' were among the genotypes with the lowest SMoCc and SMoCt. The values of these variables were 61 and 90 %, respectively, higher for 'Majestoso' than those for 'Valente'. Our results suggest that common bean genotypes differ in their capacity to accumulate foliar-applied Mo in the seeds. Mo-rich seeds of large-seeded genotypes or of small-seeded of small-seeded genotypes with good capacity to accumulate Mo in seeds can be produced with relatively less Mo fertilizer.

Dry matter and macronutrient accumulation in fruits of Conilon coffee with different ripening cycles

The period between anthesis and fruit ripening varies according to the Conilon coffee (Coffea canephora) genotype. Therefore, the time of the nutritional requirements for fruit formation may differ, depending on the formation phase and the genotype, and may directly affect split application of fertilizer. The aim of this study was to quantify the accumulation of dry matter and N, P, K, Ca, Mg and S at several stages in the fruit of the Conilon coffee genotype with different ripening cycles, which may suggest the need for split application of fertilizer in coffee. The experiment was carried out in the municipality of Nova Venecia, Espírito Santo, Brazil, throughout the reproductive cycle. The treatments were composed of four coffee genotypes with different ripening cycles. A completely randomised experimental design was used. with five replicates. Plagiotropic branches were harvested from flowering to fruit ripening at 28-day intervals to determine the dry matter of the fruits and the concentration and accumulation of the nutrients they contained. The behavior of dry matter and macronutrient accumulation during the study period was similar and increasing, but it differed among genotypes sampled in the same season. Early genotypes exhibited a higher speed of dry matter and nutrient accumulation. Split application of fertilizer should differ among coffee genotypes with different ripening cycles (early, intermediate, late and very late).