Comparação de dois tipos de amostragem de chuva: deposição total e deposição apenas úmida em àrea costeira tropical

In a tropical coastal area. During 6 months the composition of rain samples collected simultaneously over 24h with an open collector and with an automatic opened collector (KFA - J¸lich Type) at 500m of the Atlantic coastline of Salvador were compared. All average concentrations were higher for the "total" samples than for the "wet only" samples, except for hydrogen ions, nitrate and ammonium.

Ninety-day oral toxicity studies on two genetically modified maize MON810 varieties in Wistar Han RCC rats (EU 7th Framework Programme project GRACE)

The GMO Risk Assessment and Communication of Evidence (GRACE; www.grace-fp7.eu) project is funded by the European Commission within the 7th Framework Programme. A key objective of GRACE is to conduct 90-day animal feeding trials, animal studies with an extended time frame as well as analytical, in vitro and in silico studies on genetically modified (GM) maize in order to comparatively evaluate their use in GM plant risk assessment. In the present study, the results of two 90-day feeding trials with two different GM maize MON810 varieties, their near-isogenic non-GM varieties and four additional conventional maize varieties are presented. The feeding trials were performed by taking into account the guidance for such studies published by the EFSA Scientific Committee in 2011 and the OECD Test Guideline 408. The results obtained show that the MON810 maize at a level of up to 33 % in the diet did not induce adverse effects in male and female Wistar Han RCC rats after subchronic exposure, independently of the two different genetic backgrounds of the event

O papel dos sulfetos volatilizados por acidificação no controle do potencial de biodisponibilidade de metais em sedimentos contaminados de um estuário tropical, no sudeste do Brasil

Measurements of acid volatile sulfide (AVS) and simultaneously extracted metals (SEM) were combined in order to verify the ecological hazard of contaminated sediments from the Santos-Cubatão Estuarine System (SE Brazil), which is located in one of the most industrialized areas in the Latin America. Intertidal sediments from the Morrão River estuary were collected seasonally in short cores. The redox conditions, organic matter contents and grain-size were the main controlling factors on SEM distribution. However, clear relationships among these variables and AVS were not observed. The molar SEM/AVS ratios were frequently > 1 especially in the summer, suggesting major metal bioavailability hazard in this humid hot season.

Influência da temperatura, umidade e profundidade do solo na persistência do diurom e sulfato de endossulfam em um solo tropical

The influence of temperature (30 and 40 ºC) and soil humidity (20, 50 and 70% of water holding capacity) on the degradation of the herbicide diurom and the endosulfan metabolite, endosulfan sulfate was studied under laboratory conditions, in different soil layers (0-30, 30-38 and 38-83 cm) of an Oxisol (Yellow Latosol) collected in an agricultural area of Mato Grosso State, Brazil. Endosulfan sulfate was rapidly degraded under lower soil humidity, higher temperature and deeper soil layers. For diurom the opposite was observed as a consequence of its higher water solubility and lower soil sorption coefficient.

Biodegradação de alcoóis, ftalatos e adipatos em um solo tropical contaminado

The adipic and phthalic acid esters are plasticizers, have low water solubility, high partition octanol/water coefficients (Kow) and accumulate in soil and sediments. These compounds are considered teratogenic, carcinogenic and endocrine disruptors chemicals. This study evaluated the bioremediation of tropical soil contaminated with plasticizers process wastes, in aerobic conditions, with and without introduction of acclimated bacteria. It was selected 200 kg of contaminated tropical soil for the biodegradation study. The plasticizers concentrations in soil ranged between 153 mgDOA/kg up to 15552 mgDIDP/kg and after 90 days of biodegradation, the lower removal efficiencies were 72% with a 1-2 log simultaneous bacterial growth.

Lipídios como indicadores de fontes e distribuição de matéria orgânica particulada em um complexo estuarino-lagunar tropical (Mundaú-Manguaba, AL)

Fatty acids, alcohols and sterols were considered as markers of the source and distribution of particulate organic matter during the dry season in the Mundaú-Manguaba estuarine-lagoon system, NE Brazil. Lipid composition showed an overwhelming influence of autochthonous sources of organic matter in all system´s compartments, including the probable occurrence of algal blooms in specific areas. On the other hand, contamination by sewage was restricted to Mundaú lagoon. This scenario differed from known conditions observed in the wet season, illustrating the usefulness of the lipid biomarker approach for the characterization of other complex and dynamic systems in the Brazilian coastal zone.

Esterois como indicadores do acúmulo de esgotos domésticos em sedimentos de um sistema estuarino-lagunar tropical (Mundaú-Manguaba, AL)

The history of sewage contamination in the Mundaú-Manguaba estuarine lagoon system (NE Brazilian coastal zone) was evaluated through the concentration of sterols in sediment cores. The concentration of coprostanol increased towards the surface sediments, with the maximum of 5.65 µg g-1 at 0-2 cm sediment layer in Mundaú. Manguaba exhibited a lower level of contamination. The ratio cholestanol/cholesterol suggested degradation of coprostanol only before the burial of organic matter in the sediment. This feature, together with information of population growth in the watershed, allowed the estimation of a sedimentation rate of 0.90 cm year-1 to the Mundaú lagoon.

Tropical biodiversity: has it been a potential source of secondary metabolites useful for medicinal chemistry?

The use of natural products has definitely been the most successful strategy in the discovery of novel medicines. Secondary metabolites from terrestrial and marine organisms have found considerable use in the treatment of numerous diseases and have been considered lead molecules both in their natural form and as templates for medicinal chemistry. This paper seeks to show the great value of secondary metabolites and emphasize the rich chemical diversity of Brazilian biodiversity. This natural chemical library remains understudied, but can be a useful source of new secondary metabolites with potential application as templates for drug discovery.

Corrosion of steel reinforced concrete in the tropical coastal atmosphere of Havana City, Cuba

The influence of chloride deposition rate on concrete using an atmospheric corrosion approach is rarely studied in the literature. Seven exposure sites were selected in Havana City, Cuba, for exposure of reinforced concrete samples. Two significantly different atmospheric corrosivity levels with respect to corrosion of steel reinforced concrete were observed after two years of exposure depending on atmospheric chloride deposition and w/c ratio of the concrete. Changes in corrosion current are related to changes in chloride penetration and chloride atmospheric deposition. The influence of sulphur compound deposition could also be a parameter to consider in atmospheric corrosion of steel reinforced concrete.

Epidemiologia comparativa entre os patossistemas temperado e tropical: conseqüências para a resistência a fungicidas

O patossistema tropical difere do patossistema temperado tanto em estrutura quanto em comportamento. Nesta revisão, ambos os patossistemas são caracterizados e, com base nessa caracterização, o risco de origem e de seleção de resistência a fungicidas é discutido para ambas as situações. As características diferenciais relevantes para análise foram: sobrevivência I (entre estações de cultivo); sobrevivência II (entre ciclos do patógeno); taxa aparente de infecção; via anti-horária de infecção; ingresso e/ou manutenção de mutantes resistentes; via horária de infecção; persistência de mutantes resistentes; adaptabilidade dos mutantes resistentes. Conclui-se que o patossistema tropical não apresenta risco maior para a seleção de mutantes resistentes, mas pode, em alguns casos, apresentar risco maior de origem de mutantes resistentes.

Genetic variation among pathogens causing "Helminthosporium" diseases of rice, maize and wheat

Twenty isolates of four fungal species, agents of "Helminthosporium" diseases in cereals, were collected from different regions: nine Bipolarisoryzae isolated from rice (Oryza sativa), seven B.sorokiniana from wheat (Triticum aestivum), two B. maydis, and two Exserohilumturcicum from maize (Zea mays). The strains were compared by PCR-RFLP and RAPD analysis. Size polymorphism among the isolates in the ITS region comprising the 5.8 S rDNA indicated genetic differences among the isolates, while a UPGMA phenogram constructed after the digestion of this region with restriction enzymes showed inter- and intra-specific polymorphism. The RAPD profiles indicated an expressive level of polymorphism among different species, compared with a low level of polymorphism among isolates of the same species. A UPGMA phenogram grouped the isolates according to the species and their host plant. RAPD profiles did not reveal polymorphism that directly correlated climatic factors with geographic source of the isolates of B. sorokiniana, and B. oryzae. Teleomorphic species revealed high similarity with their correspondent anamorphs.

Temporal progress of southern rust in maize under different environmental conditions

The progress of the severity of southern rust in maize (Zea mays) caused by Puccinia polysora was quantified in staggered plantings in different geographical areas in Brazil, from October to May, over two years (1995-1996 and 1996-1997). The logistic model, fitted to the data, better described the disease progress curves than the Gompertz model. Four components of the disease progress curves (maximum disease severity; area under the disease progress curve, AUDPC; area under the disease progress curve around the inflection point, AUDPCi; and epidemic rate) were used to compare the epidemics in different areas and at different times of planting. The AUDPC, AUDPCi, and the epidemic rate were analyzed in relation to the weather (temperature, relative humidity, hours of relative humidity >90%, and rainfall) and recorded during the trials. Disease severity reached levels greater than 30% in Piracicaba and Guaíra in the plantings between December and January. Lower values of AUDPC occurred in later plantings at both locations. The epidemic rate was positively correlated (P < 0.05) with the mean daily temperatures and negatively correlated with hours of relative humidity >90%. The AUDPC was not correlated with any weather variable. The AUDPCi was negatively related to both variables connected to humidity, but not to rain. Long periods (mostly >13 h day-1) of relative humidity >90% (that corresponded to leaf wetness) occurred in Castro. Severity of southern rust in maize has always been low in Castro, thus the negative correlations between disease and the two humidity variables.

Effect of Fusarium graminearum and infection index on germination and vigor of maize seeds

Pathogens in maize (Zea mays) seeds cause serious problems, such as the loss of their capacity to germinative. The objectives of this study were to identify the optimal period for infection of maize seeds on agar colonized by Fusarium graminearum, when incubated for 4, 8, 16 and 32 h, and to evaluate the effect of the fungus on the germination and vigor of seeds with different infection levels. After the respective incubation periods, the seeds were removed from the culture medium and submitted to the blotter test for 3 min with and without superficial disinfection with 1% solution of sodium hypochlorite. Once the optimal period for seed incubation was identified, seeds from the same sample were again placed on the colonized agar for infection. Germination and vigor tests (accelerated aging and cold test) were performed with a mixture of healthy seeds (placed on PDA medium) and inoculated seeds, resulting in seeds with 0, 20, 40, 60, 80 and 100% rates of infection. The results showed that a period of 32 h was long enough to obtain seeds infected by the pathogen. There were no significant effects of fungal infection on seed germination at any of the infection levels, probably due to the high vigor of the maize seed lot tested. Regarding vigor tests, infection levels differed significantly from the control (0% infection), but there were no significant differences among the infection levels.

Adsorption isotherm studies of Cd (II), Pb (II) and Zn (II) ions bioremediation from aqueous solution using unmodified and EDTA-modified maize cob

The need to clean-up heavy metal contaminated environment can not be over emphasized. This paper describes the adsorption isotherm studies of Cd (II), Pb (II) and Zn (II) ions from aqueous solution using unmodified and EDTA-modified maize cob. Maize cob was found to be an excellent adsorbent for the removal of these metal ions. The amount of metal ions adsorbed increased as the initial concentration increased. Also, EDTA - modification enhanced the adsorption capacity of maize cob probably due to the chelating ability of EDTA. Among the three adsorption isotherm tested, Dubinin-Radushkevich gave the best fit with R² value ranging from 0.9539 to 0.9973 and an average value of 0.9819. This is followed by Freundlich isotherm (Ave. 0.9783) and then the Langmuir isotherm (Ave. 0.7637). The sorption process was found to be a physiosorption process as seen from the apparent energy of adsorption which ranged from 2.05KJ\mol to 4.56KJ\mol. Therefore, this study demonstrates that maize cob which is an environmental pollutant could be used to adsorb heavy metals and achieve cleanliness thereby abating environmental nuisance caused by the maize cob.