The influence of dietary vitamin C and E supplementation on the physiological response of pirarucu, Arapaima gigas, in net culture

This study evaluated the efficacy of dietary vitamin C (ascorbic acid or AA), vitamin E (alpha-tocopherol or alpha-T), and C+E supplementation on the blood parameters of Arapaima gigas grown in net cages for 45 days. Four treatments were tested: control (commercial feed); C800; E500 and C+E (800+500) with supplementation of 800 mg AA kg(-1), 500 mg alpha-T kg(-1) and 800+500 mg AA+alpha-T kg(-1), respectively. Hematocrit (Ht), red blood cells (RBC), and hemoglobin concentration (Hb) (oxidative status indicators), thrombocytes and leukocytes (immunological indicators), plasma protein and glucose were evaluated. Fish fed vitamin C and C+E supplemented diets showed greater weight gain and survival. Dietary vitamin C and C+E diet supplementation resulted in increased Ht, Hb, RBC, MCHC, total leukocytes, total proteins, thrombocytes and eosinophils compared to the control and alpha-T. The alpha-tocopherol-supplemented diet reduced the number of total thrombocytes, lymphocytes and neutrophils and increased glucose and eosinophils relatively to the control. In general, leukocytes and thrombocytes were good indicators of the efficiency of vitamin on the defense mechanism of the A. gigas reared in cages. Results indicate that high alpha-T diet supplementation provides no benefit for the maintenance of the oxidative or the immunological status of A. gigas. However, it was demonstrated that high dietary AA improves A. gigas immunological status. Red blood cell indices and immune system indicators showed no synergistic effect between the vitamins after supplementing the A. gigas diet with alpha-T+AA.     

Distance to the Scaling Law: A Useful Approach for Unveiling Relationships between Crime and Urban Metrics

We report on a quantitative analysis of relationships between the number of homicides, population size and ten other urban metrics. By using data from Brazilian cities, we show that well-defined average scaling laws with the population size emerge when investigating the relations between population and number of homicides as well as population and urban metrics. We also show that the fluctuations around the scaling laws are log-normally distributed, which enabled us to model these scaling laws by a stochastic-like equation driven by a multiplicative and log-normally distributed noise. Because of the scaling laws, we argue that it is better to employ logarithms in order to describe the number of homicides in function of the urban metrics via regression analysis. In addition to the regression analysis, we propose an approach to correlate crime and urban metrics via the evaluation of the distance between the actual value of the number of homicides (as well as the value of the urban metrics) and the value that is expected by the scaling law with the population size. This approach has proved to be robust and useful for unveiling relationships/behaviors that were not properly carried out by the regression analysis, such as the non-explanatory potential of the elderly population when the number of homicides is much above or much below the scaling law, the fact that unemployment has explanatory potential only when the number of homicides is considerably larger than the expected by the power law, and a gender difference in number of homicides, where cities with female population below the scaling law are characterized by a number of homicides above the power law.     

Temporal trends and effects of diversity on occurrence of exotic macrophytes in a large reservoir

Two exotic invasive macrophyte species (the emergent Urochloa subquadripara - tenner-grass - and the submersed Hydrilla verticillata - hydrilla) were investigated in a large sub-tropical reservoir. We analyzed their occurrences over an extended period and tested the hypothesis that macrophyte richness decreases their invasibility. The alternative hypothesis that the occurrence of these exotics is affected by fetch and underwater radiation (important determinants of macrophyte assemblage composition in this reservoir) was also tested. Incidence data (presence/absence) was obtained over 9.5 years at 235 stations. Logistic regression was applied to test whether the likelihood of occurrence of these two species was affected by macrophyte richness, fetch or underwater radiation. Tenner-grass was recorded at a high frequency and quickly recovered from disturbances caused by water drawdown. In contrast, H. verticillata was first recorded in 3 sites in January 2007, but it spread quickly, reaching 30.5% of the sites 19 months later. The main channel of the Paraná River was the main source of propagules for this species. The likelihood of occurrence of tenner-grass was positively affected by macrophyte richness but negatively affected by fetch. Thus, wave disturbance is probably more important than diversity in preventing invasion by this species. Hydrilla, by contrast, was negatively affected by macrophyte richness and positively affected by fetch and underwater radiation. Although this result might indicate that macrophyte diversity prevents hydrilla invasion, this is probably not true because hydrilla colonized deeper sites where few species of plant exist. Resistance to disturbances caused by water drawdown (tenner-grass) and waves (hydrilla) as well as persistency of tenner-grass and fast spread of hydrilla make these exotic species a cause for concern because of their potential impacts on water uses and maintenance of diversity.     

Immobilized 4-aminophenyl 1-thio-beta-D-galactofuranoside as a matrix for affinity purification of an exo-beta-D-galactofuranosidase

An alternative and fast method for the purification of an exo-beta-D-galactofuranosidase has been developed using a 4-aminophenyl 1-thio-beta-D-galactofuranoside affinity chromatography system and specific elution with 10 mM D-galactono-1,4-lactone in a salt gradient. A concentrated culture medium from Penicillium fellutanum was chromatographed on DEAE-Sepharose CL 6B followed by chromatography on the affinity column, yielding two separate peaks of enzyme activity when elution was performed with 10 mM D-galactono-1,4-lactone in a 100-500 mM NaCl salt gradient. Both peaks behaved as a single 70 kDa protein, as detected by SDS-PAGE. Antibodies elicited against a mixture of the single bands excised from the gel were capable of immunoprecipitating 0.2 units out of 0.26 total units of the enzyme from a crude extract. The glycoprotein nature of the exo-beta-D-galactofuranosidase was ascertained through binding to Concanavalin A-Sepharose as well as by specific reaction with Schiff reagent in Western blots. The purified enzyme has an optimum acidic pH (between 3 and 6), and Km and Vmax values of 0.311 mM and 17 mumol h-1 microgram-1 respectively, when 4-nitrophenyl beta-D-galactofuranoside was employed as the substrate.     

Antibody response in mice immunized with a plasmid DNA encoding the colonization factor antigen I of enterotoxigenic Escherichia coli

The colonization factor antigen I (CFA/I) is one of the most epidemiologically relevant enterotoxigenic Escherichia coli (ETEC) fimbrial adhesins, which mediates the binding to human small intestine epithelium. A recombinant eukaryotic expression plasmid, pRECFA, encoding the CFA/I protein fused to the glycoprotein D of herpes simplex type 1 virus, was used to generate an antibody response in a murine model following intramuscular inoculation of purified DNA. Eukaryotic cells (BHK-21) transfected with pRECFA expressed the CFA/I protein in vitro, as revealed by Western blot and immunofluorescence microscopy. Administration of a single pRECFA 100-microg dose induced a long-term CFA/I-specific antibody response in BALB/c mice composed mainly of IgG and, to a lesser extent, IgA isotypes. The major CFA/I-specific IgG subclass was IgG2a, suggesting a Th-1-type immune response. A second dose with the same amount of purified DNA, given 2 weeks later, caused a booster effect on the immunoglobulin levels, but did not qualitatively alter the isotypes and subclasses of the induced antibody response. Immunization with different amounts of purified DNA and/or number of doses showed that maximal transient CFA/I-specific antibody levels could be obtained after two 100-microg doses of pRECFA given 2 weeks apart, but long-term antibody levels were similar.     

Fuel ethanol after 25 years

After 25 years, Brazil and North America are still the only two regions that produce large quantities of fuel ethanol, from sugar cane and maize, respectively. The efficiency of ethanol production has steadily increased and valuable co-products are produced, but only tax credits make fuel ethanol commercially viable because oil prices are at an all-time low. The original motivation for fuel-ethanol production was to become more independent of oil imports; now, the emphasis is on its use as an oxygenated gasoline additive. There will only be sufficient, low-cost ethanol if lignocellulose feedstock is also used.