Genotypic and phenotypic detection of capsular polysaccharide and biofilm formation in <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> isolated from bovine milk collected from Brazilian dairy farms

Staphylococcus aureus is a pathogen that frequently causes mastitis in bovine herds worldwide. This pathogen produces several virulence factors, including cell-associated adhesins, toxic and cytolytic exoproteins, and capsular polysaccharides. The aim of the present study was to test for the presence of genes involved in capsular polysaccharide production and biofilm formation in S. aureus isolated from bovine mastitis samples collected from 119 dairy herds located in three different Brazilian regions, as well as to assay the production of capsular polysaccharides and biofilm, in vitro. The detection of the cap, icaAD, and bap genes was performed using PCR. The detection and quantification of capsular polysaccharide production was performed using ELISA assays. The ability of the isolates to form a biofilm was examined using the polystyrene surface of microtiter plates. All 159 S. aureus isolates investigated harboured the cap gene: 80 % carried the cap5 gene and 20 % carried the cap8 gene. Sixty-nine percent of the isolates expressed capsular polysaccharide (CP) in vitro, 58 % expressed CP5 and 11 % expressed CP8. All of the isolates harboured the icaA and icaD genes, and 95.6 % of the isolates carried the bap gene. Of the 159 isolates analysed, 97.5 % were biofilm producers. A significant association between the capsular genotype and phenotype and the amount of biofilm formation was detected: cap5/CP5 isolates tended to form more biofilm and to produce a thinner CP layer than cap8/CP8 isolates. The results indicate a high potential for pathogenicity among S. aureus isolated from bovine milk collected from three different regions in Brazil.     

Effect of different penetrating and non‐penetrating cryoprotectants and media temperature on the cryosurvival of vitrified in vitro produced porcine blastocysts

The aim of this study was to determine the most efficient vitrification protocol for the cryopreservation of day 7 in vitro produced (IVP) porcine blastocysts. The post‐warm survival rate of blastocysts vitrified in control (17% dimethyl sulfoxide + 17% ethylene glycol [EG] + 0.4 mol/L sucrose) and commercial media did not differ, nor did the post‐warm survival rate of blastocysts vitrified in medium containing 1,2‐propandiol in place of EG. However, vitrifying embryos in EG alone decreased the cryosurvival rate (55.6% and 33.6%, respectively, p < .05). Furthermore, the post‐warm survival rates of blastocysts vitrified with either trehalose or sucrose as the non‐penetrating cryoprotectant did not differ. There was also no significant difference in post‐warm survival of blastocysts vitrified in control (38°C) media and room temperature (22°C) media with extended equilibration times, although when blastocysts were vitrified using control media at room temperature, the post‐warm survival rate increased (56.8%, 57.3%, 72.5%, respectively, p < .05). The findings show that most cryoprotectant combinations examined proved equally effective at supporting the post‐warm survival of IVP porcine blastocysts. The improved post‐warm survival rate of blastocysts vitrified using media held at room temperature suggests that the cryoprotectant toxicity exerted in 22°C media was reduced.     

Muscle growth of triploid Atlantic cod juveniles (Gadus morhua)

This study has investigated the muscle growth of diploid and triploid Atlantic cod (Gadus morhua) juveniles raised in replicate tanks over a period of 29 weeks and analysed at three sampling points (February, June and September). Data for weight, length, condition factor (K), muscle fibre growth and myogenic progenitor cells (MPCs) number were collected and results were analysed in relation to body growth and ploidy status. Diploids were significantly heavier than triploids throughout the trial (~10–20%) and had K in June and September samplings. Over the whole period, the rate of muscle fibres' recruitment was 318 fibres per day and 252 fibres per day for diploid and triploid cod respectively. The larger body weight of diploids resulted in a total number of fast fibre number of 114 979 compared to 91 086 in triploids. The average diameter of the 2.5% of the smallest fibres (2.5th percentile) was higher in diploids than triploids at the start of the trial, with a reversed picture for the average of the upper 2.5% (97.5th percentile) at the end of the trial. The probability density function of the estimated muscle fibre diameters showed similar fibre size distribution between size‐matched diploids and triploids at all sample points. The peak fibre diameter was approximately 25 μm in February and increased to approximately 50 μm in June and September, irrespectively of ploidy. Pax 7 were used as molecular markers for MPCs. A positive correlation between Pax 7⁺ cells and total body length was observed only among triploid fish at the onset of the experiment.     

Ammonia Removal from Oil Refinery Effluent in Vertical Upflow Macrophyte Column Systems

Constructed vertical macrophyte systems, for nitrogen removal from oil refinery wastewater, were investigated. Detailed studies were carried out in laboratory columns (diameter, 0.06 m; depth, 0.5 m; operating volume, 0.6 L) planted with common reed, Phragmites australis. Through a vertical flow format, collected oil refinery wastewater was supplied directly to the columns. Wastewater quality varied through the experimental period with initial ammonia concentrations ranging from 3 to 20 mg N L^-1. Effective ammonia removal was obtained for the planted columns with a hydraulic detention time of 5 hr. Removal efficiencies above 90% was obtained for high (above 6 mg N L^-1) ammonia inflow concentrations. A satisfactory ammonia removal was obtained at shorter detention times for the low initial concentrations. Longer detention times also provided organic nitrogen removal. Recirculation of the flow, which provides the same total detention time but a higher hydraulic loading, provides the possibility to adjust the flow rate and the inflow ammonia concentration with detention time to achieve a target outflow concentration.     

Are populations of the candy barrel cactus (Echinocactus platyacanthus) in the desert of Tehuacán, Mexico at risk? Population projection matrix and life table response analysis

Echinocactus platyacanthus is a candy barrel cactus endemic to Mexico and an endangered species owing to its exploitation and the destruction of its habitat. The population dynamic of this species is analyzed using matrix models. Three consecutive censuses were carried out (1997, 1998, and 1999) for six populations of this species in the Tehuacán-Cuicatlán Biosphere Reserve. Fruit contain many seeds (mean = 171 ± S.E. 11.03 seeds/fruit); seedling establishment and survival are low (2 × 10⁻⁶), and fecundity increases as the diameter of the individuals increases (62 seeds in adult 1-4322 in adult 4). The rates of population growth (λ) range from 0.9285 to 1.0005. Elasticity values for demographic processes indicate that the stasis of the adults is the greatest contribution (S = 0.982), followed by growth (G = 0.017) and fecundity (F = 0.001) to λ. The populations are located in the lower left corner of the demographic triangle; however, there are variations for a given population from one year to the next. Life table response experiments indicate that although there are local variations, the most important differences in the values of λ between populations and between years are associated with changes in the stasis of the adults. The disturbance index is not directly related to population density or to the current value of λ. The protection of adult E. platyacanthus must be taken into account for the management of this species and its conservation in the study area.     

Evaluation of antioxidant activity of some natural polyphenolic compounds using the Briggs-Rauscher reaction method

A new method based on the inhibitory effects of antioxidants on the oscillations of the hydrogen peroxide, acidic iodate, malonic acid, and Mn(II)-catalyzed system (known as the Briggs-Rauscher reaction), was used for the evaluation of antioxidative capacity. With this method, which works near the pH of the fluids in the stomach (pH approximately 2), a group of natural compounds present in fruits and vegetables or in medicinal plants assumed to have antioxidant capacity, was tested successfully. The aim of the present study is to evaluate the antioxidative properties of some active principles contained in vegetables and aromatic plants, namely, cynarin (from Cynara scolymus), rosmarinic acid (from Rosmarinus officinalis), echinacoside (from Echinacea species), puerarin (from Pueraria lobata), and oleuropein (from Olea europea). Also studied with the Briggs-Rauscher reaction method was the antioxidant activity of cyanidin 3-O-beta-glucopyranoside (from Citrus aurantium) in order to compare the results with those obtained by other methods. The conclusions on the dependency of the antioxidative activity on the pH of the testing system are given.     

Effects of forest fragmentation, anthropogenic edges and fruit colour on the consumption of ornithocoric fruits

We investigated effects of fruit colour (red, black or white), habitat (anthropogenic edges and forest interior) and fragment size on the removal of artificial fruits in semideciduous forests in south-east Brazil. Eight forest fragments ranging from 251 to 36,000 ha were used. We used artificial fruits, which were placed on shrubs between 1 and 2 m in height and checked after 48 and 96 h for peck marks in the fruits. All three variables affected the probability of consumption of our fruit models. Red and black fruits were statistically more pecked than the white fruits. The probability of fruit consumption was lower in the interior than at the edge and less in small than in large fragments. However, the decrease fruit consumption in small compared with large fragments was more accentuated for red and black fruits than for white fruits. Our results show that habitat reduction and edges affect the chances of a fruit being eaten by birds, which may ultimately affect plant fitness in forest fragments.     

Ghrelin antagonist D-Lys3-GHRP-6 counteract ghrelin effects in bovine cumulus-oocytes complexes matured in vitro

Ghrelin is a gut hormone related to energy balance and reproductive functions. The aim of this study was to evaluate the effect of ghrelin antagonist D-Lys3-GHRP-6 (GA) as a potential agent that prevents ghrelin effects during bovine oocyte maturation on progesterone production, cumulus cell (CC) viability, CC DNA damage and embryo development and hatching rates. Ghrelin's potential to induce oxidative stress in cumulus-oocyte complexes (COC) was also evaluated. COCs were cultured for 24 hr in medium without supplementation (C) or supplemented with 60 pM ghrelin (Ghrelin60), Ghrelin60 + 20 pM GA (GA20), Ghrelin60 + 60 pM GA (GA60) or Ghrelin60 + 100 pM GA (GA100) for experiment I. For experiment II, C and Ghrelin60 treatments were used. Differences between C and Ghrelin60 and the linear or quadratic association between GAs on Ghrelin60 were evaluated. Results demonstrated that Ghrelin60 increased progesterone concentration, reduced CC viability, induced CC DNA damage and decreased blastocyst and hatching rate compared with C (p < .05). GA20, GA60 and GA100 had a linear effect on CC genetic damage index (p ≤ .05) and a quadratic effect on CC viability (p < .01). GA20 counteracted the low hatching rate produced by Ghrelin60. However, GAs did not counteract progesterone concentration and blastocyst rate (p ≥ .21). GRH60 did not differ from C in the oxidative status (p ≥ .19). Our study highlights that GA could prevent the negative effects of ghrelin during bovine IVM.     

Application of the CSM-CERES-Rice model for evaluation of plant density and nitrogen management of fine transplanted rice for an irrigated semiarid environment

The objectives of this study were to evaluate the performance of the cropping system model (CSM)-CERES-Rice to simulate growth and development of an aromatic rice variety under irrigated conditions in a semiarid environment of Pakistan and to determine the impact of various plant densities and nitrogen (N) application rates on grain yield and economic return. The crop simulation model was evaluated with experimental data collected in experiments that were conducted in 2000 and 2001 in Faisalabad, Punjab, Pakistan. The experimental design was a randomized complete block design with three replications and included three plant densities (one seedling hill⁻¹, PD₁; two seedlings hill⁻¹, PD₂; and three seedlings hill⁻¹, PD₃) and five N fertilizer regimes (control, N₀; 50 kg ha⁻¹, N₅₀; 100 kg ha⁻¹, N₁₀₀; 150 kg ha⁻¹, N₁₅₀; and 200 kg ha⁻¹, N₂₀₀). To determine the most appropriate combination of plant density and N levels, four plant densities from one seedling hill⁻¹ to four seedlings hill⁻¹ and 13 N levels ranging from 0 to 300 kg N ha⁻¹ (52 scenarios) were simulated for 35 years of historical daily weather data under irrigated conditions. The evaluation of CSM-CERES-Rice showed that the model was able to simulate growth and yield of irrigated rice in the semiarid conditions, with an average error of 11% between simulated and observed grain yield. The results of the stimulation analysis result showed that two seedlings hill⁻¹ along with 200 kg N ha⁻¹ (PD₂N₂₀₀) produced the highest yield as compared to all other scenarios. Furthermore, the economic analysis through the mean gini dominance also showed the dominance of this treatment (PD₂N₂₀₀) compared to the other treatment combinations. Thus, the management scenario that consisted of two seedlings hill⁻¹ and 200 kg N ha⁻¹ was the best for high yield and monitory return of irrigated rice in the semiarid environment. The mean monetary returns ranged from 291 US $ ha⁻¹ to 1 460 US $ ha⁻¹ to 1 460 US  ha⁻¹ among the 52 production options that were simulated. This approaching was demonstrated as effective way to optimize the density and N management for high yield and monetary return. It will help the rice production.