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.     

Immunohistochemical identification and localization of orexin A and orexin type 2 receptor in the horse gastrointestinal tract

The aim of the present study was to investigate the presence and the distribution of cells containing orexin A and orexin type 2 receptor in the horse stomach and gut, by means of immunohistochemical techniques.Orexin A was identified in the stomach fundic and pyloric regions and in the duodenum. In the same stomach regions, a large subset of orexin A-positive cells also showed orexin type 2 receptor-like immunoreactivity. Moreover, in the duodenum, many of them, seemed to store serotonin.Characteristically, enteric neurons or ganglia also displayed orexin A and, sometimes, orexin type 2 receptor immunoreaction.Orexin A and orexin type 2 receptor immunoreactivity was also found in the nerve fibers in the enteric submucosal layer.Our results, together with data present in the literature, could contribute to the understanding of complex mechanisms regulating the horse gut functionality that are depending very likely on the consequence of the co-operation of both a central and a peripheral control.     

Small strongyle infection: consequences of larvicidal treatment of horses with fenbendazole and moxidectin

The study was undertaken to evaluate adverse effects of larvicidal treatment in horses naturally infected with cyathostomins. Out of 24 ponies kept on pasture, four animals were housed in September and anthelmintically cured to serve as worm-free controls (group C-0). The others were housed in December. Eight animals each were treated 8 weeks later with 5 x 7.5mg/kg fenbendazole (FBZ) or 1 x 0.4 mg/kg moxidectin (MOX). Four animals remained untreated (group C-i). Two, 4, 6 and 14 days after the end of treatment two animals of each of the treated groups were necropsied together with group C-0 and C-i animals. Infected animals before treatment showed weight loss, eosinophilia, increased plasma protein and globulin contents. Treatment was followed by weight gain and temporal plasma protein and globulin increase. Proportions of CD4+ and CD8+ T lymphocytes in the peripheral blood did not differ between the groups before treatment but dropped significantly temporally after FBZ treatment. Group C-0 was worm-free at necropsy. Group C-i animals contained variable numbers of luminal and tissue cyathostomins. Histological sections showed larval stages in the lamina propria und submucosa surrounded by macrophages. Either treatment was effective against luminal parasites and reduced the number of larvae in the bowel wall beginning 4-6 days after FBZ and 6-14 days after MOX treatment. Histologically, as a first reaction after FBZ application T lymphocytes accumulated around morphologically intact L4 in the submucosa. Subsequently T lymphocytes associated with eosinophils infiltrated the submucosa. Parasites became enclosed by granulomas with eosinophils adhering to and invading the larvae which started to disintegrate on day 4. Later on, particularly on day 14 inflammation extended into the mucosa and was frequently associated with ulcerations. Third stage larvae in general and L4 in the lamina propria, however, seemed not to be affected until day 14 and even then, parasites did usually not generate extensive inflammation. After MOX treatment severe morphologically detectable alterations of tissue larvae could not be observed earlier than day 14. Different from FBZ treatment, larvae disintegrated and were obviously resorbed without causing severe inflammation in the gut wall. In conclusion treatment with either drug was efficacious against tissue larvae of cyathostomins but there may be different clinical consequences: in contrast to MOX effects, killing of larvae due to FBZ was associated with severe tissue damage, which clinically may correspond to reactions caused by synchronous mass emergence of fourth stage larvae, i.e., may mimic larval cyathostominosis.     

Caveolin-1 is essential for liver regeneration

Liver regeneration is an orchestrated cellular response that coordinates cell activation, lipid metabolism, and cell division. We found that caveolin-1 gene-disrupted mice (cav1-/- mice) exhibited impaired liver regeneration and low survival after a partial hepatectomy. Hepatocytes showed dramatically reduced lipid droplet accumulation and did not advance through the cell division cycle. Treatment of cav1-/- mice with glucose (which is a predominant energy substrate when compared to lipids) drastically increased survival and reestablished progression of the cell cycle. Thus, caveolin-1 plays a crucial role in the mechanisms that coordinate lipid metabolism with the proliferative response occurring in the liver after cellular injury.     

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.