Strecker type degradation of phenylalanine by 4-hydroxy-2-nonenal in model systems

The reaction of 4-hydroxy-2-nonenal, an oxidative stress product, with phenylalanine in acetonitrile-water (2:1, 1:1, and 1:2) at 37, 60, and 80 degrees C was investigated to determine whether 4-hydroxy-2-alkenals degrade amino acids, analogously to 4,5-epoxy-2-alkenals, and to compare the reactivities of both hydroxyalkenals and epoxyalkenals for production of Strecker aldehydes. In addition to the formation of N-substituted 2-pentylpyrrole and 2-pentylfuran, the studied hydroxyalkenal also degraded phenylalanine to phenylacetaldehyde with a reaction yield of 17%. The reaction mechanism is suggested to be produced through the corresponding imine, which is then decarboxylated and hydrolyzed. This reaction also produced a conjugated amine, which both may be one of the origins of the produced 2-pentyl-1H-pyrrole and may contribute to the development of browning in these reactions. 4-Hydroxy-2-nonenal and 4,5-epoxy-2-decenal degraded phenylalanine in an analogous extent, which is likely a consequence of the similarity of the degradation mechanisms involved. These results suggest that different lipid oxidation products are able to degrade amino acids; therefore, the Strecker type degradation of amino acids produced by oxidized lipids may be quantitatively significant in foods.     

Bioequivalence of four preparations of enrofloxacin in poultry

In various parts of the world, many 10% enrofloxacin commercial preparations for water medication of chicken are being employed. To avoid the development of bacterial resistance to this agent, the original trademark and similar preparations must be bioequivalent. To assess whether or not bioequivalence exists among the pioneer vs. three commercial preparations of enrofloxacin, a controlled pharmacokinetic study was conducted. The following variables were compared: maximal plasma concentration (Cpeak), time to Cpeak, bioavailability (expressed as the area under the concentration vs. time curve), elimination half-life, and the shapes of the respective time-serum concentrations of enrofloxacin profiles. Results indicate that all three similar commercial preparations had lower Cpeak values than the reference formulation, being 39.62 to 67.77% of the corresponding Cpeak reference. Additionally, bioavailability of enrofloxacin in the pioneer product was statistically higher (P < 0.05). Based upon these results, we conclude that although all preparations were formulated as water-soluble products, bioequivalence studies are mandatory for the analogue formulations to ensure product comparability. Lack of product bioequivalence could facilitate the development of bacterial resistance and limit the useful life span of the product.     

Influence of cultivar and fruit ripening on olive (Olea europaea) fruit protein content, composition, and antioxidant activity

Proteins of olive fruit mesocarp are not very well-known at present. However, they have been shown to pass, at least partially, to the olive oil during its elaboration and therefore might be contributing to some of the special characteristics of this vegetable oil. In this study, protein content and composition were determined in olive fruits, cv. Arbequina and Picual, at three stages of ripening: green, spotted, and purple. Mesocarp proteins constituted 1.3-1.8% of the dry weight of the olive fruit, and cultivar and fruit ripening did not produce important changes in mesocarp protein content or composition. In addition, this composition was also similar to the amino acid composition of a 4.6-kDa polypeptide, which is the major protein component of olive oils and of oil bodies of olive fruit mesocarp, suggesting that this polypeptide is likely to be a major component of mesocarp proteins. There was, also, a relationship between the oil content of the olive fruit and the protein content determined, suggesting a stabilizing function of these proteins in the oil bodies of the olive fruit, analogously to the role suggested for oleosins. This stabilizing function does not seem to be extended to olive oils because when the polypeptides isolated were added at 20 ppm to soybean oil, the stability of the oil increased only slightly, suggesting that if these compounds play some role in the stability of the oils, this should be mostly a consequence of the possible interactions among these protein components and other olive oil antioxidant constituents.     

Advances in biosecurity to 2010 and beyond: Towards integrated detection,analysis and response to exotic pest invasions

In order to limit the number and impact of exotic pest invasions, leading-edge technologies must be embraced and embedded within integrated national and international biosecurity systems. Outlined here are recent advances in the detection of exotic pests, and prospects for the early recognition of disease. Applications of new tools are described, using our understanding of the genomes of pathogens and vectors. In addition, the role of mathematical and simulation models to aid both biosecurity planning, and decision making in the face of an epidemic, are discussed, and recent attempts to unify epidemiology and evolutionary dynamics are outlined. Given the importance of emerging diseases and zoonoses, the need to align human and veterinary surveillance within fully integrated systems is underlined.     

Purification of secretory immunoglobulin A from milk of the brushtail possum (Trichosurus vulpecula)

AIM: To identify and purify secretory immunoglobulin A (sIgA), a key effecter molecule in mucosal immune responses, from milk of the brushtail possum (Trichosurus vulpecula).

METHODS: Milk samples were collected from female possums with pouch young, and clarified by centrifugation and precipitation methods. The clarified fraction was purified by gel filtration and affinity chromatography to yield sIgA. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting techniques were used to assess the purity of the final product, and to identify the heavy (H) chain, light (L) chain and secretory component (SC) of possum sIgA.

RESULTS: Immunoblotting, using antibodies raised against cloned possum sIgA SC and H-chain, and a synthetic peptide fragment of the H-chain, confirmed the identity of the purified protein. The N-terminal amino acid sequence of purified possum sIgA showed strong homology to reported sequences of H-chain variable regions of marsupial immunoglobulins.

CONCLUSIONS: Milk was shown to be a convenient source of mucosal secretion containing sIgA, and a process involving 2 precipitation and 2 chromatography steps produced purified sIgA. This IgA preparation will prove useful for the generation of sIgA-specific immunological reagents for measurement of immune responses in the development of mucosal-based vaccines for biological control of possums.     

Evaluation of the formulated diet MySpat for feeding hatchery‐reared spat of the green‐lipped mussel,Perna canaliculus (Gmelin, 1791)

As with most bivalves, a high cost component of hatchery and nursery culture of the green‐lipped mussel (Perna canaliculus) is the raising of live micro‐algae feeds. To remedy this, artificial feeds have been developed, however, these have had mixed success for this species. In this experiment, we tested the formulated diet MySpat (sourced from INVE Aquaculture) on P. canaliculus spat of approximately 1 mm in size. Performance measures under study were mussel spat growth and survivorship after 21 days feeding on varying proportions of MySpat. The experimental diets tested, consisted of a mix of T‐Isochrysis galbana, Pavlova lutheri and Tetraselmis suecica micro‐algae that were replaced with increasing proportions of MySpat, i.e. 25%, 50%, 67%, 75%, 90% and 100% MySpat replacement. Our results revealed no significant increase in spat mortality with increasing MySpat diet levels, and growth was equivalent to the micro‐algae only dietary control in all diets except the 90% and 100% MySpat replacement diets. Such results highlight the role MySpat could have for P. canaliculus hatchery operations, particularly with regard to reducing the costs of raising micro‐algae when producing seed for industry. A greater understanding of the particle selection process of this species would be beneficial for future studies seeking to employ artificial diets.     

Amine degradation by 4,5-epoxy-2-decenal in model systems

The reactions of 4,5-epoxy-2-decenal with octylamine, benzylamine, and 2-phenylglycine methyl ester were studied to investigate if amines may suffer a Strecker type degradation by epoxyalkenals analogously to amino acids. In addition to other reactions, the studied amines were converted into their corresponding Strecker aldehydes (octanal, benzaldehyde, and methyl 2-oxo-2-phenylacetate, respectively) to an extent that depended on the pH, the temperature, the amount of epoxyalkenal, and the amine involved. Each amine exhibited an optimum pH for the reaction, but the corresponding Strecker aldehydes were produced to a significant extent within a broad pH range. In addition, the temperature mostly influenced the reaction rate, which was increased between 6.5 and 9.5 times when the reaction was carried out at 60 degrees C than when it took place at 37 degrees C. Furthermore, Strecker aldehyde formation was linearly correlated with the amount of the epoxyalkenal present in the reaction mixture. Nevertheless, the reaction yield mostly depended on the amine involved. Thus, octylamine only produced trace amounts of octanal, benzylamine was converted into benzaldehyde with a yield of 4.3%, and 2-phenylglycine methyl ester was converted into methyl 2-oxo-2-phenylacetate with a reaction yield of 49%. All of these results suggest that suitable amines can be degraded by epoxyalkenals to their corresponding Strecker aldehydes to a significant extent.     

European seabass (Dicentrarchus labrax) ability to discriminate between diets made with different dietary fat sources

The aim of this work was to determine whether juvenile and adult European seabass (Dicentrarchus labrax L.), fed ad libitum manually and with self‐feeding demand feeders, respectively, were able to discriminate between a fish oil‐based diet and a series of diets made with vegetable oils (soybean, linseed, rapeseed and sunflower oil), as well as a fat‐free diet. Adult D. labrax (443.6 ± 108.8 g) selected diets made from soybean (SYO) and rapeseed (RO) in proportions similar to fish oil (FO). Demand levels for the other two diets, sunflower (SUO) and linseed (LO) oils, were significantly lower than FO, whilst juveniles (56.4 ± 11.2 g) displayed a preference for SYO and FO. The lowest demand levels were associated with a fat‐free diet (FF). Selection percentages of the diets for adult and juvenile fish were, respectively, FF—22.96% and 39.76%, SYO—43.02% and 53.26%, LO—36.48% and 36.19%, SUO—39.87% and 37.32%, and RO—46.38% and 40.94%. The animals’ size and feeding method did not significantly affect dietary selection. However, a statistical difference in specific growth rate (1.37% ± 0.26% day^?1) for juveniles was only observed for FO+FF combination. For juveniles, no differences were observed in the conversion index. The juvenile group (FO + FF) had the highest food intake (2.00 ± 0.35 g 100 g^?1 body weight). Moreover, the groups fed FO + SUO and FO + RO consumed the least. In conclusion, this study shows D. labrax can discriminate between diets where the only difference is the lipid source. These findings should be used to understand the acceptance or rejection of different source oils, which are increasingly being used in aquaculture such as aquafeeds for European seabass.