Biomimetic models of radical stress and related biomarkers

The biological consequences of free radical production is the central subject of a very lively scientific debate, focusing on the estimation of the type and extent of damage, as well as the efficiency of the protective and repair systems. When studying free radical based chemical mechanisms, it is very important to establish biomimetic models, which allow the experiments to be performed in a simplified environment, but suitably designed to be in strict connection with cellular conditions. The biomimetic modeling approach has been coupled with physical organic chemistry methodologies and knowledge of free radical reactivity. Molecular basis of important processes have been identified, building up molecular libraries of products concerning unsaturated lipids, sulfur-containing proteins and nucleic acids, to be developed as biomarkers. Ongoing projects in our group deal with lipidomics, genomics and proteomics of free radical stress and some examples will be described.     

Insect Egg Deposition Induces Indirect Defense and Epicuticular Wax Changes in Arabidopsis thaliana

Egg deposition by the Large Cabbage White butterfly Pieris brassicae on Brussels sprouts plants induces indirect defense by changing the leaf surface, which arrests the egg parasitoid Trichogramma brassicae. Previous studies revealed that this indirect defense response is elicited by benzyl cyanide (BC), which is present in the female accessory reproductive gland (ARG) secretion and is released to the leaf during egg deposition. Here, we aimed (1) to elucidate whether P. brassicae eggs induce parasitoid-arresting leaf surface changes in another Brassicacean plant, i.e., Arabidopsis thaliana, and, if so, (2) to chemically characterize the egg-induced leaf surface changes. Egg deposition by P. brassicae on A. thaliana leaves had similar effects to egg deposition on Brussels sprouts with respect to the following: (a) Egg deposition induced leaf surface changes that arrested T. brassicae egg parasitoids. (b) Application of ARG secretion of mated female butterflies or of BC to leaves had the same inductive effects as egg deposition. Based on these results, we conducted GC-MS analysis of leaf surface compounds from egg- or ARG-induced A. thaliana leaves. We found significant quantitative differences in epicuticular waxes compared to control leaves. A discriminant analysis separated surface extracts of egg-laden, ARG-treated, untreated control and Ringer solution-treated control leaves according to their quantitative chemical composition. Quantities of the fatty acid tetratriacontanoic acid (C34) were significantly higher in extracts of leaf surfaces arresting the parasitoids (egg-laden or ARG-treated) than in respective controls. In contrast, the level of tetracosanoic acid (C24) was lower in extracts of egg-laden leaves compared to controls. Our study shows that insect egg deposition on a plant can significantly affect the quantitative leaf epicuticular wax composition. The ecological relevance of this finding is discussed with respect to its impact on the behavior of egg parasitoids.     

Amino acid sequence of myoglobin from white-tailed deer (Odocoileus virginianus)

Our objective was to determine the primary structure of white-tailed deer myoglobin (Mb). White-tailed deer Mb was isolated from cardiac muscles employing ammonium sulfate precipitation and gel-filtration chromatography. The amino acid sequence was determined by Edman degradation. Sequence analyses of intact Mb as well as tryptic- and cyanogen bromide-peptides yielded the complete primary structure of white-tailed deer Mb, which shared 100% similarity with red deer Mb. White-tailed deer Mb consists of 153 amino acid residues and shares more than 96% sequence similarity with myoglobins from meat-producing ruminants, such as cattle, buffalo, sheep, and goat. Similar to sheep and goat myoglobins, white-tailed deer Mb contains 12 histidine residues. Proximal (position 93) and distal (position 64) histidine residues responsible for maintaining the stability of heme are conserved in white-tailed deer Mb.     

Effect of the use of autochthonous Lactobacillus curvatus, Lactobacillus plantarum and Staphylococcus xylosus strains on microbiological and biochemical properties of the Sardinian fermented sausage

In this study, a starter culture was tentatively made by testing autochthonous Lactobacillus and Staphylococcus strains, isolated from traditional ‘Salsiccia Sarda’ sausage. Three sausage-making trials were carried out using an association of Staphylococcus xylosus + Lactobacillus curvatus (A), Staphylococcus xylosus + Lactobacillus plantarum (B), and Lactobacillus plantarum alone (C). Microbiological profiles, free amino acids, biogenic amines, and free fatty acids were evaluated after 21 days of ripening. Sausages A and B showed the highest number of lactic acid bacteria that produced a rapid acidification of substrates and reduced the number of spoilage microorganisms. Sausages made with L. plantarum alone or together with S. xylosus had the highest content of free amino acids, whereas the one produced with S. xylosus + L. curvatus showed the lowest content of total biogenic amines and best acceptance score. No significant differences among samples were found as to the free fatty acids concentration.     

Low prevalence of Escherichia coli O157:H7 in horses in Ohio, USA

Manure from draft animals deposited in fields during vegetable and fruit production may serve as a potential source of preharvest pathogen contamination of foods. To better quantify this risk, we determined the prevalence of Escherichia coli O157:H7 in horses. Between June and September 2009, freshly voided fecal samples were collected from horses stabled on 242 separate premises in Ohio, USA. Overall, the prevalence of E. coli O157:H7 was 1 of 242 (0.4% prevalence, 95% confidence interval [CI] = 0.01 to 2.28). E. coli O157:H7 was recovered from none of the 107 equine fecal samples (0% prevalence, 95% CI = 0.00 to 3.39) that originated from locations without ruminant presence, and only 1 of the 135 horse fecal samples (0.7% prevalence, 95% CI = 0.02 to 4.06) from sites where ruminants were also present. The lone positive sample was collected from a horse that was costabled with a goat. Subsequent sampling at that location identified indistinguishable subtypes of E. coli O157:H7 present in the cohoused goat, in the environment, insects, sheep, and other goats housed in an adjacent field. E. coli O157:H7 was not isolated from the five subsequent samples from this horse. These data indicate that E. coli O157:H7 carriage by horses is an uncommon event.     

Vacuum-packed ripened sausages: Evolution of oxidative and hydrolytic degradation of lipid fraction during long-term storage and influence on the sensory properties

An experimental investigation was carried out with the aim to understand the oxidative and hydrolytic phenomena involving the lipid fraction of vacuum-packed sausages during long-term storage (5 months) and to verify their influence on the sensory characteristics. The data obtained pointed out that the oxidation was more pronounced in the initial stages of storage than in the further period, while the hydrolysis of lipid fraction significantly advanced during the whole storage time, supported by the high moisture level of the product. Both these phenomena resulted to be correlated with the sensory decay of the product. In particular, in the first stage of vacuum storage overall acceptability was found to be negatively correlated (p < 0.05) with rancid taste, acid value, and oxidized triacylglycerols. In the further stage the oxidative processes slowed down and affected in a lesser extent the sensory properties, which were more distinctly characterized by the onset of pungent perception attributed to compounds arising from multiple origins such as carbohydrate fermentation. This investigation confirmed the unreliability of thiobarbituric acid reactive substances test and the usefulness of high performance size exclusion chromatography analysis of the polar compounds of the lipid fraction to correctly determine the levels of the oxidative and hydrolytic degradation of the lipid fraction of vacuum-packed ripened sausages during long-term storage.     

你是否遇到遮蔽问题吗？了解太阳光电系统中的遮蔽效应

将太阳能透过由太阳能面板组成的太阳光电数组转换成一般电力能源是目前市场中最具发展潜力的再生能源技术。太阳光电是成熟、强大且可靠的技术。由于政府透过补贴以及税率优惠等措施的奖励性计划大力推动太阳能应用,再加上传统电力价格势必将会逐渐提高的预期心理,使得太阳光电系统成为一项引人注目的投资项目。     

Probing the Peptidylglycine α‐Hydroxylating Monooxygenase Active Site with Novel 4‐Phenyl‐3‐butenoic Acid Based Inhibitors

Specific inhibition of the copper‐containing peptidylglycine α‐hydroxylating monooxygenase (PHM), which catalyzes the post‐translational modification of peptides involved in carcinogenesis and tumor progression, constitutes a new approach for combating cancer. We carried out a structure–activity study of new compounds derived from a well‐known PHM substrate analogue, the olefinic compound 4‐phenyl‐3‐butenoic acid (PBA). We designed, synthesized, and tested various PBA derivatives both in vitro and in silico. We show that it is possible to increase PBA affinity for PHM by appropriate functionalization of its aromatic nucleus. Compound 2 d , for example, bears a meta‐benzyloxy substituent, and exhibits better inhibition features (K_i=3.9 μM , k_inact/K_i=427 M ^?1 s^?1) than the parent PBA (K_i=19 μM , k_inact/K_i=82 M ^?1 s^?1). Docking calculations also suggest two different binding modes for PBA derivatives; these results will aid in the development of further PHM inhibitors with improved features.     

Polynomial evaluation over finite fields: new algorithms and complexity bounds

An efficient evaluation method is described for polynomials in finite fields. Its complexity is shown to be lower than that of standard techniques, when the degree of the polynomial is large enough compared to the field characteristic. Specifically, if n is the degree of the polynomiaI, the asymptotic complexity is shown to be ${O(\sqrt{n})}$ , versus O(n) of classical algorithms. Applications to the syndrome computation in the decoding of Reed-Solomon codes are highlighted.