Marine and farmed fish in the Polish market: Comparison of the nutritional value

The proximate composition and fatty acids profiles of the muscle tissues of nine fish species that are popular on the Polish market were examined. The nine studied fish species were: Baltic fish (cod, herring, salmon), fish farmed in Poland (carp, trout), oceanic fish imported from China (walleye pollock, sole), and farmed fish imported from Vietnam and China (sutchi catfish, tilapia). The lowest lipid content (below 0.1%) was noted in the muscle tissues of Baltic cod and walleye pollock caught in the Pacific. The muscle tissue of walleye pollock also had the lowest protein content (12.2 ± 2.0%). The highest lipid content was noted in the muscle tissues of Baltic salmon (13.1 ± 2.4%). The highest percentage content of eicosapentaenoic (C20:5 n − 3 – EPA) and docosahexaenoic (C22:6 n − 3 – DHA) acids (over 40%) was noted in the fat extracted from the oceanic fish and Baltic cod. However, due to the low fat content, the concentrations of EPA + DHA in these fish species and in imported farmed fish expressed in mg/100 g of muscle tissues are the lowest and range on average from 24.8 ± 5.7 mg/100 g (sutchi catfish) to 207.4 ± 125.4 mg/100 g (sole). This is why the consumption of these fish species has no significant meaning for coronary heart disease prevention. Consumers with symptoms of cardiovascular diseases should include the following fish species, which have high concentrations of EPA + DHA: Baltic salmon (3807.2 ± 666.3 mg/100 g); Polish farmed trout (1804.0 ± 279.2 mg/100 g); and Baltic herring (940.9 ± 306.6 mg/100 g) in their diets. However, the consumption of Baltic salmon must be limited on account of the levels of persistent organic pollutants found in it.     

Characterisation of lipoxygenase from pea seeds (Pisum sativum var. Telephone L.)

Lipoxygenase (LOX) from pea seeds (Pisum sativum var. Telephone L.) was extracted and studied of biochemical properties. The molecular mass of purified lipoxygenase was 93 kDa. The effects of substrate specificity, pH, and sensibility to various inhibitors: caffeic acid, ferulic acid, benzoic acid, catechin, quercetin and kaempferol of LOX were investigated. Lipoxygenase showed the highest activity toward linoleic acid and the lowest toward oleic acid as substrates. Kinetic studies indicated that V_max of the LOX activity was 151.5 U/min and corresponding K_m value of 0.44 × 10⁻³ M. Optimum pH of lipoxygenase was reported at 5.5. Caffeic acid was the most effective inhibitor and kaempferol was the least effective.     

Improvement of <Emphasis Type="Italic">Candida parapsilosis</Emphasis> by genome shuffling for the efficient production of arabitol from <Emphasis Type="SmallCaps">l</Emphasis>-arabinose

Arabitol is used in the food industry as a low-calorie sweetener. It is produced by yeasts during the biotransformation process of l-arabinose. Genome shuffling was performed in Candida parapsilosis DSM 70125, an efficient producer of arabitol, to obtain fusants with improved arabitol production ability. Four mutants from the parental library were used for the first round of genome shuffling. The best fusants, GSI-1 and GSI-10A, were subjected to a second round of genome shuffling. Finally, two fusants, GSII-3 and GSII-16, produced concentrations of arabitol that were 50% higher than that of the wild-type strain during selection culture. Under the optimal conditions established for C. parapsilosis, the two fusants produced 11.83 and 11.75 g/L of arabitol and were approximately 15–16% more efficient than the wild-type strain. Flow cytometry analysis showed that the ploidy of the new strains did not change.     

Curing of epoxy/novolac system modified with reactive liquid rubber and carbon filler

The curing behaviour of epoxy resins modified with reactive liquid rubber, using a novolac resin as a hardner was studied by means of differential scanning calorimetry in isothermal (100, 130 and 150 °C) and non-isothermal conditions (2, 5, 10 and 15 °C min^-1). The influence of carboxyl- (CTBN) and epoxy- (ETBN) terminated butadiene-acrylonitrile copolymers on the kinetic parameters and glass transition temperature (T_g) of cured epoxy systems was determined. The effect of grinded bituminous coal as an organic filler into epoxy network was also investigated. The carboxyl-end groups strongly enhanced the curing rate, in contrast to the epoxy-terminated rubber (ETBN) that had only a minor effect on the curing reactions. The presence of coal accelerated curing in its early stage. The T_g of completely cured epoxy was practically unaffected by the presence of carbon filler and reactive rubbers and was equal about 132 °C. The apparent curing activation energies were determined. A smaller activation energy was observed only for CTBN/epoxy/novolac system. The effect of reactive rubber and coal on the Charpy impact resistance of cured epoxy systems was also discussed.     

Myo-inositol phosphates profile of buckwheat and quinoa seeds: Effects of hydrothermal processing and solid-state fermentation with Rhizopus oligosporus

Phytate content, bioavailability and myo-inositol phosphates profile were analysed in pseudocereals (i.e., white and coloured quinoa, buckwheat) subjected to thermal processing and solid-state fermentation with Rhizopus oligosporus. Fair buckwheat groats were characterised by the highest level of phytate (18.3 µmol/g), with 54% share of InsP₆ fraction. Processing (cooking, roasting, tempe-type fermentation) resulted in the significant decrease in phytate content, its bioavailability and the share of higher phosphorylated forms of myo-inositol (InsP_6-5) in the profile of all the samples. Fermentation of cereals resulted in generation of high amounts of inositol triphosphates, particularly in the case of buckwheat (32% share in the whole profile). The path of dephosphorylation, identified after fermentation of quinoa seeds including intermediate products – Ins(1,2,4,5,6)P₅ and Ins(1,2,6)P₃ – confirmed that the dominant phytase activity could be attributed to the presence of microbial 3-phytases from R. oligosporous.     

Structural Determinants of Substrate Specificity of SplF Protease from Staphylococcus aureus

Accumulating evidence suggests that six proteases encoded in the spl operon of a dangerous human pathogen, Staphylococcus aureus, may play a role in virulence. Interestingly, SplA, B, D, and E have complementary substrate specificities while SplF remains to be characterized in this regard. Here, we describe the prerequisites of a heterologous expression system for active SplF protease and characterize the enzyme in terms of substrate specificity and its structural determinants. Substrate specificity of SplF is comprehensively profiled using combinatorial libraries of peptide substrates demonstrating strict preference for long aliphatic sidechains at the P1 subsite and significant selectivity for aromatic residues at P3. The crystal structure of SplF was provided at 1.7 Å resolution to define the structural basis of substrate specificity of SplF. The obtained results were compared and contrasted with the characteristics of other Spl proteases determined to date to conclude that the spl operon encodes a unique extracellular proteolytic system.     

Candidate Alzheimer’s Disease Biomarker miR-483-5p Lowers TAU Phosphorylation by Direct ERK1/2 Repression

MicroRNAs have been demonstrated as key regulators of gene expression in the etiology of a range of diseases including Alzheimer’s disease (AD). Recently, we identified miR-483-5p as the most upregulated miRNA amongst a panel of miRNAs in blood plasma specific to prodromal, early-stage Alzheimer’s disease patients. Here, we investigated the functional role of miR-483-5p in AD pathology. Using TargetScan and miRTarBase, we identified the microtubule-associated protein MAPT, often referred to as TAU, and the extracellular signal-regulated kinases 1 and 2 (ERK1 and ERK2), known to phosphorylate TAU, as predicted direct targets of miR-483-5p. Employing several functional assays, we found that miR-483-5p regulates ERK1 and ERK2 at both mRNA and protein levels, resulting in lower levels of phosphorylated forms of both kinases. Moreover, miR-483-5p-mediated repression of ERK1/2 resulted in reduced phosphorylation of TAU protein at epitopes associated with TAU neurofibrillary pathology in AD. These results indicate that upregulation of miR-483-5p can decrease phosphorylation of TAU via ERK pathway, representing a compensatory neuroprotective mechanism in AD pathology. This miR-483-5p/ERK1/TAU axis thus represents a novel target for intervention in AD.     

Removal of Adsorbable Organic Halides from Water Containing Bromide Ions by Conventional and Advanced Oxidation

The article focuses on an assessment of adsorbable organic halides degradation during the process of conventional ozonation and advanced oxidation as far as the water containing bromides is concerned. The amount of AOX in the water examined varied from 59 to 105 μg Cl^?/L, and the bromides concentration exceeded 200 μg Br^?/L. The effects obtained by O₃ and O₃/UV methods were compared with the results achieved for the water which underwent only UV irradiation. The analysis of presented research results shows that out of the examined oxidation methods, in water of pH 6.8–9.5 and temperature of approximately 287 K, the highest degree of AOX decomposition, was achieved by UV irradiation of water, which was previously subjected to ozonation. However, when the ozone dose reached ≥ 0.3 mg O₃/mg C in an alkaline environment, bromates were formed in amounts exceeding the maximum contaminant level in both processes.