Mathematical modeling of maize starch liquefaction catalyzed by α-amylases from Bacillus licheniformis: effect of calcium, pH and temperature

The first step of starch hydrolysis, i.e. liquefaction has been studied in this work. Two commercial α-amylases from Bacilllus licheniformis, known as Termamyl and Liquozyme have been used for this purpose. Using starch as the substrate, kinetics of both enzymes has been determined at optimal pH and temperature (pH 7, T = 80 °C) and at 65 °C and pH 5.5. Michaelis–Menten model with uncompetitive product inhibition was used to describe enzyme kinetics. Mathematical models were developed and validated in the repetitive batch and fed-batch reactor. Enzyme inactivation was described by the two-step inactivation model. All experiments were performed with and without calcium ions. The activities of both tested amylases are approximately one hundred times higher at 80 °C than at 65 °C. Lower inactivation rates of enzymes were noticed in the experiments performed at 65 °C without the addition of calcium than in the experiments at 80 °C. Calcium ions in the reaction medium significantly enhance amylase stability at 80 °C and pH 7. At other process conditions (65 °C and pH 5.5) a weaker calcium stabilizing effect was detected.     

Interaction of Insulin-Like Growth Factor-Binding Protein 2 with α2-Macroglobulin in the Circulation

Insulin-like growth factors (IGFs) play active role in mitogenic and metabolic processes. In the peripheral circulation, they are mostly bound to specific IGF-binding proteins (IGFBPs). Proteolysis of IGFBPs releases free, active IGFs. IGFBP-2 is the second most abundant of the six binding proteins and its concentration increases in catabolic states. The possible interaction between IGFBP-2 and other proteins in the circulation was investigated in this study. Our results showed that IGFBP-2 associates with α2-macroglobulin (α2M), a protease inhibitor. Formation of IGFBP-2/α2M complexes most likely contributes to the regulation of IGFBP-2 proteolysis and, thus, the activity of IGFs.     

Salinity stress response of non-transformed and AtCKX transgenic centaury (Centaurium erythraea Rafn.) shoots and roots grown in vitro

Common centaury (Centaurium erythraea Rafn.) is a plant species that can inhabit saline soils. It is known as a plant with high spontaneous regeneration potential in vitro. In the present work we evaluated shoots and roots salinity tolerance of non-transformed and three AtCKX transgenic centaury lines to graded NaCl concentrations (0, 50, 100, 150, 200 mM) in vitro. Overexpression of AtCKX genes in transgenic centaury plants resulted in an altered cytokinins (CKs) profile leading to a decline of bioactive CK levels and, at the same time, increased contents of storage CK forms, inactive CK forms and/or CK nucleotides. Significant increment of fresh shoot weight was obtained in shoots of non-transformed and AtCKX1 transgenic line only on medium supplemented with 50 mM NaCl. However two analysed AtCKX2 transgenic lines reduced shoot growth at all NaCl concentrations. In general, centaury roots showed higher tolerance to salinity than shoots. Non-transformed and AtCKX1 transgenic lines tolerated up to 100 mM NaCl without change in frequency of regeneration and number of regenerated plants. Roots of two analysed AtCKX2 transgenic lines showed different regeneration potential under salt stress. Regeneration of transgenic AtCKX2-26 shoots even at 200 mM NaCl was recorded. Salinity stress response of centaury shoots and roots was also evaluated at biochemical level. Free proline, malondialdehyde and hydrogen peroxide content as well as antioxidative enzymes activities were investigated in shoots and roots after 1, 2, 4 and 8 weeks. In general, adition of NaCl in culture medium elevated all biochemical parameters in centaury shoots and in roots. Considering that all analysed AtCKX transgenic centaury lines showed altered salt tolerance to graded NaCl concentrations in vitro it can be assumed that CKs might be involved in plant defence to salt stress conditions.     

Polymorphisms in the IL-18 and IL-12B genes and their association with the clinical outcome in Croatian patients with Type 1 diabetes

Genetic variants of IL-18 and IL-12B may be important in immunoregulatory abnormalities, observed in the patients with Type 1 diabetes mellitus (T1DM), that contribute to individual differences in response to a treatment. Therefore, we examined the significance of IL-18-137G/C, IL-18-607C/A, and IL-12B A/C polymorphisms in Croatians (187 patients, 236 controls), not only as factors that contribute to susceptibility to T1DM, but also as determinants of the clinical presentation of disease.     

Entrapment of Ovalbumin into Liposomes—Factors Affecting Entrapment Efficiency,Liposome Size,and Zeta Potential

Various amounts of Ovalbumin (OVA) were encapsulated into positively and negatively charged multilamellar liposomes, with the aim to investigate the entrapment efficiency in different buffers and to study their effects on the liposome size and zeta potential. Results showed that the entrapment efficiency of OVA in anionic liposomes was the same in 10 mM Phosphate Buffer (PB) as in Phosphate-Buffered Saline (PBS; PB?+?0.15 M NaCl). Also, liposome size was approximately 1200 nm for all anionic liposomes incorporating OVA. The entrapment efficiency of OVA in cationic liposomes was highly dependent on ionic strength. The size of cationic liposomes was approximately 1200 nm in PBS, regardless of protein content, but increased with the amount of the incorporated protein in PB. Aggregation of cationic liposomes in PB was observed when the mass of the protein was 2.5 mg or greater. The zeta potential of anionic liposomes was negative and of cationic liposomes positive in the whole range of protein mass tested. These results show how different compositions of lipid and aqueous phases can be used to vary the entrapment efficiency, liposome size, and zeta potential—the factors that are of great importance for the use of liposomes as drug carriers.     

A review of the West Palaearctic aphidiines (Hymenoptera: Braconidae: Aphidiinae) parasitic on Uroleucon spp., with the description of a new species

A review of aphidiine wasps (Hymenoptera: Braconidae) parasitizing the Uroleucon species in the West Palaearctic is presented. Eleven species are keyed and illustrated. In addition, a new hymenopteran parasitoid species: Praon nonveilleri n. sp. from Uroleucon inulicola (Hille Ris Lambers) infesting Inula ensifolia L., is described. The new species is diagnosed and illustrated. It belongs to the “dorsale-yomenaé” species group and was collected from the Djetinja canyon in Serbia and Montenegro. The aphidiines presented in this work were identified from 97 aphid taxons occurring on 236 plant taxons. Furthermore, 361 original parasitoid – host aphid – host plant associations of the species mentioned in the key are presented. Finally, phylogenetic relationships inside the “dorsale-yomenae” species group and related species were reconstructed using cladistic distance methods.     

Identification, phylogenetic relationships and a new maximum size of two rudd populations (Scardinius, Cyprinidae) from the Adriatic Sea drainage, Croatia

In order to determine an unknown fish population from the Vrana Lake, mitochondrial cytochrome b gene and non-coding nuclear region Cyfun P were investigated. Stabile population of Bulldog rudd, Scardinius dergle Heckel & Kner, the endemic Croatian freshwater fish in the Krka River, was genetically characterized with the same markers in order to compare it with the material from the Vrana Lake. Genetic markers were sequenced and aligned with the similar ones obtained from the GenBank in order to determine taxonomic and phylogenetic position of these two species. A significant discrepancy between nuclear genetic markers of our specimens and the sequence from the GenBank was found. Phylogenetic analysis suggested that the specimens from the Vrana Lake belong to the species S. hesperidicus. Morphometric characteristics, the maximum length and body mass showed new maximum values for both S. dergle and S. hesperidicus.