Interaction of flavonoids with bovine serum albumin: a fluorescence quenching study

The interaction between four flavonoids (catechin, epicatechin, rutin, and quercetin) and bovine serum albumin (BSA) was investigated using tryptophan fluorescence quenching. Quenching constants were determined using the Stern-Volmer equation to provide a measure of the binding affinity between the flavonoids and BSA. The binding affinity was strongest for quercetin and ranked in the order quercetin > rutin > epicatechin = catechin. The pH in the range of 5-7.4 does not affect significantly (p < 0.05) the association of rutin, epicatechin, and catechin with BSA, but quercetin exhibited a stronger affinity at pH 7.4 than at lower pH (p < 0.05). Quercetin has a total quenching effect on BSA tryptophan fluorescence at a molar ratio of 10:1 and rutin at approximately 25:1. However, epicatechin and catechin did not fully quench tryptophan fluorescence over the concentration range studied. Furthermore, the data suggested that the association between flavonoids and BSA did not change molecular conformation of BSA and that hydrogen bonding, ionic, and hydrophobic interaction are equally important driving forces for protein-flavonoid association.     

Molecular aspects of cereal β-glucan functionality: Physical properties,technological applications and physiological effects

Cereals β-glucans are linear homopolysaccharides of consecutively linked (1→4)-β-d-glucosyl residues (i.e. oligomeric cellulose segments) that are separated by single (1→3)-linkages. β-Glucans display all the functional properties of viscous and gel forming food hydrocolloids combined with all the physiological properties of dietary fibres. This review focuses on the relationships between the molecular–structural characteristics of β-glucans and their physicochemical properties in aqueous dispersions and in food systems as well as their physiological functions in the gastro-intestinal tract. The physical properties of β-glucans, such as solubility and rheological behaviour in the solution and gel states, are controlled by their molecular features, such as their distribution of cellulosic oligomers, their linkage pattern and their molecular weight as well as by temperature and concentration. The technological and nutritional functionality of β-glucans is often related to their rheological behaviour. Incorporation of β-glucans into various products (bread, muffins, pasta, noodles, salad dressings, beverages, soups, reduced-fat dairy and meat products) showed that attributes, such as breadmaking performance, water binding and emulsion stabilising capacity, thickening ability, texture, and appearance appear to be related to the concentration, molecular weight and structure of the polysaccharide. The health benefits of β-glucans, such as reducing blood serum cholesterol and regulating blood glucose levels, are also correlated with the amount and molecular weight of the solubilised β-glucans in the gastro-intestinal tract.     

Nitrogen leaching from a forest soil exposed to fire retardant with and without fire: A laboratory study

The application of Long Term fire Retardants (LTRs) for forest fire prevention and/or suppression purposes can result in chemicals leaching, from soil to the drainage water, during the annual rain fall period. In leachates, large concentrations of nitrogen (N), one of the major components of LTRs, could affect the groundwater quality. N leaching due to the application of a nitrogen phosphate based LTR was studied in laboratory microcosms. The concentrations of nitrate (NO ₃ ^? -N) and ammonium nitrogen (NH ₄ ⁺ -N) were measured in the resulting leachates from pots with forest soil and pine seedlings (Pinus halepensis) alone and in combination with fire. Up to 30% of the total N in the retardant was lost to leaching, primarily as NO ₃ ^? -N. The vegetation seems to decrease to some extent the N leaching. The N leaching from treated pots with a burnt tree is lower compared with that from treated pots with a living tree, due to the partial N volatilization during the fire. Although this is a laboratory study, these results may be considered as rough indications of LTR environmental implications, due to the leaching of a significant part of the retardant’s N into groundwater.     

Efficiency of three boar sperm enrichment techniques

The objective of the study was to investigate the efficiency of three enrichment methods to separate boar spermatozoa. Twenty-four ejaculates from 12 boars (2 ejaculates/boar) were extended (30 × 10⁶ spermatozoa/mL) in commercial Beltsville Thawing Solution. Each semen sample was processed with glass wool column (GW) and glass beads (GB) filtration and with the single-layer centrifugation (SLC) technique. Semen samples before (control; C) and after treatment were evaluated for sperm CASA motility/kinetics and concentration, viability, morphology and chromatin integrity. Data were analysed with mixed models. The concentration of total and motile spermatozoa was significantly decreased after treatment in groups GW and SLC, but not in group GB. Group GW showed increased values of WOB compared with both groups C and GB. Group GB showed greater values of rapid movement spermatozoa and lower values of slow movement spermatozoa compared with group C. In group SLC, higher values of VSL, LIN and STR were observed compared with group C. In conclusion, all techniques under examination enhanced various CASA variables. Based on our results, the GB method is a promising alternative separation technique for boar sperm and deserves further research regarding swine in vitro fertilization.     

Where water is oxidized to dioxygen: structure of the photosynthetic Mn4Ca cluster

The oxidation of water to dioxygen is catalyzed within photosystem II (PSII) by a Mn(4)Ca cluster, the structure of which remains elusive. Polarized extended x-ray absorption fine structure (EXAFS) measurements on PSII single crystals constrain the Mn(4)Ca cluster geometry to a set of three similar high-resolution structures. Combining polarized EXAFS and x-ray diffraction data, the cluster was placed within PSII, taking into account the overall trend of the electron density of the metal site and the putative ligands. The structure of the cluster from the present study is unlike either the 3.0 or 3.5 angstrom-resolution x-ray structures or other previously proposed models.     

Litter quality and decomposition of Vitis vinifera L. residues under organic and conventional farming systems

In viticulture, residue decomposition may be important in terms of fertilization, due to the low grapevine nutritional demands. Grapevine residue quality, mass loss and nutrient release rates were studied in an organic (Vorg) and a conventional vineyard (Vconv) for 19-months. Leaf and cane residues of the Vorg (Lorg, Corg) and of Vconv (Lconv, Cconv) were buried in litterbags in both vineyards. Lorg contained in mg g^?1 526 C, 14.7 N, 1.2 P and 5.4 K; Lconv 509 C, 17.9 N, 1 P and 7.3 K; Corg 556 C, 5.7 N, 1.4 P and 6.9 K; Cconv 554 C, 7.6 N, 0.9 P and 7.7 K. Mean mass loss and N, P and K release rates (k′ = k × 10⁵) were higher in leaf (k′ = 543, 541, 448, 725) than in cane residues (k′ = 146, 90, 136, 494). In Vorg, mass loss and N, P and K release rates were higher in Lconv (k′ = 904, 748, 630, 1287) than in Lorg (k′ = 293, 357, 336, 502). For Lorg, mass loss and N release rates and for Corg mass loss rate were lower in Vorg (k′ = 293, 357, 102) than in Vconv (k′ = 537, 541, 218). For Lconv, mass loss and N and K release rates were lower in Vconv (k′ = 440, 518, 557) than in Vorg (k′ = 904, 748, 1287). Incorporation of plant residues in Vconv allowed reductions of nutrient applications of 25, 2 and 21 kg ha^?1 y^?1 of N, P and K, respectively; in Vorg nutrient applications reduced by 7, 1, 5.5 kg ha^?1 y^?1.     

Early Embryo-Sac Development in Faba Beans (Vicia faba L.)

Cuphea viscosissima Jacq. is an herbaceous annual dicot indigenous to the U.S. This species is being developed as a new oilseed crop and commercial source of medium-chain fatty acids (MCFAs). In this paper, the phenotypes and genetics of the mcm-1 and cpy-1 mutations of C. viscosissima are described. These mutations affect the percentages of fatty acids of seed storage lipids. They were induced by treating seeds with 0.04 M ethyl methanesulfonate for 5 h. Observed segregation ratios for these mutations were not significantly different from expected ratios for codominant genes. The mcm-1 mutation eliminates 95.0 % of wildtype MCFAs — caproic (C6: 0), caprylic (C8: 0), and capric (Cio: 0) acid percentages are decreased from 0.8 to 0.0 %, 20.7 to 0.5 %, and 68.6 to 6.7%, respectively. The cpy-1 mutation decreases C6: 0 and C8: 0 from 0.9 to 0.0 % and 19.8 to 3.9 %, respectively, whereas it increases C12: 0 and C14: 0 from 2.2. to 14.3 % and 0.8 to 7.4 %, respectively.     

Intraspecific Variation in Mean Endosperm Cell Cycle Time in Vicia faba (L.) and Interspecific Hybridization with Vicia narbonensis (L.)

The rate of early embryo-sac development was studied in seven faba bean (Vicia faba L.) cultivars grown in a controlled environment. The embryo-sac stage was determined from the number of endosperm nuclei per embryo-sac and the number of embryo cells during the first 12 days after pollination. Differences in early embryo-sac development were observed between the genotypes studied. In addition, five different V. faba×V. narbonensis crosses and reciprocals were made using genotypes with small differences in mean endosperm cell cycle time and genotypes with large differences. The percentage of success (pod set) in V. faba×V. narbonensis crosses ranged between 9 % and 59 % while in the reciprocals it ranged from 12 % up to 30 %. However, cytological studies showed that the high percentage of success (pod set) observed in the cross A-107 × A-202 was not associated with a higher percentage of interspecific hybrid embryos. The results indicate that genotypes of the two species with smaller differences in mean endosperm cell cycle time result neither in a higher percentage pod set nor in bigger hybrid embryos.     

Antifungal activity and biotransformation of diisophorone by Botrytis cinerea

Diisophorone (1) was tested against two strains of the necrotrophic plant pathogen Botrytis cinerea.Fungal sensitivity varied according to the strain. B. cinera 2100 was more sensitive than B. cinereaUCA992: its mycelial growth was significantly inhibited at concentrations of 50 ppm and above. Although diisophorone (1) showed an effective control of B. cinerea, a detoxification mechanism was present. The detoxification of racemic diisophorone (1) by B. cinerea was investigated. Incubation with two strains of B. cinerea gave one and four biotransformation products (2-5), respectively. Their structures were established as the known 8beta-hydroxydiisophorone (2), 6alpha-hydroxydiisophorone (3), 6beta-hydroxydiisophorone (4) and 8beta,14beta-dihydroxydiisophorone (5) on the basis of their spectroscopic data, including two-dimensional NMR analysis [heteronuclear multiple quantum coherence (HMQC), heteronuclear multiple bond correlation (HMBC), and nuclear Overhauser enhancement spectroscopy (NOESY)] and an X-ray crystallographic study.     

Could European marine conservation policy benefit from systematic conservation planning?

相似文献