Preliminary study of genetic diversity in Swedish flax (Linum usitatissimum)

To investigate the genetic diversity of Linum usitatissimumL. in Sweden, 18 accessions, including 13 cultivars and five landraces, were analysed. This study was based on genetic variation in three enzyme systems (i.e., PGD, GPI and MDH) by using horizontal starch gel electrophoresis. The total genetic diversity of the studied flax material was very high (H _T= 0.62). Even though the highest genetic diversity lies within the accessions (G _ST= 0.07), a clear differentiation between fibre and oil flax was found with respect to three polymorphic loci (Pgd-1, Gpi-2 and Mdh-1). A phenogram, based on Nei's genetic distances between the accessions studied, showed five clearly defined groups but with low variation within the groups. The unexpected high genetic diversity found within accessions in the studied flax material may indicate that flax is more outbreeding than earlier believed.     

Release of lipids during yeast autolysis in a model wine system

The release of lipids during the aging of sparkling wines in contact with yeast can influence wine sensory attributes and, especially, foam characteristics. Model systems allow study of the autolysis process in a reasonable period of time compared to natural conditions, at which it can last several months. In this paper, the release of the different classes of lipids during the autolysis of three commercial yeast strains in a model wine medium has been monitored. Due to the absence of accurate quantitative methods, an HPLC method for separating and quantifying the different neutral and polar yeast lipid classes was developed. Lipids were eluted through a YMC PVA-Sil column with a complex solvent mixture. Detection was carried out with a light-scattering detector. The yeasts were suspended in the model wine buffer and incubated at 30 degrees C for up to 12 days. A release of triacylglycerols, 1,3-diacylglycerols, 2-monoacylglycerols, free fatty acids, sterol esters, and sterols was observed over the first 2 days, a period that corresponded to the maximum loss of yeast viability. A decrease in most of these lipids was observed from day 2, possibly indicative of the release of yeast hydrolytic enzymes due to the breakdown of the cell wall. Phospholipids were not detected in any of the autolysates. The mean lipid content in the autolysates as a percentage of the total lipid content in the yeasts was 8.6% for sterol esters, 3.8% for sterols, 2% for triacylglycerols, and <2% for 1,3-diacylglycerols and free fatty acids.     

Purification and partial characterization of three turnip (Brassicanapus L. var. esculenta D.C.) peroxidases

Three turnip peroxidases (fractions C1, C2, and C3) were partially purified and characterized, to permit study of their feasibility for use in clinical and enzyme immunoassays. These fractions represented 20% of the initial activity, and fractions C1 and C2 were purified to homogeneity. The optimum pH was between 5.0 and 5.5, while optimum temperature ranged from 40 to 55 degrees C. The ABTS K(m) values for the two acidic fractions (C2 and C3) were 0.70 and 0.42 mM, respectively; about 5 times lower than that reported for the acidic commercial horseradish peroxidase (HRP). Fraction C3 had 4 times higher K(m) value than commercial cationic HRP. The molecular weights determined by SDS-PAGE ranged from 39.2 to 42.5 kDa. Activation energies for inactivation were 113 (C1), 130 (C2), and 172 kJ/mol (C3) which are higher or comparable to other peroxidase isoenzymes reported. Fractions C1 and C3 represent an alternative source of peroxidase because of their higher purification yield and specific activity, when compared to fraction C2.     

Geochemistry of Aluminium and Iron in Mine Soils from As Pontes,Galicia (N.W. Spain)

The geochemical processes influencing iron and aluminium mobilization and immobilization processes in mine soils are discussed. The study was carried out on 11 soils from the As Pontes mine dump, in the process of reclamation. The soils differ in age, spoils nature, reclamation tasks and type of vegetation, covering a wide range of physico-chemical conditions. Oxalate and pyrophosphate extractable Al and Fe (Alo, Alp, Feo, Fep), and dithionite extractable Fe (Fed) were analysed. These fractions were related to the solution Al and Fe forms and contents and to other soil properties (Eh, pH, sulfides, organic matter, cation exchange capacity, and composition of the soil solution). Alo ranged between 2.2 and 111.2 cmolc kg-1; 5 to 80% of this Alo was organic aluminium (Alp). Fed ranged between 8.5 and 215.6 cmolc kg-1; 20 to 70% was poorly-criystalline iron (Feo). The solution concentrations of Al and Fe ranged between <0.1 and 319.2, and between <0.1 and 46.7 mg L-1, respectively. The results showed that the spoil nature (mostly carbonaceous clays and slates differing in sulfide content) and the reclamation tasks undertaken (topsoiling, liming with fly ash) determine the forms and contents of Al and Fe in the solid phase as well as in the soil solution and also its distribution between the solid and liquid phases.     

Heavy Metal and Nitrogen Monitoring Using Moss and Topsoil Samples in a Pyrenean Forest Catchment

This study was carried out in order to assess both the deposition of heavy metal and nitrogen in a mountain ecosystem with low levels of metal deposition and its possible interactions with factors such as lithology and topography. For this purpose, samples of Hypnum cupressiforme Hedw. and topsoils were collected in a forest catchment within Bertiz Natural Park, an International Cooperative Programme on Integrated Monitoring site. Trace metals levels in mosses can be considered low compared with values reported elsewhere in Europe, and the dust soil mineral particles seemed to be the main source of these values. Only Cd and Hg presented external inputs, probably with an anthropic origin, for mosses according to the enrichment factor values, whereas historical pollution-related deposition in soils was determined for Pb, Cu, and Ni, attending to their total/extractable ratio.     

An Exploratory Study of Particulate PAHs in Low-Polluted Urban and Rural Areas of Southwest Spain: Concentrations, Source Assignment, Seasonal Variation and Correlations with Other Air Pollutants

A set of 72?PM₁₀ samples from low-polluted urban and rural locations belonging to the regional air monitoring network of Extremadura (Spain) were collected in a 1?year sampling period. Sample pre-treatment and analytical determination by gas chromatography?Cion trap mass spectrometry were optimised and validated for the analysis of the priority 16 US Environmental Protection Agency polycyclic aromatic hydrocarbons (PAHs). The influence of meteorological conditions (temperature, relative humidity and solar radiation) and other atmospheric pollutants (O₃, NO₂, SO₂, PM₁₀) has been covered in detail and Pearson correlation test were used for this purpose. Spatial distribution of particulate PAHs was evaluated and the comparison with other European sites was also established. Possible emission sources were identified and assigned by using molecular diagnostic criteria.     

Carotenoid profile modification during refrigerated storage in untreated and pasteurized orange juice and orange juice treated with high-intensity pulsed electric fields

A comparative study was made of the evolution and modification of various carotenoids and vitamin A in untreated orange juice, pasteurized orange juice (90 degrees C, 20 s), and orange juice processed with high-intensity pulsed electric fields (HIPEF) (30 kV/cm, 100 micros), during 7 weeks of storage at 2 and 10 degrees C. The concentration of total carotenoids in the untreated juice decreased by 12.6% when the juice was pasteurized, whereas the decrease was only 6.7% when the juice was treated with HIPEF. Vitamin A was greatest in the untreated orange juice, followed by orange juice treated with HIPEF (decrease of 7.52%) and, last, pasteurized orange juice (decrease of 15.62%). The decrease in the concentrations of total carotenoids and vitamin A during storage in refrigeration was greater in the untreated orange juice and the pasteurized juice than in the juice treated with HIPEF. During storage at 10 degrees C, auroxanthin formed in the untreated juice and in the juice treated with HIPEF. This carotenoid is a degradation product of violaxanthin. The concentration of antheraxanthin decreased during storage, and it was converted into mutatoxanthin, except in the untreated and pasteurized orange juices stored at 2 degrees C.     

Thermal inactivation kinetics of recombinant proteins of the lipoxygenase pathway related to the synthesis of virgin olive oil volatile compounds

The aim of this work was to characterize the thermal inactivation parameters of recombinant proteins related to the biosynthesis of virgin olive oil (VOO) volatile compounds through the lipoxygenase (LOX) pathway. Three purified LOX isoforms (Oep2LOX1, Oep1LOX2, and Oep2LOX2) and a hydroperoxide lyase (HPL) protein (OepHPL) were studied. According to their thermal inactivation parameters, recombinant Oep1LOX2 and Oep2LOX2 could be identified as the two LOX isoforms active in olive fruit crude preparations responsible for the synthesis of 13-hydroperoxides, the main substrates for the synthesis of VOO volatile compounds. Recombinant Oep2LOX1 displayed a low thermal stability, which suggests a weak actuation during the oil extraction process considering the current thermal conditions of this industrial process. In addition, recombinant OepHPL could be identified as the HPL activity in crude preparations. The thermal stability was the highest among the recombinant proteins studied, which suggests that HPL activity is not a limiting factor for the synthesis of VOO volatile compounds.     

Modeling the Interfacial Interactions between CrtS and CrtR from Xanthophyllomyces dendrorhous , a P450 System Involved in Astaxanthin Production

Xanthophyllomyces dendrorhous is a natural source of astaxanthin, a carotenoid widely used in the food industry. In this yeast, astaxanthin is synthesized from β-carotene by a cytochrome P450, CrtS, which depends on CrtR, the four-domain cytochrome P450 reductase (CPR). Although Saccharomyces cerevisiae has an endogenous CPR (ScCPR), expression of CrtS does not result in astaxanthin production unless it is coexpressed with CrtR. Assuming that CrtS could interact with the FMN-binding domain of either CrtR or ScCPR (XdFMNbd and ScFMNbd, respectively), the aim of this work was to identify possible interaction differences between these alternative complexes by protein modeling and short molecular dynamics simulations. Considering the recently proposed membrane orientation of a mammalian P450, our CrtS-CrtR model predicts that both N-terminal ends stand adjacent to the membrane plane, allowing their anchoring. Compared with the possible interface between CrtS and both FMNbd, the Xanthophyllomyces system appears to be stabilized by more saline bridges.