Effects of static and low-frequency alternating magnetic fields on the ionic electrolytic currents of glutamic acid aqueous solutions

A current peak has been observed and measured in ionic electrolytic current of a glutamic acid aqueous solution, placed in a static magnetic field of flux density of 40 microT, with a superimposed low-frequency alternating magnetic field of flux density of 40 nT. The peak occurs at the frequency of the cyclotronic resonance of the molecular mass of a single charged glutamic acid ion, placed in a magnetic flux density equal to that of the static field. The amplitude of the current peak is about 30% of the background electrolytic current. Qualitative considerations and a listing of unsolved problems related to the phenomenology are given. The result is the first contribution to the study we have undertaken on the effects of low-frequency alternating electromagnetic fields on the ionic current of amino acid aqueous solutions which are the basic structural units of the proteins.     

Strategies and perspectives for genetic improvement of wine yeasts

Recent developments in expression profile and proteomic techniques illustrated that the main oenological traits of wine yeasts are complex and influenced by several genes, each of them identified as absolutely essential. Only for monogenic properties the genetic improvement programmes of wine yeasts can be performed by alteration of individual genes. Ideally the most productive way of improving the whole-cell biocatalysts is by evolution of the entire cell genome. In this article we briefly review the main genetic improvement techniques applied in new and optimised wine strains construction, paying particular attention to blind and whole genome strategies, such as the sexual recombination and genome shuffling.     

Interaction of viscotoxins A3 and B with membrane model systems: implications to their mechanism of action

Viscotoxins are small proteins that are thought to interact with biomembranes, displaying different toxic activities against a varied number of cell types, being viscotoxin A(3) (VtA(3)) the most cytotoxic whereas viscotoxin B (VtB) is the less potent. By using infrared and fluorescence spectroscopies, we have studied the interaction of VtA(3) and VtB, both wild and reduced ones, with model membranes containing negatively charged phospholipids. Both VtA(3) and VtB present a high conformational stability, and a similar conformation both in solution and when bound to membranes. In solution, the infrared spectra of the reduced proteins show an increase in bandwidth compared to the nonreduced ones indicating a greater flexibility. VtA(3) and VtB bind with high affinity to membranes containing negatively charged phospholipids and are motional restricted, their binding being dependent on phospholipid composition. Whereas nonreduced proteins maintain their structure when bound to membranes, reduced ones aggregate. Furthermore, leakage experiments show that wild proteins were capable of disrupting membranes whereas reduced proteins were not. The effect of VtA(3) and VtB on membranes having different phospholipid composition is diverse, affecting the cooperativity and fluidity of the membranes. Viscotoxins interact with membranes in a complex way, most likely organizing themselves at the surface inducing the appearance of defects that lead to the destabilization and disruption of the membrane bilayer.     

Occurrence and dominance of yeast species in sourdough

AIMS: The aim of this work is to identify the dominant yeast species in homemade sourdoughs. METHODS AND RESULTS: PCR/restriction fragment length polymorphism analysis of internal transcribed spacer regions was used for the identification of isolates and the data were confirmed with phenotypic tests. The strains belonging to Saccharomyces cerevisiae were identified to strain level by analysis of inter-delta regions. CONCLUSION: This work shows that the dominant species in homemade sourdoughs can differ from each other. Saccharomyces cerevisiae was found to be the dominant species, followed by the Candida milleri, C. humilis, S. exiguus and Issatchenkia orientalis. The inter-delta regions of S. cerevisiae strains showed high polymorphism. SIGNIFICANCE AND IMPACT OF THE STUDY: Occurrence of single, non-Saccharomyces species and S. cerevisiae polymorphism in the yeast populations of sourdough samples.     

Antifungal effects and mechanism of action of viscotoxin A3

Viscotoxins are cationic proteins, isolated from different mistletoe species, that belong to the group of thionins, a group of basic cysteine-rich peptides of approximately 5 kDa. They have been shown to be cytotoxic to different types of cell, including animal, bacterial and fungal. The aim of this study was to obtain information on the cell targets and the mechanism of action of viscotoxin isoform A3 (VtA3). We describe a detailed study of viscotoxin interaction with fungal-derived model membranes, its location inside spores of Fusarium solani, as well as their induced spore death. We show that VtA3 induces the appearance of ion-channel-like activity, the generation of H2O2, and an increase in cytoplasmic free Ca2+. Moreover, we show that Ca2+ is involved in VtA3-induced spore death and increased H2O2 concentration. The data presented here strongly support the notion that the antifungal activity of VtA3 is due to membrane binding and channel formation, leading to destabilization and disruption of the plasma membrane, thereby supporting a direct role for viscotoxins in the plant defence mechanism.     

Development of a sequence-characterized amplified region marker-targeted quantitative PCR assay for strain-specific detection of Oenococcus oeni during wine malolactic fermentation

Control over malolactic fermentation (MLF) is a difficult goal in winemaking and needs rapid methods to monitor Oenococcus oeni malolactic starters (MLS) in a stressful environment such as wine. In this study, we describe a novel quantitative PCR (QPCR) assay enabling the detection of an O. oeni strain during MLF without culturing. O. oeni strain LB221 was used as a model to develop a strain-specific sequence-characterized amplified region (SCAR) marker derived from a discriminatory OPA20-based randomly amplified polymorphic DNA (RAPD) band. The 5' and 3' flanking regions and the copy number of the SCAR marker were characterized using inverse PCR and Southern blotting, respectively. Primer pairs targeting the SCAR sequence enabled strain-specific detection without cross amplification of other O. oeni strains or wine species of lactic acid bacteria (LAB), acetic acid bacteria (AAB), and yeasts. The SCAR-QPCR assay was linear over a range of cell concentrations (7 log units) and detected as few as 2.2 × 10(2) CFU per ml of red wine with good quantification effectiveness, as shown by the correlation of QPCR and plate counting results. Therefore, the cultivation-independent monitoring of a single O. oeni strain in wine based on a SCAR marker represents a rapid and effective strain-specific approach. This strategy can be adopted to develop easy and rapid detection techniques for monitoring the implantation of inoculated O. oeni MLS on the indigenous LAB population, reducing the risk of unsuccessful MLF.     

Significance of the clonal and sporadic chromosome abnormalities in non-neoplastic renal tissue

Summary Trisomy 7, trisomy 10 and loss of the Y chromosome have been found by some authors in presumptive normal parts of human kidneys. We describe cytogenetic findings in short-term cultures from 58 biopsies obtained from non-neoplastic and neoplastic (renal cell carcinoma, RCC) tissues from the same kidney, the same types of tissues from independent kidneys, and tissue from kidneys without neoplasia. The results indicate the following. Non-neoplastic tissue from kidneys involved in RCC have (in mosaics) trisomies 5, 7, 10, 18 and loss of the Y as non-random clonal changes. They are not the result of local metastasis but are also found in kidneys with non-tumoral chronic pathologies and should thus not be considered specific for RCC. They are neither culturing artefacts nor a general phenomenon found in cultured normal solid tissues, but are acquired abnormalities, possibily related to various reactive cellular states in the tissues that are histologically normal.