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At least 883 records · Page 49Linked to original sources
PubMed2004

Assimilation of grape phytosterols by Saccharomyces cerevisiae and their impact on enological fermentations.

Although yeasts are known to be able to incorporate a wide variety of exogenous sterols under strict anaerobiosis, no data are available on the assimilation of grapevine phytosterols under enological conditions and the eventual impact on fermentation kinetics. We used therefore a mixture of pure phytosterols, in a proportion representative of the different grape skins phytosterols, to supplement a synthetic fermentation medium simulating a grape must. Under anaerobiosis, normal biomass formation was achieved with 5 mg phytosterols l(-1). Similar results were obtained in comparison with the observed maximal fermentation rates. These results clearly indicated that grape phytosterols may efficiently act as a substitute for ergosterol in the yeast membrane for promoting yeast growth and initial fermentative activity. Analysis of total yeast sterols indicated that phytosterols are accumulated without further modification, mainly in their esterified form. However, all the fermentations performed with synthetic media supplemented with phytosterols led to stuck fermentations, linked to a correlative strong decrease in cell viability during the stationary phase. Therefore, grape phytosterols are easily incorporated by yeast cells under enological conditions for promoting initial growth and fermentative activity, but rapidly perturb the yeast membrane properties by being the predominant sterols.

Culture Media↗
PubMed2005

Hydrolysis of terpenyl glycosides in grape juice and other fruit juices: a review.

The importance of monoterpenes on varietal flavour of must and other fruit juices has been reviewed. These compounds were mainly found linked to sugar moieties in grape juice and wines, showing no olfactory characteristics. In this way, analytical techniques developed to study these compounds, in both free or glycosidically forms, are discussed. Mechanisms to liberate terpenes were studied, making a comparative study between acidic and enzymic hydrolysis of terpene glycosides; as enzymic hydrolysis seems to be the most natural way to liberate terpenes, the ability to use glycosidases from grapes, yeasts, bacterial or exogenous, i.e. fungal commercial preparations, were reviewed. Re-arrangements of terpenes after acidic hydrolysis of glycoconjugated are discussed as well as potential adverse effects of enzyme preparations.

Bacteria↗
PubMed2001

Improved antifungal activity of a mutant of Trichoderma harzianum CECT 2413 which produces more extracellular proteins.

Trichoderma harzianum is a well-known biological control agent against fungal plant diseases. In order to select improved biocontrol strains from Trichoderma harzianum CECT 2413, a mutant has been isolated for its ability to produce wider haloes than the wild type, when hydrolysing pustulan, a polymer of beta-1,6-glucan. The mutant possesses between two and four times more chitinase, beta-1,3- and beta-1,6-glucanase activities than the wild type, produces about three times more extracellular proteins and secretes higher amounts of a yellow pigment (alpha-pyrone). This mutant performed better than the wild type during in vitro experiments, overgrowing and sporulating on Rhizoctonia solani earlier, killing this pathogen faster and exerting better protection on grapes against Botrytis cinerea.

Antifungal Agents↗
PubMed2002

Secretion of beta-1,3-glucanases by the yeast Pichia membranifaciens and its possible role in the biocontrol of Botrytis cinerea causing grey mold disease of the grapevine.

Pichia membranifaciens strain FY-101, isolated from grape skin, was found to be antagonistic to Botrytis cinerea, the causal organism of the grey mold disease of the grapevine. When grown together on solid as well as in liquid media, the yeast brings about the inhibition of Botrytis cinerea, which in turn loses its ability to produce the grey mold symptoms on the grapevine plantlets. The secretion of beta-1,3-glucanases by P. membranifaciens is one of the possible mechanisms related to this antagonism. In vitro experiments confirm that this yeast can be used as a biological control organism against B. cinerea. An account of this antagonism and the production of beta-1,3-glucanases by P. membranifaciens is given here.

Botrytis↗
PubMed2002

An evolutionary perspective of Pierce's disease of grapevine, citrus variegated chlorosis, and mulberry leaf scorch diseases.

Xylella fastidiosa causes diseases on a growing list of economically important plants. An understanding of how xylellae diseases originated and evolved is important for disease prevention and management. In this study, we evaluated the phylogenetic relationships of X. fastidiosa strains from citrus, grapevine, and mulberry through the analyses of random amplified polymorphic DNAs (RAPDs) and conserved 16S rDNA genes. RAPD analysis emphasized the vigorous genome-wide divergence of X. fastidiosa and detected three clonal groups of strains that cause Pierce's disease (PD) of grapevine, citrus variegated chlorosis (CVC), and mulberry leaf scorch (MLS). Analysis of 16S rDNA sequences also identified the PD and CVC groups, but with a less stable evolutionary tree. MLS strains were included in the PD group by the 16S rDNA analysis. The Asiatic origins of the major commercial grape and citrus cultivars suggest the recent evolution of both PD and CVC disease in North and South America, respectively, since X. fastidiosa is a New World organism. In order to prevent the development of new diseases caused by X. fastidiosa, it is important to understand the diversity of X. fastidiosa strains, how strains of X. fastidiosa select their hosts, and their ecological roles in the native vegetation.

Citrus↗
PubMed2003

Characterization of Cr(VI)-resistant bacteria isolated from chromium-contaminated soil by tannery activity.

Bacterial strains, previously isolated from a chromium-polluted soil, were identified on the basis of Gram reaction and biochemical characteristics (Biolog system). Moreover, chromate MICs, chromate reduction capability, multiple heavy metal tolerance, and antibiotic susceptibility were tested for each isolate. All strains but one were Gram-positive and resistant to high concentrations of chromate. The most Cr(VI)-resistant isolate (22m M) was identified as Corynebacterium hoagii. All Cr(VI)-resistant strains except the isolate ChrC20 were capable of catalyzing the reduction of Cr(VI) to Cr(III), a less toxic and less water-soluble form of chromium. The only isolate Cr(VI)-sensitive, attributed to the Pseudomonas genus, also exhibited Cr(VI)-reduction. Isolates were also screened for the presence of plasmid DNA. The strains ChrC20 and ChrB20 harbored one and two plasmids of high molecular mass, respectively. This approach permitted selection of some bacterial strains, which could be used for bioremediation of Cr(VI)-polluted environments.

Bacteria↗
PubMed2003

Genotypic diversity of oscillatoriacean strains belonging to the genera Geitlerinema and Spirulina determined by 16S rDNA restriction analysis.

Genotypic diversity of several cyanobacterial strains mostly isolated from marine or brackish waters, belonging to the genera Geitlerinema and Spirulina, was investigated by amplified 16S ribosomal DNA restriction analysis and compared with morphological features and response to salinity. Cluster analysis was performed on amplified 16S rDNA restriction profiles of these strains along with profiles obtained from sequence data of five Spirulina-like strains, including three representatives of the new genus Halospirulina. Our strains with tightly coiled trichomes from hypersaline waters could be assigned to the Halospirulina genus. Among the uncoiled strains, the two strains of hypersaline origin clustered together and were found to be distant from their counterparts of marine and freshwater habitat. Moreover, another cluster, formed by alkali-tolerant strains with tightly coiled trichomes, was well delineated.

Bacterial Proteins↗
PubMed2004

Characterization of Penicillium species isolated from grape berries by their internal transcribed spacer (ITS1) sequences and by gas chromatography-mass spectrometry analysis of geosmin production.

Geosmin (trans-1,10-dimethyl-trans-9-decalol), an earthy-musty compound, has been identified in wines and in grape juice, in which its presence is highly detrimental to the aromatic quality. Geosmin has a biological origin, and the analysis of rotten grape microflora has been done on two grape varieties (Semillon, Cabernet Sauvignon) from six parcels of the Bordeaux region over 3 years (1999, 2000, 2001). Forty-three Penicillium-related species have been analyzed by gas chromatography-mass spectrometry (GC-MS) for their geosmin production. GC-MS analysis has demonstrated that the earthy odor was always correlated with the presence of geosmin. Phenotypic characterization of Penicillium spp. being ambiguous, a molecular characterization by rDNA internal transcribed spacer (ITS1) sequencing was performed for all strains. The results evidenced that all strains producing geosmin belonged to only one species, P. expansum, and that the other strains, not producing geosmin, belonged to three species: P. purpurogenum, P. thomii, and Talaromyces wortmanii.

DNA, Fungal↗
PubMed2004

Expression of green fluorescent protein in Xylella fastidiosa is affected by passage through host plants.

Xylella fastidiosa, a Gram-negative bacterial plant pathogen, causes Pierce's disease of grapevine in North America. In South America the pathogen causes citrus variegated chlorosis, which is widespread in Brazil. We have introduced into Xylella fastidiosa a mini-Tn5 transposon that encodes a green fluorescent protein (GFP) gene optimized for expression in bacteria. The mini-Tn5 derivative was inserted into different sites of the genome in independent transconjugants as determined by Southern blotting. The GFP gene was expressed well and to different levels in different transconjugants. Four independent transconjugants were separately used to inoculate sweet orange and tobacco seedlings. The transconjugants were able to colonize the plants and were subsequently isolated from points distal to the inoculation sites. When the relative fluorescence of the transconjugants that had been passed through either tobacco or sweet orange was compared with that of the same transconjugant maintained continuously in vitro, we observed that passage through either plant host significantly increased the level of expression of the GFP. The increased level of expression of GFP was transient, and was lost upon further culture in vitro. Xylella fastidiosa forms biofilms in planta which are believed to represent a metabolically differentiated state. The increased expression of GFP observed after passage through plants may be accounted for by this phenomenon.

Citrus↗
PubMed2004

Secondary metabolites of the grapevine pathogen Eutypa lata inhibit mitochondrial respiration, based on a model bioassay using the yeast Saccharomyces cerevisiae.

Acetylenic phenols and a chromene isolated from the grapevine fungal pathogen Eutypa lata were examined for mode of toxicity. The compounds included eutypine (4-hydroxy-3-[3-methyl-3-butene-1-ynyl] benzyl aldehyde), eutypinol (4-hydroxy-3-[3-methyl-3-butene-1-ynyl] benzyl alcohol), eulatachromene, 2- isoprenyl-5-formyl-benzofuran, siccayne, and eulatinol. A bioassay using the yeast Saccharomyces cerevisiae showed that all compounds were either lethal or inhibited growth. A respiratory assay using 2,3,5-triphenyltetrazolium (TTC) indicated that eutypinol and eulatachromene inhibited mitochondrial respiration in wild-type yeast. Bioassays also showed that 2- isoprenyl-5-formyl-benzofuran and siccayne inhibited mitochondrial respiration in the S. cerevisiae deletion mutant vph2Delta, lacking a vacuolar type H (+) ATPase (V-ATPase) assembly protein. Cell growth of tsa1Delta, a deletion mutant of S. cerevisiae lacking a thioredoxin peroxidase (cTPx I), was greatly reduced when grown on media containing eutypinol or eulatachromene and exposed to hydrogen peroxide (H(2)O(2)) as an oxidative stress. This reduction in growth establishes the toxic mode of action of these compounds through inhibition of mitochondrial respiration.

Alkynes↗
PubMed2003

Antiproliferative effect of antioxidant polyphenols from grape in murine Hepa-1c1c7.

BACKGROUND: Grapes and wine contain high concentrations of polyphenolic compounds. Although their cancer protective effect has been well documented, their activity as anticarcinogens should be cautiously considered since the molecular bases of action and their applicability to human cancer prevention are still unclear. AIM OF THE STUDY: We studied the antioxidant/antiradical activity and the antiproliferative effect in vitro of different polyphenolic mixtures, extracted from grapes and fractionated through RP-HPLC. METHODS: The polyphenolic fractions were chemically characterized and their antioxidant/antiradical activity was determined by the DPPH assay. Mouse hepatoma Hepa-1c1c7 cells were used to study the cell growth inhibition capacity of these fractions by MTT assay. Their capacity of altering cell cycle and possible induction of apoptosis was examined using FACS analysis. RESULTS: The original polyphenolic fraction OW, which contained gallic acid (GA), (+)-catechin (Cat), (-)-epicatechin (Ec), glycosylated flavonols (F) and procyanidin oligomers was fractionated into fraction I, composed of monomers and small oligomers, and fraction II that included flavonols and procyanidin oligomers of higher molecular weight. The three polyphenolic fractions tested showed quite similar antiradical activity, although fraction I was the most potent antiradical agent (lowest ED(50) value: 9 microg). Fraction II was the least potent cell growth inhibitor (highest IC(50) value: 100 microg/ml) but showed the strongest effect on the cell cycle of Hepa-1c1c7, inducing apoptosis in those cells. The original fraction OW was demonstrated to have the most potent cell growth inhibition effect (lowest IC(50) value: 43 microg/ml). However, it only appeared to alter cell cycle of Hepa-1c1c7 at concentrations higher than its IC(50) and did not induce apoptosis in those cells. A similar effect on cell cycle and apoptosis was encountered for fraction I. CONCLUSIONS: The polyphenolic fractions tested in this study were potent antiradical agents and exerted an antiproliferative effect in mouse hepatoma Hepa-1c1c7 cells; the fraction with the highest degree of polimerization and galloylation (fraction II) had the most influence on the cell cycle and induction of apoptosis on Hepa-1c1c7.

Animals↗
PubMed2004

The grape and wine polyphenol piceatannol is a potent inducer of apoptosis in human SK-Mel-28 melanoma cells.

BACKGROUND & AIM: The resveratrol analogue piceatannol (3,5,3',4'-tetrahydroxy- trans-stilbene; PICE) is a polyphenol present in grapes and wine. PICE is a protein kinase inhibitor that modifies multiple cellular targets exerting immunosuppressive, antileukemic and antitumorigenic activities in several cell lines and animal models. The present work aims to evaluate the antimelanoma effect of PICE on human melanoma cells for the first time. To this purpose, the pro-apoptotic capacity, uptake and metabolism of PICE as well as its effect on cell cycle and cyclins A, E and B1 expression will be studied. METHODS: . Human SK-Mel-28 melanoma cells were incubated with PICE (1-200 microM) for 72 hours. Cell cycle and viability were examined using flow cytometry analysis. Apoptosis was determined using the annexin V assay and also by fluorescence microscopy. Cyclins A, E and B1 were detected by Western blotting. Stability, cellular uptake and metabolism of PICE were evaluated using HPLC-DAD-MS-MS. RESULTS: The lowest PICE concentration assayed (1 microM) increased about 6-fold over the control the apoptotic population of melanoma cells (10.2% at 8 hours which remained constant during 48 h). 100 microM PICE induced 13% apoptosis at 8 h increasing up to 41.5% at 48 h. The decrease in cell viability was highly correlated with the increase of apoptotic cells ( R = 0.996; P < 0.0001) revealing that significant cytotoxic, unspecific effects did not occur in melanoma cells upon incubation with PICE. Cell cycle was arrested at G(2) phase which was supported by the down-regulation of cyclins A, E and B1. Two methyl-PICE derived metabolites, 3,5,4'-trihydroxy-3'-methoxy- trans-stilbene and 3,5,3'-trihydroxy-4'-methoxy- trans-stilbene (corresponding to 36% of the initially PICE added) were excreted by cells to the medium. The same methyl-PICE derivatives were also found inside the cells (0.01% of the initially PICE added; 0.0183 picograms/cell). CONCLUSION: The antimelanoma properties of dietary piceatannol cannot be ruled out taking into account its fast and potent pro-apoptotic capacity at low concentration (1 microM).

Apoptosis↗
PubMed2006

Defatted milled grape seed protects adriamycin-treated hepatocytes against oxidative damage.

Defatted milled grape seed (DMGS) is a wine by-product obtained from the oil extraction of the grape seed that contains different types of phenolic compounds. The present study was designed to evaluate the possible protective effect of DMGS on toxicity induced by adriamycin (ADR) in isolated rat hepatocytes. The study was carried out by examining the results of lactate dehydrogenase (LDH) release to estimate cytotoxicity; the thiobarbituric acid reactant substances (TBARS) and carbonyl group levels were measured as biomarkers of oxidative stress and ATP and GSH levels as estimation of intracellular effect. The results showed that DMGS extract protects the cellular membrane from oxidative damage and consequently prevents protein and lipid oxidation. The levels of ATP and GSH changes for the ADR toxicity were restored to control value in the presence of DMGS extract. The experimental results suggest that this wine by-product may be used to decrease oxidative stress.

Adenosine Triphosphate↗
PubMed2000

The contribution of fast-FLAIR MRI for lesion detection in the brain of patients with systemic autoimmune diseases.

Fast fluid-attenuated inversion recovery (fFLAIR) is more sensitive that conventional or fast spin echo T2-weighted magnetic resonance imaging (MRI) for detecting lesions in the brain of patients with ischemic, inflammatory, or demyelinating diseases of the CNS. We investigated whether the use of fFLAIR also increases the sensitivity of brain MRI assessment in patients with systemic autoimmune disorders. Turbo spin echo (TSE) dual-echo and fFLAIR scans of the brain were obtained from patients affected by systemic lupus erythematosus (SLE) with (NSLE, n = 9) and without clinical CNS involvement (n = 15), Behçet disease (n = 5), Wegener granulomatosis (n = 9), and antiphospholipid antibody syndrome (n = 6). Brain hyperintense lesions were counted and classified according to their size and their location by two observers by consensual agreement. The total lesion volume was measured using a semiautomated technique for lesion segmentation on both TSE and fFLAIR scans. The imaging modalities showed brain hyperintense lesions in all 9 SLE patients with CNS involvement, 5 of 15 SLE patients without CNS involvement, 5 of 9 patients with Wegener granulomatosis, 1 of 5 with Behçet disease, and 3 of 6 with antiphospholipid antibody syndrome. A total of 342 lesions were seen on both sequences; 88 were seen only on TSE and 54 only on fFLAIR scans. The average number of brain lesions per scan was higher on TSE than on fFLAIR, since significantly more discrete (P<0.002) and small (P = 0.004) lesions were seen on TSE than on fFLAIR. The median total lesion volume, however, was similar on TSE and fFLAIR. Our study indicates that the use of fFLAIR does not improve the sensitivity of fast dual-echo MRI for detecting brain abnormalities in patients with systemic autoimmune disorders.

Adult↗
PubMed1999

Multiple sclerosis: interobserver agreement in reporting active lesions on serial brain MRI using conventional spin echo, fast spin echo, fast fluid-attenuated inversion recovery and post-contrast T1-weighted images.

Previous studies have addressed the question of the precision in assessing multiple sclerosis (MS) activity by counting enhancing lesions on gadolinium enhanced brain magnetic resonance imaging (MRI). However, counting the active lesions on serial unenhanced MRI obtained by various pulse sequences has not been yet considered. We compared the interobserver levels of agreement in reporting active MS lesions on serial enhanced and unenhanced MRI to assess whether the use of various unenhanced techniques may change the degree of interobserver measurement reproducibility. Dual-echo conventional spin echo (CSE), dual-echo fast spin echo (FSE), fast fluid-attenuated inversion recovery (FLAIR) and Gd-enhanced T1-weighted brain MRI were obtained from five MS patients at baseline and monthly for 2 months. Six experienced observers independently identified and counted active MS lesions on the two follow-up MRI scans. Active lesions were considered to be all the enhancing lesions and any new or enlarging lesion on enhanced and unenhanced scans. Interobserver levels of agreement were calculated by weighted kappa values. Very good agreement was reached only for counting total and new Gd-enhancing lesions. Good agreement was achieved for counting new lesions on the three unenhanced techniques, whereas the agreement for counting enlarging lesions was poor with all the MRI techniques. The level of agreement was significantly heterogeneous for various MRI techniques but not for various lesion sites. These results confirm that counting enhancing lesions is the most reliable method for assessing MS activity, but the use of any of the available unenhanced MRI techniques did not result in different levels of interobserver agreement when reporting new and enlarging MS lesions on serial scans.

Brain↗
PubMed2002

Biomechanical strains on the hand-wrist system during grapevine pruning.

OBJECTIVES: In order to understand the high prevalence of musculoskeletal disorders of the hand among vineyard workers, we conducted a study to evaluate biomechanical strains on the hand-wrist system during grapevine pruning. METHODS: Surface electromyography (sEMG) activity of the right flexor digitorum muscle and wrist posture were analysed in six healthy vineyard workers using the same hand-powered pruning shears during grapevine pruning. RESULTS: The biomechanical strains on the hand-wrist system were high during grapevine pruning. Mean sEMG activity during pruning was high [23.5% (standard error of the mean (SEM): 0.4) in the maximal voluntary handgrip contraction (MVC)], as was the mean cutting frequency per minute (38; range=24-48). Approximately 14% of cuts were performed with the wrist in extreme flexion/extension (F/E) (>60% of the maximum range). Numerous cuts required moderate (20%-40% of the maximum range) or extreme (>50% of the maximum range) ulnar deviation (17% and 12% of cuts, respectively). Approximately 18% of cuts required both high muscular activity (sEMG >15% MVC) and extreme ulnar/radial (U/R) deviation of the wrist (>50% of the maximum range). CONCLUSION: Pruning imposes high biomechanical strains on the hand-wrist system in view of the repetitiveness of the task. The magnitude of physical exposure during pruning explains the high prevalence of hand disorders among vineyard workers. The use of ergonomic pruning shears is advised to lower force exertion and to reduce the frequency of awkward wrist postures during pruning.

Adult↗
PubMed2004

Polyamines inhibit NADPH oxidase-mediated superoxide generation and putrescine prevents programmed cell death induced by polyamine oxidase-generated hydrogen peroxide.

Our previous results indicate that during protoplast isolation an oxidative burst occurs [A.K. Papadakis and KA Roubelakis-Angelakis (1999) Plant Physiol 127:197-205] and that suppression of totipotency is correlated with reduced antioxidant activity and low redox state [A.K. Papadakis et al. (2001b) Plant Physiol 126:434-444]. Polyamines are known to affect cell development and to act as antioxidants. Polyamines applied during isolation of tobacco (Nicotiana tabacum L.) protoplasts reduced the accumulation of O2*- but not that of H2O2. This antioxidant effect is probably due to the inhibition of microsomal membrane NADPH oxidase, which occurred in a concentration-dependent manner, with spermine exerting the highest inhibitory effect. However, during protoplast culture, polyamine oxidase activity increased severalfold in spermidine- and spermine-treated protoplasts, concomitant with H2O2 titers. A cell death program was executed in untreated protoplasts, as documented by membrane malfunction, induced DNase activity, DNA fragmentation and a positive TUNEL reaction. Protoplast cell death was prevented in protoplasts treated with putrescine, but not by treatment with spermidine or spermine, which rather had the opposite effect. The data presented suggest that PAs may be implicated in the expression of plant protoplast totipotency.

Apoptosis↗
PubMed2003

Effect of grape seed extract on puromycin-aminonucleoside-induced nephrosis in rats.

Recent studies indicate that an excessive production of oxidants plays an important role in the pathogenesis of glomerular disease. Grape seed extract (GSE) is a potent antioxidant, and the aim of this pilot study was to evaluate its effect on puromycin-aminonucleoside (PAN)-induced nephrosis in rats. Fifty Sprague-Dawley rats were divided into five groups. Groups 1 and 2 rats received water from day 0 to day 30. Rats in groups 3, 4, and 5 received GSE at 10 mg/100g of body weight (BW), which was started on day 0, 6, and 3 of the experiment, respectively. In group 5 animals the GSE dose was increased (40 mg/100g BW) on day 9. Intraperitoneal dextrose (group 1) or PAN 15 mg/100g BW (groups 2-5) was administered on day 3. Urine and blood specimens were collected at regular intervals, and the comparison between the various groups was made by analysis of variance (ANOVA). Rats in all study groups (groups 3-5) showed a decrease in urine protein and serum cholesterol and triglyceride levels, which was statistically significant in group 3 animals. No significant changes were noted in serum albumin and creatinine levels. In conclusion, GSE administration decreases urine protein excretion and serum cholesterol and triglyceride levels in rats with PAN-induced nephrosis.

Animals↗