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Skin Extract (skin + extract)
Selected AbstractsChemical Alarm Signals Enhance Survival of Brook Charr (Salvelinus fontinalis) During Encounters with Predatory Chain Pickerel (Esox niger)ETHOLOGY, Issue 11 2001Reehan S. Mirza A diversity of aquatic organisms release chemical alarm signals when attacked or captured by a predator. These alarm signals are thought to warn other conspecifics of danger and, consequently, may benefit receivers by increasing their survival. Here we experimentally investigated the differences in behaviour and survival of hatchery-reared juvenile brook charr Salvelinus fontinalis that had been exposed to either brook charr skin extract (experimental treatment) or a control of swordtail skin extract (control treatment). Charr exposed to conspecific skin extract exhibited a significant reduction in movement and/or altered their foraging behaviour in the laboratory when compared with charr exposed to swordtail skin extract. We also exposed charr to either water conditioned by a single brook charr disturbed by a predatory bird model or water conditioned by a single undisturbed brook charr. Charr exposed to disturbance signals reduced activity significantly more than charr exposed to chemical stimuli from undisturbed charr. These results demonstrate the existence of both damage-released alarm signals and disturbance signals in brook charr. Wild brook charr also responded to damage-released alarm cues under natural conditions. Charr avoided areas of a stream with minnow traps labelled with conspecific alarm cues vs. control cues. During staged encounters with chain pickerel Esox niger in the laboratory, predator-naive charr fry were better able to evade the predator if they were previously warned by an alarm signal, thus suggesting a survival benefit to receivers. Collectively, these results demonstrate that the presence of alarm signals in brook charr has important implications for understanding predator,prey interactions. [source] Ontogenetic Changes in the Response of Largemouth Bass (Micropterus salmoides, Centrarchidae, Perciformes) to Heterospecific Alarm PheromonesETHOLOGY, Issue 5 2001Grant E. Brown Juvenile largemouth bass (Micropterus salmoides) undergo an ontogenetic niche shift from invertebrate feeding members of the cyprinid prey guild to piscivory during their first year of growth. We conducted laboratory and field trials to determine whether juvenile bass show a similar ontogenetic shift in their response to the alarm pheromone of finescale dace (Phoxinus neogaeus, Cyprinidae). When exposed to dace skin extract (with alarm pheromone), juvenile bass exhibited a significant positive relationship between standard length and horizontal and vertical area use and time spent moving. Small bass (< 50 mm standard length) tended to reduce area use and time spent moving (indicative of an anti-predator response), while larger bass (> 50 mm standard length) increased area use and time spent moving (indicating a foraging response). Bass exhibited no change in behaviour when exposed to swordtail (Xiphophorus helleri) skin extract, which lacks Ostariophysan alarm pheromone. During field trials, small (30,45 mm standard length) and medium (46,60 mm standard length) bass actively avoided areas labelled with dace alarm pheromone and exhibited a significant increase in dashing behaviour. Large bass (61,80 mm standard length) were attracted to such areas and exhibited a significant increase in approach behaviour. These data suggest that largemouth bass undergo an ontogenetic shift in response to heterospecific chemical alarm signals. [source] Potential of peanut skin phenolic extract as antioxidative and antibacterial agent in cooked and raw ground beefINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 7 2010Jianmei Yu Summary This study investigated the potential of peanut skin extract (PSE) as inhibitor of lipid oxidation in cooked and raw ground beef (GB) and as antimicrobial agent in raw GB. Results show that addition of PSE to raw GB before cooking significantly inhibited the formation of peroxides and TBARS in cooked GB during the refrigerated storage. PSE at concentration ,0.06% was as effective as BHA/BHT at 0.02% in inhibiting lipid oxidation. PSE also inhibited the oxidation of meat pigments thereby preserving the fresh redness of treated meat when used at 0.02,0.10%. Microplate assay showed complete inhibition of test bacteria (Bacillus subtilis, Salmonella typhimurium, Staphylococcus aureus, Streptococcus faecalis and Escherichia coli) in the presence of PSE at 0.4% or higher. However, the antimicrobial effect of PSE in GB was less potent. Hence, PSE can primarily serve the dual purposes of preserving the colour of raw GB and preventing lipid oxidation in cooked products. [source] Development changes of anthocyanins in Vitis vinifera grapes grown in the Douro Valley and concentration in respective winesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2002Nuno Mateus Abstract Grapes of Touriga Nacional and Touriga Francesa red Vitis vinifera varieties have been sampled from two vineyard sites at different altitudes during three consecutive vintage years (1997, 1998 and 1999) in the Douro Valley. The total anthocyanidin monoglucosides (AMGs) detected by HPLC/DAD and the red colour of grape skin extracts were monitored during the last month of maturation. Microvinifications were performed with the grapes studied and the resulting Port wines were analysed. Malvidin 3-glucoside and its acylated esters were the major AMGs irrespective of cultivar at harvest date. Vineyard altitude, together with other variables, was found to be an important factor contributing to the amount of anthocyanin compounds found in grapes of Touriga Nacional and Touriga Francesa. Overall, the climatic conditions observed at higher vineyard sites appeared to be advantageous, resulting in larger amounts of AMGs in grapes. The same outcome was obtained in the resulting wines, which showed higher levels of AMGs when made from grapes grown at higher altitude, especially for Touriga Francesa. © 2002 Society of Chemical Industry [source] Exogenous ethylene stimulates the long-term expression of genes related to anthocyanin biosynthesis in grape berriesPHYSIOLOGIA PLANTARUM, Issue 2 2003Ashraf El-Kereamy The treatment of grape berries (Vitis vinifera L. cv. Cabernet Sauvignon) with the ethylene-releasing compound, 2-chloroethylphosphonic acid (2-CEPA), at veraison is a method known to enhance grape skin colour. We observed that it produced a 6-fold increase, up to 30 pmol g,1 FW, of the cluster internal ethylene compared to untreated controls within the 24 h following treatment. This ethylene upsurge was associated with increased levels of chalcone synthase (CHS) and flavanone 3-hydroxylase (F3H) transcripts, which persisted over the following 20 days. Transcript levels of leucoanthocyanidin dioxygenase (LDOX) and UDP glucose-flavonoid 3- O -glucosyl transferase (UFGT) were similarly enhanced by 2-CEPA, although to a lesser extent. The effect on UFGT was confirmed at the protein level by an immunoblot analysis. The transcript accumulation of dihydroflavonol 4-reductase (DFR) was unaffected by 2-CEPA treatment. Examination of the levels of CHS, F3H and UFGT mRNAs in berries during bunch exposure to ethylene, revealed elevated levels of each transcript within the first 6 h of treatment when compared to nonethylene-treated controls. HPLC analyses of berry skin extracts showed that levels of each of the anthocyanins analysed (delphinidin, cyanidin, petunidin, peonidin and malvidin) increased over the 10 days following the ethylene burst, and decreased thereafter. However, anthocyanin levels at harvest were still higher in ethylene treated grapes than in controls. This data is the first evidence that ethylene triggers gene expression related to anthocyanin synthesis in grapes, and in addition, our results also confirm the existence of other regulatory modes in the anthocyanin biosynthetic pathway. [source] Differences in the amount and structure of extractable skin and seed tannins amongst red grape varietiesAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 1 2009F. MATTIVI Abstract Background and Aims:, Red wine is a very rich source of flavanols, consisting of catechins and oligomeric and polymeric proanthocyanidins (PAs). The aim of this study was to investigate the composition of the fraction of flavanols, which is extractable from the grape into the wine. Methods and Results:, Using HPLC-DAD-MS analysis carried out before and after thioacidolysis of wine-like extracts obtained from skins and seeds, the flavanol composition of 20 samples derived from Cabernet Sauvignon, Carmenere, Marzemino, Merlot, Pinot Noir, Syrah and Teroldego was determined. Conclusions:, It was confirmed that grape extracts are mainly rich in monomers and small oligomers (mean degree of polymerization <8). Grape seed extracts contained three monomers (catechin, epicatechin and epicatechin gallate) and procyanidin oligomers. Grape skin extracts contained four monomers (catechin, epicatechin, gallocatechin and epigallocatechin), procyanidins and prodelphinidins oligomers. Upper and extension units of PAs were constituted mainly of epicatechin units, with the co-presence of catechin and epicatechin gallate in the seed PAs, and of gallocatechin in the case of skin PAs. The terminal units of the grape PAs were a mixture of five compounds, the same found also as monomers. Catechin gallate, gallocatechin gallate and epigallocatechin gallate, which are found in other flavanol-rich, plant-derived foods and beverages, were not present in grape extracts. Significance of the Study:, The grape variety determines both the amount and the structure of wine flavanols, leading to differences in the composition, which are likely to play an important role in the nutritional and sensorial properties of the wines. [source] Anthocyanin profile of Spanish Vitis vinifera L. red grape varieties in danger of extinctionAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 3 2007S. GÓMEZ-ALONSO Abstract This paper reports on a study of the anthocyanin fraction in berry skins of ten minority red and pink grapevine varieties from Castilla-La Mancha (Spain) and two traditional varieties from this growing region, Tempranillo and Garnacha Tinta, as references. These varieties were correctly identified beforehand by analysing six microsatellite regions recommended by the GENRES 081 project; five varieties were identified with genotypes identical to those described previously, and five new genotypes not described for any variety according to the literature consulted. Grape skin extracts of each variety were analysed by HPLC-UV-Vis, and four perfectly differentiated anthocyanin profiles were obtained. In six out of ten varieties (Churriago, Unknown 1, Unknown 2, Ariño, Brujidera and Moravia Agria) the major anthocyanin was malvidin-3-glucoside (39%). Tinto Velasco contained more than 29% delphinidin-3-glucoside, Gordera Roja and Teta de Vaca Tinta more than 40% peonidin-3-glucoside, and Rojal more than 29% cyanidin-3-glucoside. Results of this work point out the existence of unusual anthocyanic profiles in several of these indigenous varieties, and highlight the necessity of studying the effects of variety on other flavonoids and their impact on wine colour. [source] | |||||||||||||