Home About us Contact
|
Home About us Contact | ||
|
|
||
Descending Order (descending + order)
Selected AbstractsAssessment of potential ecological disruption based on heavy metal toxicity, accumulation and distribution in media of the Lagos LagoonAFRICAN JOURNAL OF ECOLOGY, Issue 4 2007Otitoloju A. Adebayo Abstract Toxicity evaluations of heavy metals against three benthic animals, Tympanotonus fuscatus, Clibanarius africanus and Sesarma huzardi of the Lagos Lagoon were carried out under laboratory conditions. On the basis of the 96hLC50 values, Cd was found to be the most toxic metal tested followed by Cu, Zn and Pb, in a descending order of toxicity against T. fuscatus and S. huzardi; however, against C. africanus, Cu was the most toxic followed by Cd, Zn and Pb (least toxic). The determination of the metal concentrations in the water column and sediment of the Lagos Lagoon revealed that these media of the lagoon contained measurable concentrations of heavy metals but the levels were still several folds lower than the concentrations that will cause 50% mortality of exposed animals under laboratory conditions. The significance of the observed differences between the 96hLC50 values of the test metals, the concentration of heavy metals detected in tissues of field animals and ambient levels of the metals in the Lagos lagoon were discussed in relation to the protection of aquatic lives and potential public health risks. The need to verify the possibilities of synergistic interactions between the constituent metals when acting jointly against the exposed animals was recommended. Resume On a procédé en laboratoire à des évaluations de la toxicité des métaux lourds chez trois animaux benthiques, Tympanotonus fuscatus, Clibanarius africanus et Sesarma huzardi, du lagon de Lagos. Sur la base des valeurs de 96hLC50, on a trouvé que le Cd était le métal testé le plus toxique suivi par le Cu, le Zn et le Pb, en ordre de toxicité décroissant pour T. fuscatus et S. huzardi; cependant, pour C. africanus, le Cu était le plus toxique, suivi par Zn et Pb (le moins toxique). La détermination des concentrations de métaux dans l'eau et les sédiments du lagon de Lagos a révélé que ces milieux contenaient des concentrations mesurables de métaux lourds, mais que les niveaux étaient encore plusieurs fois plus bas que les concentrations qui causaient 50% de mortalité chez les animaux qui y étaient exposés en laboratoire. La signification des différences constatées entre les valeurs de 96hLC50 des métaux testés, la concentration des métaux lourds détectés dans les tissus des animaux du lagon et les niveaux observés dans le lagon ont été discutés en relation avec la protection de la vie aquatique et des risques potentiels pour la santé des personnes. On a recommandé de vérifier s'il est possible qu'il existe des interactions synergiques entre les métaux constituants lorsqu'ils agissent conjointement sur les animaux qui y sont exposés. [source] ACTIVITY DISTRIBUTION OF DIGESTIVE PROTEASES FROM NEMIPTERUS VIRGATUS AND THEIR RESPONSES TO pH VALUE AND TEMPERATUREJOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2008HONG TAO ABSTRACT In the present study, three groups (I,III) of Nemipterus virgatus, with average body weights of 154.36, 250.72 and 329.09 g, respectively, were used to investigate the changes in the activity and distribution of digestive proteases in different organs and sections of the digestive tract. Another group of N. virgatus (average body weight of 188.41 g) was used to analyze the changes in the activity of digestive proteases in response to various pH values and temperatures. The activity of digestive proteases in all analyzed organs increased with the increase of body weight at the range of 154.36,329.09 g. The activities of digestive proteases in the different sections of the digestive tract were compared, and a similar change was found among groups I,III. The activities of digestive proteases from various organs were in a descending order: pylorus ceca > stomach > foregut > midgut > hindgut > hepatopancreas. Through observing the zymograms of substrate,sodium dodecil sulphate-polyacrylamide gel electrophoresis, many kinds of digestive proteases could be found in different organs and the varieties were changed with the change of body weight. Two peaks in the diagram between protease activity and pH value were found at pH 3.0 and 10.0, respectively. The activity under alkaline condition was 60% higher than that under acidic condition. The optimal temperature for protease activity was 50C, while the protease activity at 10C was only 30% of that at 50C. PRACTICAL APPLICATIONS Nemipterus virgatus is one of the most important commercial fishes in the East China Sea and South China Sea. The digestive tract of N. virgatus is rich in digestive proteases and they can be employed as important biotechnological tools. The activities of digestive proteases from various organs and the effects of pH value and temperature on them were investigated in this study. The effect of body weight of N. virgatus was also evaluated. All these information would be helpful to extensively utilize this resource for the fish process industry. [source] Growth and Viability of Commercial Bifidobacterium spp in Skim Milk Containing Oligosaccharides and InulinJOURNAL OF FOOD SCIENCE, Issue 5 2000H.-S. Shin ABSTRACT Two commercial strains of Bifidobacterium spp (Bf -1 and Bf -6) were cultured in 12% (w/w) reconstituted nonfat dry milk (NDM) containing 0, 0.5, 1.0, 3.0, or 5.0% (w/v) fructooligosaccharide (FOS), galactooligosaccharide (GOS), and inulin. Inoculated samples were incubated anaerobically at 37° for 48 h. Growth and activity of the cultures in the presence of FOS, GOS, and inulin were determined. Viability of each strain was assessed after 4 weeks of refrigerated storage at 4°. Growth promotion, enhancement of activity and retention of viability were greatest when Bifidobacterium Bf-1 and Bf-6 were grown in the presence of FOS followed in a descending order by GOS and inulin. The effects of oligosaccharides and inulin increased with increasing carbohy drate concentration and was maximal at 5% (w/v). [source] Inactivation Kinetics of Foodborne Spoilage and Pathogenic Bacteria by OzoneJOURNAL OF FOOD SCIENCE, Issue 3 2000J.-G. Kim ABSTRACT: Ozone was tested against Pseudomonas fluorescens, Escherichia coli O157:H7, Leuconostoc mesenteroides, and Listeria monocytogenes. When kinetic data from a batch reactor were fitted to a dose-response model, a 2-phased linear relationship was observed. A continuous ozone reactor was developed to ensure a uniform exposure of bacterial cells to ozone and a constant concentration of ozone during the treatment. Survivors plots in the continuous system were linear initially, followed by a concave downward pattern. Exposure of bacteria to ozone at 2.5 ppm for 40 s caused 5 to 6 log decrease in count. Resistance of tested bacteria to ozone followed this descending order: E. coli O157:H7, P. fluorescens, L. mesenteroides, and L. monocytogenes. [source] Antioxidant activities of some Lamiaceae plant extractsPHYTOTHERAPY RESEARCH, Issue 1 2006Nurgun Erdemoglu Abstract The antioxidant activities of four Lamiaceae plants, Salvia viridis L., Salvia multicaulis Vahl, Stachys byzantina C. Koch and Eremostachys laciniata (L.) Bunge have been determined by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) as well as by flow injection analysis-luminol chemiluminescence (FIA-CL). All extracts were shown to possess a significant scavenger activity against DPPH free radical and an inhibitory effect on H2O2 - or HOCl-luminol chemiluminescence. The extracts scavenged 50% of DPPH radical ranging in the following descending order: Salvia viridis > Stachys byzantina > Salvia multicaulis > Eremostachys laciniata. The most potent extract on H2O2 -induced peak chemiluminescence was that of Salvia viridis and on HOCl-induced peak chemiluminescence was that of Stachys byzantina. The results concluded that the extracts have a potential source of antioxidants of natural origin. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||