Search results for "biochemistry"
showing 10 items of 20172 documents
Active vanadate-sensitive H+ translocation in corn roots membrane vesicles and proteoliposomes
1988
Abstract A member fraction from corn roots which contains a vanadate-sensitive ATPase activity has been prepared. The specific activity at 38°C is between 3 and mol 12 μmol · min −1 · mg −1 , depending on the age of roots. Addition of ATP promotes a very rapid quenching of the fluorescence of 9-amino-6-chloro-3-methoxy-acridin (ACMA). Proton pumping exhibits a delayed sensitivity to vanadate but is strongly and instantaneously inhibited by the new inhibitor SW 26. Both proton pumping, measured by the initial quenching rate, and ATP hydrolysis show maximum activities at ATP concentrations in the millimolar range, but the apparent K m -value for hydrolysis is higher than that observed for pro…
Influence of ATPase activity on PPi dependent H+-transport in tonoplast vesicles of Acer pseudoplatanus
1994
Abstract Tonoplast H + -ATPase and H + -pyrophosphatase (H + -PPase) were previously characterized in Acer pseudoplatanus cells (A. Pugin et al., Plant Sci., 73 (1991) 23–34; A. Fraichard et al., Plant Physiol. Biochem., 31 (1993) 349–359). The present study concerns the relationships between these two enzymes in vitro. ATP and PPi hydrolysis were additive and the inhibition of one did not affect the activity of the second one. ATP and PPi H + -transports were also additive. The H + -PPase inhibition did not change ATP-dependent H + -transport but H + -ATPase inhibition inhibited the PPi dependent H + -transport. Because H + -PPase was reported to transport H + and K + into the vacuole (Dav…
How to Deal with Uninvited Guests in Wine: Copper and Copper-containing Oxidases
2020
Copper is one of the most frequently occurring heavy metals in must and wine. It is introduced by pesticides, brass fittings, and as copper sulphate for treatment of reductive off-flavors. At higher concentrations, copper has harmful effects on the wine. It contributes to the oxidation of wine ingredients, browning reactions, cloudiness, inhibition of microorganisms, and wine fermentation. Last but not least, there is also a danger to the consumer. At present, some physicochemical methods exist to reduce the copper content in must and wine, but they all have their shortcomings. A possible solution is the biosorption of metals by yeasts or lactobacilli. Copper can also reach must and wine in…
Spatial distribution ofVespa velutinaindividuals hunting at domestic honeybee hives: heterogeneity at a local scale
2014
Since its recent introduction into Europe, the yellow-legged hornet, Vespa velutina, has become a major predator of the domestic honeybee, Apis mellifera, but little is known about its hunting behavior. We studied V. velutina hunting behavior by a capture-mark-recapture procedure in an experimental apiary. A total of 360 hornets were captured and tagged, and we determined: (i) the number of hornets visiting the apiary and the changes in time, (ii) the average number of individual visits per half-day and the time elapsed between consecutive recaptures, and (iii) the individual and global distribution of the hornets in the apiary. More than 50% of the marked hornets were recaptured at least o…
Behavioral syndrome in a native and an invasive hymenoptera species
2014
Recent studies have focused on the role of behavior in biological invasions. Individuals may differ consistently in time for several behavioral traits (personality) which covary(behavioralsyndrome)resultingindifferentbehavioraltypes,someofthemfavoring invasion. Social hymenopterans have a strong potential to be invaders and their success depends primarily on the foundresses' ability to found viable colonies. They are expected to be active, explorative and bold for optimally establishing their nest. In Europe, 2 hornet species coexist: the native Vespa crabro and the invasive Vespa velutina. These 2 species may compete for nesting sites and we suggest that the initial success of V. velutina …
Real-time reverse transcription polymerase chain reaction development for rapid detection of Tomato brown rugose fruit virus and comparison with othe…
2019
Background Tomato brown rugose fruit virus (ToBRFV) is a highly infectious tobamovirus that causes severe disease in tomato (Solanum lycopersicum L.) crops. In Italy, the first ToBRFV outbreak occurred in 2018 in several provinces of the Sicily region. ToBRFV outbreak represents a serious threat for tomato crops in Italy and the Mediterranean Basin. Methods Molecular and biological characterisation of the Sicilian ToBRFV ToB-SIC01/19 isolate was performed, and a sensitive and specific Real-time RT-PCR TaqMan minor groove binder probe method was developed to detect ToBRFV in infected plants and seeds. Moreover, four different sample preparation procedures (immunocapture, total RNA extractio…
The antioxidant power of horseradish, Armoracia rusticana, underlies antimicrobial and antiradical effects, exerted in vitro
2018
Armoracia rusticana (AR) was tested for antimicrobial and antioxidants power. The compound demonstrated to inhibit fish pathogens such as Vibrio anguillarum, V. harvey, V. alginolyticus, Aeromonas hydrophila, A. salmonicida, Photobacterium damselae subspecie piscicida, Tenacibaculum marinum and Pseudomonas anguilliseptica,. The total phenolic content and the reducing power resulted higher in the water extract of AR, respect to the hydroalcoolic. In vitro test demonstrated that AR significantly protect cells against death, induced by oxidative stress.
Variation and covariation in infectivity, virulence and immunodepression in the host-parasite association Gammarus pulex-Pomphorhynchus laevis.
2009
Parasites often manipulate host immunity for their own benefit, either by exacerbating or suppressing the immune response and this may directly affect the expression of parasite virulence. However, genetic variation in immunodepression, which is a prerequisite to its evolution, and the relationship between immunodepression and virulence, have rarely been studied. Here, we investigated the variation among sibships of the acanthocephalan parasite, Pomphorhynchus laevis , in infecting and in immunodepressing its amphipod host, Gammarus pulex . We also assessed the covariation between infectivity, parasite-induced immune depression and host mortality (parasite virulence). We found that infecti…
Effect of acyl-CoA oxidase activity on the accumulation of gamma-decalactone by the yeast Yarrowia lipolytica: a factorial approach.
2007
International audience; beta-Oxidation is a cyclic pathway involved in the degradation of lipids. In yeast, it occurs in peroxisomes and the first step is catalyzed by an acyl-CoA oxidase (Aoxp). The yeast Yarrowia lipolytica possesses several genes (POX) coding for Aoxps. This study is based on the factorial analysis of results obtained with the many POX derivative strains that have been constructed previously. The effect of interactions between Aoxps on the acyl-CoA oxidase (Aox) activity was important even at the second order. We then investigated the effect of Aox activity on growth and lactone production. Aox activity was correlated with acidification of the medium by cells and with ce…
An air-lift biofilm reactor for the production of γ-decalactones by Yarrowia lipolytica
2014
Decalactones are interesting flavouring compounds that can be produced from ricinoleic acid. In this study, the production of lactones in biofilms using Yarrowia lipolytica is investigated. The hydrophobia of cells increased for increased aeration rates resulting in higher adhesion when the reactor wall was hydrophobic (plastic). To increase adhesion, sheets of methyl-polymethacrylate (PMMA) were added in the reactor and the production of lactones increased with the surface of plastic added, reaching 850 mg/L of 3-hydroxy-γ-decalactone for 60 cm2. In an Airlift bioreactor made of PMMA, biofilms were present at the top of the reactor for increased aeration. In the meantime, a metabolic shift…