Search results for "ALK"
showing 10 items of 4314 documents
Effects of mowing on fungal endophytes and arbuscular mycorrhizal fungi in subalpine grasslands
2013
International audience; In French subalpine grasslands, cessation of mowing promotes dominance of Festuca paniculata, which alters plant diversity and ecosystem functioning. One of the mechanisms underpinning such effects may be linked to simultaneous changes in the abundance of fungal symbionts such as endophytes and arbuscular mycorrhizal fungi. In field conditions, mowing reduced the abundance of the endophyte Neotyphodium sp. in leaves of F. paniculata by a factor of 6, and increased mycorrhizal densities by a factor of 15 in the soil. In greenhouse experiments, the mycorrhizal colonization of Trifolium pratense and Allium porrum increased 3- fold and 3.8- fold respectively in mown vs u…
Cross-Talk between ROS and Calcium in Regulation of Nuclear Activities
2010
International audience; Calcium and Reactive Oxygen Species (ROS) are acknowledged as crucial second messengers involved in the response to various biotic and abiotic stresses. However, it is still not clear how these two compounds can play a role in different signaling pathways leading the plant to a variety of processes such as root development or defense against pathogens. Recently, it has been shown that the concept of calcium and ROS signatures, initially discovered in the cytoplasm, can also be extended to the nucleus of plant cells. In addition, it has been clearly proved that both ROS and calcium signals are intimately interconnected. How this cross-talk can finally modulate the tra…
Volatile components of ripe fruits of Morinda citrifolia and their effects on Drosophila
1996
Abstract The only larval resource of the specialist species, Drosophila sechellia , is ripe fruits of Morinda citrifolia . The chemical composition of this fruit, which is very toxic to most Drosophila species, was investigated and 51 compounds were abundant enough to be identified by GC-MS. The ripe fruit is characterized by a large amount of carboxylic acids, especially octanoic and hexanoic acids. The biological effects of the ripe fruit and its main acids were investigated with behavioural studies. Octanoic acid is responsible for the general toxicity of the fruit to most Drosophila species; D. sechellia is the only species which is resistant to this acid. Hexanoic acid has a unique eff…
Characterization of Purified Green Bell Pepper Hydroperoxide Lyase Expressed by Yarrowia Lipolytica: Radicals Detection during Catalysis
2007
International audience; The optimization of the expression of recombinant 6-His-tagged HPO lyase in Yarrowia lipolytica is described: 1800U/L of culture was detected at 24h of culture on a medium containing olive oil as the sole carbon source. The enzyme was purified by IMAC and showed an optimal pH at 5.5, an optimal temperature at 20^\circC and a Km value of 9μM with 13-HPOD substrate. The participation of radicals during the catalysis of purified bell pepper fruit hydroperoxide lyase has been observed by electron paramagnetic resonance spectroscopy and the yet unidentified radical species might be an alkyl or alkoxyl radical linked to the enzyme.
Changes of bioactive compounds in barley industry by‐products during submerged and solid state fermentation with antimicrobial Pediococcus acidilacti…
2019
Abstract In this study, changes of bioactive compounds (crude protein (CP), crude fat (CF), dietary fiber (DF), fatty acids (FAs), free amino acids (FAAs), phenolic compounds (PCs), biogenic amines (BAs), lignans, and alkylresorcinols) in barley industry by‐products (BB) during submerged and solid state fermentation (SSF) with Pediococcus acidilactici were analyzed. It was established that both fermentation conditions reduce the CP and CF content in BB (by 25.8% and 35.9%, respectively) and increase DF content (on average by 25.0%). Fermentation increases the oleic, arachidic, eicosadienoic, behenic, and lignoceric FA in BB samples. The highest total BA content was found in untreated sample…
Influence of warming temperatures on coregonine embryogenesis within and among species
2021
The greatest response of lakes to climate change has been the increase in water temperatures on a global scale. The responses of many lake fishes to warming water temperatures are projected to be inadequate to counter the speed and magnitude of climate change, leaving some species vulnerable to decline and extinction. We experimentally evaluated the responses of embryos from a group of cold, stenothermic fishes (Salmonidae Coregoninae) - within conspecifics across lake systems, between congeners within the same lake system, and among congeners across lake systems - to a thermal gradient using an incubation method that enabled global comparisons. Study groups included cisco (Coregonus artedi…
Genetic variation in the behavioural mechanisms involved in the response of the egg parasitoid Trissolcus brochymenae to contact chemical cues left b…
2021
International audience; 1. The ability of parasitoid females to perceive chemical traces left by theirhosts is of utmost importance in the host location process. The behaviours involved insuch ability have thus most likely been promoted by natural selection in the course ofthe evolutionary time. For this to happen, however, there must be signicant geneticvariation in natural populations on which natural selection could act.2. Using the isofemale line method and motion analysis, we detected signicantintra-population genetic variation for several walking behaviour traits of the eggparasitoid Trissolcus brochymenae (Hymenoptera: Scelionidae) females responding tochemical traces left by its h…
Managing conservation values of protected sites: How to maintain deciduous trees in white-backed woodpecker territories
2020
Successional and other temporal habitat changes may also affect conservation areas and reduce their conservation value. Active management to promote vulnerable habitat features may be an effective, but controversial, solution. Old deciduous trees and deciduous dead wood in boreal forest reserves are examples of habitat features that may be lost during succession, yet several threatened species, including the white-backed woodpecker (Dendrocopos leucotos), are dependent on them. Encroaching spruce have been removed from white-backed woodpecker territories to promote the regeneration of deciduous trees and to preserve habitat quality, although the efficiency of this treatment is unclear. In t…
Corrosion in alkanolamine used for acid gas removal: From natural gas processing to CO2 capture
2010
The aim of this paper is to review some of the parameters influencing the corrosivity of alkanolamine solvents used for natural gas purification or for CO2 capture. In the light of literature data and of new experimental results, the influences of temperature and of acid gas loading are discussed. These two parameters appear to have a strong impact on corrosion rates of carbon steel, with extrapolated corrosion rates of several tens of mm/year for the highest temperature and acid gas loading condition.
Embryonic Growth of Face-Center-Cubic Silver Nanoclusters Shaped in Nearly Perfect Half-Cubes and Cubes.
2016
Demonstrated herein are the preparation and crystallographic characterization of the family of fcc silver nanoclusters from Nichol’s cube to Rubik’s cube and beyond via ligand-control (thiolates and phosphines in this case). The basic building block is our previously reported fcc cluster [Ag14(SPhF2)12(PPh3)8] (1). The metal frameworks of [Ag38(SPhF2)26(PR′3)8] (22) and [Ag63(SPhF2)36(PR′3)8]+ (23), where HSPhF2 = 3,4-difluorothiophenol and R′ = alkyl/aryl, are composed of 2 × 2 = 4 and 2 × 2 × 2 = 8 metal cubes of 1, respectively. All serial clusters share similar surface structural features. The thiolate ligands cap the six faces and the 12 edges of the cube (or half cube) while the phosp…