Search results for "Algal"
showing 10 items of 94 documents
In vivo imaging of an elicitor-induced nitric oxide burst in tobacco
2000
A growing body of evidence suggests that nitric oxide (NO), an important signalling and defence molecule in mammals, plays a key role in activating disease resistance in plants, acting as signalling molecule and possibly as direct anti-microbial agent. Recently, a novel fluorophore (diaminofluorescein diacetate, DAF-2 DA) has been developed which allows bio-imaging of NO in vivo. Here we use the cell-permeable DAF-2 DA, in conjunction with confocal laser scanning microscopy, for real-time imaging of NO in living plant cells. Epidermal tobacco cells treated with cryptogein, a fungal elicitor from Phytophthora cryptogea, respond to the elicitor with a strong increase of intracellular NO. NO-i…
Cryptogein affects expression of alpha3, alpha6 and beta1 20S proteasome subunits encoding genes in tobacco.
2001
Twelve a and b 20S proteasome subunits cDNAs showing 70–82% identity with the corresponding genes in Arabidopsis or rice, and features of eukaryotic proteasome subunits were cloned in tobacco. Only b1-tcI 7, a3 and a6, 20S proteasome subunits encoding genes were up-regulated by cryptogein, a proteinaceous elicitor of plant defence reactions. These results led to the hypothesis that the activation of b1-tcI 7, a3 and a6 could induce a specific proteolysis involved in the hypersensitive response and systemic acquired resistance monitored by cryptogein. In eukaryotes, the 26S proteasome is the central multicatalytic proteinase complex comprising two subcomplexes: the 20S core particle that per…
Purification, crystallization and preliminary X-ray studies of sylvaticin, an elicitin-like protein from Pythium sylvaticum.
2003
Sylvaticin belongs to the elicitin family. These 10 kDa oomycetous proteins induce a hypersensitive response in plants, including necrosis and cell death, but subsequently leading to a non-specific systemic acquired resistance (SAR) against other pathogens. Sylvaticin has been crystallized using PEG 2000 MME as a precipitant agent in the presence of nickel chloride. The crystals belong to space group C2, with unit-cell parameters a = 99.29, b = 25.67, c = 67.45 A, beta = 99.66 degrees. Diffraction data were recorded to 2.1 A resolution at a synchrotron-radiation source.
Welfare status of cage farmed European sea bass (Dicentrarchus labrax): A comparison between submerged and surface cages
2011
Abstract Submersible sea-cages represent an alternative method to standard surface-based cages, and could help solve several production problems that exist in surface-based farming, such as heavy storms, algal and jellyfish blooms and attacks by predators. In this study, we investigated growth, haematological, biochemical and immunological parameters of European sea bass ( Dicentrarchus labrax ) farmed in surface and submersible cages, to compare the physiological status under different rearing conditions. In addition, we evaluated the use of erythrocyte HSP70 levels as a biomarker of fish welfare. The study was conducted in two submerged and two surface cages filled with D. labrax . No sig…
Sunscreen Products as Emerging Pollutants to Coastal Waters
2013
A growing awareness of the risks associated with skin exposure to ultraviolet (UV) radiation over the past decades has led to increased use of sunscreen cosmetic products leading the introduction of new chemical compounds in the marine environment. Although coastal tourism and recreation are the largest and most rapidly growing activities in the world, the evaluation of sunscreen as source of chemicals to the coastal marine system has not been addressed. Concentrations of chemical UV filters included in the formulation of sunscreens, such as benzophehone 3 (BZ-3), 4-methylbenzylidene camphor (4-MBC), TiO2 and ZnO, are detected in nearshore waters with variable concentrations along the day a…
A Comparative Ultrastructural Investigation of Some Nannochloris Species (Chlorococcales) with Particular Reference to the Systematic Position of Nan…
1989
Nanochlorum eucaryotum was described by Wilhelm et al. (1982) as a new algal species with an uncertain taxonomic position. Whereas some features were chlorococcacean, others suggested an isolated position in the sense of a “pre-eucaryote” (Wilhelm, 1983; Zahn, 1984; Geisert et al., 1987). Our comparative ultrastructural, physiological and biochemical examinations of coccoid microalgae (Menzel, 1988) gave no arguments for the separation of Nanochlorum eucaryotum from the genus Nannochloris. This paper is concerned with the ultrastructural composition of the cell wall and mode of reproduction in Nanochlorum eucaryotum as well as in three Nannochloris species. The systematic position of Nanoch…
A lipid transfer protein binds to a receptor involved in the control of plant defence responses
2001
AbstractLipid transfer proteins (LTPs) and elicitins are both able to load and transfer lipidic molecules and share some structural and functional properties. While elicitins are known as elicitors of plant defence mechanisms, the biological function of LTP is still an enigma. We show that a wheat LTP1 binds with high affinity sites. Binding and in vivo competition experiments point out that these binding sites are common to LTP1 and elicitins and confirm that they are the biological receptors of elicitins. A mathematical analysis suggests that these receptors could be represented by an allosteric model corresponding to an oligomeric structure with four identical subunits.
Mediation of Elicitin Activity on Tobacco Is Assumed by Elicitin-Sterol Complexes
2001
Elicitins secreted by phytopathogenic Phytophthora spp. are proteinaceous elicitors of plant defense mechanisms and were demonstrated to load, carry, and transfer sterols between membranes. The link between elicitor and sterol-loading properties was assessed with the use of site-directed mutagenesis of the 47 and 87 cryptogein tyrosine residues, postulated to be involved in sterol binding. Mutated cryptogeins were tested for their ability to load sterols, bind to plasma membrane putative receptors, and trigger biological responses. For each mutated elicitin, the chemical characterization of the corresponding complexes with stigmasterol (1:1 stoichiometry) demonstrated their full functionali…
The 1.45 A resolution structure of the cryptogein-cholesterol complex: a close-up view of a sterol carrier protein (SCP) active site.
2002
Cryptogein is a small 10 kDa elicitor produced by the phytoparasitic oomycete Phytophthora cryptogea. The protein also displays a sterol carrier activity. The native protein crystallizes in space group P4(1)22, with unit-cell parameters a = b = 46.51, c = 134.9 A (diffraction limit: 2.1 A). Its complex with cholesterol crystallizes in space group C222(1), with unit-cell parameters a = 30.96, b = 94.8, c = 65.3 A and a resolution enhanced to 1.45 A. The large inner non-specific hydrophobic cavity is able to accommodate a large variety of 3-beta-hydroxy sterols. Cryptogein probably acts as a sterol shuttle helping the pathogen to grow and complete its life cycle.
Questioning the role of salicylic acid and cytosolic acidification in mitogen-activated protein kinase activation induced by cryptogein in tobacco ce…
2001
Elicitors of plant defence reactions, oligogalacturonides and cryptogein, an elicitin produced by Phytophthora cryptogea, were previously shown to induce a rapid and transient activation of two mitogen-activated protein kinases (MAPKs) in cells of tobacco [ Nicotiana tabacum L. cv. Xanthi; A. Lebrun-Garcia et al. (1998) Plant J 15:773-781]. We verified that these two MAPKs correspond to the salicylic acid-induced protein kinase (SIPK) and the wound-induced protein kinase (WIPK). The involvement of salicylic acid (SA) in cryptogein-induced MAPK activation was investigated using transgenic NahG tobacco cells expressing the salicylate hydroxylase gene and thus unable to accumulate SA. The larg…