Search results for "Sterol"

Elicitins, proteinaceous elicitors of plant defense, are a new class of sterol carrier proteins

1998

Some phytopathogenic fungi within Phytophthora species are unable to synthesize sterols and therefore must pick them up from the membranes of their host-plant, using an unknown mechanism. These pseudo-fungi secrete elicitins which are small hydrophilic cystein-rich proteins. The results show that elicitins studied interact with dehydroergosterol in the same way, but with some time-dependent differences. Elicitins have one binding site with a similar strong affinity for dehydroergosterol. Using a non-steroid hydrophobic fluorescent probe, we showed that phytosterols are able to similarly bind to elicitins. Moreover, elicitins catalyze sterol transfer between phospholipidic artificial membran…

From elicitins to lipid-transfer proteins: a new insight in cell signalling involved in plant defence mechanisms.

2002

Elicitins and lipid-transfer proteins are small cysteine-rich lipid-binding proteins secreted by oomycetes and plant cells, respectively, that share some structural and functional properties. In spite of intensive work on their structure and diversity at the protein and genetic levels, the precise biological roles of lipid-transfer proteins remains unclear, although the most recent data suggest a role in somatic embryogenesis, in the formation of protective surface layers and in defence against pathogens. By contrast, elicitins are known elicitors of plant defence, and recent work demonstrating that elicitins and lipid-transfer proteins share the same biological receptors gives a new perspe…

Ergosterol elicits oxidative burst in tobacco cells via phospholipase A2 and protein kinase C signal pathway

2004

Ergosterol, a typical fungal sterol, induced in tobacco (Nicotiana tabacum L. cv. Xanthi) suspension cells the synthesis of reactive oxygen species and alkalization of the external medium that are dependent on the mobilization of calcium from internal stores. We used specific inhibitors to elucidate the signal pathway triggered by ergosterol compared with cryptogein, a proteinaceous elicitor of Phytophthora cryptogea. HerbimycinA and genistein, inhibitors of tyrosine protein kinases, had no effect on the oxidative burst and pH changes induced by bothelicitors.Similarly,H-89,aninhibitorofproteinkinaseA,hadnoeffectontheinductionofthesedefensereactions.However,theresponse to both elicitors was…

Cytosolic calcium rises and related events in ergosterol-treated Nicotiana cells

2011

International audience; The typical fungal membrane component ergosterol was previously shown to trigger defence responses and protect plants against pathogens. Most of the elicitors mobilize the second messenger calcium, to trigger plant defences. We checked the involvement of calcium in response to ergosterol using Nicotiana plumbaginifolia and Nicotiana tabacum cv Xanthi cells expressing apoaequorin in the cytosol. First, it was verified if ergosterol was efficient in these cells inducing modifications of proton fluxes and increased expression of defence-related genes. Then, it was shown that ergosterol induced a rapid and transient biphasic increase of free [Ca2þ]cyt which intensity dep…

Lipid composition of the vacuolar membrane of Acer pseudoplatanus cultured cells

1993

Tonoplast was prepared by osmotic lysis of a pure vacuolar fraction isolated from protoplasts derived from Acer pseudoplatanus cultured cells. After their extraction, neutral and polar lipids were separated by a thin layer chromatography. Phospholipids, glycolipids and neutral lipids represented 44.5%, 39.1% and 16.4% of total lipids, respectively. Sterols (glycosylated plus non-glycosylated forms) constituted 30.8% of total lipids; 75% of sterols were glycosylated. The most prominent lipids were phosphatidylethanolamine (20.8%), phosphatidylcholine (13.5%), ceramide monohexoside (12.8%), steryl glycoside (12.2%) and acylated steryl glycoside (10.9%). Glucose was the only sugar released by …

Trophic upgrading via the microbial food web may link terrestrial dissolved organic matter to Daphnia

2017

Direct consumption of allochthonous resources generally yields poor growth and reproduction in zooplankton, but it is still unclear how trophic upgrading of terrestrial dissolved organic matter (tDOM) via the microbial food web may support zooplankton. We compared survival, somatic growth and reproduction of Daphnia magna fed with the heterotrophic flagellate Paraphysomonas vestita and three algal diets. Paraphysomonas was fed lake bacteria that used tDOM as a substrate to simulate an allochthonous diet that zooplankton encounter in lakes. The highest survival, growth and reproduction was achieved with a diet of Cryptomonas, while Daphnia performance was the worst when fed Microcystis. Para…

Comparison of chemical composition and biological activities of Algerian seed oils of Pistacia lentiscus L., Opuntia ficus indica (L.) mill. and Arga…

2020

Abstract Many parameters can influence the chemical profiles and the biological activities of seed oils. It was therefore of interest to study Algerian seed oils, whose caharacteristics are not well known. So, the physicochemical properties and nutrient profiles (fatty acids, phytosterols, polyphenols) of seed oils from Pistacia lentiscus L. (PL), Opuntia ficus-indica (L.) mill. (OFI), and Argania spinosa L. Skeels (AS) were determined. The antioxidant and antimicrobial activities of the oils were also characterized. The physicochemical parameters of the oils are closely related to the standard values. PL oil is distinguished by its high content of pigments. AS and OFI oils were dominated b…

In vitro colonic fermentation of a plant sterol-enriched beverage in a dynamic-colonic gastrointestinal digester

2021

Abstract The impact of a plant sterol-enriched beverage on the sterol metabolism, organic acid production and microbiota composition was evaluated by means of a dynamic gastrointestinal and colonic fermentation model. After one week of fermentation, an absence of sterol metabolites was reported, in accordance with the lack of microbiota related to their metabolism. Although total organic acid content was lower in the ascending colon (AC) compared to the transversal (TC) and descending colon (DC) (28–57 mmol/L vs. 55-87 and 44–64 mmol/L, respectively), its increments, with respect to the initial value, were higher (2-fold vs. 1.6- and 1.5-fold). Increments of acetate, butyrate and propionate…

Terrestrial organic matter quantity or decomposition state does not compensate for its poor nutritional quality for Daphnia

2019

Lake restoration influences nutritional quality of algae and consequently Daphnia biomass

2020

AbstractFood quality is one of the key factors influencing zooplankton population dynamics. Eutrophication drives phytoplankton communities toward the dominance of cyanobacteria, which means a decrease in the availability of sterols and long-chain polyunsaturated fatty acids (EPA and DHA). The effects of different restoration measures on the nutritional quality of the phytoplankton community and subsequent impacts on zooplankton biomass have rarely been considered. We analyzed the nutritional quality of phytoplankton in the eutrophic Lake Vesijärvi in southern Finland over a 37-year period, and studied the impacts of two restoration measures, biomanipulation and hypolimnetic aeration, on th…