Search results for "Tassi"

Modulation of voltage-gated Na+ and K+ channels by pumiliotoxin 251D: A “joint venture” alkaloid from arthropods and amphibians

2008

Abstract Certain amphibians provide themselves with a chemical defense by accumulating lipophilic alkaloids into skin glands from dietary arthropods. Examples of such alkaloids are pumiliotoxins (PTXs). In general, PTXs are known as positive modulators of voltage-gated sodium channels (VGSCs). Unlike other PTXs, PTX 251D does not share this characteristic. However, mice and insect studies showed that PTX 251D is highly toxic and to date the basis of its toxicity remains unknown. In this work, we searched for the possible target of PTX 251D . The toxin was therefore made synthetically and tested on four VGSCs (mammalian rNa v 1.2/β 1 , rNa v 1.4/β 1 , hNa v 1.5/β 1 and insect Para/tipE ) and…

Astrocytic potassium and calcium channels as integrators of the inflammatory and ischemic CNS microenvironment.

2021

Abstract Astrocytes are key regulators of their surroundings by receiving and integrating stimuli from their local microenvironment, thereby regulating glial and neuronal homeostasis. Cumulating evidence supports a plethora of heterogenic astrocyte subpopulations that differ morphologically and in their expression patterns of receptors, transporters and ion channels, as well as in their functional specialisation. Astrocytic heterogeneity is especially relevant under pathological conditions. In experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis (MS), morphologically distinct astrocytic subtypes were identified and could be linked to transcriptome changes dur…

Natural and artificial radioactivity levels in Livingston Island (Antarctic regions).

1994

Radioactive contamination of the sea and land is due, on the one hand, to fallout from atmospheric atomic explosions since 1945, and, on the other, to emissions produced by nuclear and radioactive facilities. Given its geographic position far distant from the aforementioned main sources of radioactive contamination, Antarctica should have the lowest levels that can be measured on the Earth of artificial radionuclides in the various receptor media which are characteristic of the trophic chain. In the case of Antarctica, these are melt-water, sea-water, mosses, algae, and lichens. With the aim of contributing basic information on the radiation levels present in the Antarctic ecosystem, we hav…

Author response: Oligodendrocytes control potassium accumulation in white matter and seizure susceptibility

2018

Modeling hexanal production in oxido-reducing conditions by the yeast Yarrowia lipolytica

2009

International audience; Hexanal produced by cells of a recombinant Yarrowia lipolytica yeast expressing the hydroperoxide lyase (HPL) from green bell pepper fruit was studied under oxido-reducing conditions using the reducing dithiotreitol and oxidizing potassium ferricyanide compounds. The combined effect of pH, linoleic acid 13-hydroperoxides concentration, temperature and oxido-reducing molecules on the hexanal production was studied. Significant positive effects for the hexanal production were found using high concentrations of hydroperoxides (100 mM, 30 g/L). Adding reducing molecules enhanced significantly hexanal production while the oxidizing molecules had an inhibitory effect. Comb…

Cyanide inhibits respiration yet stimulates aerobic growth of Zymomonas mobilis

2000

Potassium cyanide at submillimolar concentrations (20-500 microM) inhibited the high respiration rates of aerobic cultures of Zymomonas mobilis but, remarkably, stimulated culture growth. In batch culture, after an extended lag phase, exponential growth persisted longer, resulting in higher biomass densities. In aerobic chemostat cultures, elevated biomass concentration was observed in the presence of cyanide. This growth stimulation effect is attributed to decreased production of the inhibitory metabolite acetaldehyde at lowered respiration rates, when more reducing equivalents are channelled to alcohol dehydrogenase. Growth in the presence of cyanide did not alter the membrane cytochrome …

Osmotic stress affects the stability of freeze-dried Lactobacillus buchneri R1102 as a result of intracellular betaine accumulation and membrane char…

2014

Aims To help cells to better resist the stressful conditions associated with the freeze-drying process during starter production, we investigated the effect of various osmotic conditions on growth, survival and acidification activity of Lactobacillus buchneri R1102, after freeze-drying and during storage for 3 months at 25°C. Methods and Results High survival rates during freeze-drying, but not during storage, were obtained when 0·1 mol l−1 KCl was added at the beginning of fermentation, without any change in membrane properties and betaine accumulation. This condition made it possible to maintain a high acidification rate throughout the process. In contrast, the addition of 0·6 mol l−1 KCl…

Microglia and α-synuclein implication in Parkinson's disease

2011

Age-related neurodegenerative disorders like Parkinson’s disease take an enormous toll on individuals and on society. Despite extensive efforts, Parkinson’s disease remains incurable and only very limited treatments exist. Indeed, Parkinson’s pathogenesis is still not clear and research on its molecular mechanisms is ongoing. In this study, we focused our interest on two abnormal events occurring in Parkinson’s patients, namely α-synuclein aggregation and microglial activation. We first investigated α-synuclein and its abnormal polymerisation. For this purpose, we developed novel methods, which allowed the in vitro production of different types of α-synuclein oligomers. Using highly sensiti…

Recherche de systèmes de transport de potassium impliqués dans le transfert de K+ de la mycorhize arbusculaire au riz lors d'interactions symbiotiques

2022

Les champignons mycorhiziens à arbuscules (CMA) développent des connexions interdépendantes avec les racines d'environ 90% des espèces végétales. Ces interactions augmentent la disponibilité ainsi que la translocation des nutriments (en particulier N et P), et améliorent ainsi la nutrition et la croissance des plantes. De plus, la résistance à une variété de stress, parmi lesquels le stress salin, s'est avérée améliorée par les interactions CMA-plante, par exemple chez le riz. Des recherches intenses pour expliquer les mécanismes moléculaires des interactions bénéfiques CMA-plante ont conduit à l'identification de transporteurs de phosphate et d'ammonium impliqués dans les échanges de nutri…

Effect of Tire-Char Ash on the Extent of Synergy during CO2 Cogasification with Hydrochar from Potassium-Rich Coconut Fiber

2020

The influence of inherent tire char ash during co-gasification with coconut hydrochar prepared at different intensities was investigated by thermogravimetric analysis to ascertain the extent to which synergistic interaction, reactivity, and activation energy reduction were altered. High-ash tire tread (TT) and low-ash sidewall (SW) both exhibited enhanced synergy, reactivity, and activation reduction upon co-gasification with hydrochars; however, the extent of promotion was more pronounced in SW-hydrochar blends. This difference was caused by the inhibiting nature of TT inherent ash, particularly the role of Si-containing compounds. Inhibition in TT-hydrochar blends was mainly due to the pr…