Summary Na+, K+ exchanges were studied in isolated hepatocytes of the rainbow trout, Salmo gairdneri. Ouabain at 10–4M produced maximal inhibition (95%) of K+ uptake and enhanced intracellular Na+ accumulation, showing that active fluxes account for a very large proportion of Na+ and K+ exchanges. Inhibition of the Na–K pump by ouabain was significant at low concentrations (10–8M). When external K+ concentration was reduced from 7 mM to 0.5 mM, half maximum inhibition (IC50) of K+ uptake was obtained at a 22-fold lower concentration of ouabain confirming that ouabain and potassium compete at the same pump site. Time-course analysis of [3H]ouabain binding indicated a two-component kinetics: one component saturable and dependent on K+ concentration in the medium, the other linear and independent of external K+. The ouabain binding site number, determined by Scatchard plots, remained constant (ca. 2.5·105 per cell) and independent of the external K+ concentration (7, 0.5 or 0 mM), while the dissociation constant (KD) decreased from 4.2 M to 7.3 nM when K+ was removed from the Hank's medium. These ouabain binding sites are characterized by an exceptionally low turnover rate (400 min–1), as estimated from ouabain-sensitive K+ flux, in comparison to those described in other cell types of higher vertebrates. At each external K+ concentration studied, the inhibition of K+ uptake and ouabain binding measured as a function of ouabain concentration indicated a strict correlation between the degree of K pump inhibition and the amount of bound glycoside. 相似文献
Polysaccharides extracted from seaweeds can function as plant biostimulants. The aim of this study was to assess the effects of Polysaccharide Enriched Extracts (PEEs) obtained from 17 Moroccan seaweeds, on tomato seed germination and plant growth. Three concentrations (0.02, 0.05 and 0.1 mg mL−1) of PEEs were applied to tomato seeds to evaluate their effect on 3 germination parameters: germination percentage (GP), germination speed (GS) and mean germination time (MGT). Metabolomic analysis by GC–MS was subsequently performed on seedlings. In the second experiment, four PEEs concentrations (0.02, 0.05, 0.1 and 0.2 mg mL−1) were used as foliar spray or as soil application to tomato plants. Their growth parameters (number of leaves, shoot length, fresh and dry weight of stem and roots) and biochemical parameters (chlorophyll a and b) were measured. Results indicated a significant increase of GP and GS associated with a significant reduction of MGT of tomato seeds treated with 0.02 mg mL−1 of PEEs obtained from Gigartina sp., Gigartina pistillata, Chondracanthus acicularis, Gelidium crinale, Schizymenia dubyi, Cystoseira. foeniculacea and Fucus spiralis. Similar results were also obtained by application of higher PEEs concentration (0.1 mg mL−1) extracted from Ulva rigida, Codium tomentosum, Codium decorticatum and Bifurcaria bifurcata. Metabolomic analysis on seedlings detected the presence of some metabolites which could possibly be involved in seed germination enhancement or inhibition. The results of the second experiment showed that the same PEEs cited above at the same concentrations enhanced plant dry weight and chlorophyll a content except Gigartina sp., C. foeniculacea and C. decorticatum. Furthermore, soil application of PEEs was more effective in improving plant growth parameters than foliar application. The study shows the potential of PEEs from Moroccan seaweed to be used as biostimulants for a sustainable agriculture.
This work aimed to investigate, for the first time, the chemical composition, antioxidant, antiparasitic, cytotoxicity, and antimicrobial activities of the aromatic plant Limonium oleifolium Mill. essential oil (EO) and organic extracts. L. oleifolium aerial parts essential oil was analyzed by GC-FID and GC-MS, and 46 constituents representing 98.25±1.12 % of the oil were identified. γ-Muurolene (10.81±0.07 %), cis-caryophyllene (7.71±0.06 %), o-cymene (7.07±0.01 %) and α-copaene (5.02±0.05 %) were the essential oil main compounds. The antioxidant activity of L. oleifolium EO and organic extracts (MeOH, CHCl3, AcOEt, BuOH) was explored using 2,2-diphenyl-1-picrylhydrazyl (DPPH), ABTS, β-carotene/linoleic acid, cupric reducing antioxidant capacity (CUPRAC), and ferric reducing power assays. The results showed that L. oleifolium EO exhibit antioxidant capacity (IC50=17.40±1.32 μg/mL for DPPH assay, IC50=29.82±1.08 μg/mL for β-carotene assay, IC50=25.23±1.01 μg/mL for ABTS assay, IC50=9.11±0.08 μg/mL for CUPRAC assay and IC50=19.41±2.06 mg/mL for reducing power assay). Additionally, the EO showed significant activity against trophozoite form of Acanthamoeba castellanii (IC50=7.48±0.41 μg/mL) and promastigote form of Leishmania amazonensis (IC50=19.36±1.06 μg/mL) and low cytotoxicity on murine macrophages (LC50 90.23±1.09 μg/mL), as well as good antimicrobial activity against Staphylococcus aureus, Escherichia coli, Klebsiella oxytoca, and Pseudomonas aeruginosa. These results suggest that L. oleifolium essential oil is a valuable source of bioactive compounds presenting antioxidant, antiparasitic, and antimicrobial activities. Furthermore, it is considered nontoxic. 相似文献
Mutations in the CLDN14 gene, encoding the tight junction claudin 14 protein has been reported to date in an autosomal recessive form of isolated hearing loss DFNB29. In order to identify the contribution of CLDN14 to inherited deafness in Moroccan population, we performed a genetic analysis of this gene in 80 Moroccan familial cases. Our results show the presence of 7 mutations: 6 being conservative and one leading to a missense mutation (C11T) which was found at heterozygous and homozygous states, with a general frequency of 6.87%. The pathogenicity of the resulting T4M substitution is under discussion. 相似文献
Winged morphs of aphids were investigated from 2002 to 2004 in 4 Tunisian regions of potato seeds production in order to know the aphid diversity and the potential vectors of Potato Virus Y. This is a very important contribution to the knowledge of aphid fauna in Maghreb. A total of 50,030 aphids were caught using yellow water traps and one suction trap. 130 taxa were identified including 103 species. Ten species are well represented in all regions prospected and typical species were also observed in every region. Some differences in species diversity appeared between regions which are discussed considering weather condition and vegetation. 相似文献
Three hundred and fifty‐nine isolates of actinobacteria collected from different Moroccan soils were evaluated for their in vitro antimicrobial activity against the oomycete pathogen Aphanomyces euteiches, the causal agent of damping‐off of pea and other legumes. Eighty‐seven isolates (24%) had an inhibitory in vitro effect against A. euteiches. Fourteen bioactive isolates with the greatest inhibitory effect against A. euteiches and no inhibitory effect on plant beneficial rhizobia were tested for their ability to protect pea seeds and seedlings against the damping‐off disease using culture supernatants or spore suspensions as treatments. The two most protective isolates, OB21 and BA15, significantly reduced, compared to untreated control plants, damping‐off by 33% and 47%, respectively. The two bioactive isolates were classified as species of the genus Streptomyces based on 16S rDNA analysis and morphological and chemical characteristics. 相似文献