ABSTRACT
Grevillea exul var. exul, an endemic serpentinic Proteaceae of New Caledonia, was chosen to study the spatial distribution of Ni because this species supports strong content of metals, which can allow important absorptions thus detectable by microanalysis. Fine transversal sections of axenic G. exul var. exul plants grown during 15 days on nickel sulphate medium were examined by EDXS microanalysis. It showed that in Ni treated plants, Ni was concentrated mostly in the phloem compared to the xylem and the epidermis, either in roots or in the basal part of the stems and was mostly in the epidermis in the upper part of the stems and not detectable in the leaves. This metal took the place of P and K in the treated plants whereas the localization of these macroelements was quite uniform in control sections. We assume that a mechanism of phloem loading is implicated to restrict Ni accumulation in G. exul var. exul.
Subject(s)
Nickel/toxicity , Proteaceae/chemistry , Soil Pollutants/toxicity , Biodegradation, Environmental , Chlorine/analysis , Image Interpretation, Computer-Assisted , Microscopy, Electron , Nickel/analysis , Phloem/chemistry , Phosphorus/analysis , Plant Epidermis/chemistry , Plant Roots/chemistry , Plant Stems/chemistry , Potassium/analysis , Sodium/analysis , Soil Pollutants/analysis , Spectrometry, X-Ray Emission , Xylem/chemistryABSTRACT
Cyanobacteria including genus Oscillatoria are known to release toxins into waterbodies. To study the occurrence of toxic blooms in Lake Nantua, the Planktothrix rubescens species (Oscillatoria rubescens) was considered. At the same time, some physicochemical parameters were analysed to estimate their impact on toxin production. The investigations were conducted during summertime and the highest toxin concentration analysed by HPLC was detected in August (10.8 microg/l of lake water). The results of this work suggested that the toxin production increased when the light intensity, temperature, alkaline pH and phosphorus contents were at low levels. Moreover, the toxin production was positively related with NT/PT ratio. TLC analysis of the purified fractions revealed the occurrence of 4-7 polypeptide or protein bands. Two of them were shown to be toxic using Artemia bioassays and the most toxic one was identified as MCYST-RR.
Subject(s)
Bacterial Toxins/biosynthesis , Bacterial Toxins/chemistry , Cyanobacteria/physiology , Marine Toxins/biosynthesis , Marine Toxins/chemistry , Chromatography, High Pressure Liquid , Cyanobacteria Toxins , France , Fresh Water , Humans , Microcystins , Seasons , Water Microbiology , Water SupplyABSTRACT
The volatile fraction of Hypericum coris aerial parts, consisting mainly of alpha-curcumene was screened for activity against five microbial strains. The maximum activity was against Saccharomyces cerevisiae.
