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Poly(amidoamine) (PAMAM) dendrimers hold great promises for biomedicine. This study sought to examine the toxicity of generation 4 (G4) cationic PAMAM dendrimer to the green microalga, Chlamydomonas reinhardtii, using physiological and molecular biomarkers. Results revealed that the G4 dendrimer at 15 and 25 nM stimulated the photosynthetic process and the production of reactive oxygen species (ROS) in algae. However, the over-production of ROS did not induce the expression of antioxidant enzyme genes, catalase and glutathione peroxidase. In addition, genes encoding light-harvesting proteins ( lhca and lhcb), a ferredoxin ( fdx) and an oxygen-evolving enhancer protein ( psb) involved in photosynthesis were repressed after treatment. Nevertheless, the expression of the lhcbm9 gene, encoding a major light harvesting polypeptide, was increased. These results suggest that the strong modulation of photosynthesis induced by the dendrimer could lead to elevated ROS levels in microalgae. [ABSTRACT FROM AUTHOR]

Pesticides are being detected in water bodies on an increasingly frequent basis. The present study focused on toxicity and phytoremediation potential of aquatic plants to remove phytosanitary products from contaminated water. We investigated the capacity of Lemna minor (L. minor) to eliminate two herbicides isoproturon and glyphosate from their medium. Since phytoremediation relies on healthy plants, pesticide toxicity was evaluated by exposing plants to 5 concentrations (0–20 μg L−1 for isoproturon and 0–120 μg L−1 for glyphosate) in culture media for 4 d using growth rate and chlorophyll a fluorescence as endpoints. At exposure concentrations of 10 μg.L−1 for isoproturon and 80 μg.L−1 for glyphosate, effects on growth rate and chlorophyll fluorescence were minor (< 25%), so that this initial concentration was selected to study herbicide removal. After a 4-d incubation, removal yields were 25% and 8% for isoproturon and glyphosate, respectively. [ABSTRACT FROM AUTHOR]

This study sought to develop a convenient and sensitive method to measure carbamazepine in biological tissues. Levels of carbamazepine were quantified with a competitive enzymatic immunoassay using a peroxidase label with fluorescence detection. The assay is sensitive with a detection limit of 0.7 pg per well. The 96-well format of the assay permits rapid analysis of more than 100 samples per day. Testing with freshwater mussel (Elliptio cornplanata) soft tissue homogenate extracts revealed no significant matrix interferences at dilutions of at least 10-fold with good recovery of the compound. This cost-effective multi-well method allows studying the bioavailability and accumulation of this persistent xenobiotic in aquatic organisms. [ABSTRACT FROM AUTHOR]

In etiolated leaves, saturating flash of 200 ms induces phototransformation of protochlorophyllide (Pchlide) F655 into chlorophyllide (Chlide), then into Chi through reactions which do not need light sensibilisation. The synthesis of Chi is known to be slowed down in etiolated leaves exposed to desiccation stress. In order to analyse the intensity and time-course of Chlide transformation into Chi, we used the fluorescence emission of etiolated leaves previously exposed to a 200 ms saturating flash. We used lowtemperature fluorescence spectroscopy to reveal the inhibition site of Chi synthesis in etiolated barley leaves exposed to water stress. Shibata shift appears as the main target point of the water deficit. It was found that water deficit inhibits partially active Pchlide F655 regeneration. Also, esterification of Chlide into Chi is impaired. It appears that these inhibitory effects alter the appearance of PSII active reaction centres. [ABSTRACT FROM AUTHOR]

A sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed for the determination of carbamazepine in microgram quantities of crustacean Thamnocephalus platyurus and the algae Pseudokirchneriella subcapitata at the ng L(-1) level. This fully validated method applied to a bioaccumulation study was found suitable for the detection of carbamazepine in small aquatic tissues.