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The marine alga Isochrysis galbana was grown under the integrated influence of nitrogen starvation and sodium acetate, specifically to understand the associated remodelling of the fatty acid profiles. This is the first comparative proteomics study under four different set of conditions namely nutrient sufficient, with/without sodium acetate and N-deficient with/without sodium acetate. A total set of 546 unique peptides were detected. Due to the addition of sodium acetate, 56 proteins were down-regulated and 7 proteins showed up-regulation respectively in the nutrient complete and the nitrogen starvation media. Both cell growth and docosahexaenoic acid (DHA) accumulation in the nutrient replete cultures were favoured by the addition of reduced carbon source in the form of sodium acetate. The 14 days old sodium acetate supplemented nitrogen starved cells showed highest amounts of total fatty acids and an over accumulation of the oleic acid. Of the seven key genes of the lipid and fatty acid metabolic pathway that were studied, the IgTeCe, IgFad12, and IgFad4 showed over expressions under nitrogen starvation. The gene expressions of lipases and desaturases involved in the fatty acids metabolism were not found to be correlated with the changes observed in the fatty acid profiles under the experimental conditions. This suggested the presence of an alternative metabolic route and/or possibly the variants of fatty acid desaturase genes in I. galbana which was beyond the scope of this study. A translational or post-translational control can not either be ignored.

International audience; Classical methods, used for large scale treatments such as mechanical or chemical extractions, affect the integrity of extracted cytosolic protein by releasing proteases contained in vacuoles. Our previous experiments on flow processes electroextraction on yeasts proved that pulsed electric field technology allows preserving the integrity of released cytosolic proteins, by not affecting vacuole membranes. Furthermore, large cell culture volumes are easily treated by the flow technology. Based on this previous knowledge, we developed a new protocol in order to electro-extract total cytoplasmic proteins from microalgae (Nannochloropsis salina, Chlorella vulgaris and Haematococcus pluvialis). Given that induction of electropermeabilization is under the control of target cell size, as the mean diameter for N. salina is only 2.5 μm, we used repetitive 2 ms long pulses of alternating polarities with stronger field strengths than previously described for yeasts. The electric treatment was followed by a 24 h incubation period in a salty buffer. The amount of total protein release was observed by a classical Bradford assay. A more accurate evaluation of protein release was obtained by SDS-PAGE. Similar results were obtained with C. vulgaris and H. pluvialis under milder electrical conditions as expected from their larger size.

This study examined the effects of dietary alpha-linolenic acid [18:3(n-3)] deficiency on dopaminergic and serotoninergic neurotransmission systems in 60-d-old male rats. Rats were fed semipurified diets containing either peanut oil [the (n-3)-deficient group] or peanut plus rapeseed oil (control group). We measured the densities of the serotonin-2 (5-HT2) receptors and the dopamine-2 (D2) receptors by autoradiography and membrane-binding assays in relation to the fatty acid composition and levels of endogenous monoamines in three cerebral regions: the frontal cortex, the striatum and the cerebellum. Long-term feeding of the (n-3)deficient diet induced a significantly higher 5-HT2 receptor density in the frontal cortex compared with the control rats without any difference in the endogenous serotonin concentrations. The results also showed some modification of dopaminergic neurotransmission specifically in the frontal cortex in the rats deficient in alpha-linolenic acid, with a significantly lower density of D2 receptors and a significantly lower concentration of endogenous dopamine than in control animals. Moreover, there were lower levels of (n-3) fatty acids in all the regions studied in the deficient rats, balanced by greater levels of (n-6) fatty acids. These results suggest that chronic consumption of an alpha-linolenic acid-deficient diet could induce modifications of the neurotransmission pathways; this might induce the behavioral disturbances previously described in this fatty acid-deficient animal model.

We tested for an association between autism and genes coding for enzymes involved in monoaminergic metabolism and for a linked marker, c- Harvey-Ras-1 (HRAS 1), using restriction fragment length polymorphisms. We did not find evidence of an association between autism and genes coding for tyrosine hydroxylase, dopamine- β -hydroxylase (DBH), and tryptophan hydroxylase. However, we report a positive association between autism and the locus containing the gene for HRAS-1.

A simple method for the determination of N-acetyldopamine (NADA) (both free and conjugated) in children's urine by high-performance liquid chromatography with electrochemical detection has been developed. Conjugated NADA was measured as the free compound after enzymatic hydrolysis and purification on alumina. The total analysis time is 25 min. The results show a linearity of the whole assay from 0.005 to 20 mumol/l NADA; the sensitivity is 0.2 pmol per 20 microliters injected sample. Mean recoveries of 96.7 and 86.6% were obtained for free and total NADA, respectively. Modifications of the retention times (between 2 and 50 min) induced by changes in the eluent were determined. Conjugated NADA accounted for about 90% of the total excretion of NADA. These results suggest that this compound could play an important part in neuroblastoma; its concentration is thirteen times higher in children with neuroblastoma than in normal subjects.