Dye residues in aquaculture products: Targeted and metabolomics mass spectrometric approaches to track their abuse.

The aim of the study was to initiate an exhaustive strategy of control by implementing both targeted and non-targeted metabolomics approaches. A LC-MS/MS method including an oxidative step for most of dyes was developed and validated to target the analysis of 14 residues belonging to different families of dyes. The method was suitable for the quantitative confirmation of 13 dyes at low ppb levels. The metabolomics approach objective was to compare fingerprints between farmed fish treated with malachite green and farmed fish treated with victoria pure blue bo. Analytical information on modifications in the metabolome of muscle, liver and plasma was exploited by HRMS following by multivariate statistics and revealed some direct or endogenous metabolites among relevant mass features contributing to the constructed models. These two approaches, either appropriate biomarkers either enlarged targeted dyes are explored concomitantly to help improving the strategy for tracking new illegal practices in aquaculture.

Cytotoxicity and mycotoxin production of shellfish-derived Penicillium spp., a risk for shellfish consumers.

In order to assess the putative toxigenic risk associated with the presence of fungal strains in shellfish-farming areas, Penicillium strains were isolated from bivalve molluscs and from the surrounding environment, and the influence of the sample origin on the cytotoxicity of the extracts was evaluated. Extracts obtained from shellfish-derived Penicillia exhibited higher cytotoxicity than the others. Ten of these strains were grown on various media including a medium based on mussel extract (Mytilus edulis), mussel flesh-based medium (MES), to study the influence of the mussel flesh on the production of cytotoxic compounds. The MES host-derived medium was created substituting the yeast extract of YES medium by an aqueous extract of mussel tissues, with other constituent identical to YES medium. When shellfish-derived strains of fungi were grown on MES medium, extracts were found to be more cytotoxic than on the YES medium for some of the strains. HPLC-UV/DAD-MS/MS dereplication of extracts from Penicillium marinum and P. restrictum strains grown on MES medium showed the enhancement of the production of some cytotoxic compounds. The mycotoxin patulin was detected in some P. antarcticum extracts, and its presence seemed to be related to their cytotoxicity. Thus, the enhancement of the toxicity of extracts obtained from shellfish-derived Penicillium strains grown on a host-derived medium, and the production of metabolites such as patulin suggests that a survey of mycotoxins in edible shellfish should be considered.

Effect of the protein-synthesis-initiation inhibitor 2-(4-methyl-2,6-dinitroanilino)-N-methylpropionamide on ribonucleic acid synthesis in radish seedlings.

2-(4-Methyl-2,6-dinitroanilino)-N-methylpropionamide, an inhibitor of initiation of protein synthesis in plants, selectively alters rRNA synthesis. Ribosomal genes are transcribed in the absence of protein synthesis, but processing of the transcripts is impaired. This results in an accumulation of the 2.3 X 10(6)-dalton pre-rRNA. Synthesis of polyadenylated RNA is not affected by the drug.

Effect of the protein synthesis inhibitor cycloheximide on RNA synthesis in radish seedlings.

The effect of cycloheximide on rRNA and poly (A) (+) RNA synthesis is studied in radish seedlings. When used at a concentration of 50 microng/ml cycloheximide selectively blocks rRNA synthesis without altering poly (A) (+) RNA synthesis. Processing of the 2.3 X 10(6) dalton pre-rRNA is severely impaired. This observation should help in studies of mRNA metabolism in plants. When the concentration of cycloheximide is lowered, it is possible to completely block protein synthesis without preventing RNA synthesis. This implies that the effect of cycloheximide on RNA synthesis is probably more complex than usually assumed.

Disappearance of stored polyadenylic acid and mRNA during early germination of radish (Raphanus sativus L.) embryo axes.

Polyadenylic acid [poly (A)] is detected, characterized and quantitated in dry radish embryo axis RNA using a (3)H poly (U) probe. The amount of poly (A) gradually decreases after the onset of soaking, and, after a few hours, recovers to the initial level. This variation is shown to result from the addition of two opposed phenomena: the decay of stored poly (A) and the accumulation of newly synthesized poly (A). Stored poly (A), as well as the "in vivo" protein synthesis coded for by preformed mRNA, decreases during early germination with a half-life of two hours. As a whole, these results demonstrate that at least a fraction of the stored mRNA is translated as soon as the seed is soaked and that its role is rapidly taken over by newly-made mRNA.

Occurence of nucleoside polyphosphates in rapidly labelled RNA preparations from radish seedlings (Raphanus sativus.).

Preparations of rapidly labelled RNA are usually heavily contaminated by rapidly labelled low molecular weight components. This contaminating fraction mainly contains nucleoside triphosphates, as previously reported, but also nucleoside tetra, penta and hexaphosphates. These highly phosphorylated nucleosides are, according to recent literature, likely candidates for an important regulatory role in the coordination of a variety of biochemical reactions. This is the first demonstration of their occurence in higher plants and a method is presented to separate them from other usual nucleotides.