Transcriptomics insight into the metabolism of the toxic producing Microcystis aeruginosa PCC 7806
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ABSTRACT: Microcystis is a genus of unicellular cyanobacteria capable of growing massively in freshwater ecosystems around the world and producing various toxins such as microcystins. We studied using an RNA-Seq approach the transcriptomes of three axenic strains of Microcystis, comprising the modele strain PCC 7806, selected because of their genetic potential for natural products. We assessed the expression of biosynthetic gene clusters during a 24-hour day/night cycle.
Project description:The cyanobacterium Microcystis aeruginosa PCC 7806 was used for a systematic survey of the relationship between copper and microcystins synthesis. Here we have used microarrays to interrogate the global responses to copper additions at 0.5 micromolar (µM) and 3 µM of copper. From the gene level, microarray studies (3 µM copper supplementation) showed effects on iron, sulfur, glutaredoxin and dehydratase homeostasis gene expression. However, in 0.5 µM groups, those genes that significantly enriched in 3 µM groups regulatory were not all found. In the microarray data for copper stress (3 µM) revealed a broad effect on the expression of iron-sulphur cluster associated pathways, such as cysteine biosynthesis. All of these data indicate that Fe / S cluster biogenesis and/or repair were affected by copper in M. aeruginosa.
Project description:Microcystins are produced by the cyanobacteria, most commonly Microcystis aerµginosa. Upon ingestion, toxic microcystins are actively absorbed by fish, birds and mammals where they are primarily liver toxins.
Project description:Microcystins are produced by the cyanobacteria, most commonly Microcystis aerµginosa. Upon ingestion, toxic microcystins are actively absorbed by fish, birds and mammals where they are primarily liver toxins. Groups of 4-6 rats were exposed to 0, 1, 10, 50 or 100 µg/kg microcystin-LR for 0.5, 1, 3 or 6 hours and gene expression analysis performed on liver with samples hybridized to whole rat genome RG230_2.0 GeneChip arrays (Affymetrix, CA).
Project description:Although cyanobacteria produce a wide range of natural toxins that impact aquatic organisms, food webs and water quality, the mechanisms of toxicity are still insufficiently understood. Here, we implemented a whole-genome expression microarray to identify pathways, gene networks and paralogous gene families responsive to Microcystis stress in Daphnia pulex. Therefore, neonates of a sensitive isolate were given a diet contaminated with Microcystis to contrast with those given a control diet for sixteen days. The microarray revealed 2247 differentially expressed (DE) genes (7.6% of the array) in response to Microcystis, of which 17% are lineage specific and 49% are gene duplicates (paralogs). We identified four pathways/gene networks and eight paralogous gene families affected by Microcystis. Differential regulation of the ribosome including 3 paralogous gene families encoding 40S, 60S and mitochondrial ribosomal proteins, suggests an impact of Microcystis on protein synthesis of Daphnia. In addition, differential regulation of the oxidative phosphorylation pathway, including the NADH ubquinone oxidoreductase gene family, and trypsin paralogous gene family, major component of the digestive system in Daphnia, could explain why fitness is reduced based on energy budget considerations. For others (.e.g Neurexin IV), a link with fitness remains to be established. RNA was isolated from three independent and concurrently replicated exposures of Daphnia to control and Microcystis conditions. RNA was hybridized to 4 microarrays using a standard, control vs. treated design that included dye swaps.