Project description:As an essential primary producer, cyanobacteria play an important role in the global cycle for both carbon and nitrogen in the ecosystems. Though the influence of nanoplastics on the carbon metabolism of cyanobacteria, especial Microcystis aeruginosa, a dominant species causing cyanobacterial blooms, is well studied, little is known about nanoplastics affecting the nitrogen metabolism.
Project description:Microcystis aeruginosa cells were treated with phosphorus repletion, depletion and starvation. Isobaric tags for relative and absolute quantitation (iTRAQ) proteomic method was employed to explore to the effects of phosphorus limitation on Microcystis aeruginosa cells at the protein level. This investigation would contribute to the understanding of global cellular responses of Microcystis to phosphorus limitation and provide theoretical basis for deciding whether it is an effective way to control Microcystis blooms by phosphorus reduction.
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.
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.
Project description:The role of potassium (K+), which is an essential major bioconstituent and plant nutrient, in Microcystis aeruginosa growth and cyanobacterial blooms has not yet been clearly documented. This study presents the action and mechanism of K+ in Microcystis aeruginosa, focusing on the growth and proteomic response of the organism.
Project description:Lytic viruses have been implicated in the massive cellular lysis observed during algal blooms, through which they assume a prominent role in oceanic carbon and nutrient flows. Despite their impact on biogeochemical cycling, the transcriptional dynamics of these important oceanic events is still poorly understood. Here, we employ an oligonucleotide microarray to monitor host (Emiliania huxleyi) and virus (coccolithovirus) transcriptomic features during the course of E. huxleyi blooms induced in seawater-based mesocosm enclosures. Host bloom development and subsequent coccolithovirus infection was associated with a major shift in transcriptional profile. In addition to the expected metabolic requirements typically associated with viral infection (amino acid and nucleotide metabolism, as well as transcription- and replication-associated functions), the results strongly suggest that the manipulation of lipid metabolism plays a fundamental role during host-virus interaction. The results herein reveal the scale, so far massively underestimated, of the transcriptional domination that occurs during coccolithovirus infection in the natural environment. Six mesocosm enclosures were placed in the Raunefjorden (Western Norway coast) and filled with natural community water (in June 2008). Nutrient enrichment was applied in order to trigger the development of E. huxleyi blooms. The major transcriptomic features of those blooms and consequent viral infections were monitered through the use of an oligo microarray containing a total of 3571 gene probes; 2271 (63.6%) matching E. huxleyi ESTs, and 1300 (36.4%) matching EhV-86 and EhV-163 genomic sequences. Each microarray contains 5 technical replicates. Sampling of total RNA present in 2L of water (from each enclosure) was performed once a day from day 8 to day 16. For enclosures 2 and 3 other sampling points were taken, covering the complete dial-cycle (6h,12h,18h, and 24h).