Project description:Harmful algal blooms are induced largely by nutrient enrichment common in warm waters. An increasingly frequent phenomenon is the “red tide”: blooms of dinoflagellate microalgae that accumulate toxins lethal to other organisms in high doses. Here, we present the de novo assembled genome (~4.75 Gbp) of Prorocentrum cordatum, a globally abundant, bloom-forming dinoflagellate, and the associated transcriptome, proteome, and metabolome data from axenic cultures to elucidate the microalgal molecular responses to heat stress. We discovered, in a high-G+C genome with long introns and extensive genetic duplication, a complementary mechanism between RNA editing and exon usage that regulates dynamic expression and functional diversity of genes and proteins, and metabolic profiles that reflect reduced capacities in photosynthesis, central metabolism, and protein synthesis. These results based on multi-omics evidence demonstrate the genomic hallmark of a bloom-forming dinoflagellate, and how the complex gene structures combined with multi-level transcriptional regulation underpin concerted heat-stress responses.
Project description:Dinoflagellate blooms are natural phenomena that have drawn global attention due to their huge negative impacts on marine ecosystems, mariculture and human health. Although the understanding of dinoflagellate blooms has been significantly improved over the past half century, little is known about the underlying mechanisms sustaining the high biomass growth rate during the bloom period which is paradoxically characterized by low dissolved CO2 and inorganic nutrients. Here, we compared the metaproteomes of non-bloom, mid-bloom and late-bloom cells of a marine dinoflagellate Prorocentrum donghaiense in the coastal East China Sea, to understand the underlying mechanisms sustaining high biomass growth rate under the typically low CO2 and inorganic nutrient conditions.
Project description:Allelopathy, or the release of compounds that inhibit competitors, is a form of interference competition that is common among bloom-forming phytoplankton. Allelopathy is hypothesized to play a role in bloom propagation and maintenance and is well established in the red tide dinoflagellate Karenia brevis. K. brevis typically suppresses competitor growth through unknown mechanisms over the course of many days. When we investigated the effects of allelopathy on the lipidomes of two competing phytoplankton, Asterionellopsis glacialis and Thalassiosira pseudonana using nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS)- based metabolomics, we found that the lipidomes of both species were significantly altered, however A. glacialis maintained a more robust response whereas T. pseudonana saw significant alterations in fatty acid synthesis, cell membrane integrity, and a decrease in photosynthetic efficiency. Membrane- associated lipids were significantly suppressed for T. pseudonana exposed to allelopathy to the point of permeabilizing the cell membrane of living cells. The dominant mechanisms of K. brevis allelopathy appear to target lipid biosynthesis affecting multiple physiological pathways suggesting that exuded compounds have the ability to significantly alter competitor physiology and give K. brevis a competitive edge over sensitive species.
Project description:A comparative proteomics study to investigate a saxitoxin producing and non-toxic strains of Anabaena circinalis. Anabaena circinalis is a freshwater and bloom-forming cyanbacterium