Molecular insights into a dinoflagellate bloom

Abstract

In coastal waters worldwide, an increase in frequency and intensity of algal blooms has been attributed to eutrophication, with further increases predicted because of climate change. Yet, the cellular-level changes that occur in blooming algae remain largely unknown. Comparative metatranscriptomics was used to investigate the underlying molecular mechanisms associated with a dinoflagellate bloom in a eutrophied estuary. Here we show that under bloom conditions, there is increased expression of metabolic pathways indicative of rapidly growing cells, including energy production, carbon metabolism, transporters and synthesis of cellular membrane components. In addition, there is a prominence of highly expressed genes involved in the synthesis of membraneassociated molecules, including those for the production of glycosaminoglycans (GAGs), which may serve roles in nutrient acquisition and/or cell surface adhesion. Biotin and thiamine synthesis genes also increased expression along with several cobalamin biosynthesis-associated genes, suggesting processing of B 12 intermediates by dinoflagellates. The patterns in gene expression observed are consistent with bloom-forming dinoflagellates eliciting a cellular response to elevated nutrient demands and to promote interactions with their surrounding bacterial consortia, possibly in an effort to cultivate for enhancement of vitamin and nutrient exchanges and/or direct consumption. Our findings provide potential molecular targets for bloom characterization and management efforts.

The roles of B vitamins in phytoplankton nutrition: new perspectives and prospects

“…Specialization on certain vitamers/precursors could play an important role in niche partitioning and/or species succession in phytoplankton blooms. Expression of B 12 ‐remodeling genes during a dinoflagellate bloom (Gong et al ., ) lends support to the potential importance of remodeling strategies for competitive phytoplankton dynamics. That HMP concentrations can exceed thiamine concentrations in marine ecosystems (Carini et al ., ) is further evidence of the ecological relevance of precursors, especially considering that thiamine degrades under UV radiation (Okumura, ).…”

Current Knowledge and Recent Advances in Marine Dinoflagellate Transcriptomic Research

“…This study speculated that high expression of these genes is related to the competitive advantages of dinoflagellates against other competing organisms in the water column during the bloom formation. Metatranscriptome comparison of bloom sites with non-bloom sites showed that 42% of the taxonomically-annotated sequence reads in bloom site were from dinoflagellates, whereas only~20% of reads from the non-bloom site were from dinoflagellates [80]. In addition, metatranscriptome data under bloom conditions indicates there is increased expression of genes involved in cellular metabolism due to the higher growth rate of dinoflagellates during HABs.…”

“…The first application of DinoSL in dinoflagellates metatranscriptomics was documented by Lin et al [26]. Since then, a number of studies has been reported regarding metatranscriptomics approaches to elucidate the dynamic nature of species' interactions during HABs and gene expression patterns during bloom development [20,79,80].…”

Temporal and metabolic overlap between lipid accumulation and programmed cell death due to nitrogen starvation in the unicellular chlorophyte Chlamydomonas reinhardtii

“…, ) and in a bloom forming dinoflagellate the gene expression patterns indicate that nitrogen starvation leads to the upregulation of genes involved in lipid metabolism and cell cycle arrest (Gong et al . ), which is a precursor of PCD. However, the two processes (PCD and lipid accumulation due to nitrogen starvation) have not been examined at the same time in the same culture of C. reinhardtii .…”