Utilization of various forms of nitrogen and expression regulation of transporters in the harmful alga Heterosigma akashiwo (Raphidophyceae)

Ji, Nanjing; Zhang, Zhenzhen; Huang, Jinwang; Zhou, Liang; Deng, Shengxian; Shen, Xin; Lin, Senjie

doi:10.1016/j.hal.2020.101770

Cited by 12 publications

(11 citation statements)

References 34 publications

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“…Citrate enrichment may indicate that H. akashiwo differs from other phytoplankton in these two processes. N-stress has been reported to be linked to the initiation of the diel migration employed by H. akashiwo during blooms (Ji et al, 2018;Ji et al, 2020). The diel migration is hypothesized to serve H. akashiwo by helping it acquire dissolved nutrients below the thermocline (Smayda, 1998).…”

Section: Akashiwomentioning

confidence: 99%

Harmful Algal Bloom-Forming Organism Responds to Nutrient Stress Distinctly From Model Phytoplankton

McLean

et al. 2021

Preprint

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Resources such as nitrogen (N) and phosphorus (P) play an important role in primary production and constraining phytoplankton bloom dynamics. Models to predict bloom dynamics require mechanistic knowledge of algal metabolic shifts in response to resource limitation. For well-studied model phytoplankton like diatoms, this information is plentiful. However, for less-studied groups such as the raphidophytes, there remain significant gaps in understanding metabolic changes associated with nutrient limitation. Using a novel combination of metabolomics and transcriptomics, we examined how the harmful algal bloom-forming raphidophyte Heterosigma akashiwo shifts its metabolism under N- and P-stress. We chose H. akashiwo because of its ubiquity within estuarine environments worldwide, where bloom dynamics are influenced by N and P availability. Our results show that each stress phenotype is distinct in both the allocation of carbon and the recycling of macromolecules. Further, we identified biomarkers of N- and P-stress that may be applied in situ to help modelers and stakeholders manage, predict, and prevent future blooms. These findings provide a mechanistic foundation to model the metabolic traits and trade-offs associated with N- and P-stress in H. akashiwo, and evaluate the extent to which these metabolic responses can be inferred in other phytoplankton groups.

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Section: Akashiwomentioning

confidence: 99%

Harmful Algal Bloom-Forming Organism Responds to Nutrient Stress Distinctly From Model Phytoplankton

McLean

et al. 2021

Preprint

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“…LDs are energetically expensive; however, phytoplankton swimming under nutrient limitation could offset competitive advantage from larger storage capacity (45,46) because of enhanced molecular encounters and expansion of potential nutrient pools (40). While nutrient limitation has been associated with initiation of phytoplankton migration during blooms (47)(48)(49), contrasting reports suggest suppression of motility under depleted settings (50,51). Confounding environmental factors such as local pH (35) can additionally regulate phytoplankton swimming, alongside biomolecular parameters like variations in the cellular ATP (52), which has been reported to shift energy allocations to favor cellular motility.…”

Section: Introductionmentioning

confidence: 99%

Active reconfiguration of cytoplasmic lipid droplets governs migration of nutrient-limited phytoplankton

et al. 2022

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Nutrient availability, along with light and temperature, drives marine primary production. The ability to migrate vertically, a critical trait of motile phytoplankton, allows species to optimize nutrient uptake, storage, and growth. However, this traditional view discounts the possibility that migration in nutrient-limited waters may be actively modulated by the emergence of energy-storing organelles. Here, we report that bloom-forming raphidophytes harness energy-storing cytoplasmic lipid droplets (LDs) to biomechanically regulate vertical migration in nutrient-limited settings. LDs grow and translocate directionally within the cytoplasm, steering strain-specific shifts in the speed, trajectory, and stability of swimming cells. Nutrient reincorporation restores their swimming traits, mediated by an active reconfiguration of LD size and coordinates. A mathematical model of cell mechanics establishes the mechanistic coupling between intracellular changes and emergent migratory behavior. Amenable to the associated photophysiology, LD-governed behavioral shift highlights an exquisite microbial strategy toward niche expansion and resource optimization in nutrient-limited oceans.

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“…The specific usage of metatranscriptomic reads for this purpose is common in HAB studies, as often genomics alone do not define bloom dynamics (Ji et al. 2020, Martin et al. 2020, Metegnier et al.…”

Section: Discussionmentioning

confidence: 99%

Aureococcus anophagefferens (Pelagophyceae) genomes improve evaluation of nutrient acquisition strategies involved in brown tide dynamics

Gann

Truchon

Papoulis

et al. 2021

Journal of Phycology

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The pelagophyte Aureococcus anophagefferens causes harmful brown tide blooms in marine embayments on three continents. Aureococcus anophagefferens was the first harmful algal bloom species to have its genome sequenced, an advance that evidenced genes important for adaptation to environmental conditions that prevail during brown tides. To expand the genomic tools available for this species, genomes for four strains were assembled, including three newly sequenced strains and one assembled from publicly available data. These genomes ranged from 57.11 to 73.62 Mb, encoding 13,191–17,404 potential proteins. All strains shared ~90% of their encoded proteins as determined by homology searches and shared most functional orthologs as determined by KEGG, although each strain also possessed coding sequences with unique functions. Like the original reference genome, the genomes assembled in this study possessed genes hypothesized to be important in bloom proliferation, including genes involved in organic compound metabolism and growth at low light. Cross‐strain informatics and culture experiments suggest that the utilization of purines is a potentially important source of organic nitrogen for brown tides. Analyses of metatranscriptomes from a brown tide event demonstrated that use of a single genome yielded a lower read mapping percentage (~30% of library reads) as compared to a database generated from all available genomes (~43%), suggesting novel information about bloom ecology can be gained from expanding genomic space. This work demonstrates the continued need to sequence ecologically relevant algae to understand the genomic potential and their ecology in the environment.

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Utilization of various forms of nitrogen and expression regulation of transporters in the harmful alga Heterosigma akashiwo (Raphidophyceae)

Cited by 12 publications

References 34 publications

Harmful Algal Bloom-Forming Organism Responds to Nutrient Stress Distinctly From Model Phytoplankton

Harmful Algal Bloom-Forming Organism Responds to Nutrient Stress Distinctly From Model Phytoplankton

Active reconfiguration of cytoplasmic lipid droplets governs migration of nutrient-limited phytoplankton

Aureococcus anophagefferens (Pelagophyceae) genomes improve evaluation of nutrient acquisition strategies involved in brown tide dynamics

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