Phytoplankton ecophysiology
Exploring the dynamic interactions of phytoplankton with their environment
Vitamins are well characterised as essential nutritional components of the human and animal diet. However, accumulating evidence suggests that these organic micronutrients are important regulators of natural phytoplankton assemblages. A major focus of my work has been elucidating the molecular basis of phytoplankton vitamin dependencies, and their role in shaping biotic interactions between marine microbes. Using in silico genome mining coupled with physiological approaches I identified factors dictating the requirement for the cobalamin (vitamin B12) by eukaryotic algae (Helliwell et al, Molecular Biology and Evolution, 2011). Moreover, by applying an experimental evolution approach I demonstrated vitamin dependencies can arise rapidly in algal populations (Helliwell et al., ISME Journal., 2014). This led us to propose a novel model for the evolution of metabolic dependencies in microorganisms arising as a result of microbial interactions (Kazamia, Helliwell & Smith. Ecology Letters. 2016). More recently we discovered complex cycling of vitamin B12 between two major phytoplankton classes: the cyanobacteria and eukaryotic algae, driving competitive dynamics between these organisms (Helliwell et al., Current Biology. 2016).
The role of vitamins in regulating phytoplankton communities, is a rapidly expanding topic in biological oceanography and our work has contributed significantly to advancing our understanding of these important micronutrients in shaping marine microbial communities.
Since many phytoplankton cannot synthesise the vitamins that they need, they must obtain them from other members of the microbial community. A major focus of our work has been studying the importance of interactions of phytoplankton with bacteria to meet such vitamin demands. In collaboration with Dr Jagroop Pandhal (University of Sheffield) I developed a cross-species quantitative proteomics approach to study algal-bacterial mutualisms centred on vitamin exchange (Helliwell & Pandahl et al. New Phytologist. 2017). This work revealed metabolic trade-offs required for mutualism in a model algal-bacterial system.
More recently, we discovered that Roseobacters, a globally distributed genus of marine bacteria, are primed for mutualism with phytoplankton based on their complementary vitamin synthesis/requirements. These metabolic characteristics may have either contributed to or resulted from the tendency of members of this lineage to adopt lifestyles in close association with marine algae (Cooper., Kazamia & Helliwell et al, ISME Journal, 2018).
Moving forward, we are interested to further advance our understanding of the nature of phytoplankton-bacteria interactions and the molecular mechanisms underpinning them.
Diatoms are a globally important group of photosynthetic microbes, responsible for ~20% of global primary productivity. As major primary producers in the ocean, diatoms sustain marine ecosystems and fisheries. They are particularly important bloom-forming algae, and often dominate early bloom formation due to their exceptional ability to respond rapidly to changing environmental variables. Due to the release of harmful toxins, some diatom blooms can have a negative impact on marine ecosystems, fisheries and human health.
To better understand processes that control bloom dynamics, we need to learn more about the molecular mechanisms that enable diatoms to sense and rapidly respond to environmental drivers. To address these issues, we have developed a cutting-edge molecular toolbox including genetically encoded environmental biosensors coupled with CRISPR-Cas9 genome editing. These tools will provide unprecedented insight of the regulatory processes and 'master-regulators' that coordinate diatom cellular responses to key environmental drivers that impact diatom bloom formation.
Katherine Helliwell
NERC Independent Research Fellow
Katherine Helliwell is a molecular microbiologist focussed primarily on the fundamental biology of photosynthetic marine microbes, which critically underpin marine ecosystems. She pursued a PhD and postdoc in the Department of Plant Sciences, University of Cambridge. During this time she dissected the role of organic micronutrients (vitamins) in governing interactions between phytoplankton and bacteria, and brought significant advances to our understanding in vitamin metabolism in microbes. Following her time in Cambridge, Katherine joined the MBA as a senior postdoctoral researcher working on phytoplankton signalling mechanisms. In summer 2018, Katherine was awarded a NERC Independent Research Fellowship and holds a joint fellowship between the MBA and the University of Exeter. Moving forward as a new lab, Katherine intends to couple her expertise in studying interactions between marine microbes, and phytoplankton signalling mechanisms, to better understand how marine microbes sense and respond to biotic cues.
Dominic Absolon
PhD Candidate (Cambridge Earth System Sciences NERC DTP, in partner with the MBA)
Department of Plant Sciences
University of Cambridge
Downing Street
Cambridge CB2 3EA
Email: dea33@cam.ac.uk
Staff List
Bunbury F., Helliwell K. E., Mehrshahi P., Davey M. P., Salmon D., Smirnoff N., Smith A. G. (2019) Physiological and molecular responses of a newly evolved auxotroph of Chlamydomonas to B12 deprivation. BioRXiv. doi: https://doi.org/10.1101/836635
Leebens-Mack et al, inc. Helliwell K. E. (2019) One thousand plant transcriptomes and the phylogenomics of green plants. Nature. https://doi.org/10.1038/s41586-019-1693-2
Helliwell K. E., Chrachri A., Koester J., Wharam S., Verret, F., Taylor A., Wheeler G., and Brownlee C. (2019). Alternative mechanisms for fast Na+/Ca2+ signalling in eukaryotes via a novel class of single-domain voltage-gated channels. Current Biology. 29(9) 1502-1511.
Cooper M.C., Kazamia E., Helliwell K. E.*, Kudahl U. J., Wheeler G. L., Smith A.G. (2018) Complex cross-exchange of B-vitamins underpins a mutualistic interaction between Ostreococcus tauri and Dinoroseobacter shibae. The ISME Journal.13(2):334-345 (*joint first authorship)
Wheeler G., Helliwell K. E., and Brownlee C. (2018) Diversity of calcium signalling toolkits in algae. Perspectives in Phycology. DOI: 10.1127/pip/2018/0082
Helliwell K. E., Pandhal J., Cooper M, Longworth J., Kudahl U., Russo D., Tomsett E., Bunbury F., Salmon D., Smirnoff N., Wright P., and Smith A. G., (2017). Quantitative proteomics of a B12‐dependent alga grown in coculture with bacteria reveals metabolic tradeoffs required for mutualism. New Phytologist. 217(2): 599-612
Helliwell K. E. (2017). The roles of B vitamins in phytoplankton nutrition: new perspectives and prospects. New Phytologist. 216(1): 62-68 (*Corresponding author).
Brawley S. H., Blouin N. A., Ficko-Blean E., Wheeler G. L., Lohr M., Goodson H., Jenkins J., Blaby-Haas C. E., Helliwell K. E., et al., (2017). Insights into the red algae and eukaryotic evolution from the genome of Porphyra umbilicalis (Bangiophyceae, Rhodophyta). PNAS. 14 (31) E6361-E6370
Helliwell K. E., Lawrence A., Holzer A., Kudahl U. J., Sasso S., Krautler B., Scanlan D., Warren M., Smith A. G. (2016). Cyanobacteria and eukaryotic algae use different chemical variants of vitamin B12. Current Biology. 26(8): 999-1008 (*Corresponding author).
Kazamia E., Helliwell K. E., Smith A. G. (2016). How mutualisms arise in phytoplankton communities: building eco-evolutionary principles for aquatic microbes. Ecology Letters. 19(7):810-822.
Nguyen G., Scaife M. A., Helliwell K. E., Smith A. G. (2016). Algal riboswitches: rare or yet to be discovered? Journal of Phycology. 52(3):320-328
Wells M., Potin P., Craigie J., Raven J., Merchant S., Helliwell K. E., Smith A., Brawley S. (2016) Algal products as nutritional and functional foods: The status of our understanding. Journal of Applied Phycology. 29(2):949-982
Helliwell K. E.*, Collins S., Kazamia E., Purton S., Wheeler G. L., Smith A. G. (2015). Fundamental shift in vitamin B12 eco-physiology of a model alga demonstrated by experimental evolution. The ISME Journal. 9(6):1446-55 (*Corresponding author).
Scaife M. A., Nguyen G. T., Rico J., Lambert D., Helliwell K. E., Smith A. G. (2015). Establishing Chlamydomonas as an industrial biotechnology host. The Plant Journal. 82(3):532-546.
Helliwell K. E., Scaife M. A., Sasso S., Ulian Araujo A., Purton S., Smith A. G. (2014). Unraveling vitamin B12-responsive gene regulation in algae. Plant Physiology. 165(1):388–397
Helliwell K. E.*, Wheeler G. L, Smith A. G. (2013). Widespread decay of vitamin-related pathways: coincidence or consequence? Trends in Genetics. 29(8):469–78 (*Corresponding author). See piece in NY Times exploring this work: http://www.nytimes.com/2013/12/10/science/vitamins-old-old-edge.html?_r=0
Helliwell K. E., Wheeler G. L., Leptos K., Goldstein R., Smith A. G. (2011). Insights into the evolution of vitamin B12 auxotrophy from sequenced algal genomes. Molecular Biology and Evolution. 28(10):2921–33.
Kazamia E., Helliwell K. E., Smith A. G. (2010). Vitamin B12- Keeping a Clear Head. The Biochemist: 32(6).
Science Communication and outreach
Article in NERC Planet Earth
Helliwell K. E., Vitamins in the Sea: the role of vitamins in shaping phytoplankton evolution and ecology. The Marine Biologist (2018).
New York Times: Vitamins' Old, Old Edge
Cambridge University Meet the Algae video
Kazamia E., Helliwell K.E. and Smith A.G. Keeping a clear head with vitamin B12. (2010). The Biochemist 32(6): 20 -24.
The Marine Biological Association of the United Kingdom,
The Laboratory,
Citadel Hill,
Plymouth,
Devon,
UK
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