Katherine E. Helliwell
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Metagenomics of the MAST-3 stramenopile, Incisomonas, and its associated microbiome reveals unexpected metabolic attributes and extensive nutrient dependencies Open
Protists are polyphyletic single-celled eukaryotes that underpin global ecosystem functioning, particularly in the oceans. Most remain uncultured, limiting the investigation of their physiology and cell biology. MA rine ST ramenopiles (MAS…
View article: A plasma membrane Ca <sup>2+</sup> -dependent protein kinase PtCDPK2 promotes phosphorus starvation resilience in <i>Phaeodactylum tricornutum</i>
A plasma membrane Ca <sup>2+</sup> -dependent protein kinase PtCDPK2 promotes phosphorus starvation resilience in <i>Phaeodactylum tricornutum</i> Open
Phosphorus (P) is an essential element limiting algal growth and productivity in aquatic ecosystems. Diatoms are important microalgae that thrive in nutrient-variable environments. Determining how diatoms perceive and respond to P availabi…
Nitrogen status exerts dynamic control over phosphorus sensing and acquisition via PSR1 in colimited marine diatoms Open
Nutrient availability controls phytoplankton growth in aquatic ecosystems globally. Phytoplankton frequently experience a limiting supply of multiple nutrients simultaneously (colimitation). Ocean warming is predicted to exacerbate marine …
Metagenomics of the MAST-3 stramenopile, <i>Incisomonas,</i> and its associated microbiome reveals unexpected metabolic attributes and extensive nutrient dependencies Open
Protists are polyphyletic singled-celled eukaryotes that underpin global ecosystem functioning, particularly in the oceans. Most remain uncultured, limiting investigation of their physiology and cell biology. MA rine ST ramenopiles (MASTs)…
Diatoms exhibit dynamic chloroplast calcium signals in response to high light and oxidative stress Open
Diatoms are a group of silicified algae that play a major role in marine and freshwater ecosystems. Diatom chloroplasts were acquired by secondary endosymbiosis and exhibit important structural and functional differences from the primary p…
Crossed wires: diatom phosphate sensing mechanisms coordinate nitrogen metabolism Open
Phytoplankton can encounter dynamic changes in their environment including fluctuating nutrient supply, and therefore require survival mechanisms to compete for such growth-limiting resources. Diatoms, single-celled eukaryotic microalgae, …
Seasonal niche overlap of diverse facultative antagonistic bacteria of diatoms in a productive coastal ecosystem Open
Biotic interactions between microbes underpin marine ecosystem health, governing the flux of carbon and other nutrients in the ocean. However, studying aquatic microbial interactions is challenging. Model systems can provide in depth under…
Channels of Evolution: Unveiling Evolutionary Patterns in Diatom Ca2+ Signalling Open
Diatoms are important primary producers in marine and freshwater environments, but little is known about the signalling mechanisms they use to detect changes in their environment. All eukaryotic organisms use Ca2+ signalling to perceive an…
Cryptic bacterial pathogens of diatoms peak during senescence of a winter diatom bloom Open
Summary Diatoms are globally abundant microalgae that form extensive blooms in aquatic ecosystems. Certain bacteria behave antagonistically towards diatoms, killing or inhibiting their growth. Despite their crucial implications to diatom b…
Diatoms exhibit dynamic chloroplast calcium signals in response to high light and oxidative stress Open
Diatoms are a group of silicified algae that play a major role in marine and freshwater ecosystems. Diatom chloroplasts were acquired by secondary endosymbiosis and exhibit important structural and functional differences from the primary p…
Cryptic bacterial pathogens of diatoms peak during senescence of a winter diatom bloom Open
Diatoms are globally abundant algae that form extensive blooms in aquatic ecosystems. Certain bacteria behave antagonistically towards diatoms, killing or inhibiting their growth. Despite their crucial implications to diatom health and blo…
Emerging trends in nitrogen and phosphorus signalling in photosynthetic eukaryotes Open
Phosphorus (P) and nitrogen (N) are the major nutrients that constrain plant and algal growth in nature. Recent advances in understanding nutrient signalling mechanisms of these organisms have revealed molecular attributes to optimise N an…
View article: Cold-induced [Ca2+]cyt elevations function to support osmoregulation in marine diatoms
Cold-induced [Ca2+]cyt elevations function to support osmoregulation in marine diatoms Open
Diatoms are a group of microalgae that are important primary producers in a range of open ocean, freshwater, and intertidal environments. The latter can experience substantial long- and short-term variability in temperature, from seasonal …
Reduced H <sup>+</sup> channel activity disrupts pH homeostasis and calcification in coccolithophores at low ocean pH Open
Significance Coccolithophore calcification is a major ocean biogeochemical process. While this process is likely to be sensitive to acidification-driven changes in ocean carbonate chemistry, incomplete understanding of the underlying mecha…
View article: Cold-induced [Ca <sup>2+</sup> ] <sub>cyt</sub> elevations function to support osmoregulation in marine diatoms
Cold-induced [Ca <sup>2+</sup> ] <sub>cyt</sub> elevations function to support osmoregulation in marine diatoms Open
Diatoms are a group of microalgae that are important primary producers in a range of open ocean, freshwater and intertidal environments. The latter can experience significant long- and short-term variability in temperature, from seasonal v…
View article: Reduced H <sup>+</sup> channel activity disrupts pH homeostasis and calcification in coccolithophores at low ocean pH
Reduced H <sup>+</sup> channel activity disrupts pH homeostasis and calcification in coccolithophores at low ocean pH Open
Coccolithophores produce the bulk of ocean biogenic calcium carbonate but this process is predicted to be negatively affected by future ocean acidification scenarios. Since coccolithophores calcify intracellularly, the mechanisms through w…
View article: Spatiotemporal patterns of intracellular Ca<sup>2+</sup> signalling govern hypo‐osmotic stress resilience in marine diatoms
Spatiotemporal patterns of intracellular Ca<sup>2+</sup> signalling govern hypo‐osmotic stress resilience in marine diatoms Open
Summary Diatoms are globally important phytoplankton that dominate coastal and polar‐ice assemblages. These environments exhibit substantial changes in salinity over dynamic spatiotemporal regimes. Rapid sensory systems are vital to mitiga…
View article: A Novel Single-Domain Na <sup>+</sup> -Selective Voltage-Gated Channel in Photosynthetic Eukaryotes
A Novel Single-Domain Na <sup>+</sup> -Selective Voltage-Gated Channel in Photosynthetic Eukaryotes Open
The evolution of Na+-selective four-domain voltage-gated channels (4D-Navs) in animals allowed rapid Na+-dependent electrical excitability, and enabled the development of sophisticated systems for rapid and long-range signaling. While bact…
A novel Ca <sup>2+</sup> signalling pathway co-ordinates environmental phosphorus sensing and nitrogen metabolism in marine diatoms Open
Diatoms are a diverse and globally important phytoplankton group, responsible for an estimated 20% of carbon fixation on Earth. They frequently form spatially extensive phytoplankton blooms, responding rapidly to increased availability of …
View article: A novel single-domain Na <sup>+</sup> -selective voltage-gated channel in photosynthetic eukaryotes
A novel single-domain Na <sup>+</sup> -selective voltage-gated channel in photosynthetic eukaryotes Open
The evolution of Na + -selective four-domain voltage-gated channels (4D-Na v s) in animals allowed rapid Na + -dependent electrical excitability, and enabled the development of sophisticated systems for rapid and long-range signalling. Whi…
Responses of a Newly Evolved Auxotroph of Chlamydomonas to B <sub>12</sub> Deprivation Open
The corrinoid B12 is synthesized only by prokaryotes yet is widely required by eukaryotes as an enzyme cofactor. Microalgae have evolved B12 dependence on multiple occasions, and we previously demonstrated that experimental evolution of th…
Physiological and molecular responses of a newly evolved auxotroph of Chlamydomonas to B <sub>12</sub> deprivation Open
The corrinoid B 12 is synthesised only by prokaryotes yet is widely required by eukaryotes as an enzyme cofactor. Microalgae have evolved B 12 dependence on multiple occasions and we previously demonstrated that experimental evolution of t…
Shining a light on microbial dark matter: a role for the forgotten B vitamins in marine algal communities? Open
The ocean is home to a huge diversity of life that perform a wide range of functions key to earth systems. Marine algae communities contribute a significant proportion of net carbon fixation of the globe as well as forming the basis of the…
Cross-exchange of B-vitamins underpins a mutualistic interaction between <i>Ostreococcus tauri</i> and <i>Dinoroseobacter shibae</i> Open
Ostreococcus tauri, a picoeukaryotic alga that contributes significantly to primary production in oligotrophic waters, has a highly streamlined genome, lacking the genetic capacity to grow without the vitamins thiamine (B1) and cobalamin (…
Quantitative proteomics of a B<sub>12</sub>‐dependent alga grown in coculture with bacteria reveals metabolic tradeoffs required for mutualism Open
Summary The unicellular green alga Lobomonas rostrata requires an external supply of vitamin B 12 (cobalamin) for growth, which it can obtain in stable laboratory cultures from the soil bacterium Mesorhizobium loti in exchange for photosyn…
Insights into the red algae and eukaryotic evolution from the genome of <i>Porphyra umbilicalis</i> (Bangiophyceae, Rhodophyta) Open
Significance Fossil evidence shows that red algae (Rhodophyta) are one of the most ancient multicellular lineages. Their ecological, evolutionary, and commercial importance notwithstanding, few red algal nuclear genomes have been sequenced…
The roles of B vitamins in phytoplankton nutrition: new perspectives and prospects Open
Summary B vitamins play essential roles in central metabolism. These organic water‐soluble molecules act as, or as part of, coenzymes within the cell. Unlike land plants, many eukaryotic algae are auxotrophic for certain B vitamins. Recent…