Biology subjects

Harrison, E. L.

Publications and source records attributed to Harrison, E. L..

3 recordsLinked to original sources

bioRxiv2026

Cellular basis of B12 uptake and remodelling in microalgae revealed using a novel bioassay

O_LIVitamin B12, an essential micronutrient for many microalgae and humans, is synthesised only by certain prokaryotes. B12 is a complex tetrapyrrole that can exist in many forms (vitamers), some more bioavailable than others. Some microalgae are able to interconvert, or remodel, different B12 vitamers. As microalgae are important primary producers, it is crucial to understand how diverse microalgae acquire, utilise, and remodel this micronutrient. C_LIO_LIThrough the development of a novel algal bioassay for B12 quantification that distinguishes between B12 vitamers with different lower axial ligands, and the generation of targeted knock-out lines, we characterised the role of proteins involved in algal B12 uptake and remodelling. C_LIO_LIWe found that the previously characterised protein CoBalamin-Acquisition protein 1 (CBA1) is also necessary for the acquisition of pseudocobalamin, a less bioavailable form of B12. In addition, we provide the first experimental evidence that COBT is required for Chlamydomonas reinhardtii to remodel B12. C_LIO_LIWe apply the algal B12 bioassay to show that the edible alga Chlorella vulgaris can accumulate pseudocobalamin but is unable to remodel it, highlighting the need for thorough investigation of the metabolic requirements and capabilities of microalgae, especially given the growing interest in microalgae-based food additives. C_LI

microbiology↗

bioRxiv2023

Cryptic bacterial pathogens of diatoms peak during senescence of a winter diatom bloom

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 bloom control, insight of the prevalence and dynamics of antagonistic bacteria in nature is lacking. We report an ecosystem assessment of the diversity and seasonal patterns of bacterial antagonists of diatoms via regular plaque-assay sampling in the Western English Channel (WEC), where diatoms frequently bloom. Unexpectedly, peaks in antagonist detection did not occur during characteristic spring blooms, but coincided with a winter bloom of Coscinodiscus, suggesting bacterial pathogens likely influence distinct diatom host populations. We isolated multiple antagonists, spanning 4 classes and 10 bacterial orders. Many species had no prior reports of pathogenicity towards diatoms, and we verified diatom growth inhibitory effects of 8 isolates. In all cases tested, pathogenicity was activated by pre-exposure to diatom organic matter. Discovery of widespread cryptic antagonistic activity evident under specific conditions, indicates that bacterial pathogenicity towards diatoms is more prevalent than previously recognised. Finally, mining Tara Oceans data revealed the global biogeography of WEC antagonists and co-occurrence patterns with diatom hosts. Our study indicates that multiple, diverse antagonistic bacteria have potential to impact diatom growth and bloom dynamics in marine waters globally.

microbiology↗

bioRxiv2022

The Influences of Stomatal Size and Density on Rice Drought, Salinity and VPD Resilience

O_LIA warming climate coupled with reductions in water availability and rising salinity are increasingly affecting rice yields (Oryza sativa L.). Elevated temperatures are causing vapour pressure deficit (VPD) rises, leading to stomata closure, further reducing plant productivity and cooling. It is unclear which conformation of stomatal size (SS) and stomatal density (SD) will best suit these future environmental extremes. C_LIO_LITo understand the influence of stomatal characteristics on rice abiotic stress tolerance, we screened the stomatal characteristics of 72 traditionally-bred varieties. We found significant variation in SS, SD and maximal stomatal conductance (gsmax) but did not identify any varieties with SD and gsmax as low as the genetically manipulated stomatal development mutant OsEPF1oe. C_LIO_LITraditionally-bred varieties with high SD and small SS (resulting in high gsmax) typically had lower biomasses, and these plants were more resilient to drought than low SD and large SS plants, which were physically larger. None of the varieties tested were as resilient to drought or salinity as low SD OsEPF1oe mutants. High SD and small SS rice displayed faster stomatal closure during rising VPD, but photosynthesis and plant cooling were reduced. C_LIO_LICompromises will be required when choosing rice SS and SD to tackle multiple future environmental stresses. C_LI

plant biology↗