Molecular Interactions in a Microalgae-Virus System

Recent developments, led by Bristol NanoDynamics, in High Speed Atomic
Force Microscopy (HS-AFM) allow nanometre resolution for imaging
millimetre sized areas and the provision of real-time videos of dynamic nano
or micro scale structures or surface processes. This project will exploit HSAFM
to characterise the molecular interactions between the
coccolithoviruses and their coccolithophore host.
Viruses are like lubricants in the Earth system's engine room and their role in
transforming planktonic cells into dissolved material means they are crucial
to global biogeochemical cycling - the pathways that all elements and
molecules move along in an ongoing cycle, passing through both living
things and inorganic processes. Coccolithophores are some of the most
abundant and widespread organisms in the oceans. These photosynthetic
microscopic algae form the base of the oceans' food chain, and play a major
role in the global carbon cycle, drawing down vast volumes of carbon dioxide
from the atmosphere. They use this carbon to build hard chalk-like shells of
calcium carbonate. Emiliania huxleyi is the most numerous coccolithophore
in our oceans, and satellite observations often show massive blooms that
grow rapidly before abruptly disappearing. Until recently, the mechanisms of
E. huxleyi bloom disintegration were poorly understood, but most scientists
now accept that viruses play an important part in these sudden crashes.
Analysis of these viruses' genetic makeup revealed large double-stranded
DNA viruses with genomes of approximately 410,000 base pairs which
belong to the genus Coccolithovirus. The type species, EhV-86, has a
circular genome with 407,339 base pairs and is full of genes of unknown
function and novel repetitive DNA units. The few genes of known function
encode classical virus-associated functions (such as DNA polymerase, RNA
polymerase, Topoisomerase etc) as well as an almost complete pathway for
the production of sphingolipids obtained via horizontal gene transfer from the
host genome. Three families of repetitive DNA are present which evidence
suggests are acting as novel promoters for transcriptional control, genome
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condensation and as an origin of replication. This project will look to
characterising the molecular features and interactions that occur before,
during and after infection between the coccolithoviruses and
coccolithophores including mechanisms of viral adsorption/release and
genomic characterisation.