Summary
This project will address the evolution of biomineralization in haptophytes, potentially triggered by changing oxygen concentrations in the oceans in deep time.
Project background
Before the Triassic, the carbonate sediment factory was located solely in shallow marine waters. But from ~210 million years ago, marine phytoplankton known as coccolithophores started to calcify. In today’s oceans, coccolithophores are responsible for 10-40% of global primary productivity and phytoplankton biomass, and form the foundation for marine food webs. Additionally, they provide ballast that assists the transport of organic matter to the deep ocean and form the largest geological sink of carbon from the ocean/atmosphere reservoir. Coccolithophores therefore underpin the workings of the modern marine ecosystem and Earth’s biogeochemical cycles.
Despite their importance, little is known about the mechanisms of calcification, the biological function of the coccolithophores, and indeed the triggers for initial calcification and how the biomineralisation mechanisms may have evolved through geological time (Monteiro et al., 2016). The rise of calcification by coccolithophores may have triggered the increase in the oxygen levels in the oceans. However, there is as yet insufficient evidence from the geological record to support this hypothesis. Given that calcification has high energy demands, we hypothesize that in fact the opposite has happened: that the increase in the oxygen levels in the oceans enabled the evolution of calcification in haptophytes by enabling a higher energy production metabolism by the cells.
Research questions
The overall aim of this project is to study the role that oxygen levels in sea water play in the metabolism of coccolithophores and in their calcification process. We will probe how cells respond to growth under different oxygen levels how the biochemical processes involving in calcification and the overall production of the coccoliths are affected. To gain an insight in the evolution of biomineralisation in cocccolithophores, we will compare between closely related calcifying and non-calcifying species.
Methodology
Initial work will involve the culturing of different species of calcifying coccolithophores which have varying ages of initial origination under different sea water conditions, such as oxygen and CO2 saturation. The effect that these conditions will have on the rate of coccolith production and shape of the crystals will be studied via electron microscopy. After the initial characterisation phase, confocal microscopy will be used to trace and compare the transport pathway of calcium ions through the cells in calcifying and non-calcifying species.
Training
A comprehensive training programme will be provided comprising both specialist scientific training and generic transferable and professional skills.The candidate will join a vibrant research group and take part in a multi-institutional collaboration involving the University of Edinburgh and Oxford University. The project is multidisciplinary, combining chemical/structural analysis, biochemical analytical techniques geochemistry and evolutionary biology to answer a key question: the triggers for the evolution of biomineralisation.
Requirements
A very good first degree in Chemistry, or Geochemistry, or GeoSciences, or Biosciences, or other closely-related subject is required.
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