The University of Southampton
University of Southampton Institutional Repository

A comparative analysis of the calcification transcriptome and proteome of Emiliania huxleyi

A comparative analysis of the calcification transcriptome and proteome of Emiliania huxleyi
A comparative analysis of the calcification transcriptome and proteome of Emiliania huxleyi
Calcium carbonate precipitation by marine organisms is an acknowledged contributor to the global carbon cycle. Coccolithophores are unicellular marine phytoplankton, that by excreting calcium scales and performing photosynthesis, contribute largely to the flux of atmospheric carbon to the surface and deeper oceans. The impact of elevated future ocean temperature and ocean acidity on the mechanism and rates, by which coccolithophores secret their calcium carbonate scales internally and contribute to the global carbon cycle, has been widely studied. However, biomineralisation in coccolithophores, the expression of molecular pathways, and the timing of gene expression related to calcification are still poorly understood. To better understand the process of calcification the transcriptome and proteome of calcifying G1-phase Emiliania huxleyi cells were investigated in the light and dark using next generation techniques. The results showed clear differences in both the transcriptomic and proteomic profiles between the photosynthetically enhanced calcification and the dark calcification phase. Interestingly, the bulk of the biomineralisation genes were higher expressed in the dark calcification phase at low calcification rates, suggesting that a large proportion of the molecular calcification machinery is bound to the Golgi apparatus and endoplasmic reticulum, which are complemented in the early G1-phase following cytokinesis. Furthermore, the results suggest that a set of biomineralisation genes exhibits continuous expression in both conditions of the G1 phase, whereas other genes are more abundantly expressed in the calcification phase. The importance of the calcium binding proteins calreticulin, calnexin, and calmodulin in the calcification phase was confirmed by transcriptomic and proteomic data. Proton pumping V-type ATPases were found higher expressed in dark phase but was still highly expressed in the enhanced calcification phase in the light. Calcium transport related gene expression of members of the NCKX (Na+/Ca2+-K+ exchanger), NCX (Na+/Ca2+exchanger), and CAX (calcium exchanger) were stronger in the low calcification phase, whereas SERCA-type calcium transporting ATPases were nearly equally expressed in both condition but originating from different genes that were expressed in either the light or the dark. Furthermore, transcriptome exploration suggested syntaxin and synaptobrevin could play an important role in calcification related vesicle fusion. The results have important implications for better understanding the timing of calcification related gene expression throughout the E. huxleyi cell cycle and for potential transcriptomic plasticity in response to changing environmental conditions.
Anlauf, Holger
57125626-70ef-42dd-a6b1-66d0897f5cb1
Anlauf, Holger
57125626-70ef-42dd-a6b1-66d0897f5cb1
Hauton, Christopher
7706f6ba-4497-42b2-8c6d-00df81676331

Anlauf, Holger (2015) A comparative analysis of the calcification transcriptome and proteome of Emiliania huxleyi. University of Southampton, Ocean & Earth Science, Doctoral Thesis, 286pp.

Record type: Thesis (Doctoral)

Abstract

Calcium carbonate precipitation by marine organisms is an acknowledged contributor to the global carbon cycle. Coccolithophores are unicellular marine phytoplankton, that by excreting calcium scales and performing photosynthesis, contribute largely to the flux of atmospheric carbon to the surface and deeper oceans. The impact of elevated future ocean temperature and ocean acidity on the mechanism and rates, by which coccolithophores secret their calcium carbonate scales internally and contribute to the global carbon cycle, has been widely studied. However, biomineralisation in coccolithophores, the expression of molecular pathways, and the timing of gene expression related to calcification are still poorly understood. To better understand the process of calcification the transcriptome and proteome of calcifying G1-phase Emiliania huxleyi cells were investigated in the light and dark using next generation techniques. The results showed clear differences in both the transcriptomic and proteomic profiles between the photosynthetically enhanced calcification and the dark calcification phase. Interestingly, the bulk of the biomineralisation genes were higher expressed in the dark calcification phase at low calcification rates, suggesting that a large proportion of the molecular calcification machinery is bound to the Golgi apparatus and endoplasmic reticulum, which are complemented in the early G1-phase following cytokinesis. Furthermore, the results suggest that a set of biomineralisation genes exhibits continuous expression in both conditions of the G1 phase, whereas other genes are more abundantly expressed in the calcification phase. The importance of the calcium binding proteins calreticulin, calnexin, and calmodulin in the calcification phase was confirmed by transcriptomic and proteomic data. Proton pumping V-type ATPases were found higher expressed in dark phase but was still highly expressed in the enhanced calcification phase in the light. Calcium transport related gene expression of members of the NCKX (Na+/Ca2+-K+ exchanger), NCX (Na+/Ca2+exchanger), and CAX (calcium exchanger) were stronger in the low calcification phase, whereas SERCA-type calcium transporting ATPases were nearly equally expressed in both condition but originating from different genes that were expressed in either the light or the dark. Furthermore, transcriptome exploration suggested syntaxin and synaptobrevin could play an important role in calcification related vesicle fusion. The results have important implications for better understanding the timing of calcification related gene expression throughout the E. huxleyi cell cycle and for potential transcriptomic plasticity in response to changing environmental conditions.

PDF
Holger Anlauf PhD Thesis 2015.pdf - Other
Download (22MB)

More information

Accepted/In Press date: 21 September 2015
Organisations: University of Southampton, Ocean and Earth Science

Identifiers

Local EPrints ID: 403349
URI: https://eprints.soton.ac.uk/id/eprint/403349
PURE UUID: c5dfd57f-fca4-4c32-8d1c-030d300ca06b
ORCID for Christopher Hauton: ORCID iD orcid.org/0000-0002-2313-4226

Catalogue record

Date deposited: 30 Nov 2016 15:26
Last modified: 06 Jun 2018 13:03

Export record

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×