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Bioluminescence in dinoflagellates – diversity, molecular phylogeny and field ecology

Bioluminescence in dinoflagellates – diversity, molecular phylogeny and field ecology
Bioluminescence in dinoflagellates – diversity, molecular phylogeny and field ecology
Marine dinoflagellates are an ecologically important group of protists within the plankton, performing key process such as photosynthesis, heterotrophy and toxin production. Some dinoflagellates are also capable of producing bioluminescence and they are the most abundant protists that produce light in the surface waters of the oceans. This
study employed molecular tools to investigate the identity of bioluminescent species, the genetic basis, diversity and functional regulation of bioluminescence, and the distribution of marine bioluminescent dinoflagellate populations.

Using “universal” and taxon specific PCR primers designed to amplify the luciferase gene (lcf), the distribution of this gene within dinoflagellates was found to be taxon specific and the first lcf sequences obtained from four genetically distant genera revealed a previously unknown high diversity of this gene. The luciferin binding protein gene (lbp) was detected for the first time in three genera of ecologically important gonyaulacoid dinoflagellates, showing that this understudied gene is common in dinoflagellate bioluminescence systems. Phylogenetic analyses of both lcf and lbp provided new insight on species divergence within the toxic genus Alexandrium and pointed out important pitfalls in using protein coding genes for phylogenetic studies. The lcf PCR primers were
employed in the first field study using a molecular approach to detect natural populations of bioluminescent dinoflagellates, showing that this approach outperforms optical bioluminescence measurements and that their distribution and composition is intimately tied to hydrographic patterns that create distinct environmental zones. The lcf PCR primers were also employed to study the regional variation in bioluminescence of Noctiluca scintillans, showing for the first time that the environment maintains or eliminates bioluminescence, by finding that a hydrographically isolated non bioluminescent variety in the west coast of the USA has “switched off” its bioluminescence system while diverging to possibly become a different species. Also, a novel lbp was discovered in N. scintillans which improved the current model for the evolution of bioluminescence genes in dinoflagellates.

This thesis is the first study to employ molecular tools in a comprehensive and multifaceted investigation of dinoflagellate bioluminescence and has contributed significantly to building a fundamental understanding of this remarkable phenomenon.
Valiadi, Martha
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Valiadi, Martha
e245e9c5-3e97-4896-b910-c4178c5fb3c9
Iglesias-Rodriguez, Debora
34da3d8b-ca9d-4db8-91f0-abfed4a5710f
Painter, Stuart
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Purdie, Duncan
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Allen, John
2a40d9b5-1464-42f0-86c1-69ebb24ea05f

Valiadi, Martha (2011) Bioluminescence in dinoflagellates – diversity, molecular phylogeny and field ecology. University of Southampton, School of Ocean and Earth Science, Doctoral Thesis, 142pp.

Record type: Thesis (Doctoral)

Abstract

Marine dinoflagellates are an ecologically important group of protists within the plankton, performing key process such as photosynthesis, heterotrophy and toxin production. Some dinoflagellates are also capable of producing bioluminescence and they are the most abundant protists that produce light in the surface waters of the oceans. This
study employed molecular tools to investigate the identity of bioluminescent species, the genetic basis, diversity and functional regulation of bioluminescence, and the distribution of marine bioluminescent dinoflagellate populations.

Using “universal” and taxon specific PCR primers designed to amplify the luciferase gene (lcf), the distribution of this gene within dinoflagellates was found to be taxon specific and the first lcf sequences obtained from four genetically distant genera revealed a previously unknown high diversity of this gene. The luciferin binding protein gene (lbp) was detected for the first time in three genera of ecologically important gonyaulacoid dinoflagellates, showing that this understudied gene is common in dinoflagellate bioluminescence systems. Phylogenetic analyses of both lcf and lbp provided new insight on species divergence within the toxic genus Alexandrium and pointed out important pitfalls in using protein coding genes for phylogenetic studies. The lcf PCR primers were
employed in the first field study using a molecular approach to detect natural populations of bioluminescent dinoflagellates, showing that this approach outperforms optical bioluminescence measurements and that their distribution and composition is intimately tied to hydrographic patterns that create distinct environmental zones. The lcf PCR primers were also employed to study the regional variation in bioluminescence of Noctiluca scintillans, showing for the first time that the environment maintains or eliminates bioluminescence, by finding that a hydrographically isolated non bioluminescent variety in the west coast of the USA has “switched off” its bioluminescence system while diverging to possibly become a different species. Also, a novel lbp was discovered in N. scintillans which improved the current model for the evolution of bioluminescence genes in dinoflagellates.

This thesis is the first study to employ molecular tools in a comprehensive and multifaceted investigation of dinoflagellate bioluminescence and has contributed significantly to building a fundamental understanding of this remarkable phenomenon.

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Published date: June 2011
Organisations: University of Southampton, Ocean Biochemistry & Ecosystems

Identifiers

Local EPrints ID: 209735
URI: http://eprints.soton.ac.uk/id/eprint/209735
PURE UUID: 3ed15aea-a1ea-4eea-b438-647fadf383e8

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Date deposited: 01 Feb 2012 10:49
Last modified: 29 Jan 2020 14:54

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Contributors

Author: Martha Valiadi
Thesis advisor: Debora Iglesias-Rodriguez
Thesis advisor: Stuart Painter
Thesis advisor: Duncan Purdie
Thesis advisor: John Allen

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