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Free keywords:
bioluminescence; gene evolution; luciferase; PCR
Abstract:
Dinoflagellate bioluminescence systems operate with or without a luciferin
binding protein, representing two distinct modes of light production. However,
the distribution, diversity, and evolution of the luciferin binding protein gene
within bioluminescent dinoflagellates are not well known. We used PCR to
detect and partially sequence this gene from the heterotrophic dinoflagellate
Noctiluca scintillans and a group of ecologically important gonyaulacoid species.
We report an additional luciferin binding protein gene in N. scintillans
which is not attached to luciferase, further to its typical combined bioluminescence
gene. This supports the hypothesis that a profound re-organization of
the bioluminescence system has taken place in this organism. We also show
that the luciferin binding protein gene is present in the genera Ceratocorys,
Gonyaulax, and Protoceratium, and is prevalent in bioluminescent species of
Alexandrium. Therefore, this gene is an integral component of the standard
molecular bioluminescence machinery in dinoflagellates. Nucleotide sequences
showed high within-strain variation among gene copies, revealing a highly
diverse gene family comprising multiple gene types in some organisms. Phylogenetic
analyses showed that, in some species, the evolution of the luciferin
binding protein gene was different from the organism’s general phylogenies,
highlighting the complex evolutionary history of dinoflagellate bioluminescence
systems.
