title: Polyketide synthesis genes associated with toxin production in two species of Gambierdiscus (Dinophyceae).
abstract: BACKGROUND
  Marine microbial protists, in particular, dinoflagellates, produce polyketide toxins with ecosystem-wide and human health impacts. Species of Gambierdiscus produce the polyether ladder compounds ciguatoxins and maitotoxins, which can lead to ciguatera fish poisoning, a serious human illness associated with reef fish consumption. Genes associated with the biosynthesis of polyether ladder compounds are yet to be elucidated, however, stable isotope feeding studies of such compounds consistently support their polyketide origin indicating that polyketide synthases are involved in their biosynthesis.
  
  
  RESULTS
  Here, we report the toxicity, genome size, gene content and transcriptome of Gambierdiscus australes and G. belizeanus. G. australes produced maitotoxin-1 and maitotoxin-3, while G. belizeanus produced maitotoxin-3, for which cell extracts were toxic to mice by IP injection (LD50 = 3.8 mg kg(-1)). The gene catalogues comprised 83,353 and 84,870 unique contigs, with genome sizes of 32.5 ± 3.7 Gbp and 35 ± 0.88 Gbp, respectively, and are amongst the most comprehensive yet reported from a dinoflagellate. We found three hundred and six genes involved in polyketide biosynthesis, including one hundred and ninety-two ketoacyl synthase transcripts, which formed five unique phylogenetic clusters.
  
  
  CONCLUSIONS
  Two clusters were unique to these maitotoxin-producing dinoflagellate species, suggesting that they may be associated with maitotoxin biosynthesis. This work represents a significant step forward in our understanding of the genetic basis of polyketide production in dinoflagellates, in particular, species responsible for ciguatera fish poisoning.
authors.affiliation: Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, Broadway, New South Wales, 2007, Australia. Gurjeet.kohli@uts.edu.au.|School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, New South Wales, 2052, Australia. Gurjeet.kohli@uts.edu.au.
authors.forename: Gurjeet S
authors.initials: GS
authors.lastname: Kohli
authors.affiliation: Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, 27515, Germany. uwe.john@awi.de.
authors.forename: Uwe
authors.initials: U
authors.lastname: John
authors.affiliation: Aquatic Ecology, Department of Biology, Lund University, Lund, 223 62, Sweden. rosa.figueroa@biol.lu.se.
authors.forename: Rosa I
authors.initials: RI
authors.lastname: Figueroa
authors.affiliation: Cawthron Institute, Nelson, 7010, New Zealand. Lesley.rhodes@cawthron.org.nz.
authors.forename: Lesley L
authors.initials: LL
authors.lastname: Rhodes
authors.affiliation: Cawthron Institute, Nelson, 7010, New Zealand. tim.harwood@cawthron.org.nz.
authors.forename: D Tim
authors.initials: DT
authors.lastname: Harwood
authors.affiliation: Leibniz Institute for Age Research, Fritz Lipmann Institute, Jena, D-07745, Germany. mgroth@fli-leibniz.de.
authors.forename: Marco
authors.initials: M
authors.lastname: Groth
authors.affiliation: Institute for Marine and Antarctic Studies, University of Tasmania, Launceston, 7248, Tasmania, Australia. chris.bolch@utas.edu.au.
authors.forename: Christopher J S
authors.initials: CJ
authors.lastname: Bolch
authors.affiliation: Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, Broadway, New South Wales, 2007, Australia. shauna.murray@uts.edu.au.|Sydney Institute of Marine Sciences, Mosman, New South Wales, 2088, Australia. shauna.murray@uts.edu.au.
authors.forename: Shauna A
authors.initials: SA
authors.lastname: Murray
mesh_terms: D000818:Animals; D004141:Dinoflagellida / Q000737:chemistry* / Q000201:enzymology / Q000235:genetics; D020869:Gene Expression Profiling; D059646:Genome Size; D018503:Genome, Protozoan; D008387:Marine Toxins / Q000378:metabolism* / Q000633:toxicity; D051379:Mice; D005810:Multigene Family; D035964:Oxocins / Q000378:metabolism* / Q000633:toxicity; D010802:Phylogeny; D048630:Polyketide Synthases / Q000235:genetics* / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics*; D000095702:Polyether Toxins
chemical_list: D008387:Marine Toxins; D035964:Oxocins; D048630:Polyketide Synthases; D015800:Protozoan Proteins; C020394:maitotoxin; D000095702:Polyether Toxins