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Harmful algal blooms: mechanisms, monitoring, and prevention in a rapidly changing world
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Intragenomic polymorphism of ribosomal DNAs in Gambierdiscus (Dinophyceae) and its implications in molecular species delineation
Wednesday 9th @ 1510-1530, Multifunction Hall
Chui Pin Leaw* , Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, Bachok, Malaysia
Hong Chang Lim, Faculty of Applied Sciences, Tunku Abdul Rahman University College, Johor, Malaysia
Haifeng Gu, Third Institute of Oceanography, Xiamen, China
Leo Lai Chan, State Key Laboratory in Marine Pollution, City University of Hong Kong, China
Chung-Kuang Lu, National Research Institute of Chinese Medicine, Ministry of Health and Welfare, Beitou District, Taipei 1121, Taiwan
Douding Lu, Shenzhen Key Laboratory in Sustainable Use of Marine Biodiversity, Research Centre for the
Oceans and Human Health, City University of Hong Kong, Shenzhen, China
Matthias Wolf, Department of Bioinformatics, Biocenter, University of Wuerzburg, 97074 Wuerzburg, Germany
R Wayne Litaker, National Oceanic and Atmospheric Administration, National Ocean Service, National Centers for Coastal Ocean Science, Beaufort Laboratory, Beaufort, NC 28516, USA
Patricia A Tester, Ocean Tester LLC, 381 Gillikin Road, Beaufort, NC 28516, USA
Po Teen Lim, Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, Bachok, Malaysia
Presenter Email: cpleaw@um.edu.my |
| Recent molecular phylogenetic studies of the benthic harmful dinoflagellate Gambierdiscus flagged several new species and genotypes, leading to revitalizing its systematics. The phylogenetic analyses revealed by the primary sequence information of nuclear-encoded ribosomal RNA genes (nrDNA), however, can sometimes be equivocal, as nrDNA intragenomic sequence heterogeneity can be problematic for phylogenetic reconstruction and lead to ambiguous identity. In this study, we explored the extent of rDNA intragenomic variability in the regions of small and large subunits (18S and 28S) of representative species of Gambierdiscus and to determine if the variability obscures species boundaries. Gene amplification of 18S and 28S rDNA was performed on the genomic DNA extracted from clonal cultures of Gambierdiscus, and sequence variability determined using standard cloning and Sanger sequencing. Our results revealed intraspecific and intragenomic polymorphism in all Gambierdiscus species tested with numerous variants discovered (nucleotide divergence: SSU, <2.4%; LSU, <3.6%). The SSU rDNA phylogenetic inferences incorporating the sequence-structure information generally supported the species monophyly, but the rDNA genotypes in most of the culture strains within species were unresolved. It is thus crucial to examine as many strains/populations as possible and to assess multiple gene markers to avoid misleading inferences for species boundaries in Gambierdiscus. |
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