title: Molecular characterization of the toxic cyanobacterium Cylindrospermopsis raciborskii and design of a species-specific PCR.
abstract: Cylindrospermopsis raciborskii is a toxic-bloom-forming cyanobacterium that is commonly found in tropical to subtropical climatic regions worldwide, but it is also recognized as a common component of cyanobacterial communities in temperate climates. Genetic profiles of C. raciborskii were examined in 19 cultured isolates originating from geographically diverse regions of Australia and represented by two distinct morphotypes. A 609-bp region of rpoC1, a DNA-dependent RNA polymerase gene, was amplified by PCR from these isolates with cyanobacterium-specific primers. Sequence analysis revealed that all isolates belonged to the same species, including morphotypes with straight or coiled trichomes. Additional rpoC1 gene sequences obtained for a range of cyanobacteria highlighted clustering of C. raciborskii with other heterocyst-producing cyanobacteria (orders Nostocales and Stigonematales). In contrast, randomly amplified polymorphic DNA and short tandemly repeated repetitive sequence profiles revealed a greater level of genetic heterogeneity among C. raciborskii isolates than did rpoC1 gene analysis, and unique band profiles were also found among each of the cyanobacterial genera examined. A PCR test targeting a region of the rpoC1 gene unique to C. raciborskii was developed for the specific identification of C. raciborskii from both purified genomic DNA and environmental samples. The PCR was evaluated with a number of cyanobacterial isolates, but a PCR-positive result was only achieved with C. raciborskii. This method provides an accurate alternative to traditional morphological identification of C. raciborskii.
authors.affiliation: The Cooperative Research Centre for Water Quality and Treatment, Australian Water Quality Centre, SA Water Corporation, Salisbury, South Australia 5108, Australia.
authors.forename: K M
authors.initials: KM
authors.lastname: Wilson
authors.forename: M A
authors.initials: MA
authors.lastname: Schembri
authors.forename: P D
authors.initials: PD
authors.lastname: Baker
authors.forename: C P
authors.initials: CP
authors.lastname: Saint
mesh_terms: D000595:Amino Acid Sequence; D000458:Cyanobacteria / Q000145:classification* / Q000235:genetics*; D012321:DNA-Directed RNA Polymerases / Q000235:genetics*; D014644:Genetic Variation; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods*; D019105:Random Amplified Polymorphic DNA Technique; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D020080:Tandem Repeat Sequences / Q000235:genetics
chemical_list: D012321:DNA-Directed RNA Polymerases