Not all cyanobacterial strains produce toxins. However, the toxin-producing strains cannot be distinguished from the nontoxin-producing strains by traditional light microscopy, commonlyused to monitor water bodies. An alternative for the differentiation of potentially toxic strains from nontoxic strains is to use molecular methods to detect the presence of toxin biosynthetic genes. Such methods are already available and could be used for the detection and identification of potential microcystin and nodularin producers present in environmental samples (Attogene catalog number NA2024).
Screening for the toxin itself, can be very costly. In turn, real time PCR for the detection of the SxtA gene region responsible for assembling Saxitoxin in cyanobacterial strains and environmental samples can be a key indicator for the prescense of cyanobacteria capable of expressing the saxitoxin toxin. Attogene has thus, designed primer pairs and probes targeting a the conserved SxtA gene region in order to enable the amplification and detection of several producer genera using real time PCR. Screening for the toxin genes can save significant costs and act as a triage for samples needing to be analyzed for the toxin itself.
The cyanobacterial sxt gene homologs, consisting of four domains (sxtA1 to sxtA4), were also demonstrated in dinoflagellates. The domain sxtA4 in the sxt gene cluster, which encodes the unique enzyme putatively involved in the sxtA pathway for STX synthesis in marine dinoflagellates, has been adapted to develop a saxitoxin-specific quantitative PCR (qPCR) assay.
