Pereyra Joao P A, D'Agostino Paul M, Mazmouz Rabia, Woodhouse Jason N, Pickford Russell, Jameson Ian, Neilan Brett A
School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.
School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, 2052, Australia; Biosystems Chemistry, Department of Chemistry, Technische Universität München, 85748, Garching, Germany.
Toxicon. 2017 Nov;138:68-77. doi: 10.1016/j.toxicon.2017.08.006. Epub 2017 Aug 7.
The cyanobacterium Dolichospermum circinale (formerly Anabaena circinalis) is responsible for neurotoxic saxitoxin-producing blooms in Australia. Previous studies have reported distinct isolates of toxic D. circinale producing different saxitoxin analogues at varying amounts, but the mechanisms responsible remain poorly understood. To assess the characteristics that may be responsible for this variance, a morphological, molecular and chemical survey of 28 Anabaena isolates was conducted. Morphological characteristics, presence or absence of saxitoxin biosynthetic genes and toxin amount and profile were assessed. The 28 isolates were collected from 16 locations. A correlation between the size of the isolates and its reported toxicity or geographical location could not be found. Molecular screening for the presence of several sxt genes revealed eight out of the 28 strains harboured the sxt gene cluster and all tailoring genes except sxtX. Furthermore, the presence of PSTs was correlated with the presence of the sxt cluster using quantitative pre-column oxidation high performance liquid chromatography with fluorescence detection (HPLC-FLD) and LC-MS/MS. Interestingly, isolates differed in the amount and type of toxins produced, with the eight toxic strains containing the core and tailoring biosynthetic genes while non-toxic strains were devoid of these genes. Moreover, the presence of sxt tailoring genes in toxic strains correlated with the biosynthesis of analogues. A greater understanding of toxin profile/quantity from distinct sites around Australia will aid the management of these at-risk areas and provide information on the molecular control or physiological characteristics responsible for toxin production.
蓝藻环状多甲藻（原鱼腥藻）是澳大利亚产生神经毒性麻痹性贝类毒素藻华的罪魁祸首。此前的研究报道了不同的有毒环状多甲藻分离株产生不同数量的麻痹性贝类毒素类似物，但其产生机制仍知之甚少。为了评估可能导致这种差异的特征，对28株鱼腥藻分离株进行了形态学、分子学和化学研究。评估了形态特征、麻痹性贝类毒素生物合成基因的有无以及毒素含量和谱图。这28株分离株从16个地点采集。未发现分离株大小与其报道的毒性或地理位置之间存在相关性。对几个sxt基因存在情况的分子筛选显示，28株菌株中有8株含有sxt基因簇以及除sxtX之外的所有修饰基因。此外，使用柱前氧化高效液相色谱荧光检测法（HPLC-FLD）和液相色谱-串联质谱法（LC-MS/MS），麻痹性贝类毒素的存在与sxt基因簇的存在相关。有趣的是，分离株产生的毒素数量和类型不同，8株有毒菌株含有核心和修饰生物合成基因，而无毒菌株则没有这些基因。此外，有毒菌株中sxt修饰基因的存在与类似物的生物合成相关。更深入了解澳大利亚不同地点的毒素谱/数量，将有助于对这些高危地区进行管理，并提供有关毒素产生的分子控制或生理特征的信息。
