Cawthron Institute, Nelson 7010, New Zealand.
Environmental Research Institute, University of Waikato, Hamilton 3216, New Zealand.
Mar Drugs. 2017 Oct 11;15(10):307. doi: 10.3390/md15100307.
The prevalence of benthic proliferations of the anatoxin-producing cyanobacterium are increasing in cobble-bed rivers worldwide. Studies to date have shown high spatial and temporal variability in anatoxin concentrations among mats. In this study we determined anatoxin quotas (toxins per cell) in field samples and compared these results to the conventionally-used concentrations (assessed per dry weight of mat). Three mats were selected at sites in two rivers and were sampled every 2-3 h for 24-26 h. The samples were lyophilized and ground to a fine homogenous powder. Two aliquots of known weights were analyzed for anatoxin congeners using liquid chromatography-mass spectrometry, or digital droplet PCR with -specific primers to measure absolute quantities of gene copies. Anatoxin concentrations in the mats varied 59- and 303-fold in the two rivers over the study periods. A similar pattern was observed among gene copies (53- and 2828-fold). When converted to anatoxin quotas there was markedly less variability (42- and 16-fold), but significantly higher anatoxin quotas were observed in mats from the second river ( < 0.001, Student's -test). There were no obvious temporal patterns with high and low anatoxin concentrations or quotas measured at each sampling time and across the study period. These results demonstrate that variability in anatoxin concentrations among mats is primarily due to the abundance of toxic genotypes. No consistent modulation in anatoxin production was observed during the study, although significant differences in anatoxin quotas among rivers suggest that site-specific physiochemical or biological factors may influence anatoxin production.
产anatoxin 的蓝藻底栖增殖物在全球卵石床河流中的流行率正在增加。迄今为止的研究表明，垫子中的anatoxin 浓度具有很高的空间和时间变异性。在这项研究中，我们确定了现场样本中的 anatoxin 配额（每细胞毒素），并将这些结果与传统上使用的浓度（根据垫子的干重评估）进行了比较。在两条河流的两个地点选择了三个垫子，并每隔 2-3 小时采样 24-26 小时。将样品冻干并研磨成细均相粉末。使用液相色谱-质谱法或带有 -特异性引物的数字液滴 PCR 分析两个已知重量的等分试样，以测量基因拷贝的绝对数量。在研究期间，两条河流中的垫子中的 anatoxin 浓度变化了 59-和 303 倍。基因拷贝数也观察到类似的模式（53-和 2828 倍）。当转换为 anatoxin 配额时，可变性明显降低（42-和 16 倍），但第二条河流中的垫子中的 anatoxin 配额明显更高（<0.001，Student's -检验）。在每个采样时间和整个研究期间，都没有明显的时间模式，测得的 anatoxin 浓度或配额较高或较低。这些结果表明，垫子中 anatoxin 浓度的变异性主要是由于有毒基因型的丰度所致。尽管河流之间的 anatoxin 配额存在显着差异，但在研究过程中未观察到 anatoxin 产生的一致调节，这表明特定于地点的物理化学或生物学因素可能会影响 anatoxin 的产生。
