Stüken Anke, Riobó Pilar, Franco José, Jakobsen Kjetill S, Guillou Laure, Figueroa Rosa I
Department of Biosciences, University of Oslo Oslo, Norway.
U.A. Microalgas Nocivas (Consejo Superior de Investigaciones Científicas - Instituto Español de Oceanografía), Instituto de Investigaciones Marinas Vigo, Spain.
Front Microbiol. 2015 May 1;6:404. doi: 10.3389/fmicb.2015.00404. eCollection 2015.
Dinoflagellates are microscopic aquatic eukaryotes with huge genomes and an unusual cell regulation. For example, most genes are present in numerous copies and all copies seem to be obligatorily transcribed. The consequence of the gene copy number (CPN) for final protein synthesis is, however, not clear. One such gene is sxtA, the starting gene of paralytic shellfish toxin (PST) synthesis. PSTs are small neurotoxic compounds that can accumulate in the food chain and cause serious poisoning incidences when ingested. They are produced by dinoflagellates of the genera Alexandrium, Gymnodium, and Pyrodinium. Here we investigated if the genomic CPN of sxtA4 is related to PST content in Alexandrium minutum cells. SxtA4 is the 4th domain of the sxtA gene and its presence is essential for PST synthesis in dinoflagellates. We used PST and genome size measurements as well as quantitative PCR to analyze sxtA4 CPN and toxin content in 15 A. minutum strains. Our results show a strong positive correlation between the sxtA4 CPN and the total amount of PST produced in actively growing A. minutum cells. This correlation was independent of the toxin profile produced, as long as the strain contained the genomic domains sxtA1 and sxtA4.
甲藻是具有巨大基因组和异常细胞调控的微观水生真核生物。例如，大多数基因以众多拷贝存在，并且所有拷贝似乎都必须转录。然而，基因拷贝数（CPN）对最终蛋白质合成的影响尚不清楚。一个这样的基因是sxtA，它是麻痹性贝类毒素（PST）合成的起始基因。PST是小的神经毒性化合物，可在食物链中积累，并在摄入时导致严重的中毒事件。它们由亚历山大藻属、裸甲藻属和梨甲藻属的甲藻产生。在这里，我们研究了微小亚历山大藻细胞中sxtA4的基因组CPN是否与PST含量相关。SxtA4是sxtA基因的第4个结构域，其存在对于甲藻中PST的合成至关重要。我们使用PST和基因组大小测量以及定量PCR来分析15个微小亚历山大藻菌株中的sxtA4 CPN和毒素含量。我们的结果表明，在活跃生长的微小亚历山大藻细胞中，sxtA4 CPN与产生的PST总量之间存在很强的正相关。只要菌株包含基因组结构域sxtA1和sxtA4，这种相关性就与产生的毒素谱无关。
