PDF(Pubmed)
Abstract：
Dinoflagellate species that form some of the most frequent toxic blooms are also bioluminescent, yet the two traits are rarely linked when studying bloom development and persistence. P. bahamense is a toxic, bioluminescent dinoflagellate that previously bloomed in Florida with no known record of saxitoxin (STX) production. Over the past 20 years, STX was identified in P. bahamense populations. The goal of this study was to examine toxin dynamics and associated molecular mechanisms in spatially and temporally distinct P. bahamense populations from the Indian River Lagoon, FL. SxtA4 is a key gene required for toxin biosynthesis. SxtA4 genotype analysis was performed on individual cells from multiple sites. Cell abundance, toxin quota cell-1, and sxtA4 and RubisCo (rbcL) transcript abundance were also measured. There was a significant negative correlation between cell abundance and toxin quota cell-1. While the sxtA4+ genotype was dominant at all sites, its frequency varied, but it occurred at 90-100% in many samples. The underlying mechanism for toxin decrease with increased cell abundance remains unknown. However, a strong, statistically significant negative correlation was found between stxA4 transcripts and the sxtA4/rbcL ratio, suggesting cells make fewer sxtA4 transcripts as a bloom progresses. However, the influence of sxtA4- cells must also be considered. Future plans include bioluminescence measurements, normalized to a per cell basis, at sites when toxicity is measured along with concomitant quantification of sxtA4 gene and transcript copy numbers as a means to elucidate whether changes in bloom toxicity are driven more at the genetic (emergence of sxtA4- cells) or transcriptional (repression of sxtA4 in sxtA4+ cells) level. Based on the results of this study, a model is proposed that links the combined traits of toxicity and bioluminescence in P. bahamense bloom development.
摘要：
形成一些最常见的有毒花朵的鞭毛虫物种也是生物发光的，然而，在研究花朵的发育和持久性时，这两个特征很少联系在一起。P.bahamense是有毒的，生物发光的鞭毛藻，以前在佛罗里达州开花，没有已知的毒素（STX）生产记录。在过去的20年里,STX在P.bahamense种群中被鉴定。这项研究的目的是研究来自印度河泻湖的空间和时间上不同的P.bahamense种群中的毒素动力学和相关分子机制，FL.SxtA4是毒素生物合成所需的关键基因。对来自多个位点的单个细胞进行SxtA4基因型分析。细胞丰度,还测量了毒素配额细胞1和sxtA4和RubisCo（rbcL）转录本丰度。细胞丰度与毒素配额cell-1之间存在显着负相关。虽然sxtA4+基因型在所有部位都占主导地位，它的频率变化，但它发生在90-100%在许多样品。毒素随细胞丰度增加而减少的潜在机制仍然未知。然而,一个强大的,stxA4转录本与sxtA4/rbcL比值呈显著负相关,表明随着开花的进展，细胞产生更少的sxtA4转录本。然而,还必须考虑sxtA4-细胞的影响。未来的计划包括生物发光测量，归一化为每个细胞的基础，在测量毒性以及同时量化sxtA4基因和转录物拷贝数的位点，作为阐明布卢姆毒性变化是否在遗传（sxtA4-细胞的出现）或转录（在sxtA4+细胞中抑制sxtA4）水平。根据这项研究的结果，提出了一个模型，该模型将P.bahamense绽放发育中的毒性和生物发光的组合特征联系起来。
