Douglas D J, Landry D, Douglas S E
Institute for Marine Biosciences, National Research Council, Halifax, Nova Scotia, Canada.
Nat Toxins. 1994;2(4):166-74. doi: 10.1002/nt.2620020404.
The nuclear small subunit (SSU) rRNA genes from several marine diatoms, including 2 species that have been responsible for toxic blooms, were amplified from total DNA by the polymerase chain reaction (PCR), and the sequences analysed to determine their genetic relatedness. The isolates investigated include 2 morphologically similar forms of the pennate diatom Pseudonitzschia pungens: (1) P. pungens f. multiseries, a known producer of the toxin domoic acid, and (2) P. pungens f. pungens, which is not toxic. Strains of a second toxin-producing species, P. australis, and a nontoxic Thalassiosira species were also included in this study. Phylogenetic analyses of sequences by both distance and parsimony methods clearly distinguished the 2 forms of P. pungens and the 2 Pseudonitzschia species from other diatoms for which sequence data are available. Differences in the nucleotide sequences of the 2 forms of P. pungens permitted the design of PCR primers that allowed discrimination between them. This may prove a valuable tool in identifying toxic and nontoxic forms of closely related and morphologically similar diatom species.
通过聚合酶链反应（PCR）从总DNA中扩增出几种海洋硅藻的核小亚基（SSU）rRNA基因，其中包括2种曾引发有毒藻华的硅藻，并对这些序列进行分析以确定它们的遗传相关性。所研究的分离株包括羽纹硅藻尖刺伪菱形藻（Pseudonitzschia pungens）的2种形态相似的类型：（1）多列尖刺伪菱形藻（P. pungens f. multiseries），一种已知的软骨藻酸毒素产生者；（2）尖刺尖刺伪菱形藻（P. pungens f. pungens），无毒。本研究还包括第二种产毒物种南方伪菱形藻（P. australis）的菌株以及一种无毒的海链藻属（Thalassiosira）物种。通过距离法和简约法对序列进行系统发育分析，清楚地将2种尖刺伪菱形藻和2种伪菱形藻属物种与其他有序列数据的硅藻区分开来。尖刺伪菱形藻2种类型的核苷酸序列差异使得能够设计出可区分它们的PCR引物。这可能被证明是鉴定亲缘关系密切且形态相似的硅藻物种的有毒和无毒类型的一种有价值的工具。
