Balzano Sergio, Percopo Isabella, Siano Raffaele, Gourvil Priscillia, Chanoine Mélanie, Marie Dominique, Vaulot Daniel, Sarno Diana
CNRS, UMR7144, Station Biologique De Roscoff, Sorbonne Universités, UPMC Univ Paris 06, 29680, Roscoff, France.
Integrative Marine Ecology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Naples, Italy.
J Phycol. 2017 Feb;53(1):161-187. doi: 10.1111/jpy.12489. Epub 2016 Dec 5.
Seventy-five diatom strains isolated from the Beaufort Sea (Canadian Arctic) in the summer of 2009 were characterized by light and electron microscopy (SEM and TEM), as well as 18S and 28S rRNA gene sequencing. These strains group into 20 genotypes and 17 morphotypes and are affiliated with the genera Arcocellulus, Attheya, Chaetoceros, Cylindrotheca, Eucampia, Nitzschia, Porosira, Pseudo-nitzschia, Shionodiscus, Thalassiosira, and Synedropsis. Most of the species have a distribution confined to the northern/polar area. Chaetoceros neogracilis and Chaetoceros gelidus were the most represented taxa. Strains of C. neogracilis were morphologically similar and shared identical 18S rRNA gene sequences, but belonged to four distinct genetic clades based on 28S rRNA, ITS-1 and ITS-2 phylogenies. Secondary structure prediction revealed that these four clades differ in hemi-compensatory base changes (HCBCs) in paired positions of the ITS-2, suggesting their inability to interbreed. Reproductively isolated C. neogracilis genotypes can thus co-occur in summer phytoplankton communities in the Beaufort Sea. C. neogracilis generally occurred as single cells but also formed short colonies. It is phylogenetically distinct from an Antarctic species, erroneously identified in some previous studies as C. neogracilis, but named here as Chaetoceros sp. This work provides taxonomically validated sequences for 20 Arctic diatom taxa, which will facilitate future metabarcoding studies on phytoplankton in this region.
2009年夏天从波弗特海（加拿大北极地区）分离出的75株硅藻菌株，通过光学显微镜、电子显微镜（扫描电子显微镜和透射电子显微镜）以及18S和28S rRNA基因测序进行了表征。这些菌株分为20个基因型和17个形态型，隶属于Arcocellulus、Attheya、角毛藻属、Cylindrotheca、Eucampia、菱形藻属、海链藻属、拟菱形藻属、Shionodiscus、海链藻属和Synedropsis属。大多数物种的分布局限于北部/极地地区。纤细角毛藻和冰河角毛藻是最具代表性的分类群。纤细角毛藻菌株在形态上相似，共享相同的18S rRNA基因序列，但根据28S rRNA、ITS-1和ITS-2系统发育分析，它们属于四个不同的遗传分支。二级结构预测表明，这四个分支在ITS-2配对位置的半补偿性碱基变化（HCBCs）方面存在差异，这表明它们无法杂交。因此，生殖隔离的纤细角毛藻基因型可以在波弗特海夏季浮游植物群落中共存。纤细角毛藻通常以单细胞形式出现，但也会形成短的群体。它在系统发育上与一种南极物种不同，在一些先前的研究中被错误地鉴定为纤细角毛藻，但在这里命名为角毛藻属物种。这项工作为20个北极硅藻分类群提供了经过分类验证的序列，这将有助于未来对该地区浮游植物的宏条形码研究。
