Department Biologie, Systematische Botanik und Mykologie, GeoBio-Center, Ludwig-Maximilians-Universität München, Menzinger Str. 67, D 80638 München, Germany.
Mol Phylogenet Evol. 2013 Apr;67(1):217-22. doi: 10.1016/j.ympev.2013.01.003. Epub 2013 Jan 16.
Endosymbiotic dinophytes are diverse and are found in a large variety of aquatic partners. They are colloquially coined zooxanthellae, and knowledge about those dinophytes with a coral as partner (i.e., Symbiodinium) is extensive. However, Zooxanthella nutricula has been specifically described based on material isolated from radiolarians, and its phylogenetic position within the dinophyte tree is unclear at present. We isolated genomic DNA and sequenced the ribosomal RNA genes from an endosymbiotic dinophyte found in a radiolarian. In phylogenetic analyses, the endosymbiont was distantly related to Symbiodinium and the Suessiales, but clustered together with members of the Peridiniales. Specifically, it was the sister lineage of a small group, whose members host a diatom as endosymbiont (i.e., the dinotoms). Endosymbiosis is thus of multiple origin within the dinophytes, and more research is necessary to work out ecological and morphological character traits that are congruent to the DNA trees.
内共生甲藻种类繁多，存在于多种水生伙伴中。它们通常被称为虫黄藻，关于珊瑚作为伙伴（即共生藻）的那些甲藻的知识是广泛的。然而，Zooxanthella nutricula 是根据从放射虫中分离出的材料专门描述的，目前其在甲藻树中的系统发育位置尚不清楚。我们从放射虫中发现的内共生甲藻中分离出基因组 DNA 并对核糖体 RNA 基因进行了测序。在系统发育分析中，内共生体与 Symbiodinium 和 Suessiales 关系较远，但与 Peridiniales 的成员聚类在一起。具体来说，它是一个小群体的姊妹谱系，其成员的内共生体是硅藻（即甲藻）。因此，内共生在甲藻中具有多种起源，需要进一步研究以确定与 DNA 树一致的生态和形态特征。
