Department of Biology, and Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, NS, Canada.
Department of Biology, and Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, NS, Canada.
Protist. 2023 Apr;174(2):125949. doi: 10.1016/j.protis.2023.125949. Epub 2023 Mar 18.
There are several alveolate groups outside the well-studied trio - ciliates, dinoflagellates, and apicomplexans - that are crucial for understanding the evolution of this major taxon. One such assemblage is the "colponemids", which are eukaryotrophic biflagellates, usually with a ventral groove associated with the posterior flagellum. Previous phylogenetic studies show colponemids forming up to three distinct deep branches within alveolates (e.g. sister groups to Myzozoa or all other alveolates). We have developed dieukaryotic (predator-prey) cultures of four colponemid isolates. One represents the first stable culture of the halophile Palustrimonas (feeding on Pharyngomonas), while SSU rDNA phylogenies show the other isolates as two distinct new lineages. Neocolponema saponarium gen. et sp. nov. is a swimming alkaliphile with a large groove, which feeds on a kinetoplastid. Loeffela hirca gen. et sp. nov. is halophilic, has a subtle groove, usually moves along surfaces, and feeds on Pharyngomonas and Percolomonas. Prey capture in both new genera is raptorial, involves a specialized structure/region to the right of the proximal posterior flagellum, and presumed extrusomes. The relationships amongst Myzozoa, ciliates, and the (now) five described colponemid clades are unresolved, signaling that colponemid diversity represents both a challenge and important resource for tracing deep alveolate evolution.
除了研究较为充分的纤毛门、甲藻和顶复门这三个门类之外，还有几个噬藻体群体对于理解这个主要分类群的进化至关重要。其中一个集合是“colponemids”，它们是真核生物双鞭毛生物，通常具有与后鞭毛相关的腹沟。以前的系统发育研究表明，colponemids 在噬藻体中形成了三个不同的深分支（例如，与 Myzozoa 或所有其他噬藻体的姐妹群）。我们已经开发了四种 colponemid 分离物的二倍体（捕食者-猎物）培养物。一种代表嗜盐菌 Palustrimonas 的第一个稳定培养物（以 Pharyngomonas 为食），而 SSU rDNA 系统发育表明其他分离物是两个不同的新谱系。Neocolponema saponarium gen. et sp. nov. 是一种游动的嗜碱性生物，具有较大的沟，以动基体生物为食。Loeffela hirca gen. et sp. nov. 是嗜盐生物，具有细微的沟，通常沿表面移动，以 Pharyngomonas 和 Percolomonas 为食。在这两个新属中，猎物的捕获都是掠夺性的，涉及到靠近后鞭毛的右侧的一个特殊结构/区域，以及假定的外体。Myzozoa、纤毛动物和（现在）描述的五个 colponemid 分支之间的关系尚未解决，这表明 colponemid 的多样性既是挑战，也是追踪深层噬藻体进化的重要资源。
