Moreira David, López-García Purificación
Unité d'Ecologie, Systématique et Evolution, CNRS UMR8079, Université Paris-Sud, Orsay, France.
Bioessays. 2014 May;36(5):468-74. doi: 10.1002/bies.201300176. Epub 2014 Mar 10.
Algae are significant members of Earth's biodiversity. Having been studied for a long time, the discovery of new algal phyla is extremely unusual. Recently, the enigmatic "Picobiliphyta," a group of uncultured eukaryotes unveiled using molecular tools, were claimed to represent an unrecognized early branching algal lineage with a nucleomorph (remnant nucleus of a secondary algal endosymbiont) in their plastids. However, subsequent studies rejected the presence of a nucleomorph, and single-cell genomic studies failed to detect any plastid-related genes, ruling out the possibility of plastid occurrence. The isolation of the first "picobiliphyte," Picomonas judraskeda, a tiny organism that feeds on very small (<150 nm) organic particles, came as final proof of their non-photosynthetic lifestyle. Consequently, the group has been renamed Picozoa. The passage from "picobiliphytes" to "picozoa" illustrates the crucial role that classical protistology should play to provide sound biological context for the wealth of data produced by modern molecular techniques.
藻类是地球生物多样性的重要组成部分。经过长期研究，新藻类门类的发现极为罕见。最近，神秘的“皮胆藻门”（Picobiliphyta），一群通过分子工具揭示的未培养真核生物，据称代表了一种未被识别的早期分支藻类谱系，其质体中有一个核质体（次生藻类内共生体的残余细胞核）。然而，随后的研究否定了核质体的存在，单细胞基因组研究也未能检测到任何与质体相关的基因，排除了质体存在的可能性。首个“皮胆藻”（picobiliphyte）——朱氏皮胆虫（Picomonas judraskeda）的分离，这是一种以非常小（<150纳米）的有机颗粒为食的微小生物，成为其非光合生活方式的最终证据。因此，该类群被重新命名为皮虫门（Picozoa）。从“皮胆藻”到“皮虫”的转变说明了经典原生生物学在为现代分子技术产生的大量数据提供可靠生物学背景方面应发挥的关键作用。
