Lau Audrey O T, McElwain Terry F, Brayton Kelly A, Knowles Donald P, Roalson Eric H
Program in Genomics, Department of Veterinary Microbiology & Pathology, School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-7040, USA.
Exp Parasitol. 2009 Nov;123(3):236-43. doi: 10.1016/j.exppara.2009.07.007. Epub 2009 Jul 29.
Apicomplexan parasites commonly contain a unique, non-photosynthetic plastid-like organelle termed the apicoplast. Previous analyses of other plastid-containing organisms suggest that apicoplasts were derived from a red algal ancestor. In this report, we present an extensive phylogenetic study of apicoplast origins using multiple previously reported apicoplast sequences as well as several sequences recently reported. Phylogenetic analysis of amino acid sequences was used to determine the evolutionary origin of the organelle. A total of nine plastid genes from 37 species were incorporated in our study. The data strongly support a green algal origin for apicoplasts and Euglenozoan plastids. Further, the nearest green algae lineage to the Apicomplexans is the parasite Helicosporidium, suggesting that apicoplasts may have originated by lateral transfer from green algal parasite lineages. The results also substantiate earlier findings that plastids found in Heterokonts such as Odontella and Thalassiosira were derived from a separate secondary endosymbiotic event likely originating from a red algal lineage.
顶复门寄生虫通常含有一种独特的、非光合的类似质体的细胞器，称为顶质体。先前对其他含质体生物的分析表明，顶质体起源于红藻祖先。在本报告中，我们利用多个先前报道的顶质体序列以及最近报道的几个序列，对顶质体起源进行了广泛的系统发育研究。氨基酸序列的系统发育分析用于确定该细胞器的进化起源。我们的研究纳入了来自37个物种的总共9个质体基因。数据有力地支持了顶质体和眼虫质体起源于绿藻的观点。此外，与顶复门最接近的绿藻谱系是寄生虫螺旋孢子虫，这表明顶质体可能是通过从绿藻寄生虫谱系的横向转移而起源的。研究结果也证实了早期的发现，即在诸如角毛藻属和硅藻属等不等鞭毛类生物中发现的质体源自一个可能起源于红藻谱系的单独的次生内共生事件。
