系统发育分析指示细菌向Apicoplast的水平基因转移

顶复合器门的原生动物(Apicomplexan protozoa)含有一个高度退化的质体样(plastid-like)细胞器，定名为apicoplast。来自apicoplast的c／pC基因和它在其他质体和细菌中的同源物用来重建apicoplast的系统发育史。使用邻接法(Neighbor-Joining)、最小进化法(Minimum Evolution)、最大简约法(Maximum Pamimony)和最大似然法(Maximum Likelihood)建立进化树。此外为了避免由于序列之间相似的碱基组成而引起的虚假聚类，建立了基于LogDet距离的核苷酸NJ树；以及为了避免由于在核苷酸和氨基酸水平上的突变饱和而引起的长分枝吸引(Long Branch Attraction，LBA)，建立了基于非饱和位点的核苷酸和氨基酸序列的系统发育树。重建结果强有力地支持apicoplast和细菌B．buigorferi之间的单系(monophyly)起源关系，也强化了apicoplasst属于混合基因组的假设，并且提供了对这个混合基因组起源的新的认识。

Phylogenetic Analysis Indicates Bacteria-to-Apicoplast Lateral Gene Transfer

Apicomplexan protozoa contains a highly reduced plastid-like organelle termed apicoplast.Data from clpC gene in apicoplast and their homologs in other plastids and bacteria were used to reconstruct phylogeny of apicoplast.Trees were reconstructed using neighbor-joining,minimum evolution,maximum parsimony and maximum likelihood.The reconstructions robustly support the monophyly of apicoplast and B.burgdorferi.This result underpins the mixture-genome hypotheses of apicoplast,furthermore,provides a new insight into the origin of this mixture genome.