微孢子虫系统进化研究的变迁与展望

Advances in the taxonomic study of Microsporidia

摘要:

微孢子虫(Microsporidia)是一类专性细胞内寄生的单细胞真核生物，在科研、医疗、农业、商业等领域具有重要影响。由于其不具有某些典型的真核生物细胞结构，如线粒体、过氧化物酶体、高尔基体、鞭毛，曾将其归属于古真核生物谱系，认为其进化历程先于这些细胞器的起源，该假说也得到了一些生物化学和分子生物学研究证据的支持。然而，在最近十年里，通过更深入的研究，尤其是基于分子序列的系统进化分析，表明微孢子虫和真菌具有一定亲缘关系，并认为其结构的简约性恰好体现了微孢子虫营寄生生活的高度退化现象。目前对微孢子虫的系统进化仍存在各种不同意见，对其进化研究历史进行探讨有着重要意义。本文将按照时间顺序回顾微孢子虫进化分类研究过程中的各种研究成果，并讨论为什么微孢子虫独特的细胞和基因组特性会导致众多的学者在其进化分类问题上争执这么久。

Abstract:

Microsporidia are obligate intracellular eukaryotic parasites that infect a wide variety of species, including humans. Members of this phylum have some unusual characteristics compared with other eukaryotes, including the lack of mitochondria, Golgi apparatus, peroxisomes and ?agella, which therefore led to the Archezoa hypothesis, namely the origin of the Microsporidia might have preceded the endosymbiotic origin of those cellular components. However, some recent studies have indicated that Microsporidia related to the fungi and that Microsporidia retain a mitosome which is thought to be the remnant of the mitochondria. The long-branch attraction also explains the primitive placement of Microsporidia within the eukaryotic phylogenetic tree. Here we review the microsporidian taxonomic revisions and discuss the causes and results for these study.