Croan D G, Morrison D A, Ellis J T
Faculty of Science, University of Technology Sydney, NSW, Australia.
Mol Biochem Parasitol. 1997 Nov;89(2):149-59. doi: 10.1016/s0166-6851(97)00111-4.
Previous hypotheses of Leishmania evolution are undermined by limitations in the phylogenetic reconstruction method employed or due to the omission of key parasites. In this experiment, sequences of the gene encoding the DNA polymerase alpha catalytic polypeptide (POLA) were analysed phylogenetically in combination with those encoding the RNA polymerase II largest subunit gene (RPOIILS) to infer a comprehensive phylogeny of Leishmania. Nineteen species of parasites were studied, comprising representatives of each Leishmania species-complex (Leishmania Leishmania tropica, Leishmania Leishmania donovani, Leishmania Leishmania mexicana, Leishmania Leishmania hertigi and Leishmania Viannia braziliensis), as well as parasites of questionable taxonomy (Leishmania herreri, Sauroleishmania adleri, Sauroleishmania deanei, Sauroleishmania gymnodactyli and Sauroleishmania tarentolae). The analyses presented here provide strong support for the hypothesis that the Leishmania that infect reptiles (also known as Sauroleishmania) evolved from mammalian Leishmania. One implication of this finding is that the taxonomic definition of Leishmania should be broadened to encompass characteristics of the reptilian parasites. However, this taxonomic revision is complicated in that Leishmania (L.) hertigi, Leishmania (L.) deanei and Leishmania herreri, which exhibit some biological properties of Leishmania, are more closely related to Endotrypanum on the basis of these sequence comparisons. Consequently, the taxonomic discrimination between Leishmania that infect mammals, Leishmania that infect reptiles and Endotrypanum may be more problematic than has been previously thought. Since our resulting phylogenetic hypothesis is supported by the analyses of two different genes, we speculate on the origin and evolutionary expansion of this lineage of kinetoplastid protozoa.
先前关于利什曼原虫进化的假说因所采用的系统发育重建方法存在局限性或因遗漏关键寄生虫而受到削弱。在本实验中，对编码DNA聚合酶α催化多肽（POLA）的基因序列与编码RNA聚合酶II最大亚基基因（RPOIILS）的序列进行了系统发育分析，以推断利什曼原虫的综合系统发育。研究了19种寄生虫，包括每个利什曼原虫物种复合体的代表（热带利什曼原虫、杜氏利什曼原虫、墨西哥利什曼原虫、赫氏利什曼原虫和巴西维扬尼亚利什曼原虫），以及分类地位存疑的寄生虫（赫氏利什曼原虫、蜥蜴利什曼原虫、迪氏利什曼原虫、裸趾虎利什曼原虫和沙蜥利什曼原虫）。此处呈现的分析为感染爬行动物的利什曼原虫（也称为蜥蜴利什曼原虫）从哺乳动物利什曼原虫进化而来的假说提供了有力支持。这一发现的一个含义是，利什曼原虫的分类定义应扩大到包括爬行动物寄生虫的特征。然而，这种分类修订很复杂，因为基于这些序列比较，表现出一些利什曼原虫生物学特性的赫氏利什曼原虫、迪氏利什曼原虫和赫氏利什曼原虫与内锥虫关系更为密切。因此，感染哺乳动物的利什曼原虫、感染爬行动物的利什曼原虫和内锥虫之间的分类区分可能比之前认为的更具问题。由于我们得出的系统发育假说得到了两个不同基因分析的支持，我们推测了这种动基体原生动物谱系的起源和进化扩张。
