Oikomonas, a distinctive zooflagellate related to chrysomonads
Oikomonas, a distinctive zooflagellate related to chrysomonads
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DOI：
10.1016/s0003-9365(96)80014-5
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发表时间：
1996-02-01
期刊：
影响因子：
--
通讯作者：
Hourihane, SL
中科院分区：
文献类型：
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作者：
CavalierSmith, T;Chao, EE;Hourihane, SL
对常见的土壤鞭毛虫肯特进行了光镜和电镜观察，并对其18 SrRNA基因进行了测序。它有管状的线粒体嵴和一个单一的前部金属丝纤毛，覆盖在一排单侧的二分（或可能是三分）的毛（retronemes）中，有单端丝，以及简单的非管状毛;因此它显然是一个异鞭毛体。它不同于以前研究的无色chrysomonads在明显缺乏一个退化的leucoplast与eyespot，在可能的二分retronemes，在没有一个退化的光滑纤毛，并在单方面安排的retronemes。鳞片似乎不存在。然而，其18 s rRNA序列的系统发育分析清楚地表明，它是最接近的金单胞菌，但它不是特别相关的副黄单胞菌。在大多数树木上，它是金单胞菌的姐妹群;虽然它的序列，因此，显着不同于所有真正的金单胞菌，与最大parsinomy方法，它可以弱组与Ochromonas。一个可能的关系，也表明了存在许多大的皮质空泡，荧光明亮时，暴露于紫外线或蓝光。明亮的短波长光在几秒钟内杀死细胞。Oikomonas似乎是异鞭毛门内质体损失和随后的二级起源的第三个独立的例子：我们目前的分析表明，假真菌（卵菌纲和丝壶菌纲）也是通过叶绿体的损失从ochristan藻类进化而来的，从而为异鞭毛门内至少四个独立的叶绿体损失提供了证据。我们创建一个新的顺序（Oikomonadales），验证类Oikomonadea Oikomonas，并包括它与类Eustigmatophycea，和Raphidomonadea的超类Limnistia，我们提出了一个修订的分类。
We have examined the common soil zooflagellate Oikomonas mutabilis KENT in the light and electron microscope and sequenced its 18s rRNA gene. It has tubular mitochondrial cristae and a single anterior tinsel cilium clothed in a unilateral row of bipartite (or possibly tripartite) hairs (retronemes) with single terminal filaments, as well with simple non-tubular hairs; it is therefore clearly a heterokont. It differs from previously studied colourless chrysomonads in the apparent absence of a vestigial leucoplast with eyespot, in the probably bipartite retronemes, in the absence of a vestigial smooth cilium, and in the unilateral arrangement of the retronemes. Scales appear to be absent. Phylogenetic analysis of its 18s rRNA sequence, however, clearly shows that it is most closely related to the chrysomonads, but it is not specifically related to Paraphysomonas. On most trees it is the sister group to chrysomonads; though its sequence is, therefore, significantly divergent from those of all genuine chrysomonads, with the maximum parsinomy method it can group weakly with Ochromonas. A possible relationship with Ochromonas is also suggested by the presence of numerous large cortical vacuoles which fluoresce brightly when exposed to ultraviolet or blue light. Bright short wavelength light kills the cells in a few seconds. Oikomonas appears to be a third independent example of plastid loss and the consequent secondary origin of zooflagellates within the Heterokonta: our present analysis suggests that Pseudofungi (oomycetes and hyphochytriomycetes) also evolved from ochristan algae, by the loss of chloroplasts, thus providing evidence for at]east four separate losses of chloroplasts within Heterokonta. We create a new order (Oikomonadales), validate the class Oikomonadea for Oikomonas, and include it with the classes Chrysomonadea, Eustigmatophycea, and Raphidomonadea in the superclass Limnistia, for which we present a revised classification.