Shape-shifting trypanosomes: Flagellar shortening followed by asymmetric division in Trypanosoma congolense from the tsetse proventriculus.
Shape-shifting trypanosomes: Flagellar shortening followed by asymmetric division in Trypanosoma congolense from the tsetse proventriculus.
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DOI：
10.1371/journal.ppat.1007043
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发表时间：
2018-05
期刊：
影响因子：
6.7
通讯作者：
Gibson W
中科院分区：
文献类型：
--
作者：
Peacock L;Kay C;Bailey M;Gibson W
锥虫（如利什曼原虫和锥虫）是双遗传的单细胞寄生鞭毛虫，它们经历复杂的生命周期，包括形态和代谢变化，以适应它们在哺乳动物和昆虫宿主中的不同环境中生存。根据目前的共识，不对称分裂使锥虫实现与发育阶段之间的过渡相关的主要形态重排。与这种观点相反，在这里，我们表明，非洲锥虫刚果锥虫，一个重要的牲畜病原体，经历了广泛的细胞重塑，涉及缩短的细胞体和鞭毛，在其过渡期间，从自由游泳proventral形式附加epimastigotes在体外。鞭毛的缩短与PFR 1的积累有关，PFR 1是鞭毛旁杆的主要成分，在鞭毛的中部区域，它附着在基板上。然而，PFR 1贮库不是附着所必需的，因为它在腺室锥虫初始附着后数小时积累。洗涤剂和CaCl 2处理未能去除附着的寄生虫，表明鞭毛附着于底物的稳健性质; PFR 1贮库也不受这些处理的影响。重构的腺室锥虫分裂是不对称的，产生一个小子细胞。每个母细胞继续产生至少一个子细胞，而子锥虫也增殖，最终导致上鞭毛体的密集培养。通过观察采采蝇前胃中同质锥虫种群的同步发育，我们已经能够详细地研究从腺室型到附着上鞭毛体的转变。刚果语。这种转变很难在体内观察到，因为它发生在采采蝇的口器内部。于T.在布氏锥鞭毛体中，这种转变是通过前胃中长锥鞭毛体的不对称分裂来实现的，产生短的上鞭毛体，其继续定殖于唾液腺。因此，尽管它们在进化上有着密切的关系，并且在载体中有着共同的发展路线，但T. brucei和T. Congolense已经进化出不同的方式来完成从腺室形式到附着外鞭毛体的相同发育转变。采采蝇传播的锥虫是在热带非洲引起严重人类和牲畜疾病的寄生原生生物。在采采蝇的发育周期中，这些锥虫经历复杂的分化和增殖周期。在这里，我们调查了主要家畜病原体刚果锥虫的发育周期的一部分，因为它从苍蝇中肠通过前肠的口器，在那里它重新获得感染哺乳动物宿主。这种转变是很难在体内观察到的，因为迁移锥虫的数量很少，他们在苍蝇的不可访问性。然而，在迁移之前，锥虫在前胃中积累，前胃是将前肠与中肠分开的阀门，我们能够观察这些细胞的体外行为。从腺胃释放出来后，这些锥虫很容易附着在显微镜载玻片上，然后经历剧烈的重塑，变成短而结实的细胞，然后每个细胞产生一个小的子细胞。每个母细胞以同样的方式继续产生至少一个子锥虫，而子细胞也作为附着细胞增殖。我们假设这些事件通常发生在体内的舌蝇喙内。于T.布氏杆菌中，相同的发育转变发生在自由游动的前胃或前肠中，而不是附着的细胞中，并且通过不对称分裂实现。因此，尽管这两种锥虫物种的进化关系密切，但它们进化出了不同的方式来完成本质上相同的发育转变。
Trypanosomatids such as Leishmania and Trypanosoma are digenetic, single-celled, parasitic flagellates that undergo complex life cycles involving morphological and metabolic changes to fit them for survival in different environments within their mammalian and insect hosts. According to current consensus, asymmetric division enables trypanosomatids to achieve the major morphological rearrangements associated with transition between developmental stages. Contrary to this view, here we show that the African trypanosome Trypanosoma congolense, an important livestock pathogen, undergoes extensive cell remodelling, involving shortening of the cell body and flagellum, during its transition from free-swimming proventricular forms to attached epimastigotes in vitro. Shortening of the flagellum was associated with accumulation of PFR1, a major constituent of the paraflagellar rod, in the mid-region of the flagellum where it was attached to the substrate. However, the PFR1 depot was not essential for attachment, as it accumulated several hours after initial attachment of proventricular trypanosomes. Detergent and CaCl2 treatment failed to dislodge attached parasites, demonstrating the robust nature of flagellar attachment to the substrate; the PFR1 depot was also unaffected by these treatments. Division of the remodelled proventricular trypanosome was asymmetric, producing a small daughter cell. Each mother cell went on to produce at least one more daughter cell, while the daughter trypanosomes also proliferated, eventually resulting in a dense culture of epimastigotes. Here, by observing the synchronous development of the homogeneous population of trypanosomes in the tsetse proventriculus, we have been able to examine the transition from proventricular forms to attached epimastigotes in detail in T. congolense. This transition is difficult to observe in vivo as it happens inside the mouthparts of the tsetse fly. In T. brucei, this transition is achieved by asymmetric division of long trypomastigotes in the proventriculus, yielding short epimastigotes, which go on to colonise the salivary glands. Thus, despite their close evolutionary relationship and shared developmental route within the vector, T. brucei and T. congolense have evolved different ways of accomplishing the same developmental transition from proventricular form to attached epimastigote. Tsetse-transmitted trypanosomes are parasitic protists that cause severe human and livestock diseases in tropical Africa. During their developmental cycle in the tsetse fly, these trypanosomes undergo complex cycles of differentiation and proliferation. Here we have investigated part of the developmental cycle of the major livestock pathogen Trypanosoma congolense as it moves from the fly midgut via the foregut to the mouthparts, where it reacquires infectivity to mammalian hosts. This transition is difficult to observe in vivo because of the small numbers of migratory trypanosomes and their inaccessibility in the fly. However, prior to migration, trypanosomes accumulate in the proventriculus, the valve that separates the foregut from the midgut, and we were able to observe the behaviour of these cells in vitro. On release from the proventriculus, these trypanosomes readily attach to a glass microscope slide and then undergo drastic remodelling to become short, stout cells, before each produces a small daughter cell. Each mother cell goes on to produce at least one further daughter trypanosome in the same way, while the daughter cells also proliferate as attached cells. We assume that these events would normally happen in vivo inside the tsetse proboscis. In T. brucei the equivalent developmental transition takes place in the proventriculus or foregut in free-swimming rather than attached cells, and is achieved via an asymmetric division. Thus, despite their close evolutionary relationship, these two trypanosome species have evolved different ways of accomplishing what is essentially the same developmental transition.
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影响因子：
7.8
作者：
Marshall, W F;Rosenbaum, J L
通讯作者：
Rosenbaum, J L
DOI：
10.1080/00034983.1947.11685305
发表时间：
1947-01-01
影响因子：
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通讯作者：
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2.4
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通讯作者：
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影响因子：
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作者：
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影响因子：
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作者：
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通讯作者：
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