Capewell Paul, Monk Stephanie, Ivens Alasdair, Macgregor Paula, Fenn Katelyn, Walrad Pegine, Bringaud Frederic, Smith Terry K, Matthews Keith R
Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh, United Kingdom.
PLoS One. 2013 Jun 26;8(6):e67069. doi: 10.1371/journal.pone.0067069. Print 2013.
The gene expression of Trypanosoma brucei has been examined extensively in the blood of mammalian hosts and in forms found in the midgut of its arthropod vector, the tsetse fly. However, trypanosomes also undergo development within the mammalian bloodstream as they progress from morphologically 'slender forms' to transmissible 'stumpy forms' through morphological intermediates. This transition is temporally progressive within the first wave of parasitaemia such that gene expression can be monitored in relatively pure slender and stumpy populations as well as during the progression between these extremes. The development also represents the progression of cells from translationally active forms adapted for proliferation in the host to translationally quiescent forms, adapted for transmission. We have used metabolic labelling to quantitate translational activity in slender forms, stumpy forms and in forms undergoing early differentiation to procyclic forms in vitro. Thereafter we have examined the cohort of total mRNAs that are enriched throughout development in the mammalian bloodstream (slender, intermediate and stumpy forms), irrespective of strain, revealing those that exhibit consistent developmental regulation rather than sample specific changes. Transcripts that cosediment with polysomes in stumpy forms and slender forms have also been enriched to identify transcripts that escape translational repression prior to transmission. Combined, the expression and polysomal association of transcripts as trypanosomes undergo development in the mammalian bloodstream have been defined, providing a resource for trypanosome researchers. This facilitates the identification of those that undergo developmental regulation in the bloodstream and therefore those likely to have a role in the survival and capacity for transmission of stumpy forms.
布氏锥虫的基因表达已在哺乳动物宿主的血液以及其节肢动物载体采采蝇中肠内发现的形态中进行了广泛研究。然而，锥虫在哺乳动物血液中也会经历发育过程，它们会从形态上的“细长型”通过形态学中间体逐渐转变为可传播的“粗短型”。这种转变在第一次寄生虫血症浪潮中是随时间逐步进行的，因此可以在相对纯净的细长型和粗短型群体中以及在这两种极端形态之间的转变过程中监测基因表达。这种发育过程还代表了细胞从适应在宿主体内增殖的翻译活跃形式向适应传播的翻译静止形式的转变。我们利用代谢标记法来定量细长型、粗短型以及体外早期分化为前循环型的形态中的翻译活性。此后，我们研究了在哺乳动物血液中整个发育过程（细长型、中间型和粗短型）中富集的总mRNA群体，无论菌株如何，揭示出那些表现出一致的发育调控而非样本特异性变化的mRNA。还富集了在粗短型和细长型中与多核糖体共沉降的转录本，以鉴定在传播之前逃避翻译抑制的转录本。综合起来，已经确定了锥虫在哺乳动物血液中发育过程中转录本的表达和多核糖体关联情况，为锥虫研究人员提供了一种资源。这有助于识别那些在血液中经历发育调控的转录本，从而识别那些可能在粗短型的存活和传播能力中发挥作用的转录本。
