3月26日，《PLoS Biology》以封面文章发表了题为“Selecting One of Several Mating Types through Gene Segment Joining and Deletion in Tetrahymena thermophila”的研究论文（http：//www.plosbiology.org/），该研究成果由中国科学院水生生物研究所原生动物功能基因组学学科组缪炜研究员等人与美国加州大学圣巴巴拉分校Orias教授实验室合作完成。
单细胞真核生物通常是通过无性生殖方式进行繁殖的，但其生活史中一般都存在有性生殖阶段，以此来增加遗传多样性以适应多变的环境。1937年，Sonneborn首先在草履虫(Paramecium Aurelia)中发现了形态上无法区分但能够通过自我/非自我(self/non-self)识别方式进行有性生殖的交配型系统，随后该系统被证实广泛存在于从细菌到单细胞真核生物的各种微生物类群中。
嗜热四膜虫(Tetrahymena thermophila)是一种优良的单细胞真核模式生物。1953年，Nanney教授首次对嗜热四膜虫交配型进行了描述，鉴定出具有7种不同的交配型，这为后来利用嗜热四膜虫的有性生殖建立成熟的基因操作技术并将其发展为模式生物奠定了重要基础。1954至1960年间，Orias作为Nanney教授的博士生开始了四膜虫交配型的研究。然而，半个多世纪过去了，关于嗜热四膜虫交配型决定的分子基础和机制问题一直悬而未决，成为困扰四膜虫研究领域的一大难题。2011年，缪炜研究团队通过对不同交配型嗜热四膜虫在饥饿早期的转录组数据进行比较分析，精确预测出了嗜热四膜虫的交配型决定基因：一对“头对头”的基因对（a pair of genes arranged head-to-head）。之后通过和Orias教授的深入合作，最终揭示了嗜热四膜虫交配型决定的分子机制：包括所有交配型决定基因对单元的嗜热四膜虫小核，在有性生殖过程中，经过一系列的程序化DNA重排（programed DNA rearrangements）发育成只含有一个交配型决定基因对单元的大核。
该研究成果，不仅揭示了纤毛类原生动物交配型决定的机制，还对于性别决定和起源进化、细胞自我/非自我识别、肿瘤/癌症发生相关的DNA重排机制的认识具有重要价值。（生物谷Bioon.com）
doi:10.1371/journal.pbio.1001518
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Selecting One of Several Mating Types through Gene Segment Joining and Deletion in Tetrahymena thermophila
Cervantes MD, Hamilton EP, Xiong J, Lawson MJ, Yuan D, et al
The unicellular eukaryote Tetrahymena thermophila has seven mating types. Cells can mate only when they recognize cells of a different mating type as non-self. As a ciliate, Tetrahymena separates its germline and soma into two nuclei. During growth the somatic nucleus is responsible for all gene transcription while the germline nucleus remains silent. During mating, a new somatic nucleus is differentiated from a germline nucleus and mating type is decided by a stochastic process. We report here that the somatic mating type locus contains a pair of genes arranged head-to-head. Each gene encodes a mating type-specific segment and a transmembrane domain that is shared by all mating types. Somatic gene knockouts showed both genes are required for efficient non-self recognition and successful mating, as assessed by pair formation and progeny production. The germline mating type locus consists of a tandem array of incomplete gene pairs representing each potential mating type. During mating, a complete new gene pair is assembled at the somatic mating type locus; the incomplete genes of one gene pair are completed by joining to gene segments at each end of germline array. All other germline gene pairs are deleted in the process. These programmed DNA rearrangements make this a fascinating system of mating type determination.d promote diet niche partitioning of predators and thus elevates the strength of top-down control.
