Dipartimento di Biologia, University of Pisa, 56126 Pisa, Italy.
Proc Natl Acad Sci U S A. 2011 Feb 22;108(8):3181-6. doi: 10.1073/pnas.1019432108. Epub 2011 Feb 7.
Wild-type strains of the protozoan ciliate Euplotes collected from different locations on the coasts of Antarctica, Tierra del Fuego and the Arctic were taxonomically identified as the morpho-species Euplotes nobilii, based on morphometric and phylogenetic analyses. Subsequent studies of their sexual interactions revealed that mating combinations of Antarctic and Arctic strains form stable pairs of conjugant cells. These conjugant pairs were isolated and shown to complete mutual gene exchange and cross-fertilization. The biological significance of this finding was further substantiated by demonstrating that close homology exists among the three-dimensional structures determined by NMR of the water-borne signaling pheromones that are constitutively secreted into the extracellular space by these interbreeding strains, in which these molecules trigger the switch between the growth stage and the sexual stage of the life cycle. The fact that Antarctic and Arctic E. nobilii populations share the same gene pool and belong to the same biological species provides new support to the biogeographic model of global distribution of eukaryotic microorganisms, which had so far been based exclusively on studies of morphological and phylogenetic taxonomy.
从南极洲、火地岛和北极海岸的不同地点采集的原生纤毛虫 Euplotes 的野生型菌株，基于形态计量学和系统发育分析，被分类为形态种 Euplotes nobilii。随后对它们的性相互作用的研究表明，南极和北极菌株的交配组合形成稳定的配对共轭细胞。这些共轭对被分离出来，并被证明能够完成相互的基因交换和杂交受精。这一发现的生物学意义进一步得到证实，因为通过 NMR 确定的三维结构之间存在密切的同源性，这些三维结构由这些杂交菌株持续分泌到细胞外空间的水性信号信息素决定，这些分子触发了生命周期中生长阶段和性阶段之间的转换。南极和北极 E. nobilii 种群共享相同的基因库，属于同一生物物种，这为真核微生物全球分布的生物地理模型提供了新的支持，该模型迄今为止仅基于形态学和系统发育分类学的研究。
