Department of Botany, Canadian Institute for Advanced Research, University of British Columbia, 3529-6270 University Boulevard, Vancouver, British Columbia, Canada V6T 1Z4.
Nat Commun. 2010 Sep 21;1:77. doi: 10.1038/ncomms1082.
The genome of the microsporidia Encephalitozoon cuniculi is widely recognized as a model for extreme reduction and compaction. At only 2.9 Mbp, the genome encodes approximately 2,000 densely packed genes and little else. However, the nuclear genome of its sister, Encephalitozoon intestinalis, is even more reduced; at 2.3 Mbp, it represents a 20% reduction from an already severely compacted genome, raising the question, what else can be lost? In this paper, we describe the complete sequence of the E. intestinalis genome and its comparison with that of E. cuniculi. The two species share a conserved gene content, order and density over most of their genomes. The exceptions are the subtelomeric regions, where E. intestinalis chromosomes are missing large gene blocks of sequence found in E. cuniculi. In the remaining gene-dense chromosome 'cores', the diminutive intergenic sequences and introns are actually more highly conserved than the genes themselves, suggesting that they have reached the limits of reduction for a fully functional genome.
微孢子虫脑炎原虫的基因组被广泛认为是极度简化和紧凑的模型。其基因组仅有 2.9 Mbp，编码约 2000 个紧密排列的基因，其他基因很少。然而，它的姊妹种肠脑炎原虫的核基因组更为简化；其 2.3 Mbp 的基因组相较于已经高度紧凑的基因组又减少了 20%，这就提出了一个问题，还有什么可以被删除？在本文中，我们描述了肠脑炎原虫基因组的完整序列及其与脑炎原虫基因组的比较。这两个物种在其大部分基因组中具有保守的基因含量、顺序和密度。例外的是端粒区域，肠脑炎原虫染色体在端粒区域缺失了脑炎原虫中发现的大片段序列的基因。在剩余的基因密集型染色体“核心”中，微小的基因间序列和内含子实际上比基因本身更为保守，这表明它们已经达到了一个具有完整功能基因组的最小化极限。
