Fraser James A, Huang Johnny C, Pukkila-Worley Read, Alspaugh J Andrew, Mitchell Thomas G, Heitman Joseph
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.
Eukaryot Cell. 2005 Feb;4(2):401-6. doi: 10.1128/EC.4.2.401-406.2005.
Large chromosomal events such as translocations and segmental duplications enable rapid adaptation to new environments. Here we marshal genomic, genetic, meiotic mapping, and physical evidence to demonstrate that a chromosomal translocation and segmental duplication occurred during construction of a congenic strain pair in the fungal human pathogen Cryptococcus neoformans. Two chromosomes underwent telomere-telomere fusion, generating a dicentric chromosome that broke to produce a chromosomal translocation, forming two novel chromosomes sharing a large segmental duplication. The duplication spans 62,872 identical nucleotides and generated a second copy of 22 predicted genes, and we hypothesize that this event may have occurred during meiosis. Gene disruption studies of one embedded gene (SMG1) corroborate that this region is duplicated in an otherwise haploid genome. These findings resolve a genome project assembly anomaly and illustrate an example of rapid genome evolution in a fungal genome rich in repetitive elements.
诸如易位和节段性重复等大型染色体事件能够使生物体快速适应新环境。在此，我们整合了基因组、遗传学、减数分裂图谱以及物理证据，以证明在真菌人类病原体新型隐球菌构建同基因菌株对的过程中发生了一次染色体易位和节段性重复。两条染色体发生了端粒-端粒融合，产生了一条双着丝粒染色体，该染色体断裂后产生了一次染色体易位，形成了两条共享大片段重复的新染色体。该重复片段跨度为62,872个相同核苷酸，并产生了22个预测基因的第二个拷贝，我们推测这一事件可能发生在减数分裂期间。对一个嵌入基因（SMG1）的基因破坏研究证实，在原本为单倍体的基因组中该区域是重复的。这些发现解决了一个基因组计划组装异常问题，并例证了在富含重复元件的真菌基因组中快速基因组进化的一个实例。
