Bennett Sarah M, Noor Mohamed A F
Biology Department, Duke University, Durham, NC 27708, USA.
Genetica. 2009 Nov;137(2):213-9. doi: 10.1007/s10709-009-9376-9. Epub 2009 Jun 25.
The human cancer susceptibility gene, BRCA2, functions in double-strand break repair by homologous recombination, and it appears to function via interaction of a repetitive region ("BRC repeats") with RAD-51. A putatively simpler homolog, dmbrca2, was identified in Drosophila melanogaster recently and also affects mitotic and meiotic double-strand break repair. In this study, we examined patterns of repeat variation both within Drosophila pseudoobscura and among available Drosophila genome sequences. We identified extensive variation within and among closely related Drosophila species in BRC repeat number, to the extent that variation within this genus recapitulates the extent of variation found across the entire animal kingdom. We describe patterns of evolution across species by documenting recent repeat expansions (sometimes in tandem arrays) and homogenizations within available genome sequences. Overall, we have documented patterns and modes of evolution in a new model system of a gene which is important to human health.
人类癌症易感基因BRCA2通过同源重组参与双链断裂修复，它似乎是通过一个重复区域（“BRC重复序列”）与RAD-51相互作用来发挥功能的。最近在黑腹果蝇中鉴定出一种推测更为简单的同源基因dmbrca2，它也影响有丝分裂和减数分裂中的双链断裂修复。在本研究中，我们研究了拟暗果蝇内部以及现有果蝇基因组序列之间的重复序列变异模式。我们发现，在亲缘关系较近的果蝇物种内部和物种之间，BRC重复序列的数量存在广泛变异，以至于该属内的变异程度概括了整个动物界所发现的变异程度。我们通过记录现有基因组序列中最近的重复序列扩增（有时呈串联阵列）和同质化现象，描述了跨物种的进化模式。总体而言，我们在一个对人类健康至关重要的基因的新模型系统中记录了进化模式和方式。
