School of Biosciences, University of Kent, Canterbury, UK.
Heredity (Edinb). 2012 Jan;108(1):37-41. doi: 10.1038/hdy.2011.99. Epub 2011 Nov 2.
It is generally believed that the organization of avian genomes remains highly conserved in evolution as chromosome number is constant and comparative chromosome painting demonstrated there to be very few interchromosomal rearrangements. The recent sequencing of the zebra finch (Taeniopygia guttata) genome allowed an assessment of the number of intrachromosomal rearrangements between it and the chicken (Gallus gallus) genome, revealing a surprisingly high number of intrachromosomal rearrangements. With the publication of the turkey (Meleagris gallopavo) genome it has become possible to describe intrachromosomal rearrangements between these three important avian species, gain insight into the direction of evolutionary change and assess whether breakpoint regions are reused in birds. To this end, we aligned entire chromosomes between chicken, turkey and zebra finch, identifying syntenic blocks of at least 250 kb. Potential optimal pathways of rearrangements between each of the three genomes were determined, as was a potential Galliform ancestral organization. From this, our data suggest that around one-third of chromosomal breakpoint regions may recur during avian evolution, with 10% of breakpoints apparently recurring in different lineages. This agrees with our previous hypothesis that mechanisms of genome evolution are driven by hotspots of non-allelic homologous recombination.
一般认为，鸟类基因组的组织在进化过程中保持高度保守，因为染色体数目是恒定的，并且比较染色体着色表明很少有染色体间重排。斑马雀（Taeniopygia guttata）基因组的最近测序允许评估它与鸡（Gallus gallus）基因组之间的染色体内重排数量，结果显示染色体内重排数量惊人地多。随着火鸡（Meleagris gallopavo）基因组的公布，现在可以描述这三种重要禽类之间的染色体内重排，深入了解进化变化的方向，并评估鸟类中是否重新使用了断点区域。为此，我们在鸡、火鸡和斑马雀之间对整个染色体进行了比对，确定了至少 250kb 的同线块。还确定了三个基因组之间每个基因组的潜在最佳重排途径，以及一个潜在的 Galliform 祖先组织。由此，我们的数据表明，在鸟类进化过程中，大约三分之一的染色体断点区域可能会重复出现，其中 10%的断点显然在不同的谱系中重复出现。这与我们之前的假设一致，即基因组进化的机制是由非等位基因同源重组的热点驱动的。
