Lohe A R, Brutlag D L
J Mol Biol. 1987 Mar 20;194(2):161-70. doi: 10.1016/0022-2836(87)90365-2.
The evolution of simple satellite DNAs was examined by DNA-DNA hybridization of ten Drosophila melanogaster satellite sequences to DNAs of the sibling species, Drosophila simulans and Drosophila erecta. Seven of these repeat types are present in tandem arrays in D. simulans and each of the ten sequences is repeated in D. erecta. In thermal melts, six of the seven satellite sequences in D. simulans and seven of the ten sequences in D. erecta melted within 1 deg.C of the corresponding values in D. melanogaster. The remaining sequences melted within 3 deg.C of the homologous hybrids. Therefore, there is little or no alteration in those satellite sequences held in common, despite a period of about ten million years since the divergence of D. melanogaster and D. simulans from a common ancestor. Simple satellite sequences appear to be more highly conserved than coding regions of the genome, on a per nucleotide basis. Since multiple copies of three satellite sequences could not be detected in D. simulans yet are present in D. erecta, a species more distantly related to D. melanogaster than is D. simulans, these sequences show discontinuities in evolution. There were major quantitative variations between species, showing that satellite DNAs are prone to massive amplification or diminution events over timespans as short as those separating sibling species. In D. melanogaster, these sequences amount to 21% of the genome but only 5% in D. simulans and 0.4% in D. erecta. There was a general trend of lower abundance with evolutionary distance for most satellites, suggesting that the amounts of different satellite sequences do not vary independently during evolution.
通过将10种黑腹果蝇卫星序列与近缘物种拟果蝇和 erecta果蝇的DNA进行DNA-DNA杂交，研究了简单卫星DNA的进化。其中7种重复类型以串联阵列形式存在于拟果蝇中，10个序列中的每一个在erecta果蝇中都有重复。在热熔解过程中，拟果蝇中的7个卫星序列中的6个以及erecta果蝇中的10个序列中的7个在与黑腹果蝇相应值的1℃范围内熔解。其余序列在同源杂种的3℃范围内熔解。因此，尽管自黑腹果蝇和拟果蝇从共同祖先分化以来已有约一千万年的时间，但那些共同拥有的卫星序列几乎没有改变。按每个核苷酸计算，简单卫星序列似乎比基因组的编码区域更具高度保守性。由于在拟果蝇中未检测到三种卫星序列的多个拷贝，但在与黑腹果蝇的亲缘关系比拟果蝇更远的erecta果蝇中存在，这些序列显示出进化上的不连续性。物种之间存在主要的数量差异，表明卫星DNA在短至分离近缘物种的时间跨度内易于发生大规模扩增或减少事件。在黑腹果蝇中，这些序列占基因组的21%，但在拟果蝇中仅占5%，在erecta果蝇中占0.4%。对于大多数卫星而言，随着进化距离的增加，丰度普遍呈下降趋势，这表明不同卫星序列的数量在进化过程中并非独立变化。
