Mestrović N, Plohl M, Mravinac B, Ugarković D
Department of Molecular Genetics, Ruder Bosković Institute, Zagreb, Croatia.
Mol Biol Evol. 1998 Aug;15(8):1062-8. doi: 10.1093/oxfordjournals.molbev.a026005.
Satellite DNA profiles have been characterized in the congeneric species Palorus ratzeburgii, Palorus subdepressus, Palorus genalis, and Palorus ficicola (Coleoptera, Insecta), each of which contains a single, A + T-rich satellite DNA comprising a considerable portion of the genome (20%-40%). These satellites exhibit insignificant mutual sequence similarity. Using PCR assay, it has been shown that all four sequences are present in each of the tested Palorus species: one of them is amplified into a high copy number or a major satellite, while the three others are in the form of low-copy-number repeats estimated to make up approximately 0.05% of the genome. Each of the four satellites is interspecifically high conserved concerning the sequence, monomer length, and tandem repeat organization. Major, as well as low-copy-number, satellites are colocalized in the regions of pericentromeric heterochromatin on all chromosomes of the complement. The low-copy-number satellites are dispersed between the large arrays of the major satellite over the whole heterochromatic block. Our results explain satellite DNA evolution, confirming the hypothesis that related species share a "library" of conserved satellite sequences, some of which could be amplified into a major satellite. Due to the evolutionary dynamics of satellite DNAs, the content of the "library" is variable; the elimination of some sequences parallels the creation of the new ones. Quantitative changes in satellite DNAs, induced by occasional amplification of satellite repeat from the "library", could possibly occur in the course of the speciation process, thus forming a species-specific profile of satellite DNAs.
在同属物种拉氏扁谷盗（Palorus ratzeburgii）、亚扁谷盗（Palorus subdepressus）、颊扁谷盗（Palorus genalis）和菲氏扁谷盗（Palorus ficicola）（鞘翅目，昆虫纲）中已对卫星DNA图谱进行了表征，每个物种都含有单一的、富含A + T的卫星DNA，其在基因组中占相当大的比例（20%-40%）。这些卫星彼此间序列相似性不显著。通过PCR分析表明，在每个测试的扁谷盗物种中都存在所有这四种序列：其中一种被扩增为高拷贝数或主要卫星DNA，而其他三种则以低拷贝数重复序列的形式存在，估计约占基因组的0.05%。这四种卫星中的每一种在序列、单体长度和串联重复序列组织方面在种间都高度保守。主要卫星DNA以及低拷贝数卫星DNA都共定位于互补染色体组所有染色体的着丝粒周围异染色质区域。低拷贝数卫星分散在整个异染色质块中主要卫星DNA的大片段之间。我们的结果解释了卫星DNA的进化，证实了相关物种共享一个保守卫星序列“文库”的假说，其中一些序列可以扩增为主要卫星DNA。由于卫星DNA的进化动态，“文库”的内容是可变的；一些序列的消除与新序列的产生并行。由“文库”中卫星重复序列的偶尔扩增引起的卫星DNA的定量变化可能在物种形成过程中发生，从而形成物种特异性的卫星DNA图谱。
