Plohl M, Ugarković D
Department of Molecular Genetics, Ruder Bosković Institute, Zagreb, Croatia.
J Mol Evol. 1994 Nov;39(5):489-95. doi: 10.1007/BF00173418.
Two highly abundant satellite DNAs comprise 36% of the Tenebrio obscurus (Tenebrionidae, Coleoptera) genome. They are designated as satellite I and satellite II with the monomer length of 344 and 142 base pairs (bp), respectively. Both satellites differ in their nucleotide (nt) sequences, but the frequency of point mutations, well-conserved length of monomer variants, stretches of shared mutations characteristic for the process of gene conversion, and distribution of both satellites in regions of centromeric heterochromatin of all chromosomes indicate that the same evolutionary processes act on both of them with the same, or similar, rate. While satellite I shares no sequence similarity with any other known nt sequence, satellite II is 79.7% homologous with the highly abundant satellite from closely related Tenebrio molitor. Difference in the frequency of point mutations and absence of shared mutations indicating gene conversion strongly suggest that in these two closely related species mutational processes affecting satellite DNAs seem to be changed. Retarded electrophoretic mobility, due to sequence-induced curvature of DNA helix axis, was observed for T. obscurus satellite II, but not for satellite I. Although evolutionary processes act with different rates in T. obscurus and T. molitor satellites the monomer length and sequence-induced curvature are well preserved in both 142-bp satellites, as well as in, at the nt sequence level completely divergent, Palorus ratzeburgii (Tenebrionidae) satellite, indicating potential importance of these parameters in their evolution.
两种高度丰富的卫星DNA占暗黑拟步甲（拟步甲科，鞘翅目）基因组的36%。它们分别被命名为卫星I和卫星II，单体长度分别为344和142个碱基对（bp）。两种卫星的核苷酸（nt）序列不同，但点突变频率、单体变体保守的长度、基因转换过程特有的共享突变片段以及两种卫星在所有染色体着丝粒异染色质区域的分布表明，相同的进化过程以相同或相似的速率作用于它们两者。虽然卫星I与任何其他已知的nt序列没有序列相似性，但卫星II与亲缘关系密切的黄粉虫中高度丰富的卫星具有79.7%的同源性。点突变频率的差异以及表明基因转换的共享突变的缺失强烈表明，在这两个亲缘关系密切的物种中，影响卫星DNA的突变过程似乎发生了变化。暗黑拟步甲卫星II由于DNA螺旋轴的序列诱导曲率而观察到电泳迁移率延迟，但卫星I没有。尽管进化过程在暗黑拟步甲和黄粉虫卫星中的作用速率不同，但142-bp卫星以及在nt序列水平上完全不同的拉氏拟谷盗（拟步甲科）卫星中，单体长度和序列诱导曲率都得到了很好的保留，这表明这些参数在它们的进化中具有潜在的重要性。
