Plohl M, Mestrovic N, Bruvo B, Ugarkovic D
Department of Molecular Genetics, Ruder Boskovic Institute, Bijenicka 54, P.O. Box 1016, HR-10000 Zagreb, Croatia.
J Mol Evol. 1998 Feb;46(2):234-9. doi: 10.1007/pl00006298.
A novel highly abundant satellite DNA comprising 20% of the genome has been characterized in Palorus subdepressus (Insecta, Coleoptera). The 72-bp-long monomer sequence is composed of two copies of T2A5T octanucleotide alternating with 22-nucleotide-long elements of an inverted repeat. Phylogenetic analysis revealed clustering of monomer sequence variants into two clades. Two types of variants are prevalently organized in an alternating pattern, thus showing a tendency to generate a new complex repeating unit 144 bp in length. Fluorescent in situ hybridization revealed even distribution of the satellite in the region of pericentric heterochromatin of all 20 chromosomes. P. subdepressus satellite sequence is clearly species specific, lacking similarity even with the satellite from congeneric species P. ratzeburgii. However, on the basis of similarity in predicted tertiary structure induced by intrinsic DNA curvature and in repeat length, P. subdepressus satellite can be classified into the same group with satellites from related tenebrionid species P. ratzeburgii, Tenebrio molitor, and T. obscurus. It can be reasonably inferred that repetitive sequences of different origin evolve under constraints to adopt and conserve particular features. Obtained results suggest that the higher-order structure and repeat length, but not the nucleotide sequence itself, are maintained through evolution of these species.
在扁足拟谷盗（昆虫纲，鞘翅目）中鉴定出一种新型的高丰度卫星DNA，其占基因组的20%。72个碱基对长的单体序列由两个T2A5T八核苷酸拷贝与22个核苷酸长的反向重复元件交替组成。系统发育分析显示单体序列变体聚类为两个进化枝。两种类型的变体普遍以交替模式排列，因此显示出产生一个新的144个碱基对长的复杂重复单元的趋势。荧光原位杂交显示卫星在所有20条染色体的着丝粒周围异染色质区域均匀分布。扁足拟谷盗卫星序列具有明显的物种特异性，甚至与同属物种拉氏拟谷盗的卫星也缺乏相似性。然而，基于由内在DNA曲率诱导的预测三级结构和重复长度的相似性，扁足拟谷盗卫星可与来自相关拟步甲科物种拉氏拟谷盗、黄粉虫和赤拟谷盗的卫星归为同一组。可以合理推断，不同起源的重复序列在限制条件下进化以采用和保留特定特征。获得的结果表明，这些物种的进化过程中维持的是高阶结构和重复长度，而不是核苷酸序列本身。
