Harpold M M, Craig S P
Nucleic Acids Res. 1977 Dec;4(12):4425-37. doi: 10.1093/nar/4.12.4425.
Molecular hybridization of nuclear DNAs has been employed to study the evolution of the repetitive DNA sequences in four species of sea urchin. The data show that relative to S. purpuratus there has been approximately 0.1% sequence divergence per million years in the repetitive DNA sequences of S. droebachiensis, S. franciscanus, and L. pictus. These results confirm that repetitive DNA sequences are strongly conserved during evolution. However, comparison of the extent of base pair mismatch in the repetitive DNA heteroduplexes formed at Cot 20 with those formed at Cot 200 during the hybridization of S. purpuratus and L. pictus DNAs reveals that highly repetitive sequences of sea urchins may diverge more rapidly than do the more moderately repetitive sequences.
核DNA的分子杂交已被用于研究四种海胆中重复DNA序列的进化。数据表明，相对于紫球海胆（Strongylocentrotus purpuratus），在球海胆（Strongylocentrotus droebachiensis）、加州紫海胆（Strongylocentrotus franciscanus）和花斑长海胆（Lytechinus pictus）的重复DNA序列中，每百万年大约有0.1%的序列分歧。这些结果证实了重复DNA序列在进化过程中具有很强的保守性。然而，在紫球海胆和花斑长海胆DNA杂交过程中，比较在Cot 20时形成的重复DNA异源双链体与在Cot 200时形成的重复DNA异源双链体的碱基对错配程度，发现海胆的高度重复序列可能比中度重复序列分歧得更快。
