Donehower L, Furlong C, Gillespie D, Kurnit D
Proc Natl Acad Sci U S A. 1980 Apr;77(4):2129-33. doi: 10.1073/pnas.77.4.2129.
A highly repeated DNA was isolated from the West African baboon (Papio papio) as a 343-base-pair fragment after digestion of total baboon DNA with the restriction endonuclease BamHI. The DNA sequence of this fragment was obtained by chemical cleavage methods and is compared with the DNA sequence of related highly repeated primate DNAs from African green monkey (Cercopithecus aethiops) and man. The 343-base-pair baboon repeat consists of two related but nonidentical wings of 172 and 171 base pairs, respectively. The baboon 172-base-pair wing shares more homology with the African green monkey 172-base-pair repeat than with the baboon 171-base-pair wing. Comparison with the previously published monkey and human DNA sequences indicates that: (i) All the DNA sequences apparently arose from a common ancestral sequence. (ii) Evolution of the primate DNA sequences can be explained by a model involving unequal crossovers at specific points within the repeated DNA, possibly mediated by the sequence 5'-AAGG-3' 3'-TTCC-5' or its invert 5'-GGAA-3' 3'-CCTT-5'. (iii) There are alternating domains of conserved and divergent DNA sequences within each greater than 170-base-pair wing sequence. Taken together, the DNA sequences of these primates suggest a model whereby highly repeated DNAs are established and evolve as a consequence of unequal nonrandom exchanges of DNA duplexes. These exchanges may be mediated by short repeated nucleotide sequences and involve exchanges within and between the greater than 170-base-pair wings.
用限制性内切酶BamHI消化狒狒的总DNA后,从西非狒狒(Papio papio)中分离出一段高度重复的DNA,其片段长度为343个碱基对。通过化学切割方法获得了该片段的DNA序列,并将其与来自非洲绿猴(Cercopithecus aethiops)和人类的相关高度重复灵长类DNA的序列进行了比较。这个343个碱基对的狒狒重复序列分别由两个相关但不相同的侧翼组成,长度分别为172和171个碱基对。狒狒172个碱基对的侧翼与非洲绿猴172个碱基对的重复序列的同源性比与狒狒171个碱基对的侧翼的同源性更高。与先前发表的猴子和人类DNA序列的比较表明:(i)所有的DNA序列显然都起源于一个共同的祖先序列。(ii)灵长类DNA序列的进化可以用一个模型来解释,该模型涉及在重复DNA内的特定点发生不等交换,可能由序列5'-AAGG-3' 3'-TTCC-5'或其反向序列5'-GGAA-3' 3'-CCTT-5'介导。(iii)在每个大于170个碱基对的侧翼序列中,存在保守和发散DNA序列的交替结构域。综合来看,这些灵长类动物的DNA序列提示了一个模型,即高度重复的DNA是由于DNA双链的不等非随机交换而建立和进化的。这些交换可能由短的重复核苷酸序列介导,并且涉及大于170个碱基对的侧翼内部和之间的交换。