Hubbell H R, Robberson D L, Hsu T C
Nucleic Acids Res. 1979 Dec 20;7(8):2439-56. doi: 10.1093/nar/7.8.2439.
Native DNA of the Guinea pig, Cavia porcellus, purified from liver or tissue culture cells, was heat denatured and reassociated to a Cot value of 0.01 (equivalent Cot value of 7.2 x 10(-2)). The reassociated DNA was isolated by digestion with the single-strand DNA specific enzyme S1 nuclease. Spectrophotometric and radioactivity assays demonstrated that 24% of the total DNA was resistant to S1 nuclease treatment. Zero-time reassociation indicated that approximately 3% of the DNA was inverted repeat sequences. Thus, highly repeated sequences comprised 21% of the total genome. CsCl buoyant density ultracentrifugation indicated that this fraction was composed of both main band and satellite sequences. Although actinomycin D - CsCl density gradients failed to give significant separation of the repetitive sequences, distamycin A - CsCl gradients were able to fractionate the DNA into several overlapping bands. The heterogeneity of the repetitive DNA was further demonstrated by the first derivative plots calculated from their thermal denaturation profiles. This analysis revealed six major thermalytes which indicate that there may be at least six discrete components in the repetitive DNA.
从豚鼠（Cavia porcellus）的肝脏或组织培养细胞中纯化得到的天然DNA，经热变性后重新复性至Cot值为0.01（相当于7.2×10⁻²的Cot值）。通过用单链DNA特异性酶S1核酸酶消化来分离复性后的DNA。分光光度法和放射性测定表明，总DNA的24%对S1核酸酶处理具有抗性。零时复性表明，约3%的DNA为反向重复序列。因此，高度重复序列占基因组总量的21%。CsCl浮力密度超速离心表明，该部分由主带和卫星序列组成。尽管放线菌素D - CsCl密度梯度未能对重复序列进行显著分离，但偏端霉素A - CsCl梯度能够将DNA分离成几个重叠带。从其热变性图谱计算得到的一阶导数图进一步证明了重复DNA的异质性。该分析揭示了六个主要的热解峰，这表明重复DNA中可能至少有六个离散成分。
