植物基因组分析。III. 大麦（Hordeum vulgare）和小麦（Triticum aestivum）中隐蔽卫星DNA的变性与复性特性

Analysis of plant genomes. III. Denaturation and reassociation properties of cryptic satellite DNAs in barley (Hordeum vulgare) and wheat (Triticum aestivum).

作者信息

Ranjekar P K, Pallotta D, Lafontaine J G

出版信息

Biochim Biophys Acta. 1978 Aug 23;520(1):103-10. doi: 10.1016/0005-2787(78)90011-4.

Abstract

A cryptic satellite fraction was isolated from barley and wheat by preparatory ultracentrifugation of total DNA in Ag+-Cs2SO4 density gradients and was characterized by studying its denaturation-reassociation properties. Wheat satellite DNA underwent thermal denaturation as a single component with a Tm of 81 degrees C while barley satellite DNA consisted of one major (Tm = 82.5 degrees C) and one minor (Tm = 91 degrees C) component. When the barley and wheat satellites were reassociated and then melted, the Tm values were found to be 6--7 degrees C lower than those of the corresponding native DNA preparations. Examination of the C0t curves of these two satellite DNAs revealed the presence of a major, fast reassociating and a minor, slow reassociating fraction. The fast reassociating DNA fraction of barley was found to have a complexity of 9.7 . 10(5) daltons while that of wheat satellite was 5.8 . 10(5) daltons. Since these satellites reassociated with about 4--5% base mismatching, as judged by their deltsTm (6--7 degrees C), they each appear to consist of rather similar base sequences.

摘要

通过在Ag⁺-Cs₂SO₄密度梯度中对总DNA进行制备性超速离心，从大麦和小麦中分离出一种隐蔽卫星组分，并通过研究其变性-复性特性对其进行了表征。小麦卫星DNA作为单一成分进行热变性，其熔解温度（Tm）为81℃，而大麦卫星DNA由一个主要成分（Tm = 82.5℃）和一个次要成分（Tm = 91℃）组成。当大麦和小麦卫星DNA复性然后再解链时，发现其Tm值比相应的天然DNA制剂低6-7℃。对这两种卫星DNA的Cot曲线进行检查发现，存在一个主要的、快速复性的组分和一个次要的、缓慢复性的组分。发现大麦的快速复性DNA组分的复杂度为9.7×10⁵道尔顿，而小麦卫星的为5.8×10⁵道尔顿。由于根据它们的ΔTm（6-7℃）判断，这些卫星DNA复性时约有4-5%的碱基错配，因此它们似乎都由相当相似的碱基序列组成。