Sakamaki T, Takahashi N, Takaiwa F, Tanifuji S
Biochim Biophys Acta. 1976 Sep 20;447(1):76-81. doi: 10.1016/0005-2787(76)90097-6.
After a pulse of 5-10 min with [3H]thymidine, labeled DNA extracted from embryonic axes of Vicia seeds sedimented as a rather homogeneous peak at approx. 10S in an alkaline sucrose density gradient, as described in our previous paper ((1975) Biochim. Biophys. Acta 395, 314-321). The sedimentation pattern of the same pulse-labeled DNA in a neutral gradient showed a wide range of sizes from approx. 14 S to more than 40 S. However, most of these labeled DNA components, including the 14-20 S shorter fragments, were shown to have a double-stranded structure by hydroxyapatite column chromatography. Further investigations on neutral sucrose gradients revealed a decreased occurrence after a chase, and final disappearance after a longer chase period of these shorter double-stranded fragments. A possible secondary structure of the newly synthesized DNA in a higher plant (Vicia faba) is discussed.
用[³H]胸腺嘧啶核苷脉冲处理5 - 10分钟后，从蚕豆种子胚轴中提取的标记DNA在碱性蔗糖密度梯度中沉降为一个相当均匀的峰，约为10S，如我们之前的论文所述（(1975) Biochim. Biophys. Acta 395, 314 - 321）。相同脉冲标记的DNA在中性梯度中的沉降模式显示出广泛的大小范围，从约14S到超过40S。然而，通过羟基磷灰石柱色谱法表明，这些标记的DNA成分中的大多数，包括14 - 20S的较短片段，都具有双链结构。对中性蔗糖梯度的进一步研究表明，追踪后这些较短的双链片段出现频率降低，经过更长的追踪期后最终消失。本文讨论了高等植物（蚕豆）中新合成DNA可能的二级结构。
