克氏锥虫环状动基体DNA的电子显微镜观察：连环形式的出现

Proc Natl Acad Sci U S A. 1969 Jan;62(1):210-7. doi: 10.1073/pnas.62.1.210.

Circular kinetoplastic DNA was fractionated from Trypanosoma cruzi DNA by Hg-Cs(2)SO(4) gradient. Covalantly closed circular DNA was isolated by buoyant density centrifugation in ethidium bromide CsCl density gradients. Electron microscope studies have shown that kinetoplastic DNA molecules are in the form of open and closed circles of contour length 0.45 mu, the smallest known microbial DNA. DNA molecules are also in the form of catenanes consisting of two or more topologically interlocked circular units of the monomer size 0.45 mu. Associations of numerous circles have also been described and confirmed by band sedimentation. Long linear DNA molecules were also seen, their size ranging between 2 and 12 mu. These molecules are free or are attached to associations of circles.

通过汞-硫酸铯梯度从克氏锥虫DNA中分离出环状动质体DNA。通过在溴化乙锭-氯化铯密度梯度中进行浮力密度离心分离出共价闭合环状DNA。电子显微镜研究表明，动质体DNA分子呈轮廓长度为0.45微米的开放和闭合环状形式，这是已知最小的微生物DNA。DNA分子也呈连环体形式，由两个或更多拓扑互锁的单体大小为0.45微米的环状单元组成。大量环状物的缔合也已通过条带沉降得到描述和证实。还观察到长线性DNA分子，其大小在2至12微米之间。这些分子是游离的或附着在环状物的缔合上。