Leforestier A, Livolant F
Centre de Biologie Cellulaire (CNRS), Ivry-sur-Seine, France.
Biol Cell. 1991;71(1-2):115-22. doi: 10.1016/0248-4900(91)90058-u.
The ultrastructure of liquid crystalline phases of DNA raises numerous problems because of the structure itself which is fluid and which nature depends on the relative amount of DNA, water and ions. Different cryofixation methods were tested and compared after freeze-fracture of the specimen. A good ultrastructural preservation of the samples can be achieved without addition of any cryoprotectant by quick-freezing against a copper block cooled down to liquid helium temperature. Then, molecular orientations can be followed very accurately and the local disorder around a mean direction which exists in the liquid state is kept in the frozen structure.
由于DNA液晶相的结构本身具有流动性，且其性质取决于DNA、水和离子的相对含量，因此DNA液晶相的超微结构引发了诸多问题。在对标本进行冷冻断裂后，对不同的冷冻固定方法进行了测试和比较。通过在冷却至液氦温度的铜块上快速冷冻，无需添加任何冷冻保护剂即可实现对样品良好的超微结构保存。然后，可以非常精确地追踪分子取向，并且液态中存在的围绕平均方向的局部无序状态在冷冻结构中得以保留。
