Bouligand Y, Norris V
Histophysique (EPHE) & Faculté de Pharmacie, 10, rue A.-Bocquel, 49100, Angers, France.
Biochimie. 2001 Feb;83(2):187-92. doi: 10.1016/s0300-9084(00)01211-6.
The patterns characteristic of certain liquid crystals called 'twisted nematics' or 'cholesterics' have been observed in thin sections of both dinoflagellates and bacterial chromosomes. These liquid crystals have also been obtained in vitro in concentrated DNA solutions. A large part of DNA in prokaryotic chromosomes forms such a twisted liquid crystal, whilst the remainder consists of lateral loops and is less concentrated. These semi-ordered phases could help chromosome separation to occur during and after DNA replication. We suggest that, owing to chemical differences, one of the two replicated filaments is immiscible with the rest of DNA in this chromosome. This immiscibility occurs in the context of an ordered liquid, with the DNA closely layered by a regular twist, a situation proposed to strongly minimize entangling after replication and hence to facilitate segregation.
在甲藻和细菌染色体的薄片中都观察到了某些被称为“扭曲向列相”或“胆甾相”的液晶所特有的图案。这些液晶也已在体外的浓缩DNA溶液中获得。原核染色体中的大部分DNA形成了这样一种扭曲的液晶，而其余部分则由侧向环组成，浓度较低。这些半有序相可能有助于在DNA复制期间和之后发生染色体分离。我们认为，由于化学差异，两条复制的细丝之一与该染色体中的其余DNA不相溶。这种不相溶发生在有序液体的环境中，DNA通过规则的扭曲紧密分层，这种情况被认为能极大地减少复制后的缠结，从而便于分离。
