Assembly and micromanipulation of Xenopus in vitro-assembled mitotic chromosomes

Mitotic chromosomes have fascinated scientists for several decades. Despite the numerous microscopy studies, chromosome structure is, however, still poorly understood. This is due to both the high complexity of the mitotic chromosomes and the lack of other appropriate techniques suitable for studying their organization. This unit describes a novel physical approach based on measurements of mitotic chromosome elasticity. The elasticity properties are determined by the underlying structure, and knowledge of them has allowed a description of the organization of the mitotic chromosomes and critical analysis of the available models. In this unit, a detailed protocol for the measurements of the elastic response of in vitro assembled mitotic chromosomes in Xenopus egg extract is presented.