太阳能捕集器

太阳每天向地球倾泻成万倍于人类活动所需的能量，人们需要解决如何廉价地开发太阳能的问题。而自然界则不存在这个问题。“太阳能电池”就长在树上，绿叶的光合作用把太阳光转化为化学能，几乎为一切自然生态系统提供着能源。的确，人们可以从植物得到启迪：如何充分利用太阳光。差不多所有商品太阳能电池均系由无定形硅制成，问题在于硅的加工费用很大，而且这种电地转换效率不是很高，一般仅能转化13～16％的日光为电能。因此，使用不可再生的矿物燃料依然不失为比较切合实际的获取能量之途。但如果能廉价地大批最生产太阳能电池，经济性…     

The Ndc80 kinetochore complex forms oligomeric arrays along microtubules

The Ndc80 complex is a key site of regulated kinetochore-microtubule attachment (a process required for cell division), but the molecular mechanism underlying its function remains unknown. Here we present a subnanometre-resolution cryo-electron microscopy reconstruction of the human Ndc80 complex bound to microtubules, sufficient for precise docking of crystal structures of the component proteins. We find that the Ndc80 complex binds the microtubule with a tubulin monomer repeat, recognizing α- and β-tubulin at both intra- and inter-tubulin dimer interfaces in a manner that is sensitive to tubulin conformation. Furthermore, Ndc80 complexes self-associate along protofilaments through interactions mediated by the amino-terminal tail of the NDC80 protein, which is the site of phospho-regulation by Aurora B kinase. The complex's mode of interaction with the microtubule and its oligomerization suggest a mechanism by which Aurora B could regulate the stability of load-bearing kinetochore-microtubule attachments.