Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Mechanism and Dynamics of Breakage of Fluorescent Microtubules

The breakage of fluorescence-labeled microtubules under irradiation of excitation light is found in our experiments. Its mechanism is studied. The results indicate that free radicals are the main reason for the photosensitive breakage. Furthermore, the mechanical properties of the microtubules are probed with a dual-optical tweezers system. It is found that the fluorescence-labeled microtubules are much easier to extend compared with those without fluorescence. Such microtubules can be extended by 30%, and the force for breaking them up is only several piconewtons. In addition, we find that the breakup of the protofilaments is not simultaneous but step-by-step, which further confirms that the interaction between protofilaments is fairly weak