In Arabidopsis thaliana, the blue light photoreceptor cryptochromes (CRY) act to promote photomorphogenic development and the transition from vegetative to floral development in long days (LDs). We previously proposed that one of the mechanisms by which CRY regulates light responses is via its physical interaction with COP1, a RING motif-containing E3 ligase. Under LDs, the transcription of FLOWERING LOCUS T (FT) is activated by CONSTANS (CO) in leaf, and the FT protein moves to the shoot apex to induce flowering. CO protein is degraded in darkness, whereas it is stabilized by the CRYmediated signal. However, the mechanism underlying this process is unknown. We show in this report that CO acts genetically downstream of COP1 and CRY to regulate flowering time. In addition, COP1 physically interacts with CO and functions as an E3 ligase, ubiquitinating CO in vitro and reducing CO levels in vivo. These results suggest that COP1 acts as a repressor of flowering by promoting the ubiquitin-mediated proteolysis of CO in darkness and that CRY-mediated signal may negatively regulate COP1, thereby stabilizing CO, activating FT transcription, and inducing flowering.

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In order to prevent and handle all kinds of railway emergencies efficiently and improve emergency management efficiency and capability of Railway Bureau, it is of great importance to construct the emergency command system which takes geographic information system as core and is visualized, intelligent and networking. Based on the reality of railway emergency management, the three level structure of emergency command system, which takes the Railway Bureau as core and consists of the Ministry of Railways, the Railway Bureau and Divisions, is proposed. The overall frame structure of the system which consists of user layer, interface layer, application service layer and data layer is designed and the function of the system is analyzed. Some key technologies namely geographic information service platform technology, information resources integration technology and decision support techniques are introduced.

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