基于指纹识别技术的校园数字化信息管理系统

文章提出一种基于指纹识别技术的校园数字化信息管理系统的设计方法,该系统以SM-621指纹识别模块对用户进行身份确认,通过Wi-Fi或GSM/GPRS网络实现与上位机通信,上位机采用Java实现数据库管理。本系统能较好地实现对用户的个人信息进行管理,抗干扰能力强、组网灵活,运行和维护成本低,具有推广应用价值。     

Development of a pyrF-based counterselectable system for targeted gene deletion in Streptomyces rimosus

Streptomyces produces many valuable and important biomolecules with clinical and pharmaceutical applications. The development of simple and highly efficient gene editing tools for genetic modification of Streptomyces is highly desirable. In this study, we developed a screening system for targeted gene knockout using a uracil auxotrophic host(Δpyr F) resistant to the highly toxic uracil analog of 5-fluoroorotic acid(5-FOA) converted by Pyr F, and a non-replicative vector p KC1132-pyr F carrying the complemented pyr F gene coding for orotidine-5'-phosphate decarboxylase. The pyr F gene acts as a positive selection and counterselection marker for recombinants during genetic modifications. Single-crossover homologous integration mutants were selected on minimal medium without uracil by reintroducing pyr F along with p KC1132-pyr F into the genome of the mutant Δpyr F at the targeted locus. Double-crossover recombinants were generated, from which the pyr F gene, plasmid backbone, and targeted gene were excised through homologous recombination exchange. These recombinants were rapidly screened by the counterselection agent, 5-FOA. We demonstrated the feasibility and advantage of using this pyr F-based screening system through deleting the otc R gene, which encodes the cluster-situated regulator that directly activates oxytetracycline biosynthesis in Streptomyces rimosus M4018. This system provides a new genetic tool for investigating the genetic characteristics of Streptomyces species.