Biosensors have become powerful tools for real-time monitoring of specific small molecules and precise control of gene expression in biological systems. High-throughput sensors for 1, 4-butanediamine biosynthesis can greatly improve the screening efficiency of high-yielding 1, 4-butanediamine strains. However, the strategies for adapting the characteristics of biosensors are still rarely studied, which limits the applicability of 1, 4-butanediamine biosensors. In this paper, we propose the development of a 1, 4-butanediamine biosensor based on the transcriptional regulator PuuR, whose homologous operator puuO is installed in the constitutive promoter P_gapA of Escherichia coli to control the expression of the downstream superfolder green fluorescent protein (sfGFP) as the reporter protein. Finally, the biosensor showed a stable linear relationship between the GFP/OD₆₀₀ value and the concentration of 1, 4-butanediamine when the concentration of 1, 4-butanediamine was 0-50 mmol/L. The promoters with different strengths in the E. coli genome were used to modify the 1, 4-butanediamine biosensor, and the functional properties of the PuuR-based 1, 4-butanediamine biosensor were explored and improved, which laid the groundwork for high-throughput screening of engineered strains highly producing 1, 4-butanediamine.
Biosensing Techniques/methods* ; Escherichia coli/metabolism* ; Promoter Regions, Genetic/genetics* ; Green Fluorescent Proteins/metabolism* ; Transcription Factors/genetics* ; Escherichia coli Proteins/genetics* ; Diamines/metabolism* ; Gene Expression Regulation, Bacterial

Objective To discuss the differential diagnosis and treatment of bursitis around the knee. Methods 32 patients with bursitis around the knee were treated from March 2000 to March 2002 in our hospital. Their diagnosis and treatment were reviewed. The arthroscopy of knee confirmed all the initial diagnosis of the patients made by the physical examination and complaints. We gave them conservative treatment and analyzed the clinical follow ups. Results All the patients were followed up for 8 to 40 weeks. 9 of them who had no internal knee lesions but only one kind of bursitis healed within 3 weeks. 23 of them who had more than two kinds of bursitis (including four who had internal knee lesions) healed within 3 to 5 weeks. Conclusions The differential diagnosis of the bursitis around the knee can be made on the basis of complaints and physical examination. These cases can be managed by conservative treatment.