ObjectiveThe U6 promoter is an essential element for driving sgRNA expression in the clustered regularly interspaced short palindromic repeat sequences/CRISPR-associated protein 9（CRISPR/Cas9）gene editing system in dicotyledonous plants. Endogenous U6 promoters typically exhibit higher transcriptional activity， which can significantly improve gene editing efficiency. This study aims to identify endogenous U6 promoters in Artemisia annua to optimize its CRISPR/Cas9 gene editing system， which holds significant importance for its molecular breeding. MethodsOn the basis of the highly conserved U6 snRNA sequences in Arabidopsis thaliana， endogenous U6 promoters were screened in the A. annua genome. Expression vectors were constructed with candidate AaU6 promoter driving the firefly luciferase （LUC） reporter gene， and then transiently transformed into Nicotiana benthamiana. Transcriptional activities of the promoters were measured and compared by in vivo imaging and the Dual Luciferase Reporter assay. ResultsEight endogenous U6 promoters were successfully cloned from A. annua. Sequences alignment revealed that all these promoters contained the two conserved cis-acting elements， upstream sequence element （USE） and TATA-box， which affected their transcriptional activity. Dual-luciferase activity assays indicated that the transcriptional activities of AaU6-3， AaU6-1， and AaU6-5 were significantly higher than that of the Arabidopsis AtU6-26 promoter， with AaU6-3 exhibiting the highest activity. ConclusionThis study identified three endogenous AaU6 promoters with high transcriptional activity in A. annua， providing key functional elements for establishing an efficient gene editing system in A. annua. These findings will contribute to advancing precision molecular breeding and high-quality germplasm innovation in A. annua.

OBJECTIVE To study the isolation status and antimicrobial resistance of nonfermenting Gram-negative bacilli collected from intensive care unit(ICU) of our hospital so as to instruct the rational clinical application of antibiotics.METHODS The antimicrobial resistance of nonfermenting Gram-negative bacilli isolates collected from patients in ICU from Jan 2003 to Dec 2007 was analyzed.Antimicrobial susceptibility of clinical isolates were tested by Kirby-Bauer method.RESULTS Total 384 nonfermenting Gram-negative bacilli isolates were collected in 5 years.The most common species were Acinetobacter baumannii(219),Pseudomonas aeruginosa(117) and Stenotrophomonas maltophilla(36).The antimicrobial resistance rate of nonfermenting Gram-negative bacterial to most antibiotics were much higher.The antimicrobial resistance rate of Acinetobacter spp to imipenem,cefoperazone/sulbactam and piperacillin/tazobactam was 3.7%,28.3% and 42.9%.But the resistance rate of Acinetobacter spp to imipenem was increased in recent 2 years(58.0%).The antimicrobial resistance rate of P.aeruginosa to cefoperazone/sulbactam was the lowest.That of imipenem-resistant P.aeruginosa to cefoperazone/sulbactam was 34.0%.S.maltophilla was relatively susceptible to ceftazidime,cefoperazone/sulbactam and piperacillin/tazobactam.CONCLUSIONS Nonfermenters Gram-negative bacilli are the important pathogens in ICU.Surveillance of their prevalence and drug resistance may provide evidences for rational antibiotic choices.

Objective To evaluate the clinical value of serum procalcitonin (PCT) in the diagnosis and differentiation of bacterial infections in the critically ill patients. Methods A total of 53 critical patients were divided into bacterial infection group and non-bacterial infection group. Serum PCT was measured by immunoluminometric assay. Results PCT of bacterial infection group was significantly higher than that in non-bacterial infection group (?~2=0.05, P