A dynamic and multilocus metabolic regulation strategy using quorum-sensing-controlled bacterial small RNA.

Metabolic regulation strategies have been developed to redirect metabolic fluxes to production pathways. However, it is difficult to screen out target genes that, when repressed, improve yield without affecting cell growth. Here, we report a strategy using a quorum-sensing system to control small RNA transcription, allowing cell-density-dependent repression of target genes. This strategy is shown with convenient operation, dynamic repression, and availability for simultaneous regulation of multiple genes. The parameters Ai, Am, and RA (3-oxohexanoyl-homoserine lactone [AHL] concentrations at which half of the maximum repression and the maximum repression were reached and value of the maximum repression when AHL was added manually, respectively) are defined and introduced to characterize repression curves, and the variant LuxRI58N is identified as the most suitable tuning factor for shake flask culture. Moreover, it is shown that dynamic overexpression of the Hfq chaperone is the key to combinatorial repression without disruptions on cell growth. To show a broad applicability, the production titers of pinene, pentalenene, and psilocybin are improved by 365.3%, 79.5%, and 302.9%, respectively, by applying combinatorial dynamic repression.

Intervention effect of hand washing behavior in primary and secondary schools in Shanghai by non-participatory observation / 中国学校卫生

Objective@#To assess the changes of students’ hand washing behaviors after implementing comprehensive interventions, and to provide the reference for hand-washing promotion among students.@*Methods@#The implementation of comprehensive intervention projects had been carried out in three aspects: hardware transformation, system establishment, health management and health education. A randomized controlled trial method was used to select each one primary and secondary school in 2016 from 17 districts in Shanghai, and 17 intervention schools and 17 control schools were taken as object. Non-participant observation was used for students’ hand washing behaviors for 4 times during May, 2016 to May, 2017. Descriptive analysis and chi square test were used to analyze the data.@*Results@#Compared with the control group, the hand washing rate of the intervention group was lower than that of the control group at baseline. The intervention group has got a higher rate than that of the control group in the evaluation of 1, the assessment 2 and the assessment 3 after intervention. The difference was statistically significant(χ2=7.70, 24.23, 38.88, 21.71, P<0.05). Compared with the control group, the hand washing rate of the intervention group after class was lower than that of the control group. After the intervention, the rate of the intervention group was higher than that of the control group in the evaluation 1, the assessment 2 and the assessment 3 after the intervention. The difference was statistically significant (χ2=8.52, 33.79, 54.64, 13.99, P<0.05). Compared with the control group, there was no difference between the baseline intervention group and the control group before meals. The intervention group after intervention was higher than the control group in the evaluation of 1, evaluation 2 and evaluation 3. The difference was statistically significant (χ2=45.01, 42.19, 27.82, P<0.05).@*Conclusion@#After comprehensive intervention, the effect was significant under different temperature conditions, and the effect of intervention lasted for one year.