Degradation strategies of pesticide residue:From chemicals tosynthetic biology

The past 50 years have witnessed a massive expansion in the demand and application of pesticides.However,pesticides are difficult to be completely degraded without intervention hence the pesticide residue could pose a persistent threat to non-target organisms in many aspects.To aim at the problem of the abuse of pesticide products and excessive pesticide residues in the environment,chemical and biological degradation methods are widely developed but are scaled and insufficient to solve such a pollution.In recent years,bio-degradative tools instructed by synthetic biological principles have been further studied and have paved a way for pesticide degradation.Combining the customized design strategy and standardized assembly mode,the engineering bacteria for multi-dimensional degradation has become an effective tool for pesticide residue degradation.This review introduces the mechanisms and hazards of different pesticides,summarizes the methods applied in the degradation of pesticide residues,and discusses the advantages,applications,and prospects of synthetic biology in degrading pesticide residues.

基于动力学模型对北京市一起水源性诺如病毒暴发疫情防控措施的效果分析

目的针对北京市一起社区内介水传播的诺如病毒感染导致的急性胃肠炎暴发疫情进行传播动力学特征分析,对不同防控措施分别进行效果评价,探讨最佳防控措施。方法对2019年北京市某小区一起诺如病毒感染所致的急性胃肠炎暴发疫情资料,建立易感者–潜伏期–显性/隐性感染者–移出者–传播介质(SEIARW)模型,对阻断水传播的措施、健康宣教、要求病例居家休息并禁止在社区内举办聚集性活动等隔离相关措施进行效果分析。结果无干预状态下,此次疫情诺如病毒有效再生数为9.32,罹患率可达70.00%,疫情持续时间为45.26 d。当阻断水传播的时间越早,罹患率越低,疫情持续时间越长。健康宣教措施也可使疫情罹患率下降和流行曲线更低矮。隔离相关措施可以缩短疫情持续时间,且隔离率越高,罹患率越低,当日采取措施比次日采取措施防控效果更好。拟合得到疫情接报当日就采取阻断水传播的措施,同时进行健康宣教和在疫情接报当日采取隔离,隔离率为75.00%时,可达到最佳防控效果。结论越早阻断水传播的措施、持续健康宣教和早隔离能在不同程度上有效控制暴发疫情。