Quantitative Studies of Bacterial Growth Physiology

细菌生长生理学的定量研究

• 批准号: 8663926
• 负责人: TERENCE HWA
• 金额: $ 29.26万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-01 至 2015-09-21
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8663926
• 关键词: Address; Affect; Anti-Bacterial Agents; Antibiotic Resistance; Antibiotics; Bacteria; Bacterial Drug Resistance; Bacterial Genes; Behavior; Biochemical; Biological Assay; Biological Models; Cell Wall; Cells; Chloramphenicol; Chloramphenicol O-Acetyltransferase; Chloramphenicol Resistance; Data; Dependence; Development; Dose; Drug resistance; Environment; Enzymes; Epigenetic Process; Escherichia coli; Eukaryota; Evolution; Feedback; Gene Expression; Gene Expression Profile; Genes; Genetic; Genetic Transcription; Glare; Goals; Growth; Host resistance; Hypersensitivity; Individual; Kinetics; Knowledge; Lead; Light; Mediating; Medical; Metabolism; Methods; Microfluidics; Microscopy; Modeling; Molecular; Monitor; Multi-Drug Resistance; Mutation; Nutrient; Output; Pharmaceutical Preparations; Physiological; Physiology; Prokaryotic Cells; Proteins; Regulation; Research; Resistance; Salmonella; Series; System; Testing; Time; Translations; cell growth; clinically relevant; driving force; drug development; drug resistant bacteria; fitness; in vivo; insight; interest; novel; predictive modeling; programs; research study; resistance mechanism; response; self-renewal; single cell analysis; stem cell differentiation; time use

DESCRIPTION (provided by applicant): This research addresses fundamental aspects of interactions between antibiotics and antibiotic resistance expressed by bacteria. Due to a recently discovered innate growth-rate dependence of bacterial gene expression, the expressions of even unregulated genes are affected by sub-lethal doses of antibiotics. If the expressed gene product confers some antibiotic resistance, then a previously unappreciated feedback loop is realized. This feedback effect can drastically affect the response of bacteria to an applied antibiotic, leading to phenomenon such as growth bistability with abrupt transitions between growth and no-growth states. The long-term goal of this research program is to characterize different types of feedback corresponding to different modes of growth inhibition, and to quantify the consequences of these feedback effects on resistance and cell growth. Experiments will initially focus on the effect of chloramphenicol (Cm), a translation-inhibiting drug, on the growth of E. coli cells expressing chloramphenicol acetyltransferase (CAT), which modifies Cm to render them inactive. The Cm-CAT system is chosen because it is well characterized molecularly, so that efforts can be focused on isolating the global feedback effects between the components. The experiments will be carried out by a combination of biochemical assays on bulk culture and single-cell analysis using time-lapse microcopy aided by microfluidic chemostat chambers. Quantitative, predictive models of the growth dynamics will be developed by correlating CAT expression and the instantaneous rate of cell growth at a cell-by-cell level. The specific aims are to establish the predicted growth bistability effect, quantify parameters that determine its onset, and characterize the dynamics of the transition between the growth and no-growth states. In addition, other mechanisms of Cm-resistance will be explored, as will the qualitative effects of a number of other clinically relevant drugs, in order to test the generality of the models developed.

描述（由申请人提供）：本研究解决了抗生素与细菌表达的抗生素耐药性之间相互作用的基本方面。由于最近发现细菌基因表达的先天生长速率依赖性，即使是不受调节的基因的表达也会受到亚致死剂量的抗生素的影响。如果表达的基因产物赋予一定的抗生素抗性，那么就会实现以前未意识到的反馈循环。这种反馈效应会极大地影响细菌对所用抗生素的反应，导致生长双稳态等现象，在生长状态和非生长状态之间突然转变。该研究计划的长期目标是表征与不同生长抑制模式相对应的不同类型的反馈，并量化这些反馈效应对抵抗和细胞生长的影响。实验最初将集中于氯霉素 (Cm)（一种翻译抑制药物）对表达氯霉素乙酰转移酶 (CAT) 的大肠杆菌细胞生长的影响，CAT 会修饰 Cm 使其失活。 The Cm-CAT system is chosen because it is well characterized molecularly, so that efforts can be focused on isolating the global feedback effects between the components.这些实验将通过在微流体恒化室辅助下使用延时显微镜对大量培养物进行生化分析和单细胞分析相结合来进行。通过将 CAT 表达与逐个细胞水平的细胞瞬时生长速率相关联，可以开发生长动态的定量预测模型。具体目标是建立预测的生长双稳态效应，量化确定其开始的参数，并表征生长状态和非生长状态之间过渡的动态。此外，还将探索 Cm 耐药的其他机制，以及许多其他临床相关药物的定性效果，以测试所开发模型的通用性。