title: Single Cell Analysis of a Bacterial Sender-Receiver System.
abstract: Monitoring gene expression dynamics on the single cell level provides important information on cellular heterogeneity and stochasticity, and potentially allows for more accurate quantitation of gene expression processes. We here study bacterial senders and receivers genetically engineered with components of the quorum sensing system derived from Aliivibrio fischeri on the single cell level using microfluidics-based bacterial chemostats and fluorescence video microscopy. We track large numbers of bacteria over extended periods of time, which allows us to determine bacterial lineages and filter out subpopulations within a heterogeneous population. We quantitatively determine the dynamic gene expression response of receiver bacteria to varying amounts of the quorum sensing inducer N-3-oxo-C6-homoserine lactone (AHL). From this we construct AHL response curves and characterize gene expression dynamics of whole bacterial populations by investigating the statistical distribution of gene expression activity over time. The bacteria are found to display heterogeneous induction behavior within the population. We therefore also characterize gene expression in a homogeneous bacterial subpopulation by focusing on single cell trajectories derived only from bacteria with similar induction behavior. The response at the single cell level is found to be more cooperative than that obtained for the heterogeneous total population. For the analysis of systems containing both AHL senders and receiver cells, we utilize the receiver cells as 'bacterial sensors' for AHL. Based on a simple gene expression model and the response curves obtained in receiver-only experiments, the effective AHL concentration established by the senders and their 'sending power' is determined.
authors.affiliation: Physics Department, TU München, Garching, Germany.
authors.forename: Tiago
authors.initials: T
authors.lastname: Ramalho
authors.affiliation: Physics Department and ZNN/WSI, TU München, Garching, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Meyer
authors.affiliation: Physics Department and ZNN/WSI, TU München, Garching, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Mückl
authors.affiliation: Physics Department and ZNN/WSI, TU München, Garching, Germany.
authors.forename: Korbinian
authors.initials: K
authors.lastname: Kapsner
authors.affiliation: Physics Department, TU München, Garching, Germany.|Nanosystems Initiative Munich, Munich, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Gerland
authors.affiliation: Physics Department and ZNN/WSI, TU München, Garching, Germany.|Nanosystems Initiative Munich, Munich, Germany.
authors.forename: Friedrich C
authors.initials: FC
authors.lastname: Simmel
mesh_terms: D054742:Acyl-Butyrolactones / Q000494:pharmacology*; D048908:Aliivibrio fischeri / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000378:metabolism; D019149:Bioreactors; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D017930:Genes, Reporter; D056656:Lab-On-A-Chip Devices; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D053038:Quorum Sensing / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000235:genetics; D059010:Single-Cell Analysis; D014157:Transcription Factors / Q000378:metabolism; D014169:Transformation, Bacterial
chemical_list: D054742:Acyl-Butyrolactones; D001426:Bacterial Proteins; C085427:LuxI protein, Bacteria; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors