title: Screening of Chlamydomonas reinhardtii Populations with Single-Cell Resolution by Using a High-Throughput Microscale Sample Preparation for Matrix-Assisted Laser Desorption Ionization Mass Spectrometry.
abstract: The consequences of cellular heterogeneity, such as biocide persistence, can only be tackled by studying each individual in a cell population. Fluorescent tags provide tools for the high-throughput analysis of genomes, RNA transcripts, or proteins on the single-cell level. However, the analysis of lower-molecular-weight compounds that elude tagging is still a great challenge. Here, we describe a novel high-throughput microscale sample preparation technique for single cells that allows a mass spectrum to be obtained for each individual cell within a microbial population. The approach presented includes spotting Chlamydomonas reinhardtii cells, using a noncontact microarrayer, onto a specialized slide and controlled lysis of cells separated on the slide. Throughout the sample preparation, analytes were traced and individual steps optimized using autofluorescence detection of chlorophyll. The lysates of isolated cells are subjected to a direct, label-free analysis using matrix-assisted laser desorption ionization mass spectrometry. Thus, we were able to differentiate individual cells of two Chlamydomonas reinhardtii strains based on single-cell mass spectra. Furthermore, we showed that only population profiles with real single-cell resolution render a nondistorted picture of the phenotypes contained in a population.
authors.affiliation: Department of Chemistry and Applied Biosciences, Laboratory of Organic Chemistry, ETH Zurich, Zurich, Switzerland.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Krismer
authors.affiliation: Functional Genomics Center Zürich, ETH Zurich and University of Zurich, Zurich, Switzerland.
authors.forename: Jens
authors.initials: J
authors.lastname: Sobek
authors.affiliation: Department of Chemistry and Applied Biosciences, Laboratory of Organic Chemistry, ETH Zurich, Zurich, Switzerland.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Steinhoff
authors.affiliation: Department of Chemistry and Applied Biosciences, Laboratory of Organic Chemistry, ETH Zurich, Zurich, Switzerland.
authors.forename: Stephan R
authors.initials: SR
authors.lastname: Fagerer
authors.affiliation: Department of Chemistry and Applied Biosciences, Laboratory of Organic Chemistry, ETH Zurich, Zurich, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Pabst
authors.affiliation: Department of Chemistry and Applied Biosciences, Laboratory of Organic Chemistry, ETH Zurich, Zurich, Switzerland zenobi@org.chem.ethz.ch.
authors.forename: Renato
authors.initials: R
authors.lastname: Zenobi
mesh_terms: D016825:Chlamydomonas reinhardtii / Q000737:chemistry*; D057166:High-Throughput Screening Assays; D059010:Single-Cell Analysis / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*