title: A millifluidic study of cell-to-cell heterogeneity in growth-rate and cell-division capability in populations of isogenic cells of Chlamydomonas reinhardtii.
abstract: To address possible cell-to-cell heterogeneity in growth dynamics of isogenic cell populations of Chlamydomonas reinhardtii, we developed a millifluidic drop-based device that not only allows the analysis of populations grown from single cells over periods of a week, but is also able to sort and collect drops of interest, containing viable and healthy cells, which can be used for further experimentation. In this study, we used isogenic algal cells that were first synchronized in mixotrophic growth conditions. We show that these synchronized cells, when placed in droplets and kept in mixotrophic growth conditions, exhibit mostly homogeneous growth statistics, but with two distinct subpopulations: a major population with a short doubling-time (fast-growers) and a significant subpopulation of slowly dividing cells (slow-growers). These observations suggest that algal cells from an isogenic population may be present in either of two states, a state of restricted division and a state of active division. When isogenic cells were allowed to propagate for about 1000 generations on solid agar plates, they displayed an increased heterogeneity in their growth dynamics. Although we could still identify the original populations of slow- and fast-growers, drops inoculated with a single progenitor cell now displayed a wider diversity of doubling-times. Moreover, populations dividing with the same growth-rate often reached different cell numbers in stationary phase, suggesting that the progenitor cells differed in the number of cell divisions they could undertake. We discuss possible explanations for these cell-to-cell heterogeneities in growth dynamics, such as mutations, differential aging or stochastic variations in metabolites and macromolecules yielding molecular switches, in the light of single-cell heterogeneities that have been reported among isogenic populations of other eu- and prokaryotes.
authors.affiliation: Laboratoire de Colloïdes et Matériaux Divisés, Institute of Chemistry, Biology and Innovation ESPCI ParisTech/CNRS UMR 8231/PSL* Research University, Paris, France.
authors.forename: Shima P
authors.initials: SP
authors.lastname: Damodaran
authors.affiliation: Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste, Institut de Biologie Physico-Chimique, UMR CNRS/UPMC 7141, Paris, France.
authors.forename: Stephan
authors.initials: S
authors.lastname: Eberhard
authors.affiliation: Laboratoire de Colloïdes et Matériaux Divisés, Institute of Chemistry, Biology and Innovation ESPCI ParisTech/CNRS UMR 8231/PSL* Research University, Paris, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Boitard
authors.affiliation: Laboratoire de Colloïdes et Matériaux Divisés, Institute of Chemistry, Biology and Innovation ESPCI ParisTech/CNRS UMR 8231/PSL* Research University, Paris, France.
authors.forename: Jairo Garnica
authors.initials: JG
authors.lastname: Rodriguez
authors.affiliation: Laboratoire de Colloïdes et Matériaux Divisés, Institute of Chemistry, Biology and Innovation ESPCI ParisTech/CNRS UMR 8231/PSL* Research University, Paris, France; Optical Science & Engineering Research Center, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Yuxing
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Laboratoire de Colloïdes et Matériaux Divisés, Institute of Chemistry, Biology and Innovation ESPCI ParisTech/CNRS UMR 8231/PSL* Research University, Paris, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bremond
authors.affiliation: Laboratoire de Colloïdes et Matériaux Divisés, Institute of Chemistry, Biology and Innovation ESPCI ParisTech/CNRS UMR 8231/PSL* Research University, Paris, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Baudry
authors.affiliation: Laboratoire de Colloïdes et Matériaux Divisés, Institute of Chemistry, Biology and Innovation ESPCI ParisTech/CNRS UMR 8231/PSL* Research University, Paris, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Bibette
authors.affiliation: Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste, Institut de Biologie Physico-Chimique, UMR CNRS/UPMC 7141, Paris, France.
authors.forename: Francis-André
authors.initials: FA
authors.lastname: Wollman
mesh_terms: D018929:Cell Culture Techniques / Q000295:instrumentation; D002455:Cell Division; D049109:Cell Proliferation; D002478:Cells, Cultured; D016825:Chlamydomonas reinhardtii / Q000166:cytology* / Q000254:growth & development; D056656:Lab-On-A-Chip Devices