Synchronous cultures from the baby machine: Anatomy of a model

Citation
Nb. Grover et al., Synchronous cultures from the baby machine: Anatomy of a model, J THEOR BIO, 212(3), 2001, pp. 391-398
Citations number
11
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Multidisciplinary
Journal title
JOURNAL OF THEORETICAL BIOLOGY
ISSN journal
0022-5193 → ACNP
Volume
212
Issue
3
Year of publication
2001
Pages
391 - 398
Database
ISI
SICI code
0022-5193(20011007)212:3<391:SCFTBM>2.0.ZU;2-S
Abstract
The baby-machine system, which produces newborn Escherichia coli cells from cultures immobilized on a membrane, was developed many years ago in an att empt to attain optimal synchrony with minimal disturbance of steady-state g rowth. In the present article, we describe in some detail a model designed to analyse such cells with a view to characterizing the nature and quality of the synchrony in a quantitative manner; it can also serve to evaluate th e methodology itself, its potential and its limitations. The model consists of five elements, giving rise to five adjustable paramet ers (and a proportionality constant): a major, essentially synchronous grou p of cells with ages distributed normally about zero; a minor, random compo nent from a steady-state population on the membrane that had undergone only very little age selection during the elution process; a fixed background c ount, to account for the signals recorded by the electronic particle counte r produced by debris and electronic noise; a time-shift, to allow for diffe rences between collection time and sampling time; and the coefficient of va riation of the interdivision-time distribution, taken to be a Pearson type III. The model is fitted by nonlinear least-squares to data from cells grown in glucose minimal medium. The standard errors of the parameters are quite sma ll, making their estimates all highly significant; the quality of the fit i s striking. We also provide a simple yet rigorous procedure for correcting cell counts obtained in an electronic particle counter for the effect of coincidence. A n example using real data produces an excellent fit. (C) 2001 Academic Pres s.