Cell size, macromolecular composition and dimensions of Escherichia coli are well correlated with the mean complexity of its nucleoid(s), which is expressed as the ratio between the mean times to replicate the chromosome and to duplicate the cell, C/t , aka the number of replication positions n. Cell Cycle Simulation program (CCSim, described in) has enabled explanation of a set of old, puzzling observations of dimensions, consistent with the view that cell width is determined by n, and that branching results from breaching the maximum possible value nmax . This maximum is interpreted in terms of the "eclipse", a minimal distance possible between successive moving replisomes. The data are subject to analytical quantification designed to model the correlations in a way that may lead to deciphering the primary signal transduced from the nucleoid structure to the biosynthetic pathway of the shape-maintaining peptidoglycan. The physical signal invoked is related to the transcription / translation of membrane protein genes coupled to membrane-insertion of these proteins, so-called "transertion" mechanism. Means to measure the reciprocal stress imposed by transertion strings on both nucleoid and cell envelope are sorely lacking. The recent suggestion that cell length is also determined by n thus forming so-called shape homeostasis, is consistent with data but not with previous analysis. Resolving this inconsistency by comparing model with experimental results (existing as well as newly obtained) may shed light on the necessary coupling between the two unique structures in a bacterial cell, nucleoid and sacculus.
Professor emeritus Arieh Zaritsky of Ben-Gurion University's Faculty of Natural Sciences runs a laboratory investigating in parallel fields, pure (Bacterial Physiology and Molecular Biology) and applied (Biological Control of Insect Pests). During his career at BGU, Professor Zaritsky has instructed over 50 trainees and was awarded numerous research grants, allowing him to study both fields of expertise. After obtaining a distinguished M.Sc. in Genetics at The Hebrew University of Jerusalem, he graduated (Ph.D.) at Leicester University and post-doc'ed at The Copenhagen's Institute of Microbiology. Professor Zaritsky is a recognized expert on the bacterial cell cycle and the coupling between mass growth, DNA replication cell size and dimensions, as well as bacteriophage multiplication, on which he published about half of his 130 peer-reviewed articles. Professor Zaritsky was elected to Chair BGU's Life Sciences department and nominated as the Faculty Deputy-Dean. He is an Editorial Board member of Bioengineered and awardee of 1994 Burroughs-Wellcome/ASM Visiting Professorship.
Prof. Liu Chenli 刘陈立 研究员
19th, April, 14:00-15:30
20th, April, 09:00-10:30
21th, April, 09:00-10:30