Chromosome replication status and DNA content at any cell age in a bacterial cell cycle

Apoptosis induced by ursodeoxycholic acid in human melanoma cells through the mitochondrial pathway

Ursodeoxycholic acid (UDCA) is a type of hydrophilic bile acid extracted from animal bile with a wide range of biological functions. The present results demonstrated that UDCA could effectively inhibit the proliferation of two human melanoma cell line (M14 and A375) with time‑ and concentration‑dependence. Following exposure to various concentrations of UDCA, M14 cells exhibited typical morphological changes and weaker ability of colony forming. Flow cytometry analysis demonstrated that UDCA could induce a decrease of mitochondrial membrane potential and an increase in reactive oxygen species (ROS) levels in M14 cells. The cell cycle was arrested in the G2/M phase, which was confirmed by the decrease of cyclin‑dependent kinase 1 and cyclinB1 at the protein level. However, when M14 cells were treated with UDCA and Z‑VAD‑FMK (caspase inhibitor) synchronously, the apoptosis rate of the cells was reduced significantly. In addition, it was demonstrated that UDCA induced apoptosis of human melanoma M14 cells through the ROS‑triggered mitochondrial‑associated pathway, which was indicated by the increased expression of cleaved‑caspase‑3, cleaved‑caspase‑9, apoptotic protease activating factor‑1, cleaved‑poly (ADP‑ribose) polymerase 1 and the elevation of B cell lymphoma‑2 (Bcl‑2) associated X protein/Bcl‑2 ratio associated with apoptosis. Therefore, UDCA may be a potential drug for the treatment of human melanoma.

Fundamental principles in bacterial physiology-history, recent progress, and the future with focus on cell size control: a review

Bacterial physiology is a branch of biology that aims to understand overarching principles of cellular reproduction. Many important issues in bacterial physiology are inherently quantitative, and major contributors to the field have often brought together tools and ways of thinking from multiple disciplines. This article presents a comprehensive overview of major ideas and approaches developed since the early 20th century for anyone who is interested in the fundamental problems in bacterial physiology. This article is divided into two parts. In the first part (sections 1-3), we review the first 'golden era' of bacterial physiology from the 1940s to early 1970s and provide a complete list of major references from that period. In the second part (sections 4-7), we explain how the pioneering work from the first golden era has influenced various rediscoveries of general quantitative principles and significant further development in modern bacterial physiology. Specifically, section 4 presents the history and current progress of the 'adder' principle of cell size homeostasis. Section 5 discusses the implications of coarse-graining the cellular protein composition, and how the coarse-grained proteome 'sectors' re-balance under different growth conditions. Section 6 focuses on physiological invariants, and explains how they are the key to understanding the coordination between growth and the cell cycle underlying cell size control in steady-state growth. Section 7 overviews how the temporal organization of all the internal processes enables balanced growth. In the final section 8, we conclude by discussing the remaining challenges for the future in the field.

Bacterial cell cycle classification. Application to DNA synthesis and DNA content at any cell age

A proposal is presented for classifying bacterial cell cycles into twelve discrete groups. This classification translates the three temporal parameters that define a cell cycle into numbers that facilitate an algorithmic approach to analyse the replication state of a single bacterium and of a bacterial population during steady-state of exponential growth. The classification and its implementation offer easy ways to obtain the rate of DNA synthesis and the amount of DNA per cell at any age in batch cultures.

Cell-shape homeostasis in Escherichia coli is driven by growth, division, and nucleoid complexity

Analysis of recently published high-throughput measurements of wild-type Escherichia coli cells growing at a wide range of rates demonstrates that cell width W, which is constant at any particular growth rate, is related (with a CV = 2.4%) to the level of nucleoid complexity, expressed as the amount of DNA in genome equivalents that is associated with chromosome terminus (G/terC). The relatively constant (CV = 7.3%) aspect ratio of newborn cells (Lb/W) in populations growing at different rates indicates existence of cell-shape homeostasis. Enlarged W of thymine-limited thyA mutants growing at identical rates support the hypothesis that nucleoid complexity actively affects W. Nucleoid dynamics is proposed to transmit a primary signal to the peptidoglycan-synthesizing system through the transertion mechanism, i.e., coupled transcription/translation of genes encoding membrane proteins and inserting these proteins into the membrane.

Chromosome replication, cell growth, division and shape: a personal perspective

The origins of Molecular Biology and Bacterial Physiology are reviewed, from our personal standpoints, emphasizing the coupling between bacterial growth, chromosome replication and cell division, dimensions and shape. Current knowledge is discussed with historical perspective, summarizing past and present achievements and enlightening ideas for future studies. An interactive simulation program of the bacterial cell division cycle (BCD), described as "The Central Dogma in Bacteriology," is briefly represented. The coupled process of transcription/translation of genes encoding membrane proteins and insertion into the membrane (so-called transertion) is invoked as the functional relationship between the only two unique macromolecules in the cell, DNA and peptidoglycan embodying the nucleoid and the sacculus respectively. We envision that the total amount of DNA associated with the replication terminus, so called "nucleoid complexity," is directly related to cell size and shape through the transertion process. Accordingly, the primary signal for cell division transmitted by DNA dynamics (replication, transcription and segregation) to the peptidoglycan biosynthetic machinery is of a physico-chemical nature, e.g., stress in the plasma membrane, relieving nucleoid occlusion in the cell's center hence enabling the divisome to assemble and function between segregated daughter nucleoids.