Mechanics of Escherichia coli cell width homeostasis and bulge dynamics from MreB and septum inhibition.

Cell Shape and Negative Links in Regulatory Motifs Together Control Spatial Information Flow in Signaling Networks

A quantitative method to analyse F-actin distribution in cells

Experimental study on the physico-chemical properties of bio-oil and diesel emulsification has been carried out in this paper, which was based on the preliminary experiment. The effect of surface tension and viscosity on the stability of emulsions were particular concerned. It was found that the longest stable time, the lowest viscosity and lowest surface tension can be obtained simultaneously when the hydrophile and lipophile balance (HLB) value was of the optimal value, i.e. 6.5. Experimental results indicated that the stable time of emulsion decreased rapidly with the increase of bio-oil content, while the value of surface tension and viscosity increased. Meantime, it was shown that the most stable emulsions had the lowest value of viscosity and surface tension.

Bacterial cell shape control by nutrient-dependent synthesis of cell division inhibitors

Effect of cell morphology on the compressive properties of open-cell aluminum foams

Cell Size Control in Bacteria

Gene transfection has been widely studied due to its potential applications in tissue repair and gene therapy. Many studies have focused on designing gene carriers and developing novel transfection techniques. However, the influence of cell size, shape and elongation on gene transfection has rarely been investigated. In this study, poly(vinyl alcohol)-micropatterned surfaces were prepared to precisely manipulate the size, shape and elongation of mesenchymal stem cells, and the influences of these factors on gene transfection were investigated. Cell size showed a significant influence on gene transfection. Elongation could affect the gene transfection of large cells but not small cells. Cells with a large spreading area and high aspect ratio showed high transfection with exogenous plasmid DNA. In particular, the transfection efficiency was the highest in micropatterned cells with a spreading area of 5024 μm2 and an aspect ratio of 8 : 1. In contrast, cell shape had no significant influence on gene transfection. The different influences of cell size, shape and elongation were correlated with their respective impacts on cytoskeletal structures, cellular nanoparticle uptake and DNA synthesis. Cells with a large size and elongated morphology showed well-organized actin filaments with a high cellular modulus, therefore promoting cellular nanoparticle uptake and DNA synthesis. Cells with different shapes showed similarities in actin filament organization, cellular modulus, uptake capacity and DNA synthesis. The results suggest the importance of cell size and elongation in exogenous gene transfection and should provide useful information for gene transfection and gene therapy.

Topographic distribution and phenotypic heterogeneity of Schlemm's canal endothelium in human donor eyes

THE THREE‐DIMENSIONAL SHAPES OF UNDIFFERENTIATED CELLS IN THE PETIOLE OF ANGIOPTERIS EVECTA

Deep Phenotypic Mapping of Bacterial Cytoskeletal Mutants Reveals Physiological Robustness to Cell Size

Bacillus anthracis, a spore-forming pathogen, replicates as chains of vegetative cells by regulating the separation of septal peptidoglycan. Surface (S)-layer proteins and B. anthracis S-layer-associated proteins (BSLs) function as chain length determinants and are assembled in the envelope by binding to the secondary cell wall polysaccharide (SCWP). B. anthracis expresses six different genes encoding LytR-CpsA-Psr (LCP) enzymes (lcpB1 to -4, lcpC, and lcpD), which when expressed in Staphylococcus aureus promote attachment of wall teichoic acid to peptidoglycan. Mutations in B. anthracis lcpB3 and lcpD cause aberrations in cell size and chain length that can be explained as discrete defects in SCWP assembly; however, the function of the other lcp genes is not known. By deleting combinations of lcp genes from the B. anthracis genome, we generated variants with single lcp genes. B. anthracis expressing lcpB3 alone displayed physiological cell size, vegetative growth, spore formation, and S-layer assembly. Strains expressing lcpB1 or lcpB4 displayed defects in cell size and shape, S-layer assembly, and spore formation yet sustained vegetative growth. In contrast, the lcpB2 strain was unable to grow unless the gene was expressed from a multicopy plasmid (lcpB2(++)), and variants expressing lcpC or lcpD displayed severe defects in growth and cell shape. The lcpB2(++), lcpC, or lcpD strains supported neither S-layer assembly nor spore formation. We propose a model whereby LCP enzymes fulfill partially overlapping functions in transferring SCWP molecules to discrete sites within the bacterial envelope. Products of genes essential for bacterial envelope assembly represent targets for antibiotic development. The LytR-CpsA-Psr (LCP) enzymes tether bactoprenol-linked intermediates of secondary cell wall polymers to the C6 hydroxyl of N-acetylmuramic acid in peptidoglycan; however, the role of LCPs as a target for antibiotic therapy is not defined. We show here that LCP enzymes are essential for the cell cycle, vegetative growth, and spore formation of Bacillus anthracis, the causative agent of anthrax disease. Furthermore, we assign functions for each of the six LCP enzymes, including cell size and shape, vegetative growth and sporulation, and S-layer and S-layer-associated protein assembly.

In this study the effect of microorganism size and shape on the killing efficiency of pulsed electric field is investigated both experimentally and using a transient finite element program. The effect of cell size, membrane thickness, cell shape (spherical, elliptical and cylindrical) on the trans-membrane voltage is studied. It has been found that both the cell size and cell membrane thickness have significant effect on the induced field across the cell membrane. The findings of the simulation results have been evaluated by comparing the trends with some experimental results. Four different types of microorganisms that have different shapes and dimensions have been inoculated with water at a conductivity level of 100 muS/cm and have been treated with the application of a pulsed electric field of 70 kV/cm. Significant difference in bacteria reduction was noticed between the treated cells which could be attributed to the cell size and shape.

Proper location of the mitotic spindle is critical for chromosome segregation and the selection of the cell division plane. However, how mitotic spindles sense cell size and shape to regulate their own position and orientation is still largely unclear. To investigate this question systematically, we used a general model by considering chromosomes, microtubule dynamics, and forces of various molecular motors. Our results show that in cells of various sizes and shapes, spindles can always be centered and oriented along the long axis robustly in the absence of other specified mechanisms. We found that the characteristic time of positioning and orientation processes increases with cell size. Spindles sense the cell size mainly by the cortical force in small cells and by the cytoplasmic force in large cells. In addition to the cell size, the cell shape mainly influences the orientation process. We found that more slender cells have a faster orientation process, and the final orientation is not necessarily along the longest axis but is determined by the radial profile and the symmetry of the cell shape. Finally, our model also reproduces the separation and repositioning of the spindle poles during the anaphase. Therefore, our work provides a general tool for studying the mitotic spindle across the whole mitotic phase.

A developing plant organ exhibits complex spatiotemporal patterns of growth, cell division, cell size, cell shape, and organ shape. Explaining these patterns presents a challenge because of their dynamics and cross-correlations, which can make it difficult to disentangle causes from effects. To address these problems, we used live imaging to determine the spatiotemporal patterns of leaf growth and division in different genetic and tissue contexts. In the simplifying background of the speechless (spch) mutant, which lacks stomatal lineages, the epidermal cell layer exhibits defined patterns of division, cell size, cell shape, and growth along the proximodistal and mediolateral axes. The patterns and correlations are distinctive from those observed in the connected subepidermal layer and also different from the epidermal layer of wild type. Through computational modelling we show that the results can be accounted for by a dual control model in which spatiotemporal control operates on both growth and cell division, with cross-connections between them. The interactions between resulting growth and division patterns lead to a dynamic distributions of cell sizes and shapes within a deforming leaf. By modulating parameters of the model, we illustrate how phenotypes with correlated changes in cell size, cell number, and organ size may be generated. The model thus provides an integrated view of growth and division that can act as a framework for further experimental study.

RodZ, a new player in bacterial cell morphogenesis