scholarly journals Robust surface-to-mass coupling and turgor-dependent cell width determine bacterial dry-mass density

2021 ◽  
Vol 118 (32) ◽  
pp. e2021416118
Author(s):  
Enno R. Oldewurtel ◽  
Yuki Kitahara ◽  
Sven van Teeffelen
Keyword(s):  
Single Cell ◽  
Caulobacter Crescentus ◽  
Mass Density ◽  
Turgor Pressure ◽  
Cell Mass ◽  
Dry Mass ◽  
Model Organisms ◽  
Cell Width ◽  
Dependent Cell

During growth, cells must expand their cell volumes in coordination with biomass to control the level of cytoplasmic macromolecular crowding. Dry-mass density, the average ratio of dry mass to volume, is roughly constant between different nutrient conditions in bacteria, but it remains unknown whether cells maintain dry-mass density constant at the single-cell level and during nonsteady conditions. Furthermore, the regulation of dry-mass density is fundamentally not understood in any organism. Using quantitative phase microscopy and an advanced image-analysis pipeline, we measured absolute single-cell mass and shape of the model organisms Escherichia coli and Caulobacter crescentus with improved precision and accuracy. We found that cells control dry-mass density indirectly by expanding their surface, rather than volume, in direct proportion to biomass growth—according to an empirical surface growth law. At the same time, cell width is controlled independently. Therefore, cellular dry-mass density varies systematically with cell shape, both during the cell cycle or after nutrient shifts, while the surface-to-mass ratio remains nearly constant on the generation time scale. Transient deviations from constancy during nutrient shifts can be reconciled with turgor-pressure variations and the resulting elastic changes in surface area. Finally, we find that plastic changes of cell width after nutrient shifts are likely driven by turgor variations, demonstrating an important regulatory role of mechanical forces for width regulation. In conclusion, turgor-dependent cell width and a slowly varying surface-to-mass coupling constant are the independent variables that determine dry-mass density.

scholarly journals Quantitative Phase Imaging of Spreading Fibroblasts Identifies the Role of Focal Adhesion Kinase in the Stabilization of the Cell Rear

Biomolecules ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1089
Author(s):  
Olga Ramaniuk ◽  
Zuzana Klímová ◽  
Tomáš Groušl ◽  
Tomáš Vomastek
Keyword(s):  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Cell Mass ◽  
Dry Mass ◽  
Cell Polarization ◽  
Phase Imaging ◽  
Quantitative Phase Imaging ◽  
Quantitative Phase ◽  
Cell Front

Cells attaching to the extracellular matrix spontaneously acquire front–rear polarity. This self-organization process comprises spatial activation of polarity signaling networks and the establishment of a protruding cell front and a non-protruding cell rear. Cell polarization also involves the reorganization of cell mass, notably the nucleus that is positioned at the cell rear. It remains unclear, however, how these processes are regulated. Here, using coherence-controlled holographic microscopy (CCHM) for non-invasive live-cell quantitative phase imaging (QPI), we examined the role of the focal adhesion kinase (FAK) and its interacting partner Rack1 in dry mass distribution in spreading Rat2 fibroblasts. We found that FAK-depleted cells adopt an elongated, bipolar phenotype with a high central body mass that gradually decreases toward the ends of the elongated processes. Further characterization of spreading cells showed that FAK-depleted cells are incapable of forming a stable rear; rather, they form two distally positioned protruding regions. Continuous protrusions at opposite sides results in an elongated cell shape. In contrast, Rack1-depleted cells are round and large with the cell mass sharply dropping from the nuclear area towards the basal side. We propose that FAK and Rack1 act differently yet coordinately to establish front–rear polarity in spreading cells.

scholarly journals Single-cell monitoring of dry mass and dry density reveals exocytosis of cellular dry contents in mitosis

2021 ◽  
Author(s):  
Teemu P Miettinen ◽  
Kevin S Ly ◽  
Alice Lam ◽  
Scott R Manalis
Keyword(s):  
Cell Growth ◽  
Single Cell ◽  
Mammalian Cells ◽  
Cell Mass ◽  
Mitotic Cell ◽  
Dry Mass ◽  
Cell Swelling ◽  
Dry Density ◽  
Composition Change ◽  
Early Mitosis

Cell mass and composition change with cell cycle progression. Our previous work characterized buoyant mass accumulation dynamics in mitosis (Miettinen et al., 2019), but how dry mass and cell composition change in mitosis has remained unclear. To better understand mitotic cell growth and compositional changes, we develop a single-cell approach for monitoring dry mass and the density of that dry mass every ~75 seconds with 1.3% and 0.3% measurement precision, respectively. We find that suspension grown mammalian cells lose dry mass and increase dry density following mitotic entry. These changes display large, non-genetic cell-to-cell variability, and the changes are reversed at metaphase-anaphase transition, after which dry mass continues accumulating. The change in dry density causes buoyant and dry mass to differ specifically in early mitosis, thus reconciling existing literature on mitotic cell growth. Mechanistically, the dry composition changes do not require mitotic cell swelling or elongation. Instead, cells in early mitosis increase lysosomal exocytosis, and inhibition of exocytosis prevents the dry composition from changing. Overall, our work provides a new approach for monitoring single-cell dry mass and composition and reveals that mitosis is coupled to extensive exocytosis-mediated secretion of cellular contents.

Characterization of Single Platelet Mass, Volume, and Density in Response to Agonist Stimulation

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 5261-5261 ◽  
Author(s):  
Kristina M. Haley ◽  
Cassandra P. Loren ◽  
Kevin G. Phillips ◽  
Owen J.T. McCarty
Keyword(s):  
Refractive Index ◽  
Single Cell ◽  
Platelet Activation ◽  
Mass Density ◽  
Dry Mass ◽  
Physical Parameters ◽  
Platelet Volume ◽  
Mass Volume ◽  
Platelet Mass

Abstract Abstract 5261 An increase in mean platelet volume (MPV) is correlated with platelet activation and subsequent shape change. Pathologic processes marked by increased platelet activity such as myocardial infarction, cerebral vascular accidents, diabetes mellitus, and hypertension are associated with an increased MPV. Elevated MPV in these conditions reflect both a higher level of platelet activation as well as increased platelet turnover secondary to platelet consumption within thrombus formation. Assessment of MPV can be used to risk stratify patients as well as assign them to prognostic categories. However, MPV does not assess platelet heterogeneity or the specific change in single platelet mass, volume, or density. Current methods provide little insight into changes in physical parameters at the single platelet level. In order to overcome this limitation, we developed a quantitative tomographic differential interference contrast (QTDIC) microscopy technique to measure dry mass, volume, and density of platelets at the single-cell level. This technique is based on determining the axially resolved refractive index from a series of through-focus DIC images. Single cell platelet mass was observed to reduce from 1.84 ± 0.14 pg to 1.60 ± 0.13 pg in response to stimulation with thrombin-receptor agonist peptide (TRAP), while single cell platelet volume reduced from 7.28 ± 0.56 fL to 6.03 ± 0.48 fL (mean ± SEM). Single cell platelet density increased from 0.25 ± 0.001 pg/fL to 0.26 ± 0.002 pg/fL (mean ± SEM). Taken together, we have characterized the physical parameters of platelets in response to agonist stimulation. Our data suggest that platelet activation may correlate with decreased mass and volume, perhaps as a consequence of platelet degranulation. Further elucidation of the morphological changes of activated platelets at the single platelet level may allow for better understanding of platelet function and dysfunction in patients affected by platelet granule deficiencies, giant platelet syndromes, and disorders associated with membrane receptorsFigure 1.Characterization of physical parameters of platelets. (a) DIC image of human platelets, (b) refractive index map, (c) dry mass density map determined from refractive index using the Barer calibration, (d) Histogram of platelet dry mass, (e) Histogram of platelet volume, (f) Histogram of platelet density.Figure 1. Characterization of physical parameters of platelets. (a) DIC image of human platelets, (b) refractive index map, (c) dry mass density map determined from refractive index using the Barer calibration, (d) Histogram of platelet dry mass, (e) Histogram of platelet volume, (f) Histogram of platelet density. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Bacteria control cell volume by coupling cell-surface expansion to dry-mass growth

2019 ◽  
Author(s):  
Enno R. Oldewurtel ◽  
Yuki Kitahara ◽  
Baptiste Cordier ◽  
Gizem Özbaykal ◽  
Sven van Teeffelen
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Cell Volume ◽  
Mass Density ◽  
Control Cell ◽  
Turgor Pressure ◽  
Model Organism ◽  
Volume Ratio ◽  
Dry Mass ◽  
Cell Diameter

AbstractCells exhibit a high degree of intracellular crowding. To control the level of crowding during growth cells must increase their volumes in response to the accumulation of biomass. Using Escherichia coli as a model organism, we found that cells control cell volume indirectly, by increasing cell-surface area in proportion to biomass growth. Thus, dry-mass density, a readout of intracellular crowding, varies in proportion to the surface-to-volume ratio, both during the cell cycle and during perturbations such as nutrient shifts. On long time scales after shifts, initial dry-mass density is nearly restored by slow variations of the surface-to-mass ratio. Contrary to a long-standing paradigm, cell-envelope expansion is controlled independently of cell-wall synthesis but responds to the activity of cell-wall cleaving hydrolases. Finally, we observed rapid changes of Turgor pressure after nutrient shifts, which were likely responsible for initial changes of cell diameter and dry-mass-density. Together, our experiments reveal important regulatory relationships for cell volume and shape.

scholarly journals Integrated RNA Sequencing and Single-Cell Mass Cytometry Reveal a Novel Role of LncRNA HOXA-AS2 in Tumorigenesis and Stemness of Hepatocellular Carcinoma

2020 ◽  
Vol Volume 13 ◽  
pp. 10901-10916
Author(s):  
Qinchen Lu ◽  
Jiamin Gao ◽  
Shaomei Tang ◽  
Zhijian Li ◽  
Xi Wang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Single Cell ◽  
Rna Sequencing ◽  
Cell Mass ◽  
Mass Cytometry

scholarly journals Single-cell sequencing of the adult killifish (N. furzeri) brain identifies an atypical progenitor, glial and neuronal heterogeneity

2021 ◽  
Author(s):  
Rajagopal Ayana ◽  
Jolien Van houcke ◽  
Caroline Zandecki ◽  
Valerie Marien ◽  
Eve Seuntjens ◽  
...  
Keyword(s):  
Single Cell ◽  
Radial Glia ◽  
Cell Types ◽  
Model Organisms ◽  
Normal Brain ◽  
Single Cell Sequencing ◽  
Short Lifespan ◽  
Age Dependent ◽  
Normal Brain Function

The African turquoise killifish uniquely combines a short lifespan with vertebrate-specific features, including age-dependent loss of neuroregenerative capacity, that are missing from the currently used model organisms. In this study, we investigate the cellular landscape that shapes adult neuro- and gliogenesis using single-cell sequencing. Our analysis identifies seventeen cell types including neuronal cells (NC), and progenitors (PC) of glial and non-glial nature in the adult killifish telencephalon. PC subclustering unveils four radial glia types, one atypical non-glial progenitor (NGP) and two clusters representing transitioning states. NC subclustering classified neurons into immature and mature excitatory or inhibitory sub-clusters. Using lineage inference analysis, we discovered neuroepithelial-like radial glia to be the source of neuro- and gliogenesis, and a central role for NGP. Our findings are evidence for specialized progenitors within telencephalon and the data is accessible via an online database, providing a resource to understand normal brain function, as well as the role of cellular relationships in response to injury and disease.

scholarly journals Nuclear m6A reader YTHDC1 regulates the scaffold function of LINE1 RNA in mouse ESCs and early embryos

2021 ◽  
Author(s):  
Chuan Chen ◽  
Wenqiang Liu ◽  
Jiayin Guo ◽  
Yuanyuan Liu ◽  
Xuelian Liu ◽  
...  
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Embryonic Stem ◽  
Rrna Synthesis ◽  
Binding Ability ◽  
Transcriptome Regulation ◽  
Early Embryos ◽  
Intrinsic Mechanism ◽  
Regulatory Rnas

AbstractN6-methyladenosine (m6A) on chromosome-associated regulatory RNAs (carRNAs), including repeat RNAs, plays important roles in tuning the chromatin state and transcription, but the intrinsic mechanism remains unclear. Here, we report that YTHDC1 plays indispensable roles in the self-renewal and differentiation potency of mouse embryonic stem cells (ESCs), which highly depends on the m6A-binding ability. Ythdc1 is required for sufficient rRNA synthesis and repression of the 2-cell (2C) transcriptional program in ESCs, which recapitulates the transcriptome regulation by the LINE1 scaffold. Detailed analyses revealed that YTHDC1 recognizes m6A on LINE1 RNAs in the nucleus and regulates the formation of the LINE1-NCL partnership and the chromatin recruitment of KAP1. Moreover, the establishment of H3K9me3 on 2C-related retrotransposons is interrupted in Ythdc1-depleted ESCs and inner cell mass (ICM) cells, which consequently increases the transcriptional activities. Our study reveals a role of m6A in regulating the RNA scaffold, providing a new model for the RNA-chromatin cross-talk.

scholarly journals Label-Free and Quantitative Dry Mass Monitoring for Single Cells during In Situ Culture

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1635
Author(s):  
Ya Su ◽  
Rongxin Fu ◽  
Wenli Du ◽  
Han Yang ◽  
Li Ma ◽  
...  
Keyword(s):  
Cell Growth ◽  
Single Cell ◽  
Hela Cells ◽  
Quantitative Measurement ◽  
Single Cells ◽  
Dry Mass ◽  
Quantitative Detection ◽  
Label Free ◽  
Mass Sensitivity

Quantitative measurement of single cells can provide in-depth information about cell morphology and metabolism. However, current live-cell imaging techniques have a lack of quantitative detection ability. Herein, we proposed a label-free and quantitative multichannel wide-field interferometric imaging (MWII) technique with femtogram dry mass sensitivity to monitor single-cell metabolism long-term in situ culture. We demonstrated that MWII could reveal the intrinsic status of cells despite fluctuating culture conditions with 3.48 nm optical path difference sensitivity, 0.97 fg dry mass sensitivity and 2.4% average maximum relative change (maximum change/average) in dry mass. Utilizing the MWII system, different intrinsic cell growth characteristics of dry mass between HeLa cells and Human Cervical Epithelial Cells (HCerEpiC) were studied. The dry mass of HeLa cells consistently increased before the M phase, whereas that of HCerEpiC increased and then decreased. The maximum growth rate of HeLa cells was 11.7% higher than that of HCerEpiC. Furthermore, HeLa cells were treated with Gemcitabine to reveal the relationship between single-cell heterogeneity and chemotherapeutic efficacy. The results show that cells with higher nuclear dry mass and nuclear density standard deviations were more likely to survive the chemotherapy. In conclusion, MWII was presented as a technique for single-cell dry mass quantitative measurement, which had significant potential applications for cell growth dynamics research, cell subtype analysis, cell health characterization, medication guidance and adjuvant drug development.

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