Bacterial filamentation drives colony chirality

AbstractChirality is ubiquitous in nature, with consequences at the cellular and tissue scales. As Escherichia coli colonies expand radially, an orthogonal component of growth creates a pinwheel-like pattern that can be revealed by fluorescent markers. To elucidate the mechanistic basis of this colony chirality, we investigated its link to left-handed, single-cell twisting during E. coli elongation. While chemical and genetic manipulation of cell width altered single-cell twisting handedness, colonies ceased to be chiral rather than switching handedness, and anaerobic growth altered colony chirality without affecting single-cell twisting. Chiral angle increased with increasing temperature even when growth rate decreased. Unifying these findings, we discovered that colony chirality was associated with the propensity for cell filamentation. Inhibition of cell division accentuated chirality under aerobic growth and generated chirality under anaerobic growth. Thus, regulation of cell division is intrinsically coupled to colony chirality, providing a mechanism for tuning macroscale spatial patterning.

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Balanced transcription of cell division genes inBacillus subtilisas revealed by single cell analysis

Environmental Microbiology ◽

10.1111/1462-2920.12148 ◽

2013 ◽

Vol 15 (12) ◽

pp. 3196-3209 ◽

Cited By ~ 6

Author(s):

Erik Nico Trip ◽

Jan-Willem Veening ◽

Eric J. Stewart ◽

Jeff Errington ◽

Dirk-Jan Scheffers

Keyword(s):

Cell Division ◽

Single Cell ◽

Single Cell Analysis ◽

Cell Analysis

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The Plastid of Toxoplasma gondii Is Divided by Association with the Centrosomes

The Journal of Cell Biology ◽

10.1083/jcb.151.7.1423 ◽

2000 ◽

Vol 151 (7) ◽

pp. 1423-1434 ◽

Cited By ~ 163

Author(s):

Boris Striepen ◽

Michael J. Crawford ◽

Michael K. Shaw ◽

Lewis G. Tilney ◽

Frank Seeber ◽

...

Keyword(s):

Cell Division ◽

Toxoplasma Gondii ◽

Genetic Manipulation ◽

Fluorescent Proteins ◽

Recombinant Expression ◽

Molecular Genetic ◽

Time Lapse ◽

Microtubule Organization ◽

Apicomplexan Parasites ◽

Daughter Cells

Apicomplexan parasites harbor a single nonphotosynthetic plastid, the apicoplast, which is essential for parasite survival. Exploiting Toxoplasma gondii as an accessible system for cell biological analysis and molecular genetic manipulation, we have studied how these parasites ensure that the plastid and its 35-kb circular genome are faithfully segregated during cell division. Parasite organelles were labeled by recombinant expression of fluorescent proteins targeted to the plastid and the nucleus, and time-lapse video microscopy was used to image labeled organelles throughout the cell cycle. Apicoplast division is tightly associated with nuclear and cell division and is characterized by an elongated, dumbbell-shaped intermediate. The plastid genome is divided early in this process, associating with the ends of the elongated organelle. A centrin-specific antibody demonstrates that the ends of dividing apicoplast are closely linked to the centrosomes. Treatment with dinitroaniline herbicides (which disrupt microtubule organization) leads to the formation of multiple spindles and large reticulate plastids studded with centrosomes. The mitotic spindle and the pellicle of the forming daughter cells appear to generate the force required for apicoplast division in Toxoplasma gondii. These observations are discussed in the context of autonomous and FtsZ-dependent division of plastids in plants and algae.

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Extensive Regulation of Metabolism and Growth during the Cell Division Cycle

10.1101/005629 ◽

2014 ◽

Author(s):

Nikolai Slavov ◽

David Botstein ◽

Amy Caudy

Keyword(s):

Gene Expression ◽

Oxygen Consumption ◽

Cell Division ◽

Single Cell ◽

Single Cells ◽

Emergent Behavior ◽

Yeast Cells ◽

Physiological Data ◽

Synchronized Cultures ◽

Metabolic Cycle

Yeast cells grown in culture can spontaneously synchronize their respiration, metabolism, gene expression and cell division. Such metabolic oscillations in synchronized cultures reflect single-cell oscillations, but the relationship between the oscillations in single cells and synchronized cultures is poorly understood. To understand this relationship and the coordination between metabolism and cell division, we collected and analyzed DNA-content, gene-expression and physiological data, at hundreds of time-points, from cultures metabolically-synchronized at different growth rates, carbon sources and biomass densities. The data enabled us to extend and generalize our mechanistic model, based on ensemble average over phases (EAP), connecting the population-average gene-expression of asynchronous cultures to the gene-expression dynamics in the single-cells comprising the cultures. The extended model explains the carbon-source specific growth-rate responses of hundreds of genes. Our physiological data demonstrate that the frequency of metabolic cycling in synchronized cultures increases with the biomass density, suggesting that this cycling is an emergent behavior, resulting from the entraining of the single-cell metabolic cycle by a quorum-sensing mechanism, and thus underscoring the difference between metabolic cycling in single cells and in synchronized cultures. Measurements of constant levels of residual glucose across metabolically synchronized cultures indicate that storage carbohydrates are required to fuel not only the G1/S transition of the division cycle but also the metabolic cycle. Despite the large variation in profiled conditions and in the scale of their dynamics, most genes preserve invariant dynamics of coordination with each other and with the rate of oxygen consumption. Similarly, the G1/S transition always occurs at the beginning, middle or end of the high oxygen consumption phases, analogous to observations in human and drosophila cells. These results highlight evolutionary conserved coordination among metabolism, cell growth and division.

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Single-cell RNA-seq analysis revealed long-lasting adverse effects of tamoxifen on neurogenesis in prenatal and adult brains

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1918883117 ◽

2020 ◽

Vol 117 (32) ◽

pp. 19578-19589 ◽

Cited By ~ 2

Author(s):

Chia-Ming Lee ◽

Liqiang Zhou ◽

Jiping Liu ◽

Jiayu Shi ◽

Yanan Geng ◽

...

Keyword(s):

Adverse Effects ◽

Single Cell ◽

Molecular Mechanisms ◽

Genetic Manipulation ◽

Lineage Tracing ◽

In Vitro Assays ◽

Fetal Mortality ◽

Neural Lineage ◽

Cortical Neurogenesis

The CreER/LoxP system is widely accepted to track neural lineages and study gene functions upon tamoxifen (TAM) administration. We have observed that prenatal TAM treatment caused high rates of delayed delivery and fetal mortality. This substance could produce undesired results, leading to data misinterpretation. Here, we report that administration of TAM during early stages of cortical neurogenesis promoted precocious neural differentiation, while it inhibited neural progenitor cell (NPC) proliferation. The TAM-induced inhibition of NPC proliferation led to deficits in cortical neurogenesis, dendritic morphogenesis, synaptic formation, and cortical patterning in neonatal and postnatal offspring. Mechanistically, by employing single-cell RNA-sequencing (scRNA-seq) analysis combined with in vivo and in vitro assays, we show TAM could exert these drastic effects mainly through dysregulating the Wnt-Dmrta2 signaling pathway. In adult mice, administration of TAM significantly attenuated NPC proliferation in both the subventricular zone and the dentate gyrus. This study revealed the cellular and molecular mechanisms for the adverse effects of TAM on corticogenesis, suggesting that care must be taken when using the TAM-induced CreER/LoxP system for neural lineage tracing and genetic manipulation studies in both embryonic and adult brains.

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Recombination may occur in the absence of transcription in the immunoglobulin heavy chain recombination centre

Nucleic Acids Research ◽

10.1093/nar/gkaa108 ◽

2020 ◽

Vol 48 (7) ◽

pp. 3553-3566

Author(s):

Chloé Oudinet ◽

Fatima-Zohra Braikia ◽

Audrey Dauba ◽

Ahmed Amine Khamlichi

Keyword(s):

B Cells ◽

Single Cell ◽

Chromatin Remodeling ◽

Heavy Chain ◽

Single Cell Level ◽

Mouse Line ◽

Cell Level ◽

Igh Locus ◽

Chromatin Remodeling Complexes ◽

Mechanistic Basis

Abstract Developing B cells undergo V(D)J recombination to generate a vast repertoire of Ig molecules. V(D)J recombination is initiated by the RAG1/RAG2 complex in recombination centres (RCs), where gene segments become accessible to the complex. Whether transcription is the causal factor of accessibility or whether it is a side product of other processes that generate accessibility remains a controversial issue. At the IgH locus, V(D)J recombination is controlled by Eμ enhancer, which directs the transcriptional, epigenetic and recombinational events in the IgH RC. Deletion of Eμ enhancer affects both transcription and recombination, making it difficult to conclude if Eμ controls the two processes through the same or different mechanisms. By using a mouse line carrying a CpG-rich sequence upstream of Eμ enhancer and analyzing transcription and recombination at the single-cell level, we found that recombination could occur in the RC in the absence of detectable transcription, suggesting that Eμ controls transcription and recombination through distinct mechanisms. Moreover, while the normally Eμ-dependent transcription and demethylating activities were impaired, recruitment of chromatin remodeling complexes was unaffected. RAG1 was efficiently recruited, thus compensating for the defective transcription-associated recruitment of RAG2, and providing a mechanistic basis for RAG1/RAG2 assembly to initiate V(D)J recombination.

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