scholarly journals H+- and Na+- elicited rapid changes of the microtubule cytoskeleton in the biflagellated green alga Chlamydomonas

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Yi Liu ◽  
Mike Visetsouk ◽  
Michelle Mynlieff ◽  
Hongmin Qin ◽  
Karl F Lechtreck ◽  
...  
Keyword(s):  
Green Alga ◽  
Environmental Changes ◽  
Dynamic Instability ◽  
Model Organism ◽  
Plant Cells ◽  
Reporter Protein ◽  
Fluorescent Reporter ◽  
Cellular Processes ◽  
Endogenous Level ◽  
Rapid Changes

Although microtubules are known for dynamic instability, the dynamicity is considered to be tightly controlled to support a variety of cellular processes. Yet diverse evidence suggests that this is not applicable to Chlamydomonas, a biflagellate fresh water green alga, but intense autofluorescence from photosynthesis pigments has hindered the investigation. By expressing a bright fluorescent reporter protein at the endogenous level, we demonstrate in real time discreet sweeping changes in algal microtubules elicited by rises of intracellular H+ and Na+. These results from this model organism with characteristics of animal and plant cells provide novel explanations regarding how pH may drive cellular processes; how plants may respond to, and perhaps sense stresses; and how organisms with a similar sensitive cytoskeleton may be susceptible to environmental changes.

scholarly journals H+- and Na+-elicited swift changes of the microtubule system in the biflagellated green alga Chlamydomonas

2017 ◽  
Author(s):  
Yi Liu ◽  
Mike Visetsouk ◽  
Michelle Mynlieff ◽  
Hongmin Qin ◽  
Karl F. Lechtreck ◽  
...  
Keyword(s):  
Real Time ◽  
Fresh Water ◽  
Green Alga ◽  
Dynamic Instability ◽  
Animal Cells ◽  
Reporter Protein ◽  
Fluorescent Reporter ◽  
Cellular Processes ◽  
Endogenous Level ◽  
Cytoskeletal System

AbstractThe microtubule cytoskeletal system is integral to diverse cellular processes. Although microtubules are known for dynamic instability, the system is tightly controlled in typical interphase animal cells. In contrast, diverse evidence suggests that the system is mercurial in the unicellular fresh water green alga, Chlamydomonas, but intense autofluorescence from photosynthesis pigments has hindered the investigation. By expressing a bright fluorescent reporter protein at the endogenous level, we demonstrate in real time discreet sweeping changes in algal microtubules elicited by fluctuation of intracellular H+ and Na+. These results suggest disparate sensitivity of this vital yet delicate system in diverse organisms; and illuminate how pH may drive crucial cellular processes; how plants respond to, and perhaps sense stresses; and how many species could be susceptible to accelerated changes in global environments.

Recovery of Recombinant Rotavirus Expressing Fluorescent Reporter Protein

2019 ◽  
Author(s):  
Asha Philip ◽  
Jin Dai ◽  
Sarah Katen ◽  
John Patton
Keyword(s):  
Reporter Protein ◽  
Fluorescent Reporter

scholarly journals Learning the distribution of single-cell chromosome conformations in bacteria reveals emergent order across genomic scales

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Joris J. B. Messelink ◽  
Muriel C. F. van Teeseling ◽  
Jacqueline Janssen ◽  
Martin Thanbichler ◽  
Chase P. Broedersz
Keyword(s):  
Single Cell ◽  
Caulobacter Crescentus ◽  
Model Organism ◽  
Super Resolution ◽  
Chromosome Organization ◽  
General Strategy ◽  
Cell Axis ◽  
Cellular Processes ◽  
Emergent Order ◽  
Genomic Clusters

AbstractThe order and variability of bacterial chromosome organization, contained within the distribution of chromosome conformations, are unclear. Here, we develop a fully data-driven maximum entropy approach to extract single-cell 3D chromosome conformations from Hi–C experiments on the model organism Caulobacter crescentus. The predictive power of our model is validated by independent experiments. We find that on large genomic scales, organizational features are predominantly present along the long cell axis: chromosomal loci exhibit striking long-ranged two-point axial correlations, indicating emergent order. This organization is associated with large genomic clusters we term Super Domains (SuDs), whose existence we support with super-resolution microscopy. On smaller genomic scales, our model reveals chromosome extensions that correlate with transcriptional and loop extrusion activity. Finally, we quantify the information contained in chromosome organization that may guide cellular processes. Our approach can be extended to other species, providing a general strategy to resolve variability in single-cell chromosomal organization.

The role of exploratory mechanisms in evolution

1995 ◽  
Vol 349 (1329) ◽  
pp. 297-297
Keyword(s):  
Dynamic Instability ◽  
Specific Mechanism ◽  
Cellular Mechanisms ◽  
Selection Processes ◽  
Wide Range ◽  
Rapid Changes ◽  
Neuronal Processes ◽  
History Of ◽  
Variation And Selection

Many cellular mechanisms use a process of variation and selection to generate specific patterns. Among these, dynamic instability of microtubules has been shown to employ a specific mechanism to intentionally generate variation. In many systems the growth of neurons or neuronal processes is excessive, the final connections being established by stabilization of functional interactions. When changes in neuronal networks take place, such as in metamorphosis, use is made of the plasticity of neuronal connectivity. In the immune system, specific responses are generated by variation and selection. Processes that explore a wide range of conditions and a wide range of structures can be called exploratory processes. These are very robust and capable of responding to damage, variability in the environment and ontogenic changes in the organisms. Such robustness would be useful for adapting to changes that occur during phylogenetic changes as well. Given the extensive history of extinction and radiation in evolution, it may be supposed that these mechanisms have themselves been selected for their capacity to survive rapid changes in the organism and for their ability to generate cellular variation.

scholarly journals Ser/Thr phospho-regulation by PknB and Stp mediates bacterial quiescence and antibiotic persistence in Staphylococcus aureus

2021 ◽  
Author(s):  
Markus Huemer ◽  
Srikanth Mairpady Shambat ◽  
Sandro Pereira ◽  
Lies Van Gestel ◽  
Judith Bergada-Pijuan ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Ribosomal Proteins ◽  
Environmental Changes ◽  
Acid Stress ◽  
Elongation Factor ◽  
Growth Delay ◽  
Lag Phase ◽  
Cellular Processes ◽  
Translational Activity

Staphylococcus aureus colonizes 30 to 50% of healthy adults and can cause a variety of diseases, ranging from superficial to life-threatening invasive infections such as bacteraemia and endocarditis. Often, these infections are chronic and difficult-to-treat despite adequate antibiotic therapy. Most antibiotics act on metabolically active bacteria in order to eradicate them. Thus, bacteria with minimized energy consumption resulting in metabolic quiescence, have increased tolerance to antibiotics. The most energy intensive process in cells - protein synthesis - is attenuated in bacteria entering into quiescence. Eukaryote-like serine/threonine kinases (STKs) and phosphatases (STPs) can fine-tune essential cellular processes, thereby enabling bacteria to quickly respond to environmental changes and to modulate quiescence. Here, we show that deletion of the only annotated functional STP, named Stp, in S. aureus leads to increased bacterial lag-phase and phenotypic heterogeneity under different stress challenges, including acidic pH, intracellular milieu and in vivo abscess environment. This growth delay was associated with reduced intracellular ATP levels and increased antibiotic persistence. Using phosphopeptide enrichment and mass spectrometry-based proteomics, we identified possible targets of Ser/Thr phosphorylation that regulate cellular processes and bacterial growth, such as ribosomal proteins including the essential translation elongation factor EF-G. Finally, we show that acid stress leads to a reduced translational activity in the stp deletion mutant indicating metabolic quiescence correlating with increased antibiotic persistence.

scholarly journals In Vivo Validation of Bimolecular Fluorescence Complementation (BiFC) to Investigate Aggregate Formation in Amyotrophic Lateral Sclerosis (ALS)

2020 ◽  
Author(s):  
Emily K Don ◽  
Alina Maschirow ◽  
Rowan A W Radford ◽  
Natalie M Scherer ◽  
Andres Vidal-Itriago ◽  
...  
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Disease Onset ◽  
Bimolecular Fluorescence Complementation ◽  
Aggregate Formation ◽  
Reporter Protein ◽  
Fluorescent Reporter ◽  
Lateral Sclerosis ◽  
Fluorescence Complementation ◽  
Bimolecular Fluorescence

AbstractAmyotrophic lateral sclerosis (ALS) is a form of motor neuron disease (MND) that is characterized by the progressive loss of motor neurons within the spinal cord, brainstem and motor cortex. Although ALS clinically manifests as a heterogeneous disease, with varying disease onset and survival, a unifying feature is the presence of ubiquitinated cytoplasmic protein inclusion aggregates containing TDP-43. However, the precise mechanisms linking protein inclusions and aggregation to neuronal loss are currently poorly understood.Bimolecular Fluorescence Complementation (BiFC) takes advantage the association of fluorophore fragments (non-fluorescent on their own) that are attached to an aggregation prone protein of interest. Interaction of the proteins of interest allows for the fluorescent reporter protein to fold into its native state and emit a fluorescent signal. Here, we combined the power of BiFC with the advantages of the zebrafish system to validate, optimize and visualize of the formation of ALS-linked aggregates in real time in a vertebrate model. We further provide in vivo validation of the selectivity of this technique and demonstrate reduced spontaneous self-assembly of the non-fluorescent fragments in vivo by introducing a fluorophore mutation. Additionally, we report preliminary findings on the dynamic aggregation of the ALS-linked hallmark proteins Fus and TDP-43 in their corresponding nuclear and cytoplasmic compartments using BiFC.Overall, our data demonstrates the suitability of this BiFC approach to study and characterize ALS-linked aggregate formation in vivo. Importantly, the same principle can be applied in the context of other neurodegenerative diseases and has therefore critical implications to advance our understanding of pathologies that underlie aberrant protein aggregation.

scholarly journals Visualizing the dynamics of exported bacterial proteins with the chemogenetic fluorescent reporter FAST

2020 ◽  
Author(s):  
Yankel Chekli ◽  
Caroline Peron-Cane ◽  
Dario Dell’Arciprete ◽  
Jean-François Allemand ◽  
Chenge Li ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Cell Surface ◽  
Bacterial Cell ◽  
Surface Proteins ◽  
Cellular Functions ◽  
Reporter Protein ◽  
Cell Surface Proteins ◽  
Fluorescent Reporter ◽  
Bacterial Proteins

AbstractBacterial proteins exported to the cell surface play key cellular functions. However, despite the interest to study the localization of surface proteins such as adhesins, transporters or hydrolases, monitoring their dynamics in live imaging remains challenging, due to the limited availability of fluorescent probes remaining functional after secretion. In this work, we used the Escherichia coli intimin and the Listeria monocytogenes InlB invasin as surface exposed scaffolds fused with the recently developed chemogenetic fluorescent reporter protein FAST. Using both membrane permeant (HBR-3,5DM) and non-permeant (HBRAA-3E) fluorogens that fluoresce upon binding to FAST, we demonstrated that fully functional FAST can be exposed at the cell surface and specifically tagged on the external side of the bacterial envelop in both diderm and monoderm bacteria. Our work opens new avenues to study of the organization and dynamics of the bacterial cell surface proteins.

Quantification of microtubule dynamics in living plant cells using fluorescence redistribution after photobleaching

1994 ◽  
Vol 107 (4) ◽  
pp. 775-784 ◽  
Author(s):  
J.M. Hush ◽  
P. Wadsworth ◽  
D.A. Callaham ◽  
P.K. Hepler
Keyword(s):  
Mammalian Cells ◽  
Laser Scanning ◽  
Dynamic Instability ◽  
Animal Cell ◽  
Plant Cells ◽  
Preprophase Band ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Turnover Rates ◽  
Living Plant

Microtubule (MT) turnover within the four principal MT arrays, the cortical array, the preprophase band, the mitotic spindle and the phragmoplast, has been measured in living stamen hair cells of Tradescantia that have been injected with fluorescent neurotubulin. Using the combined techniques of confocal laser scanning microscopy and fluorescence redistribution after photobleaching (FRAP), we report that the half-time of turnover in spindle MTs is t 1/2 = 31 +/- 6 seconds, which is in excellent agreement with previous measurements of turnover in animal cell spindles. Tradescantia interphase MTs, however, exhibit turnover rates (t 1/2 = 67 +/- seconds) that are some 3.4-fold faster than those measured in interphase mammalian cells, and thus are revealed as being highly dynamic. Preprophase band and phragmoplast MTs have turnover rates similar to those of interphase MTs in Tradescantia. The spatial and temporal aspects of the fluorescence redistribution after photobleaching in all four MT arrays are more consistent with subunit exchange by the mechanism of dynamic instability than treadmilling. This is the first quantification of MT dynamics in plant cells.

scholarly journals More than efficacy revealed by single-cell analysis of antiviral therapeutics

2019 ◽  
Vol 5 (10) ◽  
pp. eaax4761 ◽  
Author(s):  
Wu Liu ◽  
Mehmet U. Caglar ◽  
Zhangming Mao ◽  
Andrew Woodman ◽  
Jamie J. Arnold ◽  
...  
Keyword(s):  
Viral Infection ◽  
Single Cell ◽  
Single Cell Analysis ◽  
Principal Component ◽  
Cell Analysis ◽  
Infection Cycle ◽  
Reporter Protein ◽  
Fluorescent Reporter ◽  
Infection Dynamics ◽  
Infected Cells

Because many aspects of viral infection dynamics and inhibition are governed by stochastic processes, single-cell analysis should provide more information than approaches using population averaging. We have developed a microfluidic device composed of ~6000 wells, with each well containing a microstructure to capture single, infected cells replicating an enterovirus expressing a fluorescent reporter protein. We have used this system to characterize enterovirus inhibitors with distinct mechanisms of action. Single-cell analysis reveals that each class of inhibitor interferes with the viral infection cycle in a manner that can be distinguished by principal component analysis. Single-cell analysis of antiviral candidates not only reveals efficacy but also facilitates clustering of drugs with the same mechanism of action and provides some indication of the ease with which resistance will develop.

scholarly journals “What You Need, Baby, I Got It”: Transposable Elements as Suppliers of Cis-Operating Sequences in Drosophila

Biology ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 25 ◽  
Author(s):  
Roberta Moschetti ◽  
Antonio Palazzo ◽  
Patrizio Lorusso ◽  
Luigi Viggiano ◽  
René Massimiliano Marsano
Keyword(s):  
Transposable Elements ◽  
Transcriptional Control ◽  
Environmental Changes ◽  
Model Organism ◽  
Model Organisms ◽  
Regulatory Sequences ◽  
Transcriptional Pattern ◽  
Constitutive Components ◽  
Host Genes

Transposable elements (TEs) are constitutive components of both eukaryotic and prokaryotic genomes. The role of TEs in the evolution of genes and genomes has been widely assessed over the past years in a variety of model and non-model organisms. Drosophila is undoubtedly among the most powerful model organisms used for the purpose of studying the role of transposons and their effects on the stability and evolution of genes and genomes. Besides their most intuitive role as insertional mutagens, TEs can modify the transcriptional pattern of host genes by juxtaposing new cis-regulatory sequences. A key element of TE biology is that they carry transcriptional control elements that fine-tune the transcription of their own genes, but that can also perturb the transcriptional activity of neighboring host genes. From this perspective, the transposition-mediated modulation of gene expression is an important issue for the short-term adaptation of physiological functions to the environmental changes, and for long-term evolutionary changes. Here, we review the current literature concerning the regulatory and structural elements operating in cis provided by TEs in Drosophila. Furthermore, we highlight that, besides their influence on both TEs and host genes expression, they can affect the chromatin structure and epigenetic status as well as both the chromosome’s structure and stability. It emerges that Drosophila is a good model organism to study the effect of TE-linked regulatory sequences, and it could help future studies on TE–host interactions in any complex eukaryotic genome.

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