scholarly journals Self-organised segregation of bacterial chromosomal origins

2018 ◽  
Author(s):  
Andreas Hofmann ◽  
Jarno Mäkelä ◽  
David Sherratt ◽  
Dieter Heermann ◽  
Seán M. Murray
Keyword(s):  
Model Organism ◽  
Future Studies ◽  
E Coli ◽  
Chromosomal Origin ◽  
Origin Region ◽  
Bacterial Model ◽  
Specific Association ◽  
Underlying Mechanisms ◽  
Structural Maintenance Of Chromosomes ◽  
Chromosome Organisation

AbstractIn spite of much effort, many aspects of chromosome organisation and segregation in bacteria remain unclear. Even for Escherichia coli, the most widely studied bacterial model organism, we still do not know the underlying mechanisms. Like many other bacteria, the chromosomal origin of replication in E. coli is dynamically positioned throughout the cell cycle. Initially maintained at mid-cell, where replication occurs, origins are subsequently partitioned to opposite quarter positions. The Structural Maintenance of Chromosomes (SMC) complex, MukBEF, which is required for correct chromosome compaction and organisation, has been implicated in this behaviour but the mode of action is unknown. Here, we build on a recent self-organising model for the positioning of E. coli MukBEF, to propose an explanation for the positioning and partitioning of origins. We propose that a specific association of MukBEF with the origin region, results in a non-trivial feedback between the self-organising MukBEF gradient and the origins, leading to accurate positioning and partitioning as an emergent property. We compare the model to quantitative experimental data of origin dynamics and their colocalisation with MukBEF clusters and find excellent agreement. Overall, the model suggests that MukBEF and origins act together as a self-organising system for chromosome segregation and introduces protein self-organisation as an important consideration for future studies of chromosome dynamics.

scholarly journals Self-organised segregation of bacterial chromosomal origins

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Andreas Hofmann ◽  
Jarno Mäkelä ◽  
David J Sherratt ◽  
Dieter Heermann ◽  
Seán M Murray
Keyword(s):  
Replication Origin ◽  
The Self ◽  
Experimental Measurements ◽  
Chromosomal Replication ◽  
Future Studies ◽  
Chromosome Dynamics ◽  
Origin Region ◽  
Self Organisation ◽  
Structural Maintenance Of Chromosomes ◽  
Chromosome Organisation

The chromosomal replication origin region (ori) of characterised bacteria is dynamically positioned throughout the cell cycle. In slowly growing Escherichia coli, ori is maintained at mid-cell from birth until its replication, after which newly replicated sister oris move to opposite quarter positions. Here, we provide an explanation for ori positioning based on the self-organisation of the Structural Maintenance of Chromosomes complex, MukBEF, which forms dynamically positioned clusters on the chromosome. We propose that a non-trivial feedback between the self-organising gradient of MukBEF complexes and the oris leads to accurate ori positioning. We find excellent agreement with quantitative experimental measurements and confirm key predictions. Specifically, we show that oris exhibit biased motion towards MukBEF clusters, rather than mid-cell. Our findings suggest that MukBEF and oris act together as a self-organising system in chromosome organisation-segregation and introduces protein self-organisation as an important consideration for future studies of chromosome dynamics.

Female Voice Agents in Fully Autonomous Vehicles Are Not Only More Likeable and Comfortable, But Also More Competent

2020 ◽  
Vol 64 (1) ◽  
pp. 1033-1037
Author(s):  
Jiayuan Dong ◽  
Emily Lawson ◽  
Jack Olsen ◽  
Myounghoon Jeon
Keyword(s):  
Autonomous Vehicles ◽  
Autonomous Driving ◽  
Preference Ranking ◽  
Uncanny Valley ◽  
Tracking Data ◽  
Effective Solution ◽  
User Perception ◽  
Future Studies ◽  
Underlying Mechanisms ◽  
The Voice

Driving agents can provide an effective solution to improve drivers’ trust in and to manage interactions with autonomous vehicles. Research has focused on voice-agents, while few have explored robot-agents or the comparison between the two. The present study tested two variables - voice gender and agent embodiment, using conversational scripts. Twenty participants experienced autonomous driving using the simulator for four agent conditions and filled out subjective questionnaires for their perception of each agent. Results showed that the participants perceived the voice only female agent as more likeable, more comfortable, and more competent than other conditions. Their final preference ranking also favored this agent over the others. Interestingly, eye-tracking data showed that embodied agents did not add more visual distractions than the voice only agents. The results are discussed with the traditional gender stereotype, uncanny valley, and participants’ gender. This study can contribute to the design of in-vehicle agents in the autonomous vehicles and future studies are planned to further identify the underlying mechanisms of user perception on different agents.

scholarly journals Influence of Acetylcholine Esterase Inhibitors and Memantine, Clinically Approved for Alzheimer’s Dementia Treatment, on Intestinal Properties of the Mouse

2021 ◽  
Vol 22 (3) ◽  
pp. 1015
Author(s):  
Vu Thu Thuy Nguyen ◽  
Jason Sallbach ◽  
Malena dos Santos Guilherme ◽  
Kristina Endres
Keyword(s):  
Calcium Influx ◽  
Ex Vivo ◽  
Model Organism ◽  
Nmda Receptor Antagonist ◽  
Acetylcholine Esterase ◽  
Enteric Neurons ◽  
Acetylcholine Esterase Inhibitors ◽  
E Coli ◽  
Esterase Inhibitors ◽  
Intestinal Functions

Four drugs are currently approved for the treatment of Alzheimer’s disease (AD) by the FDA. Three of these drugs—donepezil, rivastigmine, and galantamine—belong to the class of acetylcholine esterase inhibitors. Memantine, a NMDA receptor antagonist, represents the fourth and a combination of donepezil and memantine the fifth treatment option. Recently, the gut and its habitants, its microbiome, came into focus of AD research and added another important factor to therapeutic considerations. While the first data provide evidence that AD patients might carry an altered microbiome, the influence of administered drugs on gut properties and commensals have been largely ignored so far. However, the occurrence of digestive side effects with these drugs and the knowledge that cholinergic transmission is crucial for several gut functions enforces the question if, and how, this medication influences the gastrointestinal system and its microbial stocking. Here, we investigated aspects such as microbial viability, colonic propulsion, and properties of enteric neurons, affected by assumed intestinal concentration of the four drugs using the mouse as a model organism. All ex vivo administered drugs revealed no direct effect on fecal bacteria viability and only a high dosage of memantine resulted in reduced biofilm formation of E. coli. Memantine was additionally the only compound that elevated calcium influx in enteric neurons, while all acetylcholine esterase inhibitors significantly reduced esterase activity in colonic tissue specimen and prolonged propulsion time. Both, acetylcholine esterase inhibitors and memantine, had no effect on general viability and neurite outgrowth of enteric neurons. In sum, our findings indicate that all AD symptomatic drugs have the potential to affect distinct intestinal functions and with this—directly or indirectly—microbial commensals.

scholarly journals Metabolome and proteome analyses reveal transcriptional misregulation in glycolysis of engineered E. coli

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chun-Ying Wang ◽  
Martin Lempp ◽  
Niklas Farke ◽  
Stefano Donati ◽  
Timo Glatter ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Binding Site ◽  
Metabolic Pathways ◽  
Glycerol Production ◽  
Inducible Promoters ◽  
E Coli ◽  
Inhibition Of Glycolysis ◽  
Underlying Mechanisms ◽  
Rate Limiting ◽  
Engineered Bacteria

AbstractSynthetic metabolic pathways are a burden for engineered bacteria, but the underlying mechanisms often remain elusive. Here we show that the misregulated activity of the transcription factor Cra is responsible for the growth burden of glycerol overproducing E. coli. Glycerol production decreases the concentration of fructose-1,6-bisphoshate (FBP), which then activates Cra resulting in the downregulation of glycolytic enzymes and upregulation of gluconeogenesis enzymes. Because cells grow on glucose, the improper activation of gluconeogenesis and the concomitant inhibition of glycolysis likely impairs growth at higher induction of the glycerol pathway. We solve this misregulation by engineering a Cra-binding site in the promoter controlling the expression of the rate limiting enzyme of the glycerol pathway to maintain FBP levels sufficiently high. We show the broad applicability of this approach by engineering Cra-dependent regulation into a set of constitutive and inducible promoters, and use one of them to overproduce carotenoids in E. coli.

scholarly journals Droplet- Rather than Aerosol-Mediated Dispersion Is the Primary Mechanism of Bacterial Transmission from Contaminated Hand-Washing Sink Traps

2018 ◽  
Vol 85 (2) ◽  
Author(s):  
Shireen M. Kotay ◽  
Rodney M. Donlan ◽  
Christine Ganim ◽  
Katie Barry ◽  
Bryan E. Christensen ◽  
...  
Keyword(s):  
Patient Care ◽  
Sampling Methods ◽  
Fluorescent Protein ◽  
Model Organism ◽  
Air Sampling ◽  
Multidrug Resistant ◽  
Hand Washing ◽  
Content Type ◽  
E Coli ◽  
Green Fluorescent

ABSTRACT An alarming rise in hospital outbreaks implicating hand-washing sinks has led to widespread acknowledgment that sinks are a major reservoir of antibiotic-resistant pathogens in patient care areas. An earlier study using green fluorescent protein (GFP)-expressing Escherichia coli (GFP-E. coli) as a model organism demonstrated dispersal from drain biofilms in contaminated sinks. The present study further characterizes the dispersal of microorganisms from contaminated sinks. Replicate hand-washing sinks were inoculated with GFP-E. coli, and dispersion was measured using qualitative (settle plates) and quantitative (air sampling) methods. Dispersal caused by faucet water was captured with settle plates and air sampling methods when bacteria were present on the drain. In contrast, no dispersal was captured without or in between faucet events, amending an earlier theory that bacteria aerosolize from the P-trap and disperse. Numbers of dispersed GFP-E. coli cells diminished substantially within 30 minutes after faucet usage, suggesting that the organisms were associated with larger droplet-sized particles that are not suspended in the air for long periods. IMPORTANCE Among the possible environmental reservoirs in a patient care environment, sink drains are increasingly recognized as a potential reservoir to hospitalized patients of multidrug-resistant health care-associated pathogens. With increasing antimicrobial resistance limiting therapeutic options for patients, a better understanding of how pathogens disseminate from sink drains is urgently needed. Once this knowledge gap has decreased, interventions can be engineered to decrease or eliminate transmission from hospital sink drains to patients. The current study further defines the mechanisms of transmission for bacteria that colonize sink drains.

scholarly journals DNA sliding and loop formation by E. coli SMC complex: MukBEF

2021 ◽  
Author(s):  
man zhou
Keyword(s):  
Single Molecule ◽  
Atp Hydrolysis ◽  
Dna Interaction ◽  
Loop Formation ◽  
Unknown Mechanism ◽  
E Coli ◽  
Dna Compaction ◽  
And Function ◽  
Structural Maintenance Of Chromosomes

SMC (structural maintenance of chromosomes) complexes share conserved architectures and function in chromosome maintenance via an unknown mechanism. Here we have used single-molecule techniques to study MukBEF, the SMC complex in Escherichia coli. Real-time movies show MukB alone can compact DNA and ATP inhibits DNA compaction by MukB. We observed that DNA unidirectionally slides through MukB, potentially by a ratchet mechanism, and the sliding speed depends on the elastic energy stored in the DNA. MukE, MukF and ATP binding stabilize MukB and DNA interaction, and ATP hydrolysis regulates the loading/unloading of MukBEF from DNA. Our data suggests a new model for how MukBEF organizes the bacterial chromosome in vivo; and this model will be relevant for other SMC proteins.

scholarly journals Droplet rather than Aerosol Mediated Dispersion is the Primary Mechanism of Bacterial transmission from Contaminated Hand Washing Sink Traps

2018 ◽  
Author(s):  
Shireen Kotay ◽  
Rodney M. Donlan ◽  
Christine Ganim ◽  
Katie Barry ◽  
Bryan E. Christensen ◽  
...  
Keyword(s):  
Patient Care ◽  
Sampling Methods ◽  
Model Organism ◽  
Air Sampling ◽  
Multidrug Resistant ◽  
Hand Washing ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Potential Reservoir ◽  
Healthcare Associated

ABSTRACTAn alarming rise in hospital outbreaks implicating hand-washing sinks has led to widespread acknowledgement that sinks are a major reservoir of antibiotic resistant pathogens in patient-care areas. An earlier study using a GFP-expressing Escherichia coli (GFP-E. coli) as a model organism demonstrated dispersal from drain biofilm in contaminated sinks. The present study further characterizes the dispersal of microorganisms from contaminated sinks. Replicate hand-washing sinks were inoculated with GFP-E. coli, and dispersion was measured using qualitative (settle plates) and quantitative (air sampling) methods. Dispersal caused by faucet water was captured with settle plates and air sampling methods when bacteria were present on the drain. In contrast, no dispersal was captured without or in between faucet events amending earlier theory that bacteria aerosolize from P-trap and disperse. Numbers of dispersed GFP-E. coli diminished substantially within 30 minutes after faucet usage, suggesting that the organisms were associated with larger droplet-sized particles that are not suspended in the air for long periods.IMPORTANCEAmong the possible environmental reservoirs in a patient care environment, sink drains are increasingly recognized as potential reservoir of multidrug resistant healthcare-associated pathogens to hospitalized patients. With increasing antimicrobial resistance limiting therapeutic options for patients, better understanding of how pathogens disseminate from sink drains is urgently needed. Once this knowledge gap has decreased, interventions can be engineered to decrease or eliminate transmission from hospital sink drains to patients. The current study further defines the mechanisms of transmission for bacteria colonizing sink drains.

Interaction specificity between the chaperone and proteolytic components of the cyanobacterial Clp protease

2012 ◽  
Vol 446 (2) ◽  
pp. 311-320 ◽  
Author(s):  
Anders Tryggvesson ◽  
Frida M. Ståhlberg ◽  
Axel Mogk ◽  
Kornelius Zeth ◽  
Adrian K. Clarke
Keyword(s):  
Escherichia Coli ◽  
Active Sites ◽  
Terminal Sequence ◽  
Core Complex ◽  
Clp Protease ◽  
E Coli ◽  
Loop Region ◽  
N Terminus ◽  
Specific Association ◽  
The Stability

The Clp protease is conserved among eubacteria and most eukaryotes, and uses ATP to drive protein substrate unfolding and translocation into a chamber of sequestered proteolytic active sites. In plant chloroplasts and cyanobacteria, the essential constitutive Clp protease consists of the Hsp100/ClpC chaperone partnering a proteolytic core of catalytic ClpP and noncatalytic ClpR subunits. In the present study, we have examined putative determinants conferring the highly specific association between ClpC and the ClpP3/R core from the model cyanobacterium Synechococcus elongatus. Two conserved sequences in the N-terminus of ClpR (tyrosine and proline motifs) and one in the N-terminus of ClpP3 (MPIG motif) were identified as being crucial for the ClpC–ClpP3/R association. These N-terminal domains also influence the stability of the ClpP3/R core complex itself. A unique C-terminal sequence was also found in plant and cyanobacterial ClpC orthologues just downstream of the P-loop region previously shown in Escherichia coli to be important for Hsp100 association to ClpP. This R motif in Synechococcus ClpC confers specificity for the ClpP3/R core and prevents association with E. coli ClpP; its removal from ClpC reverses this core specificity.

scholarly journals Early childhood aggressive behaviour: Negative interactions with paternal antisocial behaviour and maternal postpartum depressive symptoms across two international cohorts

2018 ◽  
Vol 54 ◽  
pp. 77-84 ◽  
Author(s):  
Mijke P. Lambregtse-van den Berg ◽  
Henning Tiemeier ◽  
Frank C. Verhulst ◽  
Vincent Jaddoe ◽  
Elizabeth Tindall ◽  
...  
Keyword(s):  
Early Childhood ◽  
Postpartum Depression ◽  
Aggressive Behaviour ◽  
Antisocial Behaviour ◽  
Childhood Aggression ◽  
Negative Interaction ◽  
Future Studies ◽  
The United Kingdom ◽  
Underlying Mechanisms ◽  
Maternal Postpartum Depression

AbstractBackground:Early childhood aggressive behaviour is a predictor of future violence. Therefore, identifying risk factors for children’s aggressive behaviour is important in understanding underlying mechanisms. Maternal postpartum depression is a known risk factor. However, little research has focused on the influence of paternal behaviour on early childhood aggression and its interaction with maternal postpartum depression.Methods:This study was performed in two cohorts: the Fathers Project, in the United Kingdom (n = 143) and the Generation R Study, in The Netherlands (n = 549). In both cohorts, we related paternal antisocial personality (ASP) traits and maternal postpartum depressive (PPD) symptoms to childhood aggressive behaviour at age two (Fathers Project) and age three (Generation R Study). We additionally tested whether the presence of paternal ASP traits increased the association between maternal PPD–symptoms and early childhood aggression.Results:The association between paternal ASP traits and early childhood aggressive behaviour, corrected for maternal PPD-symptoms, was similar in magnitude between the cohorts (Fathers Project: standardized β = 0.12, p = 0.146; Generation R: β = 0.14, p = 0.001), although the association was not statistically significant in the Fathers Project. Strikingly, and in contrast to our expectations, there was evidence of a negative interaction between paternal ASP traits and maternal PPD-symptoms on childhood aggressive behaviour (Fathers Project: β = −0.20, p = 0.020; Generation R: β = −0.09, p = 0.043) in both studies. This meant that with higher levels of paternal ASP traits the association between maternal PPD-symptoms and childhood aggressive behaviour was less and vice versa.Conclusions:Our findings stress the importance of including both maternal and paternal psychopathology in future studies and interventions focusing on early childhood aggressive behaviour.

The water flea Daphnia pulex (Cladocera, Daphniidae), a possible model organism to evaluate aspects of freshwater ecosystems

Crustaceana ◽  
2019 ◽  
Vol 92 (11-12) ◽  
pp. 1415-1426
Author(s):  
Juan-Alejandro Norambuena ◽  
Jorge Farías ◽  
Patricio De los Ríos
Keyword(s):  
Phylogenetic Trees ◽  
Daphnia Pulex ◽  
Model Organism ◽  
Freshwater Ecosystems ◽  
Intraspecific Diversity ◽  
Molecular Tools ◽  
Water Flea ◽  
Future Studies ◽  
Molecular Studies

Abstract Daphnia pulex is a freshwater planktonic crustacean, allegedly a cosmopolitan species, which is found in lentic ecosystems. The aim of this study was to conduct a literature review of D. pulex related to its life history and genetic variability, in order to mark a route for future studies. We noted that D. pulex is a model species on which ecological studies have been carried out, as well as molecular studies, in which its molecular diversity has been characterized and such in specimens from different environments: both pristine and under human influence. In particular those studies are highlighted, in which molecular tools have been used to construct phylogenetic trees for study intraspecific differences. Also, in some of these molecular studies, analyses of genetic, inter- and intraspecific diversity have been performed. In addition, analyses of protein expression in D. pulex and related species seem promising in evaluating the detailed role of this species.

Sign in / Sign up

Export Citation Format

Share Document