A low Smc flux avoids collisions and facilitates chromosome organization in B. subtilis

SMC complexes are widely conserved ATP-powered DNA-loop-extrusion motors indispensable for organizing and faithfully segregating chromosomes. How SMC complexes translocate along DNA for loop extrusion and what happens when two complexes meet on the same DNA molecule is largely unknown. Revealing the origins and the consequences of SMC encounters is crucial for understanding the folding process not only of bacterial, but also of eukaryotic chromosomes. Here, we uncover several factors that influence bacterial chromosome organization by modulating the probability of such clashes. These factors include the number, the strength, and the distribution of Smc loading sites, the residency time on the chromosome, the translocation rate, and the cellular abundance of Smc complexes. By studying various mutants, we show that these parameters are fine-tuned to reduce the frequency of encounters between Smc complexes, presumably as a risk mitigation strategy. Mild perturbations hamper chromosome organization by causing Smc collisions, implying that the cellular capacity to resolve them is limited. Altogether, we identify mechanisms that help to avoid Smc collisions and their resolution by Smc traversal or other potentially risky molecular transactions.

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Fine-tuning of the Smc flux facilitates chromosome organization in B. subtilis

10.1101/2020.12.04.411900 ◽

2020 ◽

Cited By ~ 1

Author(s):

Anna Anchimiuk ◽

Virginia S. Lioy ◽

Anita Minnen ◽

Frédéric Boccard ◽

Stephan Gruber

Keyword(s):

Cell Division ◽

Residence Time ◽

Risk Mitigation ◽

Mitigation Strategy ◽

Fine Tuning ◽

Chromosome Organization ◽

Folding Process ◽

Dna Molecule ◽

Cellular Capacity ◽

Segregation Of Chromosomes

AbstractSMC complexes are widely conserved ATP-powered loop extrusion motors indispensable for the faithful segregation of chromosomes during cell division. How SMC complexes translocate along DNA for loop extrusion and what happens when two complexes meet on the same DNA molecule is largely unknown. Revealing the origins and the consequences of SMC encounters is crucial for understanding the folding process not only of bacterial, but also of eukaryotic chromosomes. Here, we uncover several factors that influence bacterial chromosome organization by modulating the probability of such clashes. These factors include the number, the strength and the distribution of Smc loading sites, the residence time on the chromosome, the translocation rate, and the cellular abundance of Smc complexes. By studying various mutants, we show that these parameters are fine-tuned to reduce the frequency of encounters between Smc complexes, presumably as a risk mitigation strategy. Mild perturbations hamper chromosome organization by causing Smc collisions, implying that the cellular capacity to resolve them is rather limited. Altogether, we identify mechanisms that help to avoid Smc collisions and their resolution by Smc traversal or other potentially risky molecular transactions.

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Selection of risk mitigation strategy in electronic supply chains using grey theory and digraph-matrix approaches

International Journal of Production Research ◽

10.1080/00207543.2014.948579 ◽

2014 ◽

Vol 53 (1) ◽

pp. 238-257 ◽

Cited By ~ 54

Author(s):

R. Rajesh ◽

V. Ravi ◽

R. Venkata Rao

Keyword(s):

Supply Chains ◽

Risk Mitigation ◽

Mitigation Strategy ◽

Grey Theory ◽

Selection Of

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The Dynamic Bacterial Cell: Part 1: Dynamics of Bacterial Chromosome Organization, Segregation, and Cytokinesis (34:32)

SciVee ◽

10.4016/8433.01 ◽

2008 ◽

Keyword(s):

Bacterial Cell ◽

Bacterial Chromosome ◽

Chromosome Organization

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Coordinated Risk Mitigation Strategy For Integrated Energy Systems Under Cyber-Attacks

IEEE Transactions on Power Systems ◽

10.1109/tpwrs.2020.2986455 ◽

2020 ◽

Vol 35 (5) ◽

pp. 4014-4025 ◽

Cited By ~ 1

Author(s):

Pengfei Zhao ◽

Chenghong Gu ◽

Da Huo

Keyword(s):

Risk Mitigation ◽

Energy Systems ◽

Mitigation Strategy ◽

Cyber Attacks ◽

Integrated Energy Systems

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Behavior of Listeria innocua during the manufacturing and pit-ripening of Formaggio di Fossa di Sogliano PDO cheese

Italian Journal of Food Safety ◽

10.4081/ijfs.2020.8552 ◽

2020 ◽

Vol 9 (2) ◽

Author(s):

Federica Giacometti ◽

Paolo Daminelli ◽

Laura Fiorentini ◽

Elena Cosciani-Cunico ◽

Paola Monastero ◽

...

Keyword(s):

Lactic Acid ◽

Lactic Acid Bacteria ◽

Risk Mitigation ◽

Scientific Evidence ◽

Challenge Test ◽

Mitigation Strategy ◽

Listeria Innocua ◽

Ripening Process ◽

Protected Designation Of Origin ◽

The Impact

Formaggio di Fossa di Sogliano is a traditional Italian Protected Designation of Origin (PDO) cheese ripened for a minimum of 5 months, with the feature of a ripening of at least 80 to at most 100 days in pits, digged into tuffaceous rocks according to medieval tradition of Italy. In this study, a challenge test using Listeria innocua as a surrogate of Listeria monocytogenes was performed, with the aim of increasing knowledge concerning the impact of the Fossa cheese process, and especially of the traditional ripening process of this PDO, on the behaviour of L. monocytogenes. Pasteurized milk was experimentally inoculated with 4.5 log CFU/mL cocktail by three L. innocua strains, and L. innocua and Mesophilic Lactic Acid Bacteria (LAB) counts as well as the evolution of temperatures, pH and aw values were monitored throughout the manufacturing and ripening processes. Throughout the ripening in maturation room a constant temperature of 8°C was observed reaching a temperature between 10 and 15.5°C during ripening into pit. In the final products data for LAB concentration, pH and aw values were roughly in accordance with literature, even if some differences were, probably due to variability of artisanal cheese productions. The numbers of L. innocua showed a slight decrease but remained stable until the end of ripening in maturation room, whereas a significant reduction of the microorganism was observed in the final product, at the end of the ripening into the pit. The findings give scientific evidence that the process of this PDO prevented the L. innocua growth, allowing us to speculate a similar behaviour of L. monocytogenes. Based on this study, the recommendation to extend as much as possible the ripening into pit (from 80 to 100 days) was provided to food business operators as a risk mitigation strategy to be implemented.

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Assembly, translocation, and activation of XerCD-difrecombination by FtsK translocase analyzed in real-time by FRET and two-color tethered fluorophore motion

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1510814112 ◽

2015 ◽

Vol 112 (37) ◽

pp. E5133-E5141 ◽

Cited By ~ 12

Author(s):

Peter F. J. May ◽

Pawel Zawadzki ◽

David J. Sherratt ◽

Achillefs N. Kapanidis ◽

Lidia K. Arciszewska

Keyword(s):

Real Time ◽

Bacterial Chromosome ◽

Dna Loops ◽

Synaptic Complex ◽

Dna Molecule ◽

Subsequent Activation ◽

Replication Terminus

The FtsK dsDNA translocase functions in bacterial chromosome unlinking by activating XerCD-difrecombination in the replication terminus region. To analyze FtsK assembly and translocation, and the subsequent activation of XerCD-difrecombination, we extended the tethered fluorophore motion technique, using two spectrally distinct fluorophores to monitor two effective lengths along the same tethered DNA molecule. We observed that FtsK assembled stepwise on DNA into a single hexamer, and began translocation rapidly (∼0.25 s). Without extruding DNA loops, single FtsK hexamers approached XerCD-difand resided there for ∼0.5 s irrespective of whether XerCD-difwas synapsed or unsynapsed. FtsK then dissociated, rather than reversing. Infrequently, FtsK activated XerCD-difrecombination when it encountered a preformed synaptic complex, and dissociated before the completion of recombination, consistent with each FtsK–XerCD-difencounter activating only one round of recombination.

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Arc flash: a risk assessment and mitigation strategy

The APPEA Journal ◽

10.1071/aj10117 ◽

2011 ◽

Vol 51 (2) ◽

pp. 737

Author(s):

Danny Norton ◽

Dale Wright

Keyword(s):

Risk Assessment ◽

Oil And Gas ◽

Capital Expenditure ◽

Risk Mitigation ◽

Cumulative Effect ◽

Mitigation Strategy ◽

Assessment Process ◽

Mitigation Measures ◽

Safe Work ◽

Arc Flash

Oil and gas facility managers are well aware that attention to detail saves lives and supports business continuity and reputation. Those tasked with stewardship of electrical assets will be aware of the need to protect their employees from the hazard of electrical arc flash and that it should be at the forefront of safety thinking. Complacency and lack of duty of care with this real and possibly un-quantified hazard can lead to fatalities. The primary solution to arc flash consequences in older installations has been the implementation of safe work procedures and personal protective equipment. While still valid, these solutions are the least effective options in the hierarchy of controls. SKM have developed a practical risk mitigation strategy that considers the hazards of prospective arc flash energy together with the cumulative effect of switchboard age, design, capability and condition. The strategy also considers the range of potential mitigation controls available through the mechanism of substitution and engineering design that focuses on reducing: The likelihood of an arc flash incident occurring; The likelihood of personnel exposure; and, The energy released should an incident occur. A structured arc flash risk assessment process can provide the asset owner the opportunity to rank individual switchboards for likelihood, consequence and risk, and thus provide direction for engineered remediation and capital expenditure. SKM proposes the way in which arc flash risk can be assessed, how appropriate layered mitigation measures might be selected, and how an asset owner may approach the issue of arc flash hazard mitigation to economically and reliably protect its employees.

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