scholarly journals Two loci single particle trajectories analysis: constructing a first passage time statistics of local chromatin exploration

2017 ◽  
Author(s):  
O. Shukron ◽  
MH. Hauer ◽  
D. Holcman
Keyword(s):  
Single Particle ◽  
First Passage Time ◽  
Passage Time ◽  
Chromatin Organization ◽  
Local Dynamic ◽  
Particle Trajectories ◽  
Dna Damages ◽  
Double Stranded Dna ◽  
Before And After ◽  
First Contact

AbstractStochastic single particle trajectories are used to explore the local chromatin organization. We present here a statistical analysis of the first contact time distributions between two tagged loci recorded experimentally. First, we extract the association and dissociation times from data for various genomic distances between loci and we show that the looping time occurs in confined nanometer regions. Second, we characterize the looping time distribution for two loci in the presence of multiple DNA damages. Finally, we construct a polymer model that accounts for the local chromatin organization before and after a double-stranded DNA break (DSB) to estimate the level of chromatin decompaction. This novel passage time statistics method allows extracting transient dynamic at scales from one to few hundreds of nanometers, predicts the local changes in the number of binding molecules following DSB and can be used to better characterize the local dynamic of the chromatin.

Advances Using Single-Particle Trajectories to Reconstruct Chromatin Organization and Dynamics

2019 ◽  
Vol 35 (9) ◽  
pp. 685-705 ◽  
Author(s):  
O. Shukron ◽  
A. Seeber ◽  
A. Amitai ◽  
D. Holcman
Keyword(s):  
Single Particle ◽  
Chromatin Organization ◽  
Particle Trajectories

scholarly journals Single particle trajectory statistic to reconstruct chromatin organization and dynamics

2019 ◽  
Author(s):  
O. Shukron ◽  
A. Seeber ◽  
A. Amitai ◽  
D. Holcman
Keyword(s):  
Single Particle ◽  
Chromatin Organization ◽  
Biophysical Parameters ◽  
Dna Damages ◽  
Chromatin Dynamics ◽  
Multiple Loci ◽  
Polymer Models ◽  
Dynamics And Function ◽  
And Function

AbstractChromatin organization remains complex and far from understood. We discuss here recent statistical methods to extract biophysical parameters from in vivo single particle trajectories of loci to reconstruct chromatin reorganization in response to cellular stress such as DNA damages. We look at the methods to analyze both single loci as well as multiple loci tracked simultaneously and explain how to quantify and describe chromatin motion using a combination of extractable parameters. These parameters can be converted into information about chromatin dynamics and function. Furthermore, we discuss how the time scale of recurrent motion of a locus can be extracted and converted into local chromatin dynamics. We also discuss the effect of various sampling rates on the estimated parameters. Finally, we discuss polymer methods based on cross-linkers that account for minimal loop constraints hidden in tracked loci, that reveal chromatin organization at the 250nmspatial scale. We list and refer to some algorithm packages that are now publicly available. To conclude, chromatin organization and dynamics at hundreds of nanometers can be reconstructed from locus trajectories and predicted based on polymer models.

Synchrony of Digestion of SV40 DNA by Exonuclease III Determined by EM

1975 ◽  
Vol 33 ◽  
pp. 674-675
Author(s):  
Ray Wu ◽  
G. Ruben ◽  
B. Siegel ◽  
P. Spielman ◽  
E. Jay
Keyword(s):  
Dark Field ◽  
Uranyl Acetate ◽  
Enzyme Digestion ◽  
Dna Molecules ◽  
Exonuclease Iii ◽  
Aluminum Films ◽  
Double Stranded Dna ◽  
Before And After ◽  
Exo Iii ◽  
Sv40 Dna

A method for determining long nucleotide sequences of double-stranded DNA is being developed. It involves (a) the synchronous digestion of the DNA from the 3' ends with EL coli exonuclease III (Exo III) followed by (b) resynthesis with labeled nucleotides and DNA polymerase. A crucial factor in the success of this method is the degree to which the enzyme digestion proceeds synchronously under proper conditions of incubation (step a). Dark field EM is used to obtain accurate measurements on the lengths and distribution of the DNA molecules before and after digestion with Exo III, while gel electrophoresis is used in parallel to obtain a mean length for these molecules. It is the measurements on a large enough sample of individual molecules by EM that provides the information on how synchronously the digestion proceeds. For length measurements, the DNA molecules were picked up on 20-30 Å thick carbon-aluminum films, using the aqueous Kleinschmidt technique and stained with 7.5 x 10-5M uranyl acetate in 90% ethanol for 3 minutes.

First passage time for the state of exact chemical equilibrium

1980 ◽  
Vol 45 (3) ◽  
pp. 777-782 ◽  
Author(s):  
Milan Šolc
Keyword(s):  
Chemical Equilibrium ◽  
First Passage Time ◽  
Passage Time ◽  
The State ◽  
Recurrence Time ◽  
First Passage ◽  
First Order ◽  
The Mean ◽  
Passage Times ◽  
Number Of Particles

The establishment of chemical equilibrium in a system with a reversible first order reaction is characterized in terms of the distribution of first passage times for the state of exact chemical equilibrium. The mean first passage time of this state is a linear function of the logarithm of the total number of particles in the system. The equilibrium fluctuations of composition in the system are characterized by the distribution of the recurrence times for the state of exact chemical equilibrium. The mean recurrence time is inversely proportional to the square root of the total number of particles in the system.

scholarly journals Credit Gap Risk in a First Passage Time Model with Jumps

2009 ◽  
Author(s):  
Natalie Packham ◽  
Lutz Schloegl ◽  
Wolfgang M. Schmidt
Keyword(s):  
First Passage Time ◽  
Passage Time ◽  
First Passage ◽  
Time Model ◽  
Gap Risk ◽  
Credit Gap
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