Kinetics of Two-break Chromosome Exchanges and the Spatial Arrangement of Chromosome Strands in Interphase Nucleus

Nature ◽  
1966 ◽  
Vol 209 (5025) ◽  
pp. 796-797 ◽  
Author(s):  
SUSHIL KUMAR ◽  
A. T. NATARAJAN
Keyword(s):  
Interphase Nucleus ◽  
Spatial Arrangement ◽  
Break Chromosome ◽  
Kinetics Of ◽  
Chromosome Exchanges

scholarly journals Diffusion-Limited Reaction Kinetics of a Reactant with Square Reactive Patches on a Plane

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1744
Author(s):  
Changsun Eun
Keyword(s):  
Reaction Kinetics ◽  
Rate Constant ◽  
Spatial Arrangement ◽  
Total Surface Area ◽  
Reaction Model ◽  
Discrete Models ◽  
Diffusion Limited ◽  
Size Number ◽  
Surface Reaction Kinetics ◽  
Kinetics Of

We present a simple reaction model to study the influence of the size, number, and spatial arrangement of reactive patches on a reactant placed on a plane. Specifically, we consider a reactant whose surface has an N × N square grid structure, with each square cell (or patch) being chemically reactive or inert for partner reactant molecules approaching the cell via diffusion. We calculate the rate constant for various cases with different reactive N × N square patterns using the finite element method. For N = 2, 3, we determine the reaction kinetics of all possible reactive patterns in the absence and presence of periodic boundary conditions, and from the analysis, we find that the dependences of the kinetics on the size, number, and spatial arrangement are similar to those observed in reactive patches on a sphere. Furthermore, using square reactant models, we present a method to significantly increase the rate constant by sequentially breaking the patches into smaller patches and arranging them symmetrically. Interestingly, we find that a reactant with a symmetric patch distribution has a power–law relation between the rate constant and the number of reactive patches and show that this works well when the total reactive area is much less than the total surface area of the reactant. Since our N × N discrete models enable us to examine all possible reactive cases completely, they provide a solid understanding of the surface reaction kinetics, which would be helpful for understanding the fundamental aspects of the competitions between reactive patches arising in real applications.

The kinetics for two-break chromosome exchanges

1962 ◽  
Vol 3 (2) ◽  
pp. 304-314 ◽  
Author(s):  
Sheldon Wolff
Keyword(s):  
Break Chromosome ◽  
Chromosome Exchanges

scholarly journals DNA origami patterning of synthetic T cell receptors reveals spatial control of the sensitivity and kinetics of signal activation

2021 ◽  
Vol 118 (40) ◽  
pp. e2109057118
Author(s):  
Rui Dong ◽  
Tural Aksel ◽  
Waipan Chan ◽  
Ronald N. Germain ◽  
Ronald D. Vale ◽  
...  
Keyword(s):  
T Cell ◽  
Spatial Configuration ◽  
Cell Model ◽  
Spatial Arrangement ◽  
Cellular Systems ◽  
Dna Origami ◽  
Ligand Density ◽  
Affinity Ligands ◽  
Signaling Dynamics ◽  
Kinetics Of

Receptor clustering plays a key role in triggering cellular activation, but the relationship between the spatial configuration of clusters and the elicitation of downstream intracellular signals remains poorly understood. We developed a DNA-origami–based system that is easily adaptable to other cellular systems and enables rich interrogation of responses to a variety of spatially defined inputs. Using a chimeric antigen receptor (CAR) T cell model system with relevance to cancer therapy, we studied signaling dynamics at single-cell resolution. We found that the spatial arrangement of receptors determines the ligand density threshold for triggering and encodes the temporal kinetics of signaling activities. We also showed that signaling sensitivity of a small cluster of high-affinity ligands is enhanced when surrounded by nonstimulating low-affinity ligands. Our results suggest that cells measure spatial arrangements of ligands, translate that information into distinct signaling dynamics, and provide insights into engineering immunotherapies.

scholarly journals Tubulin assembly sites and the organization of cytoplasmic microtubules in cultured mammalian cells.

1981 ◽  
Vol 90 (3) ◽  
pp. 554-562 ◽  
Author(s):  
B R Brinkley ◽  
S M Cox ◽  
D A Pepper ◽  
L Wible ◽  
S L Brenner ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Cultured Cells ◽  
Simian Virus 40 ◽  
Spatial Arrangement ◽  
Simian Virus ◽  
Microtubule Assembly ◽  
Daughter Cells ◽  
Pericentriolar Material ◽  
Cytoplasmic Microtubules ◽  
Kinetics Of

The number, distribution, and nucleating capacity of microtubule-organizing centers (MTOCs) has been investigated in a variety of cultured mammalian cells. Most interphase cells contain a single MTOC that is localized at the centrosome region and corresponds to the centriole and pericentriolar material. MTOCs, like centrioles, become duplicated during the S phase of the cell cycle and are equationally distributed to daughter cells in mitosis. Multiple MTOCs were rarely observed in cultured cells except in one cell line (neuroblastoma), which also displayed an equally large number of centrioles in the cytoplasm. The kinetics of microtubule assembly and the tubulin nucleating capacity of MTOCs was assayed by incubating tubulin-depleted, permeabilized 3T3 and simian virus 40-transformed 3T3 cells with phosphocellulose-purified 65 brain tubulin and microtubule assembly buffer. Initiation and assembly of 65 tubulin occurred in association with the cells' endogenous MTOCs, and the length, number, and distribution of microtubules generated about the organizing centers were regulated and cell specific. Our results are consistent with the notion that the specification of microtubule length, number, and spatial arrangement resides largely in the MTOCs and surrounding cytoplasm and not in the tubulin subunits.

On the formation kinetics of radiation-induced chromosome exchanges in human lymphocytes

1996 ◽  
Vol 35 (4) ◽  
pp. 315-316 ◽  
Author(s):  
R. Greinert ◽  
D. Harder
Keyword(s):  
Human Lymphocytes ◽  
Formation Kinetics ◽  
Radiation Induced ◽  
Kinetics Of ◽  
Chromosome Exchanges

scholarly journals Distribution of unlinked transpositions of a Ds element from a T-DNA locus on tomato chromosome 4.

Genetics ◽  
1995 ◽  
Vol 141 (1) ◽  
pp. 383-390
Author(s):  
J Bríza ◽  
B J Carroll ◽  
V I Klimyuk ◽  
C M Thomas ◽  
D A Jones ◽  
...  
Keyword(s):  
Interphase Nucleus ◽  
Chromosomal Location ◽  
Donor Site ◽  
Spatial Arrangement ◽  
Transposon Tagging ◽  
Chromosome 2 ◽  
Chromosome 4 ◽  
Receptor Sites ◽  
Tomato Chromosome ◽  
Ds Element

Abstract In maize, receptor sites for unlinked transpositions of Activator (Ac) elements are not distributed randomly. To test whether the same is true in tomato, the receptor sites for a Dissociation (Ds) element derived from Ac, were mapped for 26 transpositions unlinked to a donor T-DNA locus on chromosome 4. Four independent transposed Dss mapped to sites on chromosome 4 genetically unlinked to the donor T-DNA, consistent with a preference for transposition to unlinked sites on the same chromosome as opposed to sites on other chromosomes. There was little preference among the nondonor chromosomes, except perhaps for chromosome 2, which carried seven transposed Dss, but these could not be proven to be independent. However, these data, when combined with those from other studies in tomato examining the distribution of transposed Acs or Dss among nondonor chromosomes, suggest there may be absolute preferences for transposition irrespective of the chromosomal location of the donor site. If true, transposition to nondonor chromosomes in tomato would differ from that in maize, where the preference seems to be determined by the spatial arrangement of chromosomes in the interphase nucleus. The tomato lines carrying Ds elements at known locations are available for targeted transposon tagging experiments.

THE DISTRIBUTION OF CHROMATIN IN THE INTERPHASE NUCLEUS OF ZEBRINA PENDULA

1982 ◽  
Vol 24 (5) ◽  
pp. 583-591 ◽  
Author(s):  
Kirby J. Evans ◽  
W. Gary Filion
Keyword(s):  
Interphase Nucleus ◽  
Nuclear Organization ◽  
Spatial Arrangement ◽  
Barium Hydroxide ◽  
Root Tip ◽  
Time Intervals ◽  
Cell Cycles ◽  
Tip Cells ◽  
Root Tip Cells

An investigation of nuclear organization in interphase root tip cells of Zebrina pendula Schnizl. showed that: (1) 40% of the BSG (Barium hydroxide/saline/Giemsa) treated nuclei had nonrandomly distributed chromocenters and (2) BrdU-FPG (5′-bromodeoxyuridine-fluorescence plus Giemsa) treated nuclei showed discrete staining patterns when exposed to BrdU for time intervals of two or more cell cycles. These data were interpreted as further evidence for an ordered spatial arrangement of chromosomal regions in the interphase nucleus.

scholarly journals Effects of the Size, the Number, and the Spatial Arrangement of Reactive Patches on a Sphere on Diffusion-Limited Reaction Kinetics: A Comprehensive Study

2020 ◽  
Vol 21 (3) ◽  
pp. 997 ◽  
Author(s):  
Changsun Eun
Keyword(s):  
Reaction Kinetics ◽  
Rate Constant ◽  
Brownian Dynamics ◽  
Kinetic Studies ◽  
Spatial Arrangement ◽  
The Finite Element Method ◽  
Diffusion Limited ◽  
Diffusion Controlled ◽  
Kinetics Of ◽  
Good Agreement

We investigate how the size, the number, and the spatial arrangement of identical nonoverlapping reactive patches on a sphere influence the overall reaction kinetics of bimolecular diffusion-limited (or diffusion-controlled) reactions that occur between the patches and the reactants diffusing around the sphere. First, in the arrangement of two patches, it is known that the overall rate constant increases as the two patches become more separated from each other but decreases when they become closer to each other. In this work, we further study the dependence of the patch arrangement on the kinetics with three and four patches using the finite element method (FEM). In addition to the patch arrangement, the kinetics is also dependent on the number and size of the patches. Therefore, we study such dependences by calculating the overall rate constants using the FEM for various cases, especially for large-sized patches, and this study is complementary to the kinetic studies that were performed by Brownian dynamics (BD) simulation methods for small-sized patches. The numerical FEM and BD simulation results are compared with the results from various kinetic theories to evaluate the accuracies of the theories. Remarkably, this comparison indicates that our theory, which was recently developed based on the curvature-dependent kinetic theory, shows good agreement with the FEM and BD numerical results. From this validation, we use our theory to further study the variation of the overall rate constant when the patches are arbitrarily arranged on a sphere. Our theory also confirms that to maximize the overall rate constant, we need to break large-sized patches into smaller-sized patches and arrange them to be maximally separated to reduce their competition.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

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