| 1. |
- Alizadehheidari, Mohammadreza, 1987, et al.
(författare)
-
Nanoconfined Circular and Linear DNA: Equilibrium Conformations and Unfolding Kinetics
- 2015
-
Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 48:3, s. 871-878
-
Tidskriftsartikel (refereegranskat)abstract
- Studies of circular DNA confined to nanofluidic channels are relevant both from a fundamental polymer-physics perspective and due to the importance of circular DNA molecules in vivo. We here observe the unfolding of confined DNA from the circular to linear configuration as a light-induced double-strand break occurs, characterize the dynamics, and compare the equilibrium conformational statistics of linear and circular configurations. This is important because it allows us to determine to what extent existing statistical theories describe the extension of confined circular DNA. We find that the ratio of the extensions of confined linear and circular DNA configurations increases as the buffer concentration decreases. The experimental results fall between theoretical predictions for the extended de Gennes regime at weaker confinement and the Odijk regime at stronger confinement. We show that it is possible to directly distinguish between circular and linear DNA molecules by measuring the emission intensity from the DNA. Finally, we determine the rate of unfolding and show that this rate is larger for more confined DNA, possibly reflecting the corresponding larger difference in entropy between the circular and linear configurations.
|
|
| 2. |
- Alizadehheidari, Mohammadreza, 1987, et al.
(författare)
-
Unfolding of nanoconfined circular DNA
- 2015
-
Ingår i: BIOPHYSICAL JOURNAL. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 108:2 Supplement 1
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 3. |
- Fornander, Louise, 1984, et al.
(författare)
-
Visualizing the Nonhomogeneous Structure of RAD51 Filaments Using Nanofluidic Channels
- 2016
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 32:33, s. 8403-8412
-
Tidskriftsartikel (refereegranskat)abstract
- RAD51 is the key component of the homologous recombination pathway in eukaryotic cells and performs its task by forming filaments on DNA. In this study we investigate the physical properties of RAD51 filaments formed on DNA using nanofluidic channels and fluorescence microscopy. Contrary to the bacterial ortholog RecA, RAD51 forms inhomogeneous filaments on long DNA in vitro, consisting of several protein patches. We demonstrate that a permanent "kink" in the filament is formed where two patches meet if the stretch of naked DNA between the patches is short. The kinks are readily seen in the present microscopy approach but would be hard to identify using conventional single DNA molecule techniques where the DNA is more stretched. We also demonstrate that protein patches separated by longer stretches of bare DNA roll up on each other and this is visualized as transiently overlapping filaments. RAD51 filaments can be formed at several different conditions, varying the cation (Mg2+ or Ca2+), the DNA substrate (single-stranded or double-stranded), and the RAD51 concentration during filament nucleation, and we compare the properties of the different filaments formed. The results provide important information regarding the physical properties of RAD51 filaments but also demonstrate that nanofluidic channels are perfectly suited to study protein-DNA complexes.
|
|
| 4. |
- Westerlund, Fredrik, 1978, et al.
(författare)
-
Fluorescence microscopy of nanochannel-confined DNA
- 2018
-
Ingår i: Methods in Molecular Biology. - New York, NY : Springer New York. - 1064-3745 .- 1940-6029. ; 1665, s. 173-198
-
Bokkapitel (refereegranskat)abstract
- Stretching of DNA in nanoscale confinement allows for several important studies. The genetic contents of the DNA can be visualized on the single DNA molecule level and both the polymer physics of confined DNA and also DNA/protein and other DNA/DNA-binding molecule interactions can be explored. This chapter describes the basic steps to fabricate the nanostructures, perform the experiments and analyze the data.
|
|
| 5. |
- Fornander, Louise, 1984, et al.
(författare)
-
Using nanofluidic channels to probe dynamics of RAD51-Filaments
- 2015
-
Ingår i: 18th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2014. - 9780979806476 ; , s. 1826-1828
-
Konferensbidrag (refereegranskat)abstract
- Using nanochannels, passivated with a lipid bilayer to avoid sticking of proteins, we study Rad51 filaments bound to single- and double stranded DNA. We demonstrate how we can discern different properties of the filaments by studying them at different degrees of confinement. Unlike the bacterial homologue RecA, that forms homogeneous filaments along DNA, Rad51 forms heterogeneous filaments containing both rigid kinks as well as flexible regions. Varying the counterion, the DNA substrate as well as the initial protein concentration, we try to understand the factors governing the structure of the filaments.
|
|
| 6. |
- Freitag, C., et al.
(författare)
-
Visualizing the entire DNA from a chromosome in a single frame
- 2015
-
Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 9:4
-
Tidskriftsartikel (refereegranskat)abstract
- The contiguity and phase of sequence information are intrinsic to obtain complete understanding of the genome and its relationship to phenotype. We report the fabrication and application of a novel nanochannel design that folds megabase lengths of genomic DNA into a systematic back-and-forth meandering path. Such meandering nanochannels enabled us to visualize the complete 5.7 Mbp (1mm) stained DNA length of a Schizosaccharomyces pombe chromosome in a single frame of a CCD. We were able to hold the DNA in situ while implementing partial denaturation to obtain a barcode pattern that we could match to a reference map using the Poland-Scheraga model for DNA melting. The facility to compose such long linear lengths of genomic DNA in one field of view enabled us to directly visualize a repeat motif, count the repeat unit number, and chart its location in the genome by reference to unique barcode motifs found at measurable distances from the repeat. Meandering nanochannel dimensions can easily be tailored to human chromosome scales, which would enable the whole genome to be visualized in seconds. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
|
|
| 7. |
- McGinn, Steven, et al.
(författare)
-
New Technologies for DNA analysis-A review of the READNA Project.
- 2016
-
Ingår i: New Biotechnology. - : Elsevier BV. - 1876-4347 .- 1871-6784.
-
Forskningsöversikt (refereegranskat)abstract
- The REvolutionary Approaches and Devices for Nucleic Acid analysis (READNA) project received funding from the European Commission for 4 1/2 years. The objectives of the project revolved around technological developments in nucleic acid analysis. The project partners have discovered, created and developed a huge body of insights into nucleic acid analysis, ranging from improvements and implementation of current technologies to the most promising sequencing technologies that constitute a 3(rd) and 4(th) generation of sequencing methods with nanopores and in situ sequencing, respectively.
|
|
