Limits...
Reversibility and Viscoelastic Properties of Micropillar Supported and Oriented Magnesium Bundled F-Actin.

Maier T, Haraszti T - PLoS ONE (2015)

Bottom Line: Understanding the bundling kinetics of actin filaments is important in the formation of various cytoskeletal structures, such as filopodia and stress fibers.Microparticles attached to the filaments allowed the measurement of thermal motion, and we found that bundling takes place at lower concentrations than previously found in 3-dimensional actin gels, i.e. actin filaments formed bundles in the presence of 5-12 mM of magnesium chloride in a time-dependent manner.The filaments also displayed long term stability for up to hours after removing the magnesium ions from the buffer, which suggests that there is an extensive hysteresis between cation induced crosslinking and decrosslinking.

View Article: PubMed Central - PubMed

Affiliation: Max Planck Institute for Intelligent Systems, Department of New Materials and Biosystems, Heisenberg str. 3, D-70569 Stuttgart, Germany; University of Heidelberg, Institute of Physical Chemistry, Department of Biophysical Chemistry, Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany.

ABSTRACT
Filamentous actin is one of the most important cytoskeletal elements. Not only is it responsible for the elastic properties of many cell types, but it also plays a vital role in cellular adhesion and motility. Understanding the bundling kinetics of actin filaments is important in the formation of various cytoskeletal structures, such as filopodia and stress fibers. Utilizing a unique pillar-structured microfluidic device, we investigated the time dependence of bundling kinetics of pillar supported free-standing actin filaments. Microparticles attached to the filaments allowed the measurement of thermal motion, and we found that bundling takes place at lower concentrations than previously found in 3-dimensional actin gels, i.e. actin filaments formed bundles in the presence of 5-12 mM of magnesium chloride in a time-dependent manner. The filaments also displayed long term stability for up to hours after removing the magnesium ions from the buffer, which suggests that there is an extensive hysteresis between cation induced crosslinking and decrosslinking.

No MeSH data available.


Related in: MedlinePlus

Temporal progression of the elastic force constant.ky at Mg2+ concentrations between 2–12 mM. (A) the absolute values (errorbars smaller than the symbols; not shown), and (B) normalized to the average of the first 3 points (at time 0).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4556452&req=5

pone.0136432.g006: Temporal progression of the elastic force constant.ky at Mg2+ concentrations between 2–12 mM. (A) the absolute values (errorbars smaller than the symbols; not shown), and (B) normalized to the average of the first 3 points (at time 0).

Mentions: The time-dependent variation of the apparent spring constant ky is presented in Fig 6. A transition is clearly visible as the actin filaments form bundles; however, the individual datasets do not clearly group according to the magnesium ion concentration. The varying amount of actin filaments in the individual bundles and the number of filaments attached initially to the tracer beads results in a broad distribution of data at the outset of the experiments (Fig 6A). To decrease this effect, we normalized each dataset to the average of the first three measurement points, where the bundling was not yet present. The data could then be grouped together, yet still displaying the general concentration dependence.


Reversibility and Viscoelastic Properties of Micropillar Supported and Oriented Magnesium Bundled F-Actin.

Maier T, Haraszti T - PLoS ONE (2015)

Temporal progression of the elastic force constant.ky at Mg2+ concentrations between 2–12 mM. (A) the absolute values (errorbars smaller than the symbols; not shown), and (B) normalized to the average of the first 3 points (at time 0).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556452&req=5

pone.0136432.g006: Temporal progression of the elastic force constant.ky at Mg2+ concentrations between 2–12 mM. (A) the absolute values (errorbars smaller than the symbols; not shown), and (B) normalized to the average of the first 3 points (at time 0).
Mentions: The time-dependent variation of the apparent spring constant ky is presented in Fig 6. A transition is clearly visible as the actin filaments form bundles; however, the individual datasets do not clearly group according to the magnesium ion concentration. The varying amount of actin filaments in the individual bundles and the number of filaments attached initially to the tracer beads results in a broad distribution of data at the outset of the experiments (Fig 6A). To decrease this effect, we normalized each dataset to the average of the first three measurement points, where the bundling was not yet present. The data could then be grouped together, yet still displaying the general concentration dependence.

Bottom Line: Understanding the bundling kinetics of actin filaments is important in the formation of various cytoskeletal structures, such as filopodia and stress fibers.Microparticles attached to the filaments allowed the measurement of thermal motion, and we found that bundling takes place at lower concentrations than previously found in 3-dimensional actin gels, i.e. actin filaments formed bundles in the presence of 5-12 mM of magnesium chloride in a time-dependent manner.The filaments also displayed long term stability for up to hours after removing the magnesium ions from the buffer, which suggests that there is an extensive hysteresis between cation induced crosslinking and decrosslinking.

View Article: PubMed Central - PubMed

Affiliation: Max Planck Institute for Intelligent Systems, Department of New Materials and Biosystems, Heisenberg str. 3, D-70569 Stuttgart, Germany; University of Heidelberg, Institute of Physical Chemistry, Department of Biophysical Chemistry, Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany.

ABSTRACT
Filamentous actin is one of the most important cytoskeletal elements. Not only is it responsible for the elastic properties of many cell types, but it also plays a vital role in cellular adhesion and motility. Understanding the bundling kinetics of actin filaments is important in the formation of various cytoskeletal structures, such as filopodia and stress fibers. Utilizing a unique pillar-structured microfluidic device, we investigated the time dependence of bundling kinetics of pillar supported free-standing actin filaments. Microparticles attached to the filaments allowed the measurement of thermal motion, and we found that bundling takes place at lower concentrations than previously found in 3-dimensional actin gels, i.e. actin filaments formed bundles in the presence of 5-12 mM of magnesium chloride in a time-dependent manner. The filaments also displayed long term stability for up to hours after removing the magnesium ions from the buffer, which suggests that there is an extensive hysteresis between cation induced crosslinking and decrosslinking.

No MeSH data available.


Related in: MedlinePlus