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Two-dimensional periodic texture of actin filaments formed upon drying

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ABSTRACT

We found that a solution of actin filaments can form a periodic texture in the process of drying on a flat glass surface in the air; the periodic texture was composed of smooth meandering bundles of actin filaments. We also found that a branched salt crystal grows in the space between the meandering bundles of actin filaments. The distance between the adjacent striae (striation period) in the resulting dried two-dimensional pattern of striation decreased from about 50 to 2 μm, as the ambient temperature was increased from 4 to 40°C at 1 mg/ml actin, and showed an increasing tendency from a few to several tens μm with the increase in the initial concentration of actin filaments from 0.6 to 2.0mg/ml at room temperature. As the speed of drying is increased at a certain temperature, the striation period was also found to decrease. We propose that the formation of the two-dimensional striation pattern of bundles of actin filaments is the result of condensation of proteins due to dehydration, and suggest that the solvent flow from the center to the periphery of the sample causes the meandering of actin filaments.

No MeSH data available.


Polarizing micrograph showing the two-dimensional pattern formed by natural drying of BSA solution (a) and tropomyosin solution (b, c). Drying was performed according to method 1, as described in Materials and Methods. (a) Concentration of BSA, 1.0mg/ml. Solvent, 0.1M KCl, 0.5mM sodium bicarbonate. Scale bar, 500 μm. (b, c) Concentration of tropomyosin, 1.0mg/ml. Solvent, 1.0mM MgCl2, 0.5mM sodium bicarbonate. Photographs in (c) were taken by high magnification in a different place from that of (b). Scale bars, 250 μm (b) and 80 μm (c).
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f9-7_11: Polarizing micrograph showing the two-dimensional pattern formed by natural drying of BSA solution (a) and tropomyosin solution (b, c). Drying was performed according to method 1, as described in Materials and Methods. (a) Concentration of BSA, 1.0mg/ml. Solvent, 0.1M KCl, 0.5mM sodium bicarbonate. Scale bar, 500 μm. (b, c) Concentration of tropomyosin, 1.0mg/ml. Solvent, 1.0mM MgCl2, 0.5mM sodium bicarbonate. Photographs in (c) were taken by high magnification in a different place from that of (b). Scale bars, 250 μm (b) and 80 μm (c).

Mentions: Figure 1 shows a typical example of the two-dimensional texture obtained by natural drying of an F-actin (1.0mg/ml) solution at room temperature (method 1 described in Materials and Methods). The evaporation of solvent occurred from the periphery, so that the radius of the wet area gradually decreased. After the specimen was completely dried, a two-dimensional texture was formed with salt crystals at the center of the texture as shown by arrow i) in Figure 1a. We found that a concentric striation pattern, the outer periphery of which is indicated by arrow ii), was formed. A magnified view of the phase-contrast micrograph at a rectangular region shown by arrow iii) revealed that the average striation period was about 3.0 μm (Fig. 1b). The striation period was almost independent of the distance from the periphery, suggesting that the period may not depend on the ionic strength (note that the ionic strength of solution increases with drying, see Fig. 9c).


Two-dimensional periodic texture of actin filaments formed upon drying
Polarizing micrograph showing the two-dimensional pattern formed by natural drying of BSA solution (a) and tropomyosin solution (b, c). Drying was performed according to method 1, as described in Materials and Methods. (a) Concentration of BSA, 1.0mg/ml. Solvent, 0.1M KCl, 0.5mM sodium bicarbonate. Scale bar, 500 μm. (b, c) Concentration of tropomyosin, 1.0mg/ml. Solvent, 1.0mM MgCl2, 0.5mM sodium bicarbonate. Photographs in (c) were taken by high magnification in a different place from that of (b). Scale bars, 250 μm (b) and 80 μm (c).
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC5036779&req=5

f9-7_11: Polarizing micrograph showing the two-dimensional pattern formed by natural drying of BSA solution (a) and tropomyosin solution (b, c). Drying was performed according to method 1, as described in Materials and Methods. (a) Concentration of BSA, 1.0mg/ml. Solvent, 0.1M KCl, 0.5mM sodium bicarbonate. Scale bar, 500 μm. (b, c) Concentration of tropomyosin, 1.0mg/ml. Solvent, 1.0mM MgCl2, 0.5mM sodium bicarbonate. Photographs in (c) were taken by high magnification in a different place from that of (b). Scale bars, 250 μm (b) and 80 μm (c).
Mentions: Figure 1 shows a typical example of the two-dimensional texture obtained by natural drying of an F-actin (1.0mg/ml) solution at room temperature (method 1 described in Materials and Methods). The evaporation of solvent occurred from the periphery, so that the radius of the wet area gradually decreased. After the specimen was completely dried, a two-dimensional texture was formed with salt crystals at the center of the texture as shown by arrow i) in Figure 1a. We found that a concentric striation pattern, the outer periphery of which is indicated by arrow ii), was formed. A magnified view of the phase-contrast micrograph at a rectangular region shown by arrow iii) revealed that the average striation period was about 3.0 μm (Fig. 1b). The striation period was almost independent of the distance from the periphery, suggesting that the period may not depend on the ionic strength (note that the ionic strength of solution increases with drying, see Fig. 9c).

View Article: PubMed Central - PubMed

ABSTRACT

We found that a solution of actin filaments can form a periodic texture in the process of drying on a flat glass surface in the air; the periodic texture was composed of smooth meandering bundles of actin filaments. We also found that a branched salt crystal grows in the space between the meandering bundles of actin filaments. The distance between the adjacent striae (striation period) in the resulting dried two-dimensional pattern of striation decreased from about 50 to 2 μm, as the ambient temperature was increased from 4 to 40°C at 1 mg/ml actin, and showed an increasing tendency from a few to several tens μm with the increase in the initial concentration of actin filaments from 0.6 to 2.0mg/ml at room temperature. As the speed of drying is increased at a certain temperature, the striation period was also found to decrease. We propose that the formation of the two-dimensional striation pattern of bundles of actin filaments is the result of condensation of proteins due to dehydration, and suggest that the solvent flow from the center to the periphery of the sample causes the meandering of actin filaments.

No MeSH data available.