Limits...
Two-dimensional periodic texture of actin filaments formed upon drying

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.


Related in: MedlinePlus

Typical features of the dried sample observed under phase-contrast microscope at a high magnification. The same F-actin solution as shown in Figure 1 was dried at 30°C under normal atmospheric conditions. (a) Panel taken at the peripheral region where the complicated pattern of dried actin filaments was gradually forced to become a periodic pattern. The periphery is indicated by the arrow. (b) The periodic striation pattern spread widely at about 2mm away from the peripheral. Scale bar, 60 μm. (c) Approaching the central region, salt crystals began to grow in a winding manner. A branched salt crystal is shown by the arrow. Scale bar, 120 μm. (d, e) Panels showing close-up views of the area surrounding the salt crystals, which branched in a dendritic manner. Scale bars, 30 μm (d) and 20 μm (e). (f) Periodic textures of the sample gradually diminished as salt crystals grew. Accordingly, an irregular striation pattern appeared, as indicated by the arrow. Scale bar, 20 μm. (g) Only the salt crystals were observed near the center of the sample. Scale bar, 50 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC5036779&req=5

f2-7_11: Typical features of the dried sample observed under phase-contrast microscope at a high magnification. The same F-actin solution as shown in Figure 1 was dried at 30°C under normal atmospheric conditions. (a) Panel taken at the peripheral region where the complicated pattern of dried actin filaments was gradually forced to become a periodic pattern. The periphery is indicated by the arrow. (b) The periodic striation pattern spread widely at about 2mm away from the peripheral. Scale bar, 60 μm. (c) Approaching the central region, salt crystals began to grow in a winding manner. A branched salt crystal is shown by the arrow. Scale bar, 120 μm. (d, e) Panels showing close-up views of the area surrounding the salt crystals, which branched in a dendritic manner. Scale bars, 30 μm (d) and 20 μm (e). (f) Periodic textures of the sample gradually diminished as salt crystals grew. Accordingly, an irregular striation pattern appeared, as indicated by the arrow. Scale bar, 20 μm. (g) Only the salt crystals were observed near the center of the sample. Scale bar, 50 μm.

Mentions: Figure 2 shows the detailed structure which was formed after drying at various places from the peripheral area (Fig. 2a) to the central area (Fig. 2f). Randomly oriented F-actin bundles were frequently observed at the periphery of the dried sample (Fig. 2a); these were caused by the turbulent flow produced when the solution was initially dropped. The striation region of F-actin bundles (Fig. 2b–e) appeared about 0.5 mm within the peripheral region. As the evaporation proceeded, branched salt crystals started to grow along the wavy F-actin bundles (Fig. 2c–e). Then the branched salt crystals gradually diminished. Note that the branching of the salt crystals consistently occurred at the black region of the striation (see Fig. 7b, in the white region the density of actin bundles seems to be low as indicated by the low density of CBB staining; also see the schematic illustration shown in Fig. 10). This result implies that the salt crystal formation preferentially occurs within a space where the protein concentration is low. Approaching the central region, thick salt crystals appeared and an irregular striation-like structure began to be formed (Fig. 2f). Finally, salt crystals grew at the center of the sample (Fig. 2g).


Two-dimensional periodic texture of actin filaments formed upon drying
Typical features of the dried sample observed under phase-contrast microscope at a high magnification. The same F-actin solution as shown in Figure 1 was dried at 30°C under normal atmospheric conditions. (a) Panel taken at the peripheral region where the complicated pattern of dried actin filaments was gradually forced to become a periodic pattern. The periphery is indicated by the arrow. (b) The periodic striation pattern spread widely at about 2mm away from the peripheral. Scale bar, 60 μm. (c) Approaching the central region, salt crystals began to grow in a winding manner. A branched salt crystal is shown by the arrow. Scale bar, 120 μm. (d, e) Panels showing close-up views of the area surrounding the salt crystals, which branched in a dendritic manner. Scale bars, 30 μm (d) and 20 μm (e). (f) Periodic textures of the sample gradually diminished as salt crystals grew. Accordingly, an irregular striation pattern appeared, as indicated by the arrow. Scale bar, 20 μm. (g) Only the salt crystals were observed near the center of the sample. Scale bar, 50 μm.
© Copyright Policy
Related In: Results  -  Collection

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

f2-7_11: Typical features of the dried sample observed under phase-contrast microscope at a high magnification. The same F-actin solution as shown in Figure 1 was dried at 30°C under normal atmospheric conditions. (a) Panel taken at the peripheral region where the complicated pattern of dried actin filaments was gradually forced to become a periodic pattern. The periphery is indicated by the arrow. (b) The periodic striation pattern spread widely at about 2mm away from the peripheral. Scale bar, 60 μm. (c) Approaching the central region, salt crystals began to grow in a winding manner. A branched salt crystal is shown by the arrow. Scale bar, 120 μm. (d, e) Panels showing close-up views of the area surrounding the salt crystals, which branched in a dendritic manner. Scale bars, 30 μm (d) and 20 μm (e). (f) Periodic textures of the sample gradually diminished as salt crystals grew. Accordingly, an irregular striation pattern appeared, as indicated by the arrow. Scale bar, 20 μm. (g) Only the salt crystals were observed near the center of the sample. Scale bar, 50 μm.
Mentions: Figure 2 shows the detailed structure which was formed after drying at various places from the peripheral area (Fig. 2a) to the central area (Fig. 2f). Randomly oriented F-actin bundles were frequently observed at the periphery of the dried sample (Fig. 2a); these were caused by the turbulent flow produced when the solution was initially dropped. The striation region of F-actin bundles (Fig. 2b–e) appeared about 0.5 mm within the peripheral region. As the evaporation proceeded, branched salt crystals started to grow along the wavy F-actin bundles (Fig. 2c–e). Then the branched salt crystals gradually diminished. Note that the branching of the salt crystals consistently occurred at the black region of the striation (see Fig. 7b, in the white region the density of actin bundles seems to be low as indicated by the low density of CBB staining; also see the schematic illustration shown in Fig. 10). This result implies that the salt crystal formation preferentially occurs within a space where the protein concentration is low. Approaching the central region, thick salt crystals appeared and an irregular striation-like structure began to be formed (Fig. 2f). Finally, salt crystals grew at the center of the sample (Fig. 2g).

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.


Related in: MedlinePlus