Limits...
A physical perspective on cytoplasmic streaming.

Goldstein RE, van de Meent JW - Interface Focus (2015)

Bottom Line: While the physical and biological origins of this constraint remain poorly understood, exceptions to this rule give valuable insights.This is the most organized instance of a broad class of continuous motions known as 'cytoplasmic streaming', found in a wide range of eukaryotic organisms-algae, plants, amoebae, nematodes and flies-often in unusually large cells.In this overview of the physics of this phenomenon, we examine the interplay between streaming, transport and cell size and discuss the possible role of self-organization phenomena in establishing the observed patterns of streaming.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences , University of Cambridge , Wilberforce Road, Cambridge CB3 0WA , UK.

ABSTRACT
Organisms show a remarkable range of sizes, yet the dimensions of a single cell rarely exceed 100 µm. While the physical and biological origins of this constraint remain poorly understood, exceptions to this rule give valuable insights. A well-known counterexample is the aquatic plant Chara, whose cells can exceed 10 cm in length and 1 mm in diameter. Two spiralling bands of molecular motors at the cell periphery drive the cellular fluid up and down at speeds up to 100 µm s(-1), motion that has been hypothesized to mitigate the slowness of metabolite transport on these scales and to aid in homeostasis. This is the most organized instance of a broad class of continuous motions known as 'cytoplasmic streaming', found in a wide range of eukaryotic organisms-algae, plants, amoebae, nematodes and flies-often in unusually large cells. In this overview of the physics of this phenomenon, we examine the interplay between streaming, transport and cell size and discuss the possible role of self-organization phenomena in establishing the observed patterns of streaming.

No MeSH data available.


Rotational streaming in the characean algae. (a) A shoot of Chara corallina anchored in agar. Single-celled internodes connect nodal complexes where a whorl of six branchlets is formed. (b) Cytoplasmic streaming takes place along two domains shaped as spiralling bands. (c) This circulation is driven by the motion of myosin molecular motors along bundled actin filaments. This image shows a merged stack of confocal slices, with the colours denoting the focal position. Actin bundles can be observed below chloroplast rows at the surface of the cell. (Image courtesy S. Ganguly.) (d) The motion of myosin at the periphery entrains the outer layer of cytoplasm, which is of order 10 µm in thickness. The two moving bands are separated by a neutral line visible as a row of missing chloroplasts. The motion at the wall induces a shear flow in the central vacuole of the cell.
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RSFS20150030F3: Rotational streaming in the characean algae. (a) A shoot of Chara corallina anchored in agar. Single-celled internodes connect nodal complexes where a whorl of six branchlets is formed. (b) Cytoplasmic streaming takes place along two domains shaped as spiralling bands. (c) This circulation is driven by the motion of myosin molecular motors along bundled actin filaments. This image shows a merged stack of confocal slices, with the colours denoting the focal position. Actin bundles can be observed below chloroplast rows at the surface of the cell. (Image courtesy S. Ganguly.) (d) The motion of myosin at the periphery entrains the outer layer of cytoplasm, which is of order 10 µm in thickness. The two moving bands are separated by a neutral line visible as a row of missing chloroplasts. The motion at the wall induces a shear flow in the central vacuole of the cell.

Mentions: One of the most studied examples of cyclosis is the rotational streaming in giant cylindrical cells of the characean algae, or Charales (figure 3). Colloquially known as stoneworts after the lime deposits on their surface, these plant-like species are found in dense meadows on the bottom of lakes and ponds. Chara cells have been studied since the early days of microscopy [49], and the species are now recognized as the closest living relatives of land plants [81,82]. This high degree of similarity, and the robustness of internodal cells under manipulation, has made them a model organism in a wide range of plant physiology research, including membrane transport and electrophysiology [83], turgor-driven cell wall expansion [84–90] and cytoskeletal organization [91–97], calcification and carbon fixation [98], intercellular transport through plasmodesmata [99–103] and even lake ecology [104–108].Figure 3.


A physical perspective on cytoplasmic streaming.

Goldstein RE, van de Meent JW - Interface Focus (2015)

Rotational streaming in the characean algae. (a) A shoot of Chara corallina anchored in agar. Single-celled internodes connect nodal complexes where a whorl of six branchlets is formed. (b) Cytoplasmic streaming takes place along two domains shaped as spiralling bands. (c) This circulation is driven by the motion of myosin molecular motors along bundled actin filaments. This image shows a merged stack of confocal slices, with the colours denoting the focal position. Actin bundles can be observed below chloroplast rows at the surface of the cell. (Image courtesy S. Ganguly.) (d) The motion of myosin at the periphery entrains the outer layer of cytoplasm, which is of order 10 µm in thickness. The two moving bands are separated by a neutral line visible as a row of missing chloroplasts. The motion at the wall induces a shear flow in the central vacuole of the cell.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4590424&req=5

RSFS20150030F3: Rotational streaming in the characean algae. (a) A shoot of Chara corallina anchored in agar. Single-celled internodes connect nodal complexes where a whorl of six branchlets is formed. (b) Cytoplasmic streaming takes place along two domains shaped as spiralling bands. (c) This circulation is driven by the motion of myosin molecular motors along bundled actin filaments. This image shows a merged stack of confocal slices, with the colours denoting the focal position. Actin bundles can be observed below chloroplast rows at the surface of the cell. (Image courtesy S. Ganguly.) (d) The motion of myosin at the periphery entrains the outer layer of cytoplasm, which is of order 10 µm in thickness. The two moving bands are separated by a neutral line visible as a row of missing chloroplasts. The motion at the wall induces a shear flow in the central vacuole of the cell.
Mentions: One of the most studied examples of cyclosis is the rotational streaming in giant cylindrical cells of the characean algae, or Charales (figure 3). Colloquially known as stoneworts after the lime deposits on their surface, these plant-like species are found in dense meadows on the bottom of lakes and ponds. Chara cells have been studied since the early days of microscopy [49], and the species are now recognized as the closest living relatives of land plants [81,82]. This high degree of similarity, and the robustness of internodal cells under manipulation, has made them a model organism in a wide range of plant physiology research, including membrane transport and electrophysiology [83], turgor-driven cell wall expansion [84–90] and cytoskeletal organization [91–97], calcification and carbon fixation [98], intercellular transport through plasmodesmata [99–103] and even lake ecology [104–108].Figure 3.

Bottom Line: While the physical and biological origins of this constraint remain poorly understood, exceptions to this rule give valuable insights.This is the most organized instance of a broad class of continuous motions known as 'cytoplasmic streaming', found in a wide range of eukaryotic organisms-algae, plants, amoebae, nematodes and flies-often in unusually large cells.In this overview of the physics of this phenomenon, we examine the interplay between streaming, transport and cell size and discuss the possible role of self-organization phenomena in establishing the observed patterns of streaming.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences , University of Cambridge , Wilberforce Road, Cambridge CB3 0WA , UK.

ABSTRACT
Organisms show a remarkable range of sizes, yet the dimensions of a single cell rarely exceed 100 µm. While the physical and biological origins of this constraint remain poorly understood, exceptions to this rule give valuable insights. A well-known counterexample is the aquatic plant Chara, whose cells can exceed 10 cm in length and 1 mm in diameter. Two spiralling bands of molecular motors at the cell periphery drive the cellular fluid up and down at speeds up to 100 µm s(-1), motion that has been hypothesized to mitigate the slowness of metabolite transport on these scales and to aid in homeostasis. This is the most organized instance of a broad class of continuous motions known as 'cytoplasmic streaming', found in a wide range of eukaryotic organisms-algae, plants, amoebae, nematodes and flies-often in unusually large cells. In this overview of the physics of this phenomenon, we examine the interplay between streaming, transport and cell size and discuss the possible role of self-organization phenomena in establishing the observed patterns of streaming.

No MeSH data available.