Related Experiment Video
Updated: Jul 28, 2026
11:00
A Galvanotaxis Assay for Analysis of Neural Precursor Cell Migration Kinetics in an Externally Applied Direct Current Electric Field
Published on: October 13, 2012
Cytoplasmic streaming and gravity sensing in Chara internodal cells.
1Department of Biology, Grand Valley State University, Allendale, MI 49401, USA. stavesm@gvsu.edu
Planta
|September 7, 2001
Summary
The gravitational pressure model, not the starch-statolith model, better explains plant gravity perception. Gravity creates pressure on cells, influencing cytoplasmic streaming, which can be reversed in denser media.
Area of Science:
- Plant Biology
- Biophysics
- Cell Biology
Background:
- Two models explain plant gravity perception: gravitational pressure and starch-statolith.
- The starch-statolith model is more widely accepted.
- Plant cells exhibit gravity-dependent cytoplasmic streaming.
Purpose of the Study:
- To investigate the mechanism of plant gravity perception.
- To differentiate between the gravitational pressure and starch-statolith models.
- To explain the physiological control of gravity-induced cytoplasmic streaming.
Main Methods:
- Experiments using vertically-oriented Chara internodal cells.
- Manipulation of the density of the surrounding medium.
- Observation of cytoplasmic streaming polarity.
Main Results:
- Gravity-induced polarity of cytoplasmic streaming was observed.
- This polarity was reversed when cells were in a denser medium.
- The results contradict the starch-statolith model but support the gravitational pressure model.
Conclusions:
- Plant cells sense gravity via pressure differences, not solely by statoliths.
- Gravity induces mechanical stress on the plasma membrane, affecting cytoplasmic streaming.
- This mechanism involves mechanosensitive calcium channels.
Related Concept Videos
01:41Action Potentials
Overview
01:11Channel Rhodopsins
Most organisms use photoreceptors to sense and respond to light. Examples of photoreceptors include bacteriorhodopsins and bacteriophytochromes in some bacteria, phytochromes in plants, and rhodopsins in the photoreceptor cells of the vertebral retina. The light-sensitive property of these receptors is because of the bound chromophores, such as bilin in the phytochromes and retinal in the rhodopsins.
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
01:13Actin Polymerization and Cell Motility
Actin is a family of globular proteins that are highly abundant in eukaryotic cells. It makes up approximately 1-5% of total cell protein concentration. Actin monomers polymerize to form a complex network of polarized filaments, the actin cytoskeleton, that plays a crucial role in many cellular processes, including cell motility, division, endocytosis, and metastasis of cancer cells.
Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.
Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.
01:16Cell Motility through Blebbing
Blebs are a type of membrane protrusion formed by the internal hydrostatic pressure of the cytoplasm. Blebs are observed in several cell types, including fibroblasts, immune cells, and single-celled organisms like the amoeba. The primary function of blebs is cell locomotion and apoptosis, but they are also found during necrosis and cell division. The life cycle of a bleb comprises an initiation phase followed by the expansion and retraction phases.
Blebbing Through the Matrix
In multicellular...
Blebbing Through the Matrix
In multicellular...
01:05Mechanism of Ciliary Motion
The ciliary structures were first seen in 1647 by Antonie Leeuwenhoek while observing the protozoans. In lower organisms, these appendages are responsible for cell movement, while in higher organisms, these appendages help in the movement of the extracellular fluids within the body cavities.
The cilia are made up of microtubules in a 9+2 arrangement, with nine microtubule doublet ring bundles, surrounding a pair of central singlet microtubule bundles. The doublet microtubule bundles are...
The cilia are made up of microtubules in a 9+2 arrangement, with nine microtubule doublet ring bundles, surrounding a pair of central singlet microtubule bundles. The doublet microtubule bundles are...
01:21Electrochemical Gradient and Channel Proteins: An Overview
An electrochemical gradient is a fundamental concept in biology and chemistry. It regulates the movement of ions across cell membranes. This movement is influenced by two factors:
The electrical gradient: The electrical gradient across cell membranes refers to the difference in electric charge between the inside and outside of a cell. This difference drives the movement of ions towards or away from the cells. For instance, if the inside of the cell is more negatively charged relative to the...
The electrical gradient: The electrical gradient across cell membranes refers to the difference in electric charge between the inside and outside of a cell. This difference drives the movement of ions towards or away from the cells. For instance, if the inside of the cell is more negatively charged relative to the...