Related Experiment Video
Updated: Jun 19, 2026
18:25
Live Imaging Assay for Assessing the Roles of Ca2+ and Sphingomyelinase in the Repair of Pore-forming Toxin Wounds
Published on: August 25, 2013
EXOSMOSIS IN RELATION TO INJURY AND PERMEABILITY
1Laboratory of Plant Physiology, Harvard University, Cambridge.
The Journal of General Physiology
|October 30, 2009
Summary
The permeability of Nitella cells increases similarly during cell death, regardless of whether exosmosis or electrical resistance is measured. This finding offers a consistent way to study cell death progression in plants.
Area of Science:
- Plant Physiology
- Cell Biology
- Membrane Transport
Background:
- Nitella, a genus of large, single-celled algae, is a model organism for studying cellular processes.
- Cell death involves significant changes in membrane permeability.
- Exosomosis and electrical resistance are indicators of cellular membrane integrity.
Purpose of the Study:
- To investigate the relationship between cell death progression and membrane permeability changes in Nitella.
- To compare the utility of exosmosis and electrical resistance measurements in assessing cell death.
Main Methods:
- Measurements of exosmosis (water loss) from Nitella cells.
- Measurements of electrical resistance across Nitella cell membranes.
- Comparative analysis of time-dependent changes in both parameters during induced cell death.
Main Results:
- The time course of increasing cell permeability during death was consistent between exosmosis and electrical resistance measurements.
- Both methods demonstrated a similar rate of change in permeability as cell death progressed.
- This suggests a unified mechanism of membrane destabilization during cell death.
Conclusions:
- Membrane permeability changes during Nitella cell death can be reliably tracked using either exosmosis or electrical resistance.
- These findings validate the use of both methods for studying the biophysics of cell death in plant cells.
- The study provides a robust physiological marker for cell death progression in this model organism.
More Related Videos
Related Concept Videos
02:40Osmosis and Osmotic Pressure of Solutions
A number of natural and synthetic materials exhibit selective permeation, meaning that only molecules or ions of a certain size, shape, polarity, charge, and so forth, are capable of passing through (permeating) the material. Biological cell membranes provide elegant examples of selective permeation in nature, while dialysis tubing used to remove metabolic wastes from blood is a more simplistic technological example. Regardless of how they may be fabricated, these materials are generally...
01:30Osmosis
Osmosis is the movement of free water molecules through a semipermeable membrane. The water's concentration gradient across the membrane is inversely proportional to the solutes' concentration. Whereas diffusion transports material across membranes and within cells, osmosis transports only water across a membrane, and the membrane limits the diffusion of solutes in the water. Osmosis is a special case of diffusion.
Water, like other substances, moves from a high concentration of free water...
Water, like other substances, moves from a high concentration of free water...
00:47Osmosis
Approximately 60% to 95% of the weight of living organisms is attributed to water. Therefore, maintaining appropriate water balance within cells is of paramount importance. Osmosis is the movement of water across a semipermeable membrane, such as a cell’s plasma membrane. In living organisms, water plays a crucial role as a solvent—a molecule that dissolves other molecules.Diffusion Versus OsmosisBoth diffusion and osmosis are types of passive transport—cellular transport that does not require...
01:23Transcellular Transport of Solutes
Transcellular transport of solutes is the movement of substances like monosaccharides and amino acids through polarized cells. This transport mechanism is primarily seen in epithelial and endothelial cells aided by membrane transport proteins such as channels and transporters. The tight junctions between these cells confine the membrane proteins to the two sides of the cell. The epithelial cells have distinct apical and basolateral domains. In contrast, the endothelial cells show the luminal...
01:21Cytotoxic Edema: Pathophysiology
Cytotoxic edema is a form of cerebral edema characterized by intracellular swelling of neurons, astrocytes, and other glial cells. It develops when the mechanisms responsible for maintaining ionic gradients across the cell membrane become impaired. Under normal physiological conditions, the sodium–potassium ATPase actively transports sodium ions out of the cell and potassium ions into the cell, preserving osmotic balance and enabling electrical signaling. This pump requires a continuous supply...
01:22Cerebral Edema ll: Pathophysiology
Vasogenic edema is a major form of cerebral edema characterized by abnormal accumulation of fluid in the brain’s extracellular space due to disruption of the blood–brain barrier (BBB). The BBB is a specialized structure composed of endothelial cells connected by tight junctions, supported by astrocytic endfeet and a basement membrane. Under normal conditions, it tightly regulates the movement of ions, proteins, and solutes between the bloodstream and brain parenchyma. When this barrier loses...