Related Experiment Videos
Ca2+-sensitive and Ca2+-insensitive exocytosis in maize coleoptile protoplasts
G Thiel1, J U Sutter, U Homann
1A.v.H. Inst. Plant Sciences, Göttingen.
Pflugers Archiv : European Journal of Physiology
|February 1, 2000
Summary
Maize protoplasts showed two ways to expand their surface area: calcium influx triggered a small membrane insertion, while osmotic changes accessed a larger membrane reserve, possibly due to tension.
Area of Science:
- Plant Cell Biology
- Biophysics
- Membrane Biology
Background:
- Cell surface area expansion is crucial for plant growth.
- Membrane trafficking dynamics are key to regulating cell size.
- Calcium ions and osmotic stress are known environmental factors influencing cellular processes.
Purpose of the Study:
- To investigate the mechanisms of surface area extension in maize coleoptile protoplasts.
- To differentiate the roles of cytoplasmic calcium (Ca(i)) and osmotic potential in membrane insertion.
- To identify the membrane sources and potential driving forces for surface area changes.
Main Methods:
- Utilized capacitance measurements to quantify changes in plasma membrane surface area.
- Employed photolysis of the caged compound DM-nitrosourea to elevate cytoplasmic calcium levels.
- Manipulated external osmotic potential to induce osmotic stress.
Main Results:
- An increase in cytoplasmic Ca(i) induced a rapid, transient increase in membrane capacitance (1.3+/-1.1%).
- Subsequent reduction in external osmotic potential caused a larger, sustained increase in capacitance (26+/-6%).
- Data suggest two distinct pathways for membrane insertion into the plasma membrane.
Conclusions:
- Cytoplasmic calcium-driven membrane insertion recruits from a limited intracellular pool.
- Osmotic stress-induced surface area expansion utilizes a larger membrane reservoir, potentially regulated by membrane tension.
- Maize coleoptile protoplasts exhibit independent, differentially regulated mechanisms for plasma membrane expansion.