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AN ELECTRON MICROSCOPIC STUDY OF PINOCYTOSIS IN AMEBA : I. The Surface Attachment Phase
1Department of Anatomy and Ophthalmology, College of Physicians and Surgeons, Columbia University, New York. Dr. Brandt is a "Fight for Sight" Fellow, National Council to Combat Blindness, Inc., New York. Dr. Brandt submitted this work in partial fulfilment of the degree of Doctor of Philosophy, Anatomy Department, Columbia University.
The Journal of Biophysical and Biochemical Cytology
|October 30, 2009
Summary
This study investigated how amebas take up substances via pinocytosis. It found that attachment to the cell surface is the crucial first step for molecules and particles entering the cell.
Area of Science:
- Cell Biology
- Biochemistry
- Microscopy
Background:
- Pinocytosis is a cellular process for internalizing extracellular substances.
- The initial interactions between substances and the cell surface are critical for uptake.
Purpose of the Study:
- To investigate the initial attachment of various substances to the ameba cell surface.
- To elucidate the role of surface attachment in the process of pinocytosis.
Main Methods:
- Electron microscopy was used to observe ameba-substance interactions.
- Studied the attachment of proteins (ribonuclease, ferritin) and colloidal suspensions (thorium dioxide, gold).
Main Results:
- Ferritin and thorium dioxide attached to ameba plasmalemma extensions, initiating pinocytosis.
- Ribonuclease altered plasmalemma structure but was difficult to localize.
- Colloidal gold did not show activity in ameba pinocytosis.
Conclusions:
- Surface attachment is the initial step for pinocytosis of molecules and particles.
- A unified cellular uptake mechanism may underlie phagocytosis, pinocytosis, and other endocytic processes.
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