Plant Physiol, April 2000, Vol. 122, pp. 1365-1378
Changes in Hechtian Strands in Cold-Hardened Cells Measured by
Optical Microsurgery1
Charles S.
Buer,2
Pamela J.
Weathers,* and
Grover A.
Swartzlander Jr.
Departments of Biology/Biotechnology (C.S.B., P.J.W.)
and Physics (G.A.S.), Worcester Polytechnic Institute, 100 Institute Road, Worcester, Massachusetts 01609-2280
Optical
microsurgical techniques were employed to investigate the mechanical
properties of Hechtian strands in tobacco (Nicotiana tabacum) and Ginkgo biloba callus cells. Using
optical tweezers, a 1.5-µm diameter microsphere coated with
concanavalin A was inserted though an ablated hole in the cell wall of
a plasmolyzed cell and attached to a Hechtian strand. By displacing the
adhered microsphere from equilibrium using the optical trapping force,
the tensions of individual strands were determined. Measurements were
made using both normal and cold-hardened cells, and in both cases, tensions were on the order of 10
12 N. Significant
differences were found in the binding strengths of cold-hardened and
normal cultured cells. An increased number density of strands in
cold-hardened G. biloba compared with normal cultured
cells was also observed. Although no Hechtian strands were detected in
any Arabidopsis callus cells, strands were present in leaf epidermal
cells. Finally, the movement of attached microspheres was monitored
along the outside of a strand while cycling the osmotic pressure.
1
This work was supported by the U.S. Department
of Agriculture National Needs Fellowship (grant no. 93-38420-8804),
the Research Corporation Cottrell Scholars Program, and the National
Science Foundation (grant nos. BES 9414585 and ECS 9457481).
2
Present address: Environmental Biology and Plant
Cell Biology Groups, Research School of Biological Sciences, Building
46, The Australian National University, G.P.O. Box 475, Canberra ACT 2601, Australia.
*
Corresponding author; e-mail weathers{at}wpi.edu; fax
508-831-5936.
© 2000 American Society of Plant Physiologists
