Premium
Freeze‐induced phase transitions in the plasma membrane of isolated protoplasts
Author(s) -
Pihakaski Kaarina,
Steponkus Peter L.
Publication year - 1987
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1987.tb01982.x
Subject(s) - secale , protoplast , sorbitol , dimethyl sulfoxide , membrane , isotonic , bilayer , chromatography , ultrastructure , chemistry , dehydration , biophysics , botany , biology , biochemistry , organic chemistry , medicine
Protoplasts were enzymically isolated from 2‐week‐old non‐acclimated rye ( Secale cereale L. cv. Puma) seedlings. They were resuspended in isotonic sorbitol with different concentrations (0–10%) of dimethyl sulfoxide (DMSO). The survival of the protoplasts frozen in isotonic sorbitol solutions declined at temperatures below the freezing point with the LT 50 being ‐8°C. Addition of DMSO to the osmoticum increased survival at freezing temperatures. The optimum concentration of DMSO was 4% and lowered the LT 50 to ‐19°C. Freeze‐fracture studies of the plasma membrane revealed aparticulate lipid lamellae at ‐4°C, but the first appearance of lateral phase separations, striations and inverted cylindrical micelles (hexagonal 11 ‐type structures) occurred at ‐6°C. At lower temperatures, ‐8 and ‐10°C, the occurrence of nonbilayer structures became more common. The addition of DMSO decreased the incidence of the ultrastructural changes. With 2 or 4% DMSO, non‐bilayer structures were not observed at temperatures above ‐10°C. Instead, striations and H 11 ‐type structures were observed at ‐ 15 and ‐20°C.