ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
The survival at sub-zero temperatures of leaf blade cells of rye (Secale cereale L. cv. Voima), which had not been cold acclimated, was determined by measuring the efflux of ninhydrin-positive substances: 50% of the cells were dead at −4°C (LT50) and none survived at −12°C or below. Examination of ultrastructural changes during cold hardening and freezing injury requires frozen tissues prepared for transmission electron microscopy without thawing. Specimens were prepared from leaf blade segments at room temperature, −4°C or −12°C by plunge freezing at 3 m s−1 into a cooling medium at −170°C followed by freeze-substitution in acetone with OsO4 fixation. Comparisons of room temperature specimens were made with those prepared by chemical fixation using glutaraldehyde/paraformaldehyde/tannic acid. On freezing to −12°C, the cells were severely dehydrated and distorted, the vacuoles severely shrunken and the cytoplasm and mitochondria disorganized whereas the chloroplasts were little affected. On freezing to −4°C, some cells were as disorganized as those at −12°C, others were relatively intact, and some showed evidence of intracellular ice crystal formation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.1989.tb06189.x
