This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (76) Citing Articles via Google Scholar Google Scholar Articles by McKersie, B. D. Articles by Thompson, J. E. Search for Related Content PubMed PubMed Citation Articles by McKersie, B. D. Articles by Thompson, J. E. Agricola Articles by McKersie, B. D. Articles by Thompson, J. E.

Articles

Lipid Crystallization in Senescent Membranes from Cotyledons

Department of Biology, University of Waterloo, Waterloo, Ontario, Canada

Lipid transition temperatures for rough and smooth microsomal membranes isolated from bean (Phaseolus vulgaris) cotyledon tissue at various stages of germination were determined by wide angle x-ray diffraction. The transition temperatures were established by recording diffraction patterns through a temperature series until a sharp x-ray reflection centered at a Bragg spacing of 4.15 Å and denoting the presence of crystalline lipid was discernible. For rough and smooth microsomes from 2-day-old tissue, the transitions occurred at 0 C and 3 C, respectively, indicating that at this early stage in the germination sequence the membrane lipid is entirely liquid-crystalline at physiological temperature. By the 4th day of germination, the transition temperatures had increased to 32 C for smooth microsomes and 35 C for rough microsomes, indicating that at 29 C, which was the growth temperature, portions of the membrane lipid were crystalline. During the later stages of germination, the transition temperature for smooth microsomes continued to rise through 44 C at day 7 to 56 C at day 9, by which time the cotyledons were extensively senescent and beginning to abscise. There was also a dramatic increase in the proportion of membrane lipid in the crystalline phase at 29 C. By contrast, the rough microsomes showed little change in transition temperature and only a slight increase in the proportion of crystalline lipid during this late period in germination. The data indicate that substantial amounts of the lipid is senescing membranes are crystalline even at physiological temperature. Moreover, there is a temporal correlation between the appearance of this crystallinity and loss of membrane function, suggesting that the two may be causally related.

This article has been cited by other articles:

				J. H. Crowe, A. E. Oliver, and F. Tablin Is There a Single Biochemical Adaptation to Anhydrobiosis? Integr. Comp. Biol., July 1, 2002; 42(3): 497 - 503. [Abstract] [Full Text] [PDF]