Two-photon fluorescence microscopy studies of bipolar tetraether giant liposomes from thermoacidophilic archaebacteria Sulfolobus acidocaldarius.

LUIS A. BAGATOLLI; E. GRATTON; T. KHAN ; P.L. CHONG

BIOPHYSICAL JOURNAL

CELL PRESS

Lugar: United States; Año: 2000 vol. 79 p. 416 - 416

0006-3495

he effects of temperature and pH on Laurdan (6-lauroyl-2-(dimethylamino)naphthalene) fluorescence intensity images of giant unilamellar vesicles (GUVs) ( approximately 20-150 microm in diameter) composed of the polar lipid fraction E (PLFE) from the thermoacidophilic archaebacteria Sulfolobus acidocaldarius have been studied using two-photon excitation. PLFE GUVs made by the electroformation method were stable and well suited for microscopy studies. The generalized polarization (GP) of Laurdan fluorescence in the center cross section of the vesicles has been determined as a function of temperature at pH 7.23 and pH 2.68. At all of the temperatures and pHs examined, the GP values are low (below or close to 0), and the GP histograms show a broad distribution width (> 0.3). When excited with light polarized in the y direction, Laurdan fluorescence in the center cross section of the PLFE GUVs exhibits a photoselection effect showing much higher intensities in the x direction of the ves