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Figure 13.6. Analysis of apoptosis in U1 cells. Numbers indicate the percentage of apoptotic
nuclei, present in the higher left part of the panels; in a parallel experiment, apoptosis in U937 cells
was 40%.
cluding animals, plants, and fungi. In mammalian tissues and in yeast, CL is
found exclusively in mitochondria (Ioannou and Golding, 1979; Schlame and
Hostetler, 1997), a site in which it is speci®c and essential for the normal func-
tion of the mitochondrial inner membrane system, and, in particular, for i) the
activity of cytochrome bc1 and cytochrome c oxidase, key components of the
electron transport chain; ii) the attachment of cytochrome c to the inner mi-
tochondrial membrane; iii) the activity of mitochondrial transporters, including
adenosine diphosphate/ATP translocase, the mono-, di-, and tri-carboxylate
carriers, the a-ketoglutarate, aspartate/glutamate, and palmitoylcarnitine car-
riers, and the (acyl)carnitine translocase system; iv) the functionality of F
0
F
1
-
ATP synthase (Gomez and Robinson, 1999).
We have recently developed a cyto¯uorimetric approach to study intra-
mitochondrial cardiolipin transverse distribution in intact cells (Garcia Fer-
nandez et al., 2000). The assay is based upon the following peculiar properties
of the ¯uorescent dye 10-N-nonyl-3,6-bis(dimethylamino)acridine ( Nonyl Ac-
ridine Orange, NAO): i) two molecules of NAO can bind with high a½nity one
single CL molecule, forming NAO dimers; ii) the dye is unable to bind zwit-
terionic phospholipids and has low a½nity for other anionic phospholipids; and
iii) NAO is capable of changing its emission because of its spectral properties,
as after dimer formation the ¯uorescence can shift from green (monomeric
form) to red (dimeric form) (Petit et al., 1992, 1994). Using such an assay, we
®rst showed that the distribution of CL was markedly di¨erent in HCW-2 cells
compared with the parental HL-60 line (Garcia Fernandez et al., 2000). We
have started the analysis of CL distribution in U1 cells. Preliminary data seem
to indicate that no major di¨erences exist between the two cell types, suggesting
that infection with HIV-1 is not capable of provoking changes in mitochondrial
structure that could be responsible for functional damages.
