The present work reports changes in bioenergetic parameters and mitochondrial activities during the
manifestation of two events of programmed cell death
(PCD), linked toAbies albasomatic embryogenesis. PCD,
evidenced by in situ nuclear DNA fragmentation (TUNEL
assay), DNA laddering and cytochrome c release, was
decreased in maturing embryogenic tissue with respect to
the proliferation stage. In addition, the major cellular
energetic metabolites (ATP, NAD(P)H and glucose-6-phosphate) were highered during maturation. The main
mitochondrial activities changed during two developmental
stages. Mitochondria, isolated from maturing, with respect
to proliferating cell masses, showed an increased activity of
the alternative oxidase, external NADH dehydrogenase and
fatty-acid mediated uncoupling. Conversely, a significant
decrease of the mitochondrial KATP
?
channel activity was
observed. These results suggest a correlation between
mitochondrial activities and the manifestation of PCD
during the development of somatic embryos. In particular,
it is suggested that the KATP
?
channel activity could induce an entry of K+ into the matrix, followed by swelling and a release of cytochrome cduring proliferation, whereas the alternative pathways, acting as anti-apoptotic factors, may partially counteract PCD events occurring during maturation of somatic embryos.
