title: Aging impact on biochemical activities and gene expression of Drosophila melanogaster mitochondria.
abstract: The consequences of aging are characterized by a decline in the main cellular functions, including those of the mitochondria. Although these consequences have been much studied, efforts have often focused solely on a few parameters used to assess the "state" of mitochondrial function during aging. We performed comparative measurements of several parameters in young (a few days) and old (8 and 12 weeks) adult male Drosophila melanogaster: respiratory complex activities, mitochondrial respiration, ATP synthesis, lipid composition of the inner membrane, concentrations of respiratory complex subunits, expression of genes (nuclear and mitochondrial) coding for mitochondrial proteins. Our results show that, in the mitochondria of "old" flies, the activities of three respiratory complexes (I, III, IV) are greatly diminished, ATP synthesis is decreased, and the lipid composition of the inner membrane (fatty acids, cardiolipin) is modified. However, the respiration rate and subunit concentrations measured by Western blot are unaffected. Although cellular mitochondrial DNA (mtDNA) content remains constant, there is a decrease in concentrations of nuclear and mitochondrial transcripts apparently coordinated. The expression of nuclear genes encoding the transcription factors TFAM, TFB1, TFB2, and DmTTF, which are essential for the maintenance and expression of mtDNA are also decreased. The decrease in nuclear and mitochondrial transcript concentrations may be one of the principal effects of aging on mitochondria, and could explain observed decreases in mitochondrial efficiency.
authors.affiliation: Equipe Génome Mitochondrial, UMR CNRS 6547, Université Blaise Pascal-Clermont II, 63177 Aubière, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Dubessay
authors.forename: Isabelle
authors.initials: I
authors.lastname: Garreau-Balandier
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Jarrousse
authors.forename: Annie
authors.initials: A
authors.lastname: Fleuriet
authors.forename: Benoit
authors.initials: B
authors.lastname: Sion
authors.forename: Roger
authors.initials: R
authors.lastname: Debise
authors.forename: Serge
authors.initials: S
authors.lastname: Alziari
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000375:Aging / Q000235:genetics / Q000502:physiology*; D000818:Animals; D004272:DNA, Mitochondrial / Q000032:analysis; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism*; D005786:Gene Expression Regulation; D050259:Genes, Mitochondrial; D008297:Male; D008928:Mitochondria / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D012313:RNA / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000378:metabolism; D000077278:RNA, Mitochondrial; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D004272:DNA, Mitochondrial; D012333:RNA, Messenger; D000077278:RNA, Mitochondrial; D014157:Transcription Factors; D012313:RNA; D000255:Adenosine Triphosphate