X-Message-Number: 13378 Date: Fri, 10 Mar 2000 18:10:28 -0800 (PST) From: Doug Skrecky <> Subject: cytochrome c oxidase and senescence Citations: 1-2 <1> Authors Begel O. Boulay J. Albert B. Dufour E. Sainsard-Chanet A. Institution Centre de Genetique Moleculaire-Centre National de la Recherche Scientifique, 91198 Gif-sur-Yvette Cedex, France. Title Mitochondrial group II introns, cytochrome c oxidase, and senescence in Podospora anserina. Source Molecular & Cellular Biology. 19(6):4093-100, 1999 Jun. Abstract Podospora anserina is a filamentous fungus with a limited life span. It expresses a degenerative syndrome called senescence, which is always associated with the accumulation of circular molecules (senDNAs) containing specific regions of the mitochondrial chromosome. A mobile group II intron (alpha) has been thought to play a prominent role in this syndrome. Intron alpha is the first intron of the cytochrome c oxidase subunit I gene (COX1). Mitochondrial mutants that escape the senescence process are missing this intron, as well as the first exon of the COX1 gene. We describe here the first mutant of P. anserina that has the alpha sequence precisely deleted and whose cytochrome c oxidase activity is identical to that of wild-type cells. The integration site of the intron is slightly modified, and this change prevents efficient homing of intron alpha. We show here that this mutant displays a senescence syndrome similar to that of the wild type and that its life span is increased about twofold. The introduction of a related group II intron into the mitochondrial genome of the mutant does not restore the wild-type life span. These data clearly demonstrate that intron alpha is not the specific senescence factor but rather an accelerator or amplifier of the senescence process. They emphasize the role that intron alpha plays in the instability of the mitochondrial chromosome and the link between this instability and longevity. Our results strongly support the idea that in Podospora, "immortality" can be acquired not by the absence of intron alpha but rather by the lack of active cytochrome c oxidase. <2> Authors Sohal RS. Sohal BH. Orr WC. Institution Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, USA. Title Mitochondrial superoxide and hydrogen peroxide generation, protein oxidative damage, and longevity in different species of flies. Source Free Radical Biology & Medicine. 19(4):499-504, 1995 Oct. Abstract The objective of this study was to further elucidate the role of oxidative stress in the aging process by determining whether or not the rates of mitochondrial superoxide anion radical and hydrogen peroxide (H2O2) production, the activity of cytochrome c oxidase, and the concentration of protein carbonyls are correlated with the life span potential of different species. A comparison was made among five different species of dipteran flies, namely, Drosophila melanogaster (fruit fly), Musca domestica (house fly), Sarcophaga bullata (flesh fly), Calliphora vicina (blow fly) and Phaenecia sericata (a species of blow flies), which range more than 2-fold in their life span potentials. The average life span potential of these species was found to be inversely correlated with the rates of mitochondrial superoxide and H2O2 production and with the level of protein carbonyls, and to be directly related to the activity of cytochrome c oxidase. The significance of these findings in context of the validity of the oxidative stress hypothesis of aging is discussed. It is inferred that longer life span potential in these insect species is associated with relatively low levels of oxidant generation and oxidative molecular damage. These results accord with our previous findings on different mammalian species. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=13378