Genetic and molecular analysis of a long-lived strain of Podospora anserina.

Abstract A genetic and molecular analysis of a long-lived strain of Podospora anserina, Mn19, was undertaken to detect mutations in genes responsible for senescence. In crosses between Mn19 and wild type about 15% of the progeny were long-lived, regardless of the female parent. Molecular analysis of the long-lived progeny showed that none of the strains inherited a mtDNA rearrangement characteristic of the Mn19 parent. Instead, all long-lived strains initially inherited wild-type mtDNA. Over time the mtDNA of most long-lived strains underwent rearrangements, deletions and amplifications. The change over time in the presence of two previously characterized plasmids associated with either senescence or longevity was monitored. Crosses between Mn19 and its long-lived progeny also yielded only a small percent of individuals recovering from senescence. Analysis of mtDNA from crosses suggests that wild-type mtDNA from the paternal parent can be selected over mtDNA from the maternal parent. The life span phenotypes of progeny were not consistent with the hypothesis that mutations in a few nuclear genes were responsible for longevity.

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Mitochondrial Group II Introns, Cytochrome c Oxidase, and Senescence in Podospora anserina

Molecular and Cellular Biology ◽

10.1128/mcb.19.6.4093 ◽

1999 ◽

Vol 19 (6) ◽

pp. 4093-4100 ◽

Cited By ~ 38

Author(s):

Odile Begel ◽

Jocelyne Boulay ◽

Beatrice Albert ◽

Eric Dufour ◽

Annie Sainsard-Chanet

Keyword(s):

Life Span ◽

Integration Site ◽

Group Ii Intron ◽

Podospora Anserina ◽

Wild Type ◽

First Intron ◽

Limited Life ◽

Related Group ◽

Group Ii ◽

Mitochondrial Chromosome

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 (α) has been thought to play a prominent role in this syndrome. Intron α 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 theCOX1 gene. We describe here the first mutant of P. anserina that has the α 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 α. 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 α is not the specific senescence factor but rather an accelerator or amplifier of the senescence process. They emphasize the role that intron α 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 α but rather by the lack of active cytochromec oxidase.

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Selection of Drug-Tolerant Strains of Pythium sylvaticum Using Sublethal Enrichment

Phytopathology ◽

10.1094/phyto.1997.87.7.685 ◽

1997 ◽

Vol 87 (7) ◽

pp. 685-692 ◽

Cited By ~ 11

Author(s):

Frank N. Martin ◽

Charles R. Semer

Keyword(s):

Mitochondrial Dna ◽

Growth Rates ◽

Wild Type ◽

Maternal Parent ◽

Pythium Sylvaticum ◽

Paternal Parent ◽

High Level ◽

Selection Of

Sublethal enrichment was used to generate mutants of Pythium sylvaticum tolerant to kanamycin and tetracycline. Kanamycin tolerance was readily generated, and mutants had growth rates similar to wild-type isolates at antibiotic concentrations lethal to wild-type isolates. Based on crosses between wild-type and mutant isolates, two types of inheritance of tolerance were identified. A high level of kanamycin tolerance was inherited in progeny only when the maternal parent was drug tolerant and was correlated with the inheritance of maternal mitochondrial DNA. A lower level of tolerance was observed in some progeny when the paternal parent was tolerant to the antibiotic and, based on the lack of inheritance of paternal mitochondrial DNA, was presumably nuclear-encoded. Selection of mutants tolerant to tetracycline took longer to generate than kanamycin-tolerant mutants. Based on crosses between tolerant and wild-type parents, tolerance to tetracycline was nuclear-encoded. Tolerance to both antibiotics was stable, with cultures retaining tolerance following repeated transfers on nonamended medium and after storage for 7 years.

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Multilingualism and Ageing

Brill Research Perspectives in Multilingualism and Second Language Acquisition ◽

10.1163/2352877x-12340003 ◽

2020 ◽

Vol 1 (4) ◽

pp. 1-98

Author(s):

Kees de Bot ◽

Charlotta Plejert ◽

Hanne Gram Simonsen ◽

Valantis Fyndanis ◽

Pernille Hansen ◽

...

Keyword(s):

Life Span ◽

Language Processing ◽

Language Use ◽

Large Range ◽

Change Over Time ◽

Language And Communication ◽

The Media ◽

University Of Oslo ◽

The University ◽

Over Time

Abstract This publication provides an overview of research on a large range of topics relating to language processing and language use from a life-span perspective. It is unique in covering and combining psycholinguistic and sociolinguistic approaches, discussing questions such as: Is it beneficial to speak more than one language when growing old? How are languages processed in multilingual persons, and how does this change over time? What happens to language and communication in multilingual aphasia or dementia? How is multilingual ageing portrayed in the media? It is a joint, cross-disciplinary venture of researchers from the Centre for Multilingualism in Society across the Lifespan at The University of Oslo and the editors of this publication.

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