Elsevier

Experimental Gerontology

Volume 6, Issue 5, October 1971, Pages 327-334
Experimental Gerontology

Mitochondrial studies in senescent mice—II. Specific activity, buoyant density, and turnover of mitochondrial DNA

https://doi.org/10.1016/0531-5565(71)90001-5Get rights and content

Abstract

The specific activity of brain mitochondrial DNA, measured 2 days after injection of tritiated thymidine, is twice as high in 1- to 2-year-old mice as in young mice. There is a corresponding decrease in the amount of DNA per unit weight of mitochondrial protein. Following injection of labelled precursors, the radioactivity of mitochondrial DNA and lipids per unit of protein is found to be decreased with age. The turnover rates of mitochondrial DNA and lipids do not vary significantly with age. The buoyant density of mitochondrial DNA, and hence its base composition, does not change detectably with age.

Résumé

Mesurée deux jours après l'injection de thymidine tritiée, l'activité spécifique de l'ADN des mitochondries du cerveau est deux fois plus élevée chez les souris âgées de 1 â 2 ans que chez les jeunes souris. On relève une diminution correspondante de la quantité d'ADN par unité de poids de la protéine des mitochondries. Après l'injection de précurseurs marqués, on constate que la radioactivité de l'ADN des mitochondries et des lipides par unité de protéine diminue avec l'âge. La rotation de l'ADN et des lipides des mitochondries ne manifeste pas de modifications significatives selon l'âge. La densité de flottabilité de l'ADN des mitochondries et donc sa composition de base ne se modifient pas perceptiblement avec l'âge.

Zusammenfassung

Die spezifische Aktivität von Hirnmitochondrien-DNS ist zwei Tage nach Injektion von tritiiertem Thymidin bei 1- bis 2-jährigen Mäusen doppelt so hoch wie bei jungen Mäusen. Die Menge an DNS pro Gewichtseinheit Mitochondrienprotein liegt entsprechend niedriger. Nach Injektion markierter Vorstufen ist die Radioaktivität mitochondrialer DNS und Lipide bezogen auf Protein mit zunehmendem Alter geringer. Der Turnover mitochondrialer DNS und mitochondrialer Lipide ändert sich nicht wesentlich mit dem Alter. Die Dichte der mitochondrialen DNS und somit ihre Basenzusammensetzung ändern sich nicht meβar mit dem Alter.

Реферат

Cпeцифчecкaя aктивнocтъ митoчoндpиaлщнoй ДHК мoзгa, измepeннaя 2 дня пocлe инъeкции нacышeннoгo тpитиeм тимидинa, вдвoe вышe y гoдoвaлыч и двyчлeтнич мышeй, чeм y мoлoдыч мышeй. Oбнapyзивaeтcя cooтвeтcтвyюшee cнизeниe в кoличecтвe ДнК нa eдиницy вeca митoчoндpиaлънгoo пpoтeинa. Пocлe инъeкции мeчeныч пpeдшecтвeнникoв, paдиoaктивнocть митoчдpиaльнoй ДHК и липидoв нa eдинцy бeлкa c вoзpacтoм. Cкopocть кpyгoвopoтa митoчoндpиaльнoй ДHК и митoчoндpиaльнoгo липдa нe мeняютcя зaмeтнo c вoзpacтoм. Плaвyчaя плoтнocть митoчoдpиaльнoй ДHК—cлeдoвaтeльнo и ee ocнoвнoгo cocтaвa—нe мeняeтcя зaмcтнo c вoзpacтoм.

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    Present address: Molecular Disease Foundation, 22554 Ventura Blvd., Woodland Hills, Calif. 91364, U.S.A.

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