title: The aging biological clock in Neurospora crassa.
abstract: The biological clock affects aging through ras-1 (bd) and lag-1, and these two longevity genes together affect a clock phenotype and the clock oscillator in Neurospora crassa. Using an automated cell-counting technique for measuring conidial longevity, we show that the clock-associated genes lag-1 and ras-1 (bd) are true chronological longevity genes. For example, wild type (WT) has an estimated median life span of 24 days, while the double mutant lag-1, ras-1 (bd) has an estimated median life span of 120 days for macroconidia. We establish the biochemical function of lag-1 by complementing LAG1 and LAC1 in Saccharomyces cerevisiae with lag-1 in N. crassa. Longevity genes can affect the clock as well in that, the double mutant lag-1, ras-1 (bd) can stop the circadian rhythm in asexual reproduction (i.e., banding in race tubes) and lengthen the period of the frequency oscillator to 41 h. In contrast to the ras-1 (bd), lag-1 effects on chronological longevity, we find that this double mutant undergoes replicative senescence (i.e., the loss of replication function with time), unlike WT or the single mutants, lag-1 and ras-1 (bd). These results support the hypothesis that sphingolipid metabolism links aging and the biological clock through a common stress response.
authors.affiliation: Department of Genetics, University of Georgia Athens, Georgia, 30602.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Case
authors.affiliation: Department of Genetics, University of Georgia Athens, Georgia, 30602 ; College of Agricultural and Environmental Sciences, University of Georgia Athens, Georgia, 30602.
authors.forename: James
authors.initials: J
authors.lastname: Griffith
authors.affiliation: Department of Genetics, University of Georgia Athens, Georgia, 30602.
authors.forename: Wubei
authors.initials: W
authors.lastname: Dong
authors.affiliation: Department of Genetics, University of Georgia Athens, Georgia, 30602.
authors.forename: Ira L
authors.initials: IL
authors.lastname: Tigner
authors.affiliation: Department of Genetics, University of Georgia Athens, Georgia, 30602.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Gaines
authors.affiliation: Tulane Center for Aging and Department of Medicine, Tulane University Health Sciences Center New Orleans, Louisiana, 70112.
authors.forename: James C
authors.initials: JC
authors.lastname: Jiang
authors.affiliation: Tulane Center for Aging and Department of Medicine, Tulane University Health Sciences Center New Orleans, Louisiana, 70112.
authors.forename: S Michal
authors.initials: SM
authors.lastname: Jazwinski
authors.affiliation: Department of Genetics, University of Georgia Athens, Georgia, 30602.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Arnold
keywords: Aging; Neurospora crassa; bd; biological clock; lag-1; ras-1