title: Autofluorescence as a measure of senescence in C. elegans: look to red, not blue or green.
abstract: In C. elegans, intestinal autofluorescence (sometimes referred to as lipofuscin or "age pigment") accumulates with age and is often used as a marker of health or the rate of aging. We show that this autofluorescent material is spectrally heterogeneous, and that materials that fluoresce under different excitation wavelengths have distinct biological properties. Red autofluorescence (visible with a TRITC filter set) correlates well with an individual's remaining days of life, and is therefore a candidate marker of health. In contrast, blue autofluorescence (via a DAPI filter set) is chiefly an indicator of an individual's incipient or recent demise. Thus, population averages of blue fluorescence essentially measure the fraction of dead or near-dead individuals. This is related to but distinct from the health of the living population. Green autofluorescence (via a FITC or GFP filter set) combines both properties, and is therefore ill suited as a marker of either death or health. Moreover, our results show that care must be taken to distinguish GFP expression near the time of death from full-body green autofluorescence. Finally, none of this autofluorescence increases after oxidative stress, suggesting that the material, or its biology in C. elegans, is distinct from lipofuscin as reported in the mammalian literature.
authors.affiliation: Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA.|Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Zachary
authors.initials: Z
authors.lastname: Pincus
authors.affiliation: Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA.|Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Travis C
authors.initials: TC
authors.lastname: Mazer
authors.affiliation: Institute for RNA Medicine, Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Slack
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000502:physiology*; D016922:Cellular Senescence / Q000502:physiology*; D008856:Microscopy, Fluorescence / Q000379:methods*; D018384:Oxidative Stress / Q000502:physiology
keywords: age pigment; autofluorescence; health; lipofuscin