Model Organisms and Cellular Senescence in Aging Research

Vocabulary flashcards covering key model organisms, biomarkers, and genetic mechanisms of cellular senescence and aging.

Chronological Lifespan (CLS)

The duration of time that non-dividing yeast cells remain viable in the stationary phase.

Replicative Lifespan (RLS)

The total number of daughter cells a mother yeast cell can produce before undergoing permanent growth arrest.

Extrachromosomal rDNA Circles (ERCs)

Extrachromosomal DNA circles formed by ribosomal DNA recombination in the rDNA cluster that accumulate in mother yeast cells and cause replicative aging.

Resveratrol

A polyphenolic compound found in red wine identified as a substrate-specific activator of Sir2 that extends lifespan in lower organisms and protects mice against high-fat diet toxicity.

Rapamycin

A macrolide antibiotic, also known as sirolimus, that specifically inhibits TOR activity to increase yeast CLS and RLS as well as lifespan in nematodes, flies, and mice.

Spermidine

A naturally occurring polyamine that modulates DNA stability, transcription, translation, and apoptosis, promoting longevity in yeast, nematodes, and flies through the induction of autophagy.

Negative Geotaxis

The innate climbing behavior of flies against gravity, which declines progressively with age due to nervous system and muscle malfunction.

Smurf Phenotype

An age-dependent loss of intestinal barrier integrity in Drosophila that allows blue food dye to leak out of the digestive tract into the body cavity, predicting impending death regardless of chronological age.

Methuselah Lines

Long-lived Drosophila lines generated by Michael Rose through selective breeding for postponed reproduction that live up to three or four times as long as baseline control groups.

hsp22

A small heat shock protein gene in Drosophila that is induced during aging and expressed at twofold to tenfold higher RNA levels in genetically selected long-lived O lines compared to control B lines.

Replicative Senescence

A state of irreversibly arrested cell growth and altered physiological function entered by normal somatic cells after a finite number of cell divisions.

Senescence-Associated Beta-Galactosidase (SA-$\beta$-gal)

A biomarker histochemically detectable at pH 6 that specifically identifies senescent human cells in culture and in aging skin in vivo.

Senescence-Associated Secretory Phenotype (SASP)

A complex secretory profile produced by senescent cells consisting of proinflammatory interleukins, chemokines, growth factors, proteases, and extracellular matrix factors.

DNA Damage Response (DDR)

A signaling cascade triggered by DNA damage that halts cell cycle progression for repair and induces senescence or apoptosis if damage is severe.

Telomere Dysfunction-Induced Foci (TIFs)

Nuclear foci formed at uncapped or damaged telomeres that serve as markers of cellular senescence and accumulate exponentially with age in primate skin fibroblasts.

53BP1 Foci

Nuclear foci of p53-binding protein 1 that mark site-specific DNA damage and accumulate exponentially with age alongside TIFs in aging dermal fibroblasts.

INK-ATTAC

A transgenic construct expressing FKBP-Cas8 under the control of the $p16^{Ink4a}$ promoter, enabling targeted apoptotic destruction of $p16^{Ink4a}$-positive senescent cells.

AP20187

A synthetic drug that activates the FKBP-Cas8 suicide protein in the INK-ATTAC transgenic model to clear $p16^{Ink4a}$-expressing senescent cells and extend median lifespan in mice.

Senolytics

Pharmacological compounds or therapies specifically designed to target and eliminate senescent cells from tissues to prevent age-related deterioration.