A Decline in p38 MAPK Signaling Underlies Immunosenescence in Caenorhabditis elegans
(A) Scatter plots comparing gene expression levels in the C. elegans wild type N2 strain at Day 15 versus Day 6 of adulthood. Each dot represents an individual gene; brown, all genes on the full-genome microarray; blue, genes previously shown to exhibit enriched expression levels in the C. elegans intestine; red, genes previously identified as being regulated by the PMK-1 pathway. Genes on the solid diagonal line are expressed at equivalent levels at both time points. Genes below the dashed diagonal line are downregulated by more than 10-fold between Day 6 and Day 15 of adulthood. (B) qRT-PCR of endogenous C17H12.8 and T24B8.5 mRNA levels during aging relative to expression at Day 3 of adulthood. The average of three experiments using independent biological replicates of total RNA for cDNA synthesis is shown. Bars indicate standard deviation. (C) Fluorescence microscopy of C. elegans carrying the agIs219 transgene, a GFP reporter of PMK-1 activity, at the indicated ages. (D) qRT-PCR of pmk-1 transcript levels during aging relative to expression at L4. The average of two experiments using independent biological replicates of total RNA for cDNA synthesis is shown.