Loss of the distal-proximal GLP-1/Notch activation gradient in the aging C. elegans germline.

In C. elegans hermaphrodites, the distal tip cells (DTCs) capping the gonad arms provide a Notch ligand, the niche signal that maintains germline stem cell pools. Using fixed germlines, it was recently shown that the transcription of a Notch target gene decreased relatively early-on during adulthood. Here, we used the genetically encoded Notch Sensor Able to detect Lateral Signaling Activity (SALSA) to examine the pattern of GLP-1/Notch activity across the aging distal gonad in vivo . Interestingly, we find that the robust and progressively decreasing distal-proximal Notch activation gradient that is observed in young adults gets largely lost during aging.