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 distal gonad arms provide the niche signal, a Notch ligand, to maintain 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 entirely lost during aging.