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

## TL;DR

This study shows that a key signaling gradient in the germline of C. elegans declines with age, which may affect stem cell maintenance.

## Contribution

The study introduces the use of a genetically encoded sensor to visualize Notch activity in the aging germline in vivo.

## Key findings

- A strong distal-proximal Notch activation gradient is present in young C. elegans adults.
- This gradient is largely lost during aging, indicating reduced niche signaling.
- The loss correlates with earlier observations of decreased Notch target gene transcription.

## Abstract

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.