Niche maintenance of germline stem cells inC. elegansmales

ABSTRACT Stem cell maintenance by niche signaling is a common theme across phylogeny. In the Caenorhabditis elegans gonad, the broad outlines of germline stem cell (GSC) regulation are the same for both sexes: GLP-1/Notch signaling from the mesenchymal Distal Tip Cell (DTC) niche maintains GSCs in the distal gonad of both sexes (A ustin and K imble 1987), and does so via two key stem cell regulators, SYGL-1 and LST-1 (K ershner et al . 2014). Most analyses of niche signaling and GSC regulation have focused on XX hermaphrodites, an essentially female sex making sperm in larvae and oocytes in adults. Here we focus on XO males, which are sexually dimorphic in all tissues, including the distal gonad. The architecture of the male niche and the cellular behavior of GSCs are sex-specific. Despite these differences, males maintain a GSC pool similar to the hermaphrodite with respect to size and cell number and the male GSC response to niche signaling is also remarkably similar.