In C. elegans, the distal tip cell (DTC) niche maintains germline stem cells (GSCs) in both sexes. In addition, the same GSC regulators are used in both sexes (GLP-1/Notch signaling, the LST-1and SYGL-1 downstream effectors and FBF RNA-binding proteins). Yet, there are differences between the sexes. Hermaphrodites have a single DTC while males have two, and DTC expression of GLP-1/Notch ligands differs (1). Male germ cells have a faster cell cycle than hermaphrodites, and the male progenitor zone is longer (2).
We used a GFP marker to examine adult male DTC architecture. We find that each DTC has a cap region extending over 3-4 cell rows, similar to the extent of the cap in the single hermaphrodite DTC (3). The male DTCs also form a plexus of processes that intercalate between germ cells. Yet the male plexus is longer than the hermaphrodite plexus.
We examined the transcriptional response to GLP-1/Notch signaling in male germ cells with single molecule FISH to sygl-1 (4). As in hermaphrodites (4,5), sygl-1 transcripts are spatially restricted to the distal progenitor zone. Preliminary results indicate that sygl-1 transcripts extend further proximally in males than in hermaphrodites. Using the emb-30 assay that revealed a distal pool of undifferentiated germ cells in hermaphrodites (6), we find that males have an expanded distal pool, which correlates with the expanded sygl-1 transcriptional response.
(1) Chesney et al., Developmental Biology 331 (2009).
(2) Morgan et al., Developmental Biology 346 (2010).
(3) Byrd et al., PLoS ONE 9 (2014).
(4) Kershner et al., PNAS 111 (2014).
(5) Kimble et al. abstract this meeting.
(6) Cinquin et al., PNAS 107 (2010).