Knowing how stem cells and their progeny are positioned within their tissues is essential for understanding their regulation. One paradigm for stem cell regulation is the C. elegans germline, which is maintained by a pool of germline stem cells in the distal gonad, in a region known as the 'progenitor zone'. The C. elegans germline is widely used as a stem cell model, but the cellular architecture of the progenitor zone has been unclear. Here we characterize this architecture by creating virtual 3D models of the progenitor zone in both sexes. We show that the progenitor zone in adult hermaphrodites is organized like a folded epithelium. The progenitor zone in males is not folded. Analysis of germ cell division shows that daughter cells are born side-by-side along the epithelial-like surface of the germline tissue. Analysis of a key regulator driving differentiation, GLD-1, shows that germ cells in hermaphrodites differentiate along a folded path, with previously described "steps" in GLD-1 expression corresponding to germline folds. Our study provides a three-dimensional view of how C. elegans germ cells progress from stem cell to overt differentiation, with critical implications for regulators driving this transition.

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7Knowing how stem cells and their progeny are positioned within their tissues is essential 8 for understanding their regulation. One paradigm for stem cell regulation is the C. elegans 9 germline, which is maintained by a pool of germline stem cells in the distal gonad, in a region 10

Recent research has found that “sensory” receptors (including olfactory receptors (ORs), taste receptors (TRs), and opsins) play functional roles throughout the body. However, the expression of these receptors has not yet been carefully examined in the bladder. In this study, we utilized customized Taqman low density gene array cards to perform quantitative PCR and identify novel sensory receptors in mouse bladder tissue. We extracted RNA from murine bladder (2 male, 2 female), and then screened for the presence of sensory receptors using custom Taqman arrays which included probesets for 43 ORs, 35 bitter TRs, 3 TRs for umami/sweet, 5 opsins, and 7 G‐proteins and/or accessory proteins associated with sensory signaling pathways, as well as a Gapdh control. Using these arrays, we found the expression of 30 sensory transcripts in all male and female bladder samples, with 11 receptors being relatively well‐expressed (Ct values<~30). The 11 highly expressed receptors included 2 opsins (Opn1sw, Opn3), 3 ORs (Olfr558, Olfr99, Olfr78), 5 TRs (Tas1r3, Tas2r143, Tas2r135, Tas2r108, Tas2r126), and the G protein for olfaction (Gnal). We did not note any sex differences, and the top hit (Opn1sw) was the same for all four arrays. Notably, two of the ORs found in the bladder (Olfr78, Olfr558) are known to respond to bacterial metabolites, which may be relevant in the setting of cystitis/urinary tract infections (UTIs). In the future, determining the role of these novel bladder sensory receptors has the potential to enhance our understanding of bladder function, and may lead to novel treatments for conditions such as cystitis/UTIs. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.