29.2 Wednesday, Jan. 4 Anchor cell invasion across the Nematoda: a highly conserved cell biological process required for establishing the uterine-vulval connection MATUS, D.Q.*; YANG, M.; CHANG, E.; SHERWOOD, D.R.; Duke University; Duke University; Duke University; Duke University firstname.lastname@example.org
The rhabditid nematode vulva is a well-studied evolutionary developmental model for understanding the mechanisms of organogenesis. In Caenorhabditis elegans, the induction of the epithelial vulval precursor cells (VPCs) requires signaling from a specialized somatic gonadal cell, the anchor cell (AC). Following induction the AC also plays a pivotal role in connecting the developing uterus to the vulva, by invading through the gonadal and vulval epithelial basement membranes (BMs) to initiate direct uterine-vulval contact. After the initial breach in the BMs, the AC is not required to expand the BM gap. Instead, as the VPCs invaginate, the BM breach is widened through BM sliding and is stabilized by the innermost secondary-fated VPC cell, vulD. To examine the degree of evolutionary conservation underlying AC invasion across the Nematoda, we have investigated AC invasion in seventeen species of rhabditid nematodes representing hundreds of millions of years of nematode evolution. Using Nomarski microscopy and laser ablation, we observed little morphological diversity in terms of the timing and positioning of AC invasion in relation to the underlying VPCs. Following invasion the boundary for the expanding hole appears stabilized over vulD in all species surveyed to date. Notably, vulD is unique within these species compared with other VPCs in that it undergoes one fewer division cycles and is post-mitotic at the time of BM sliding and gap positioning. This suggests that BM boundary positioning might require vulD to be post-mitotic. Despite the large degree of evolutionary change observed in vulval development across these species, we suggest that AC invasion and stabilization of the sliding BM are under strong evolutionary pressure to ensure a secure uterine-vulval connection.