Meeting Abstract

P3-33   -   Revisiting neoblasts and their role in annelid regeneration. Ali, F/T*; Martinez Acosta, V/G; Univ. of the Incarnate Word; Univ. of the Incarnate Word vgmartin@uiwtx.edu

We examine regeneration in an annelid model system, Lumbriculus variegatus. Lumbriculus regenerates an entirely new body from a fragment that is 1/50th the size of the original animal. Remarkably, Lumbriculus not only recovers missing body structures but also demonstrates full recovery of function along any portion of the anterior-posterior (A-P) body axis following injury, suggesting that each segment along the A-P axis is poised for regeneration. In regenerating annelids, a population of stem cells called neoblasts, have been described to migrate from along the ventral nerve cord to a wound site for tissue repair (Zattara and Bely, 2016). In this study, we characterize the stem cell populations contributing to this remarkable recovery of structures and function. Using Edu and Bromodeoxyuridine (BrdU) we identify and label stem cells in fixed tissues beginning 15min post amputation and extending through 24hr post-amputation. Using an immunohistochemical approach, regenerating worm fragments are labeled by an antibody, 1D9-411, generated against Planarian blastemal tissues, which has been used as a marker for a subpopulation of stem cells called neoblasts. Neoblasts were originally described in regenerating Lumbriculid tails by Harriet Randolph (1891). Interestingly, 1D9-411 labels two protein bands, measuring 214 kDa and 137 kDa. These two bands are present in both anterior and posterior regenerating and non-regenerating fragments and are differentially expressed. Lastly, we use hybridization chain reaction (HCR) for the first time in Lumbriculus to demonstrate the expression of different stem cell related genes, including piwi, a known regulatory gene for stem cell and germ cell differentiation. Taken together this work revisits the role of the neoblast in annelid regeneration.