51.6 Thursday, Jan. 5 piwi expression during regeneration in the annelid Pristina leidyi OZPOLAT, B. D.*; ZATTARA, E. E.; BELY, A. E.; University of Maryland, College Park; University of Maryland, College Park; University of Maryland, College Park firstname.lastname@example.org
Identifying the cell types that participate in regeneration and understanding their molecular characteristics is crucial for dissecting the mechanisms of regeneration. Annelid worms have long been used in regeneration research and early studies identified putative stem cells called neoblasts believed to migrate to the wound and participate in regeneration. While there is a substantial early literature on the histology and cytology of migratory cells such as neoblasts, only recently have tools become available to investigate their molecular and behavioral characteristics. Pristina leidyi, a freshwater annelid, is able to regenerate both anteriorly and posteriorly and recent time-lapse imaging studies in our lab provide definitive evidence for widespread cell migration towards cut sites. In this study, we investigate the expression of several stem cell markers during regeneration and ask whether there are distinct populations of migratory cells that express these markers differentially. Here we focus on the gene piwi, which is required for regeneration and/or germline function in diverse metazoans. We find that piwi is dynamically and strongly expressed in the regeneration blastema and primordial gonads, as well as fission zone and posterior growth zone. In addition, piwi is expressed in a population of ventral cells that appear to be migrating along the length of the body between the gut and ventral nerve cord. Interestingly, no piwi expression is detected in the other migratory cell populations identified by time-lapse imaging. Thus, there are at least two distinct populations of cells that migrate after injury. Future studies are aimed at identifying additional molecular markers for these distinct populations and investigating their function during regeneration.