Meeting Abstract
60.3 Sunday, Jan. 5 14:00 Development and evolution of the enigmatic lateral line of clitellate annelids OZPOLAT, B. D.*; BOROVIKOV, A.; ZATTARA, E. E.; BELY, A. E.; University of Maryland, College Park; University of Maryland, College Park; University of Maryland, College Park; University of Maryland, College Park dozpolat@gmail.com
The lateral line is a bilateral cord of cells that has been described in many clitellate annelids, but its function and homologies remain enigmatic. It has been proposed to be homologous to lateral organs in polychaetes, and even to the vertebrate lateral line. The tissue origin and function of the clitellate lateral line is poorly understood, although early work suggested it may be muscular, neural, or sensory. We investigated the formation of the lateral line during post-embryonic development (fission and regeneration) in the annelid Pristina leidyi, which has a clearly delineated lateral line. Using cell proliferation assays, we found that cells that will form the lateral line arise very early during regeneration and then undergo little to no subsequent cell division. We have cloned a number of Wnt signaling pathway genes and find that several of these are expressed in a segmentally iterated pattern in the lateral line in uncut, regenerating, and fissioning worms. Expression is initiated in clusters of cells very early on in the newly developing tissues, with some converging into the lateral line. Once the new segments are formed, expression is largely restricted to segmentally iterated subsets of cells in the line, creating a dashed-line pattern. Our findings indicate that Wnt signaling is likely involved in the formation of the lateral line; that this structure forms early during post-embryonic tissue development; and that the fully formed lateral line is composed of cells with heterogeneous expression profiles, possibly indicating a more complex function than previously thought. Results from this ongoing study will help clarify the evolutionary origins of the clitellate lateral line, including possible homologies to structures in other annelids.
