Meeting Abstract

 

70-5  Saturday, Jan. 5 14:30 – 14:45  The dorsoventral patterning and asymmetry of paired fins STEWART, TA*; LEMBERG, JB; SHUBIN, NH; University of Chicago; University of Chicago; University of Chicago tomstewart@uchicago.edu http://www.tomstewart.org

Limbs are asymmetrical in the dorsoventral axis—skeleton, musculature, epithelial appendages, innervation, and sensory endings all exhibit this polarity. It is less clear whether pectoral and pelvic fins, which are homologous to limbs, exhibit similar asymmetries and, if so, when they might have evolved. Here we present a comparative study of anatomy and developmental genetics and argue that dorsoventral asymmetries are plesiomorphic among the paired fins of gnathostomes. Micro-CT data from the pectoral and pelvic fins of several species, including Danio rerio (Actinopterygii), the little skate Leucoraja erinacea (Chondrichthyes) and Tiktaalik roseae (Sarcopterygii), show that asymmetries are common among both the dermal and endoskeletal systems of paired fins. We also test whether the developmental and genetic mechanisms that establish dorsoventral asymmetry in limbs are shared with paired fins. Using laser microdissection and RNA sequencing, we compare gene expression in the dorsal and ventral portions of developing paired fins in L. erinacea. Comparing these results to what is known of mouse and chick development, we discuss how the breaking of dorsoventral symmetry might have occurred in the earliest paired fins.