Meeting Abstract

13.3  Wednesday, Jan. 4  Hoxa13 gene expression is associated with tail growth across embryonic, larval, and adult development in the non-model salamander Eurycea cirrigera REDMOND, SB*; BOTTS, EA; HILL, KL; EVANS, PK; VAGLIA, JL; DePauw University; DePauw University; DePauw University; DePauw University; DePauw University

Regulatory Hox gene expression is important throughout organismal development to establish and maintain position along the anterior-posterior body axis. Posterior Hox genes, particularly Hoxa9 and Hoxa13 have been implicated in the development and regeneration of limbs in Ambystoma mexicanum and Xenopus laevis. Like A. mexicanum and X. laevis, Eurycea cirrigera elongate their bodies throughout their lifespan and can regenerate limb and tail tissue. Unlike the common regenerative models, E. cirrigera tail growth arises, in part, from addition of new vertebrae, suggesting that signaling of cellular position along the body axis must accommodate addition of new structures rather than shifting of existing structures. To understand the role of Hox gene expression in this signaling process, we used quantitative RT-PCR to measure expression of Hoxa13 throughout E. cirrigera embryonic development and in the tail tips of larvae and adults. Hoxa13 expression was higher in embryonic stages associated with body and tail elongation compared to those stages associated with limb development. Larval E. cirrigera collected early in the summer expressed less Hoxa13 than those collected in mid or late summer, suggesting that expression may be associated with high resource availability, and therefore more rapid growth. The range of Hoxa13 expression was similar across all life stages. These data suggest that the Hox gene family plays an important role in tail extension throughout E. cirrigera development, and that Hoxa13 may be useful as a marker of tail growth in this species.