EXAMINING TAIL DEVELOPMENT MODELS IN THE FOUR-TOED SALAMANDER, HEMIDACTYLIUM SCUTATUM

Tails are common among most vertebrates. The embryonic tails of most vertebrates grow into adulthood while other vertebrates absorb their embryonic tails. Interestingly, some species of salamanders have the ability to add axial segments to their tail post-embryonically, as well as the ability to drop the tail as a defense against predation, though not all salamanders that exhibit tail autonomy have the ability to grow extra segments. Postembryonic growth of the posterior axis has been studied in multiple species of salamanders and is the result of both the growth of existing segments as well as the formation of new ones. In the salamander Hemidactylium scutatum, postembryonic segmentation of the tail is due to the development of new caudal vertebrae. The mechanisms that drive the postembryonic segmentation in salamanders are unknown and may offer insights on the molecular nature of tail development in vertebrates. By comparing the expression of Wnt8 and My5 in the developing tails of H. scutatum embryos, larvae, and adults, I can determine whether tail development is driven by a tail organizer or whether it occurs as an extension of trunk development. Primers designed from cloned segments of H. scutatum Wnt8 and Myf5 genes allowed semi-quantitative PCR analysis of the expression of transcript levels confirmed through DNA sequencing. I will present my analysis of the expression of these two genes throughout embryogenesis and in developing tail regions of larvae and adults. If trunk formation drives tail development, I expect to see Myf5 expressed in the tailbud, but if an organizer drives tail development, I expect to see Wnt8 expression.

Additional Abstract Information

Student(s): Peter Rossbach

Department: Biology

Faculty Advisor: Dr. Carol Hurney

Type: Poster

Year: 2014