Graduation Date

Spring 2024

Document Type



Master of Science degree with a major in Biology

Committee Chair Name

Karen Kiemnec-Tyburczy

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

John Reiss

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Sharyn Marks

Third Committee Member Affiliation

HSU Faculty or Staff

Fourth Committee Member Name

Amy Sprowles

Fourth Committee Member Affiliation

HSU Faculty or Staff


Olfaction, Plethodontid, Salamander, Life stage, Desmognathus

Subject Categories



The olfactory system of extant amphibians changes as the animal transitions from a fully aquatic to a terrestrial lifestyle at metamorphosis. Cellular morphology of the nose and expression patterns of olfactory genes in the nasal cavity have been examined for a variety of frogs and salamanders, but among plethodontid salamanders, molecular data are available only for Plethodon shermani. Using standard histology and micro-CT reconstruction, I investigated the structure of the olfactory organs of larvae, juveniles, and adults of six plethodontid species, with terrestrial, streamside, semiaquatic, and aquatic adults. The overall structure of the olfactory cavity was generally similar across species, but in Desmognathus aureatus, there was a great change in shape of the organ before and after metamorphosis, with a reduction of the epithelium not reported in other plethodontids. At the molecular level, I used in situ hybridization to localize the expression of three G proteins (Gαolf, Gαo and Gαi2) and one cation channel (TRPC2). The expression of all the olfactory components did not vary between the juvenile and the adult life stages in terrestrial plethodontids. Generally, the main olfactory cavity expressed Gαolf, the vomeronasal organ (VNO) expressed TRPC2, and Gαo was expressed in the whole iii cavity. Expression of Gαolf in the VNO is absent in larvae but occurs in adults of some species. In direct-developing species, TRPC2 is restricted to the VNO, while some biphasic species express it in the whole cavity. Thus, TRPC2 appears to have a crucial role in chemoreception in all life stages and species.

Citation Style





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