Type of Submission


Campus Venue

Dixon Ministry Center, Alumni Hall


Cedarville, OH

Start Date

4-10-2013 1:00 PM

End Date

4-10-2013 5:00 PM



During vertebrate development, neuronal growth is guided by chemical signals. Chemoattractants encourage neuronal growth cones to form, while chemorepellents cause growth cone collapse. Integration of these signals allows for proper neural positioning in the developing organism. Not all signaling pathways are clear-cut, however. Netrin-1, for example, can function as either a chemoattractant or a chemorepellent, depending upon the cell type involved, the signals the cell has previously received, and the concentration of the signal. Netrin-1 primarily signals through a G-protein mediated receptor via the adenylyl cyclase pathway. The semaphorins mainly serve as chemorepellents and as immune signals in vertebrates. However, signaling through the semaphorins is not well understood. Tetrahymena thenmophila are free-living, ciliated eukaryotic organisms that are often used as a model for showing behavioral responses to both chemoattractants and chemorepellents. A number of polycationic peptides function as chemorepellents in this organism, including lysozyme, VIP, PACAP, nociceptin, substance P, and ACTH derivatives. In the current study, we used two polycationic peptides derived from the vertebrate neuronal chemorepellents, semaphorin 3 C and netrin-1, in order to determine whether they were chemorepellents in Tetrahymena thermophila. Both peptides ware chemorepallents in Tetrahymena tharmophila. Semaphorin 3C peptide showed chemorepallent activity with an effective concentration of approximately 10 micromolar. Netrin-1 peptide showed chemorepellent activity over a range of concentrations from micromolar to nanomolar. However, there was a great deal of variability in the response to netrin-1. Further characterization of the pathways involved in the signaling of these repellents will allow comparison between ciliate and vertebrate signaling, and may help us better understand vertebrate development.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

Included in

Chemistry Commons


Apr 10th, 1:00 PM Apr 10th, 5:00 PM

Vertebrate Neuronal Chemorepellents, Semaphorin 3C and Netrin-1, Are Chemorepellents in Tetrahymena Thermophila

Cedarville, OH


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