Submitted on January 17, 2006
Accepted on March 3, 2006
Developmental regulation of whole-cell capacitance and membrane current in identified interneurons in C. elegans
Serge Faumont1, Thomas Boulin2, Oliver Hobert2, and Shawn R Lockery1*
1 Institute of Neuroscience, University of Oregon, Eugene, Oregon, United States
2 Howard Hughes Medical Institute, Columbia University Medical Center, New York, New York, United States
* To whom correspondence should be addressed. E-mail: shawn{at}lox.uoregon.edu.
Post-embryonic developmental changes in electrophysiological properties of the AIY interneuron class were investigated using whole-cell voltage-clamp. AIY interneurons displayed an increase in cell capacitance during larval development, whereas steady-state current amplitude did not increase. The time course of the outward membrane current, carried at least in part by K+ ions, matured, from a slowly activating, sustained current to a rapidly-activating, decaying current. We also investigated how the development of capacitance and outward current was altered by loss-of-function mutations in genes expressed in AIY. One such gene, the LIM homeobox gene ttx-3, is known to be involved in the specification of the AIY neuronal subtype. In ttx-3 mutants, capacitance and outward current matured precociously. In mutants of the gene wrk-1, an immunoglobulin superfamily (IgSF) member whose expression is regulated by ttx-3, capacitance matured normally, whereas outward current matured precociously. We conclude that AIY interneurons contain distinct pathways for regulating capacitance and membrane current.
