Kohji Miyahara et al. (2003) International Worm Meeting "Role of RhoGAP in behavioral plasticity ."

Eiko Tsuchiya, Masayuki Gosho, Kohji Miyahara

[International Worm Meeting, 2003]

In order to identify genes that associate with behavioral plasticity in C. elegans, we screened for mutants that are defective in adaptation or saturation to odorants. A screen was conducted to identify mutants that did not fail to chemotax toward a point source of odorant in a field of same odorant. From approximately 4000 EMS mutagenized genomes, we discovered 12 mutants that exhibited defects in adaptation or saturation to the AWC-sensed odorants. We cloned one mutant by transgene rescue of the mutant phenotype and found it to encode the GTPase activated protein for Rho (RhoGAP). RhoGAPs are negative regulators of Rho-GTPase signaling pathways related to actin cytoskeleton dynamics, cell proliferation, and differentiation. Our results may suggest that Rho-GTPase is associated with the mechanism of olfactory adaptation or saturation. We are currently making GFP constructs to identify the location of RhoGAP expression and are sequencing this mutation in order to understand the molecular basis of this mutant phenotype.

Kohji Miyahara et al. (2005) International Worm Meeting "Rho GTPase signaling in olfactory adaptation."

Eiko Tsuchiya, Sadaaki Tanaka, Hiroyuki Arai, Masayuki Gosho, Dai Hirata, Kohji Miyahara, Takao Inoue, Hiroyuki Kobuna

[International Worm Meeting, 2005]

Olfactory adaptation, a component of behavioral plasticity, and the signaling pathway(s) that control it are at the center of our interest. In order to identify gene(s) associated with olfactory adaptation, we screened for mutants defective in adaptation to odorants. Out of 4,000 EMS-mutagenized animals, we discovered 11 mutants that exhibiting defects in adaptation to the AWC-sensed odorants. One of the mutants turned out to contain an altered version of GEI-1, that encodes Rho-GAP (GTPase-activated protein), suggesting this protein plays an important role in adaptation. To investigate whether Rho-GTPases act in this behavior, we examined olfactory adaptation of transgenic animals expressing dominant active/negative forms of Rho-GTPases (RhoA, Cdc42, and Rac1). The dominant active RHO-1/RhoA inhibited normal olfactory adaptation similarly to the gei-1 mutant. Furthermore, the genetic analyses indicate that RHO-1 acts downstream of GEI-1 in olfactory adaptation.