Learning is one of the most complicated behavior. The habituation learning accompanied by harmless tap stimuli in C. elegans was originally noticed by C. Rankin(1). She established the desirable assay methods and proved that the behavior is suitable for the analysis of the nonassociative learning. We mainly undertook genetic analyses to clarify the behavior and isolated many mutants showing abnormal behaviors on the habituation learning(2). In parallel with genetic analyses, we applied the cDNA microarray technique for further identification of the related gene to the behavior. We observed that many gene expressions are altered during tap stimuli. From these identified genes, we found that C08F11.1, gtl-1 and cec-1 are essential for habituation learning(1). In this report, we focus our attention to the latter two genes. The gtl-1 gene encodes the TRP channel, one of a TRPM subfamily member. The mammalian GTL-1 homologue RRDC7 is highly expressed in brain.However, its role is not yet cleared.The gtl-1 gene is expressed in ASK and ASI amphidal neurons. Cec-1 is a chromobox-contains gene encoding a potential transcriptional suppressor. cec-1(RNAi) animals show similar phenotype as gtl-1(RNAi) animals on habituation behavior. Wild-type animals show chemotaxis toward NaCl but avoid NaCl after conditioning with NaCl in the absence of food. Both RNAi animals are also abnormal in associative learning with the NaCl/starvation paradigm. We then examined the learning behaviors of gtl-1(ok375) and cec-1(ok1005) animals, We found that the two learning phenotypes in ok375 and ok1005 animals are similar to phenotypes in each RNAi animals. That is, habituation behaviors in both mutants are normal when given short interval tap stimuli, but abnormal when given long interval tap stimuli. To further inquire into the contribution of both genes to LTM, channel properties of GTL-1 and target genes of CEC-1 are searching.(1)Rankin H, Beck D, Chiba M (1990) Behav Brain Res 37:89-92(2)Xu et al., (2002) J.Neurogenetics 16:1-16(3)Suzuki Y et al.,(2005) Identification of genes contributing to learning in C.elegans using cDNA microarrays( submitted to press )

Affiliations:
- Genome Biology Lab, National Institute of Genetics, Mishima, Japan
- Dept Physical Information, Kanazawa Univ, Kanazawa, Japan