Animals, including humans, sense environmental cues with their nervous system and conduct appropriate behavior. Many stereotyped behaviors must be formed during evolution and hence controlled by genes. We are studying how genes control such behaviors, using the nematode Caenorhabditis elegans. C. elegans is a good material not only for genetic analysis, but also for structural analysis, since each of the 302 neurons can be identified under a microscope and the complete neural circuitry is known. Taking these advantages, we aim to elucidate the relationship between genes, neurons, neural circuit and behavior.

Our present studies include:
• analysis of mutants in the learning with odorants and food/starvation.
• analysis of behavioral changes after prolonged exposure to “uncomfortable” stimuli.
• genetic analysis of sensory information processing as assayed by the formation of dauer larvae.
• control of defecation behavior, growth, and sensory signals by flr genes, which probably act in the intestine.

Torayama, I., Ishihara, T. and Katsura, I. (2007). Caenorhabditis elegans integrates the signals of butanone and food to enhance chemotaxis to butanone. J. Neurosci. 27, 741-750.

Yabe, T., Suzuki, N., Furukawa, T., Ishihara, T. and Katsura, I. (2005). Multidrug resistance-associated protein MRP-1 regulates dauer diapause by its export activity in Caenorhabditis elegans . Development 132, 3197-3207.

Take-uchi, M., Kobayashi, Y., Kimura, K., Ishihara, T. and Katsura, I. (2005). FLR-4, a novel Serine/Threonine protein kinase, regulates defecation rhythm in Caenorhabditis elegans. Mol. Biol. Cell 16, 1355-1365.

Miyahara, K., Suzuki, N., Ishihara, T., Tsuchiya, E. and Katsura, I. (2004). TBX2/TBX3 transcriptional factor homologue controls olfactory adaptation in Caenorhabditis elegans. J. Neurobiol. 58, 392-402.

Ohkura, K., Suzuki, N., Ishihara, T. and Katsura, I. (2003). SDF-9, a protein tyrosine phosphatase-like molecule, regulates the L3/dauer developmental decision through hormonal signaling in C. elegans. Development 130, 3237-3248.

Ishihara, T., Iino, Y., Mohri, A., Mori, I., Gengyo-Ando, K., Mitani, S. and Katsura, I. (2002). HEN-1, a novel protein with an LDL receptor motif, regulates sensory integration and learning in Caenorhabditis elegans. Cell 109, 639-649.