In C. elegans, the insulin-signaling regulates the diapause, longevity and fat metabolism via the DAF-2, a homolog of insulin/IGF-I receptor. Our search for the DAF-2 ligands revealed two insulin/IGF-like peptides named Ceinsulin-1 (INS-18) and -2 (INS-17). First, in order to obtain structural information of the peptides, we performed a computer modeling using the Discover III/Insight II. The predicted tertiary structures of the peptides were quite similar to each other, and their receptor-recognition surfaces matched significantly. Therefore, these peptides should be recognized by the same receptor. Next, to elicit the physiological function of the
ins-17 and -18 genes, we disrupted the genes using the TMP/UV method. The following sib-screening yielded an
ins-17 deletion mutant named
tm790 and an
ins-18 deletion mutant named
tm339. The
tm790 has deletion of approximately 0.6 kb on two exons in the F56.F3 gene and the
tm339 possesses deletion about 1.4 kb corresponding to two of three exons in the T28B8.2 gene. Then, we measured the life span and dauer larva formation of the mutant animals. The
tm339 exhibited a slightly extended life span, while the
tm790 showed a little bit of short life span. Both of the mutant animals formed no dauer larva under a normal growth-condition. However, in the presence of roughly purified diapause-inducing pheromone, the
tm339 and
tm790 formed more and less dauer larva, respectively, than the wild-type animal. Gengyo-Ando, K. and Mitani, S. (2000) BBRC 269: 64-69. Kawano, T., et al. (2000) BBRC 273: 431-436. Kawano, T., el al. (2003) BBB 67: 2678-2682.