Mechanisms of regeneration of insect imaginal discs.

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1. Restoration of positional values of Sarcophaga imaginal discs on regeneration in vitro.When the 1/4 sectors of imaginal discs of Sarcophaga expressing wingles (wg) gene are removed and the remeining parts are cultured in the presence of 2.5 x 10^<-8>M 20-hydroxyecdyson, restoration of their morphology occurrs. Here, we isolated a cDNA for the Sarcophaga wg gene, and analyzed whether the lost positional values revealed by wg expression were restored when the remaining parts of imaginal discs were cultured in the presence of 20-hydroxyecdyson. As results, expression of the wg gene was detected in the regenrated areas, indicating that regeneration of imaginal discs in vitro minics in vivo regeneration in that it involves restoration of positional values.2.cDNA cloning and analysis of expression of the gene for lectins that localize in the regenerating legs of American cockroach.Two humoral lectins, termed 26-kDa lectin and regenectin, appear transiently in the regenerating legs of Amer … More ican cockroach. Among them, 26-kDa lectin localizes around epidermis of the regenerating legs in the middle stage of regeneratin, whereas regenectin localizes around regenetating muscle cells in the late stage. In this study, we isoalted cDNAs for these lectins and determined their primary structures. As results, these lectins were found to be C-type (Ca^<2+>-dependent) lectins and shares about 50% sequence identities with eact other. these results suggest that these lectins belong to the same protein family and play different roles in leg regeneration. The gene for regenectin was found to express transiently in the regenerating epidermis, suggesting that it functions in the formation of muscle cells in a paracrine manner by synthesized and secreted by the epidermis.This is the first instance that identified molecules (20-hydroxyecdyson and humoral lectins) that is involved in the regeneration in insects and woud be an important clue to better undrstand the molecular mechanisms of organ regeneration. Less