Change in phenoloxidase and its precursor during silkworm (a80 strain) development

The changes in phenoloxidase and its precursor, so-called prophenoloxidase, of the silkworm, Bombyx mori (a80 strain) were examined using detection assay with or without detergent to distinguish PO and pro-PO in hemolymph (Yamamoto, et al., 1999). Little or no phenoloxidase activity was detected in hemolymph at the silkworm development during the final larval instar and pupal stage. On the other hand, prophenoloxidase was detected for same time frame. In males, after prophenoloxidase increased slightly at day 4, it decreased to a minimum level at spinning and increased to a maximum level on the day of pupation and decreased gradually to day 5 after pupation. In females, prophenoloxidase decreased gradually to a minimum level on day of spinning and a slight increase was observed at day 8 and it increased to maximum level between day 2 and 3 after pupation and decreased thereafter. Prophenoloxidase mRNA expression was preceded a day or two before, when comparing the change of phenoloxidase mRNA with its product.