Expression of prophenoloxidase mRNA during silkworm hemocyte development

Two clones encoding different prophenoloxidase isoforms were amplified by p olymerase chain reaction of RNA from the hemocytes of an experimental strai n of Bombyx mori. The nucleotide sequences of the clones and the deduced am ino acid sequences were confirmed to be nearly identical to those of the or thologous clones previously obtained from a commercial race of B. mori. Nor thern blot hybridization using these clones as probes demonstrated that the prophenoloxidase mRNA in the hemocytes is expressed in a stage-specific ma nner during the final larval instar and pupal stage, showing a peak one day before pupation in males and on the day of pupation in females. A sexual d ifference was also observed when the content of prophenoloxidase protein in the hemolymph (including hemocytes) was measured by an enzyme-linked immun osorbent assay.