OXIDASE ACTIVITY ASSOCIATED WITH THE ELEVATION OF THE PENAEOID SHRIMPHATCHING ENVELOPE

When penaeoid shrimp spawn into seawater, the ova elevate a hatching e nvelope (HE) within 30-50 min. By 60 min after spawning, the bilayered HE is completely formed. In other animal systems, peroxidatic enzymes are responsible for the hardening of the extraembryonic coat. In this study, observations are made consistent with the involvement of an ox idase in the assembly of the shrimp HE. As observed by electron micros copy, eggs of Sicyonia ingentis and Trachypenaeus similis spawned in s eawaters containing peroxidase inhibitors had abnormally assembled HEs compared to control eggs in seawater. Dihydrotetramethylrosamine, an oxidase-sensitive fluorescent dye, supravitally stained the cortex of S. ingentis eggs at the time of initial HE formation. The HE fluoresce d from elevation (40-50 min postspawn in S. ingentis) until 60-70 min postspawn. By first cleavage (90-120 min postspawn), HE staining was n o longer visible, although staining persisted in the egg cortex. In eg gs treated with the peroxidase inhibitors 3-amino-1,2,4-triazole or so dium sulfite, the egg cortex fluoresced, but no fluorescence appeared in the HE before, during, or after its elevation.