ACTIVATION MECHANISMS OF PRO-PHENOLOXIDASE ON MELANOSIS DEVELOPMENT IN FLORIDA SPINY LOBSTER (PANULIRUS-ARGUS) CUTICLE

Phenoloxidase (PO), pro-PO [1] and pro-PO [2], isolated from cuticular extracts of early premolt spiny lobster, resolved into doublets of mo lecular weights 156, 151, and 96.0, 93 kD, respectively. Trypsin-activ ated forms of pro-PO [1] and pro-PO [2] were 123 and 83.6 kD, respecti vely. Apparently melanosis of shell and hyperdermal tissue in lobsters was related to stage of molt. The pro-PO forms were activated in vitr o by extracts of molting fluid which is secreted into the cuticle just before molt, and the activated PO co-migrated in SDS-PAGE with the en dogenously activated PO. The molting fluid was hypothesized to be the source of the natural activator(s) of pro-PO.