Characterisation of proteases involved in egg hatching of the sheep blowfly, Lucilia cuprina

A number of proteases were identified in the egg shell washings (ESW) collected during the egg hatching of Lucilia cuprina (sheep blowfly). Characterization of these proteases indicated a pH optima in a similar pH range that was optimal for L. cuprina egg hatching. Mechanistic characterization of these proteases: indicated that they were predominantly of the serine class. Several protease inhibitors were tested fur their ability to inhibit L. cuprina egg hatching in vitro. Egg hatching was significantly (P < 0.05) inhibited by PMSF (61%), 1,10-Phenanthroline (42%) and Pepstatin (29%). The inhibition of egg hatching by PMSF showed a strong concentration dependence, with its effects ranging from inhibition at high concentrations to enhancement of egg hatching at low concentrations. Addition of ESW to unhatched eggs, significantly (P < 0.05) enhanced their rate of hatching above untreated control eggs. This enhancement of egg hatching was significantly (P < 0.05) reversed by the protease inhibitors Elastatinal (40%), 1,10-Phenanthroline (40%) and PMSF (38%). These studies indicate a role for serine and/or metallo-proteases in facilitating L. cuprina egg hatch. (C) 2000 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.