GROWTH AND CUTICULAR SYNTHESIS IN ASCARIS-SUUM LARVAE DURING DEVELOPMENT FROM 3RD TO 4TH STAGE IN-VITRO

Growth, molting and cuticular protein synthesis were determined during the development of Ascaris suum grown in vitro from the third (L(3)) to the fourth (L(4)) larval stage. The larvae remained highly viable ( 90%) and 70% reached the L(4) by 7 days in culture (DIG). Analysis of growth and development indicated that ecdysis was asynchronous. The sy nthesis of noncuticular and cuticular proteins was monitored using S-3 5-methionine as a metabolic label. Synthesis of noncuticular, cuticula r and collagenous cuticular proteins increased in a constant manner, r eaching maximal values at about 6 DIC. Synthesis of noncollagenous cut icular proteins (cuticlin) remained relatively constant during most of the culture period, but increased from 6 to 7 DIG. The increase in cu ticlin synthesis and the corresponding decrease in cuticular collagen synthesis noted at 7 DIC might represent the synthesis of the outer po rtions of the adult cuticle in preparation for the fourth molt. The re sults of this study suggest that this in vitro development system for A. suum, while not suitable to study events regulating the precise tim ing of molting and cuticular synthesis, might be useful for the analys is of potential growth regulators.