YOLK PROTEIN-SYNTHESIS IN THE RICELAND TADPOLE SHRIMP, TRIOPS LONGICAUDATUS, MEASURED BY IN-VITRO INCORPORATION OF H-3-LEUCINE

Investigation of reproductive control within the tadpole shrimp, Triop s longicaudatus, required the isolation and characterization of the yo lk protein (vitellin, Vn). To this end, tadpole shrimp were cultured i n environmental chambers (29 degrees C-22 degrees C, with 14:10 light: dark cycle). Desiccated cysts hatched in 2-3 days after inundation. Th e tadpole shrimp began egg deposition 7 to 8 days after hatching and e xhibited a mean growth rate of 1.85 +/- 0.24 mm/day. It was observed t hat 4-day-old shrimp had visible eggs in their ovaries. In addition, V n was isolated and characterized from reproductive animals, resolving as one protein on native PAGE, and possessing a molecular weight (MW) of 376,000 +/- 2,900 as determined by FPLC. Examination by SDS-PAGE re vealed that Vn is composed of a single molecule with a MW of 214,000 /- 2,000. Methyl farnesoate (MF), a crustacean compound whose role in reproduction is still being elucidated and is structurally similar to juvenile hormone III (JH III) was incubated with ovarian explants. The se explants were incubated for 24 h at room temperature in EAGLE's med ium adjusted to Van Harreveld's solution in six concentrations (1 pM t o 100 nM) of MF and JH III. Methyl farnesoate and JH III had no direct in vitro effect on yolk protein synthesis (P less than or equal to 0. 545 and P less than or equal to 0.815, respectively). (C) 1998 Wiley-L iss, Inc.