In vitro uptake and incorporation of [3H]glucosamine and [3H]leucine by Plagiorchis elegans metacercariae.

We examined the ability of Plagiorchis elegans metacercariae to take up [3H]glucosamine and [3H]leucine in vitro and incorporate these precursors into parasite tissues at various times in their development. Uptake of both precursors was greater by young metacercariae (< or = 8 hr postinfection [PI]) than old metacercariae (> 8 hr PI). Virtually all [3H]glucosamine was incorporated into juvenile worms, whereas only small amounts of [3H]leucine were incorporated into both juvenile worms and cyst walls. [3H]glucosamine was incorporated into a variety of proteins by 2-hr- and 5-day-old metacercariae as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis and fluorography. There was evidence of developmentally regulated or stage-specific expression of 14-, 19.5-, and 37-kDa proteins by older metacercariae. These results suggest a differential incorporation of nutrients procured from the insect host into parasite tissues by metacercariae of different ages over the course of their development.