PROGRAMMED CELL-DEATH IN THE TOBACCO HORNWORM, MANDUCA-SEXTA - ALTERATION IN PROTEIN-SYNTHESIS

The metamorphic death of the labial glands of the tobacco hornworm, Ma nduca sexta, occurs during a 4 day period during larva-to-pupa metamor phosis. The earliest changes marking the death of the cell, all occurr ing on the first day, are a sharp drop in protein synthesis, coupled w ith the selective survival or upregulation of a few messages. An early rearrangement of the rough endoplasmic reticulum is presumably relate d to the generalized decrease in protein synthesis. Lysosomal acid pho sphatase also begins to increase very early, and ultimately the bulk o f the cytoplasm is destroyed in autophagic vacuoles, but activation of lysosomes does not account for the decreased rate of synthesis. The m echanism by which most protein synthesis is depressed remains under in vestigation. (C) 1996 Wiley-Liss, Inc.