Programmed cell death in the tobacco hornworm, Manduca sexta: alteration in protein synthesis

Area of Science:

• Developmental biology
• Cell biology
• Insect physiology

Background:

• The labial glands of Manduca sexta undergo programmed cell death during the larva-to-pupa transition.
• Understanding the molecular mechanisms of this metamorphic cell death is crucial for insect development studies.

Purpose of the Study:

• To investigate the early cellular events and molecular changes associated with labial gland cell death during Manduca sexta metamorphosis.
• To elucidate the mechanisms regulating protein synthesis suppression during this developmental process.

Main Methods:

• Analysis of protein synthesis rates.
• Monitoring of specific mRNA levels.
• Examination of cellular structures, including the endoplasmic reticulum.
• Assay of lysosomal enzyme activity (acid phosphatase).

Main Results:

• Metamorphic death of labial glands occurs over a 4-day period.
• Earliest changes include a sharp decrease in protein synthesis and selective mRNA regulation.
• Early rearrangement of the rough endoplasmic reticulum was observed.
• Lysosomal acid phosphatase activity increased, leading to autophagic destruction of cytoplasm.
• Lysosome activation did not fully explain the reduced protein synthesis.

Conclusions:

• Programmed cell death in Manduca sexta labial glands involves early suppression of protein synthesis and lysosomal activation.
• The precise mechanism causing the generalized decrease in protein synthesis remains to be fully elucidated.
• Further research is needed to identify the signaling pathways responsible for inhibiting protein synthesis during metamorphosis.