THE ORIGIN, DISTRIBUTION AND FATE OF THE MOLTING FLUID PROTEINS OF THE CECROPIA SILKWORM

Area of Science:

• Insect physiology
• Biochemistry
• Developmental biology

Background:

• Molting in insects involves a molting fluid that digests the old cuticle.
• In Hyalophora cecropia, molting fluid is produced during adult development and later absorbed.

Purpose of the Study:

• To analyze the protein composition of Cecropia molting fluid.
• To investigate the origin of molting fluid proteins and their relation to blood proteins.
• To examine macromolecule exchange between molting fluid and blood, and identify molting fluid absorption sites.

Main Methods:

• Disc electrophoresis on acrylamide gels to resolve protein bands.
• Immunological analysis to detect shared antigens.
• Examination of macromolecule permeability and absorption sites.

Main Results:

• Molting fluid contains approximately fifteen protein bands, with some unique to it and others shared with blood.
• The epidermis secretes several antigens found in both molting fluid and blood.
• The epidermis and cuticle prevent significant exchange of macromolecules between blood and molting fluid, maintaining separate compartments.

Conclusions:

• The epidermis plays a key role in secreting proteins into both molting fluid and blood.
• The integument effectively prevents macromolecule exchange, highlighting the compartmentalization of fluids during molting.
• Molting fluid is absorbed through specific regions of the integument, particularly at tonofibril attachment sites.