Concurrent protein synthesis is required for in vivo chitin synthesis in postmolt blue crabs
- Mercer Univ., Macon, GA (USA)
Chitin synthesis in crustaceans involves the deposition of a protein-polysaccharide complex at the apical surface of epithelial cells which secrete the cuticle or exoskeleton. The present study involves an examination of in vivo incorporation of radiolabeled amino acids and amino sugars into the cuticle of postmolt blue crabs, Callinectes sapidus. Rates of incorporation of both 3H leucine and 3H threonine were linear with respect to time of incubation. Incorporation of 3H threonine into the endocuticle was inhibited greater than 90% in the presence of the protein synthesis inhibitor, puromycin. Linear incorporation of 14C glucosamine into the cuticle was also demonstrated; a significant improvement of radiolabeling was achieved by using 14C-N-acetylglucosamine as the labeled precursor. Incorporation of 3H-N-acetylglucosamine into the cuticle of postmolt blue crabs was inhibited 89% by puromycin, indicating that concurrent protein synthesis is required for the deposition of chitin in the blue crab. Autoradiographic analysis of control vs. puromycin-treated crabs indicates that puromycin totally blocks labeling of the new endocuticle with 3H glucosamine. These results are consistent with the notion that crustacean chitin is synthesized as a protein-polysaccharide complex. Analysis of the postmolt and intermolt blue crab cuticle indicates that the exoskeleton contains about 60% protein and 40% chitin. The predominant amino acids are arginine, glutamic acid, alanine, aspartic acid, and threonine.
- OSTI ID:
- 6072523
- Journal Information:
- Journal of Experimental Zoology; (USA), Vol. 256:3; ISSN 0022-104X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHITIN
BIOSYNTHESIS
GLUCOSAMINE
METABOLISM
LEUCINE
THREONINE
AUTORADIOGRAPHY
CARBON 14 COMPOUNDS
CRABS
INHIBITION
PUROMYCIN
TRITIUM COMPOUNDS
AMINES
AMINO ACIDS
ANIMALS
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
ANTINEOPLASTIC DRUGS
AQUATIC ORGANISMS
ARTHROPODS
CARBOHYDRATES
CARBOXYLIC ACIDS
CRUSTACEANS
DECAPODS
DRUGS
HEXOSAMINES
HEXOSES
HYDROGEN COMPOUNDS
HYDROXY ACIDS
INVERTEBRATES
LABELLED COMPOUNDS
MONOSACCHARIDES
MUCOPOLYSACCHARIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
POLYSACCHARIDES
SACCHARIDES
SYNTHESIS
550201* - Biochemistry- Tracer Techniques