Perferential loss of thin filaments during molt-induced atrophy in crab claw muscle

Journal Article · Thu Jan 01 00:00:00 EST 1981 · J. Ultrastruct. Res.; (United States)

DOI:https://doi.org/10.1016/S0022-5320(81)80088-3· OSTI ID:5403322

Mykles, D L ^[1]; Skinner, D M

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1. Univ. of Tennessee, Oak Ridge

The closer muscle of the claw of a land crab Gecarcinus lateralis consists of slow, or tonic, fibers that undergo a sequential atrophy and restoration during each molting cycle. We have examined the ultrastructural organization of claw fibers during the process of protein degradation that takes place in proecdysial muscle atrophy. The myofibrial cross-sectional area is reduced fourfold by dissolution of peripheral myofilaments and by focal erosion within the fibrila. As degradation continues, there is a preferential loss of thin filaments relative to thick filaments: (1) the average distance between thick filaments decreases from 59 to 45 nm, causing a 72% increase in packing density of thick filamets in cross section and (2) the relative numbers of thin and thick filaments decrease from an average ratio of 9:1 to 6:1. Despite these significant structural changes, the general organization of the arcomere is unaltered; the membrane surface density of the sacroplasmic reticulum and the A-band length remain unchanged. Although there is autophagy of some mitochondria, others retain their normal apperance, as do the nuclei. These data suggest that the specific degradation of contractile proteins in proecdysial atrophic muscle includes the differential breakdown of thin vesus thick filaments.

• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5403322
• Journal Information: J. Ultrastruct. Res.; (United States), Vol. 75
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
MUSCLES
ATROPHY
ULTRASTRUCTURAL CHANGES
PROTEINS
BIODEGRADATION
CRABS
FIBERS
MITOCHONDRIA
MOLTING
TRANSMISSION ELECTRON MICROSCOPY
ANIMALS
AQUATIC ORGANISMS
ARTHROPODS
CELL CONSTITUENTS
CHEMICAL REACTIONS
CRUSTACEANS
DECAPODS
DECOMPOSITION
ELECTRON MICROSCOPY
INVERTEBRATES
MICROSCOPY
MORPHOLOGICAL CHANGES
ORGANIC COMPOUNDS
ORGANOIDS
PATHOLOGICAL CHANGES
551000* - Physiological Systems