Muscle Restructuring in Crustaceans: Myofiber Death, Transfiguration and Rebirth

Research on the dimorphic claws of the snapping shrimp Alpheushas revealed moult-associated changes in structure and biochemicalcomposition—including atrophy and biochemical modification—ofclaw muscle fibers during morphological transformation of aclaw from a pincer to a snapper. Electrophysiology, SDS-PAGEgel electrophoresis, and immunocytochemistry were used to analyzechanges in claw closer muscle function and composition duringthe transformation process. Remodification of closer muscleduring claw transformation, involving the complete loss of acentral section of fast-contracting fibers and their replacementthrough enlargement of existing slowly-contracting segmentsof the muscle, may mimic similar muscle modifications duringinitial claw development. Exposure of intact animals to environmentalecdysteroid hormones accelerated the rate of these changes.These processes appear to be a product of a remarkable trophicplasticity of crustacean skeletal muscle first discovered bySkinner.