title: Crustaceans as a model for microgravity-induced muscle atrophy.
abstract: Atrophy of skeletal muscles is a serious problem in a microgravity environment.  It is hypothesized that the unloading of postural muscles, which no longer must resist gravity force, causes an accelerated breakdown of contractile proteins, resulting in a reduction in muscle mass and strength.  A crustacean model using the land crab, Gecarcinus lateralis, to assess the effects of spaceflight on protein metabolism is presented.  The model is compared to a developmentally-regulated atrophy in which a premolt reduction in muscle mass allows the withdrawal of the large claws at molt.  The biochemical mechanisms underlying protein breakdown involves both Ca(2+)-dependent and multicatalytic proteolytic enzymes.  Crustacean claw muscle can be used to determine the interactions between shortening and unloading at the molecular level.
authors.affiliation: Department of Biology, Center for Engineering Infrastructure and Sciences in Space, Colorado State University, Fort Collins 80523, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Mykles
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology / Q000648:ultrastructure; D000255:Adenosine Triphosphate / Q000032:analysis / Q000502:physiology; D000818:Animals; D003386:Brachyura / Q000378:metabolism / Q000502:physiology*; D002118:Calcium / Q000502:physiology; D002154:Calpain / Q000032:analysis / Q000502:physiology; D004195:Disease Models, Animal; D018978:Molting / Q000502:physiology*; D009124:Muscle Proteins / Q000032:analysis / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism / Q000503:physiopathology*; D009133:Muscular Atrophy / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D010447:Peptide Hydrolases / Q000502:physiology; D012107:Research Design; D013026:Space Flight; D014452:Ubiquitins / Q000032:analysis / Q000502:physiology; D014893:Weightlessness
chemical_list: D009124:Muscle Proteins; D014452:Ubiquitins; D000255:Adenosine Triphosphate; D010447:Peptide Hydrolases; D002154:Calpain; D002118:Calcium