Scallops Show That Muscle Metabolic Capacities Reflect Locomotor Style and Morphology

Abstract

Although all scallops swim using their adductor muscle to close their valves, scallop species differ considerably in how they use their muscle during escape responses, in parallel with the striking interspecific differences in shell morphology. This provides an excellent opportunity to study links between muscle metabolic capacities and animal performance. We found that the capacity for anaerobic glycolysis and aerobic metabolism, as well as phosphoarginine levels in the phasic adductor muscle, differ with escape response strategy. Phosphoarginine contents were high in species that rely on phasic contractions (Amusium balloti, Placopecten magellanicus, and Pecten fumatus). Arginine kinase activities reflect reliance on rapid initial bursts of phasic contractions. Scallops that maintain their valves in a closed position for prolonged periods (P. fumatus, Mimachlamys asperrima, and Crassadoma gigantea) have high activities of enzymes of anaerobic glycolysis in their phasic adductor muscle. Myosin ATPase activity was lower in the nonswimming scallop, C. gigantea, than in swimming scallops. The different patterns and roles of swimming are reflected in interspecific differences in the biochemical attributes of the phasic adductor muscle. These patterns suggest coevolution of muscle metabolic capacities, patterns of adductor muscle use, and shell morphology in scallops.

In vivo 31P-MRS of muscle bioenergetics in marine invertebrates: Future ocean limits scallops' performance

“…Present resting PLA concentrations match literature data reported for scallops including P. maximus [15,37]. Since the concentrations were determined in relation to assumed ATP concentrations extracted from the literature [37], our data also validate the estimated absolute ATP concentrations (see Materials and methods section, [38]). The quality, e.g.…”

Differences between fast and slow muscles in scallops revealed through proteomics and transcriptomics

“…A previous study indicates that most ATP equivalents are derived from arginine phosphate, in the striated muscle during the snap response, while the energy is mainly supplied from glycolysis, in the catch muscle during valve closure [ 65 ]. Arginine phosphate is the major fuel powering phasic contractions by the striated muscles of scallops, which can generate approximately 70% of the ATP used for phasic contractions [ 66 – 68 ]. As indicated, arginine kinase catalyses the reversible conversion of ADP and arginine phosphate into arginine and ATP, the activities of which reflect reliance on rapid initial bursts of phasic contraction [ 65 , 66 ].…”

“…Arginine phosphate is the major fuel powering phasic contractions by the striated muscles of scallops, which can generate approximately 70% of the ATP used for phasic contractions [ 66 – 68 ]. As indicated, arginine kinase catalyses the reversible conversion of ADP and arginine phosphate into arginine and ATP, the activities of which reflect reliance on rapid initial bursts of phasic contraction [ 65 , 66 ]. In this study, the central role of arginine phosphate in supporting phasic contraction is therefore supported by the transcriptional regulation of arginine kinase in striated muscle.…”

Possible Prediction of Scallop Swimming Styles from Shell and Adductor Muscle Morphology

“…The compromises embodied in the shell shape of P. fumatus extend to its behavior, muscle morphology, and metabolic capacities. Effectively, the intensive burst of phasic contractions by P. fumatus at the start of its escape response (Tremblay et al 2012), the obliqueness of its phasic muscle, and its muscle metabolic capacities (Tremblay & Guderley 2014) can been seen as means of compensating for a shell shape that is unfavorable for swimming but useful for camouflage and feeding.…”

“…by changes in their behavior (Tremblay et al 2012), and that their muscle metabolic capacities follow these changes (Tremblay & Guderley 2014). Although the behavior and the metabolism of an organism are plastic on relatively short time scales, morphological plasticity is manifested at a longer time scale.…”