Mechanism and Function of the Catch State in Molluscan Smooth Muscle: A Historical Perspective

Abstract

Molluscan smooth muscles exhibit the catch state, in which both tension and resistance to stretch are maintained with very low rates of energy consumption. The catch state is studied mainly on the anterior byssus retractor muscle (ABRM) of a bivalve molluscan animal, Mytilus, which can easily be split into small bundles consisting of parallel fibers. The ABRM contracts actively with an increase in the intracellular free Ca ion concentration, [Ca2+]i, as with all other types of muscle. Meanwhile, the catch state is established after the reduction of [Ca2+]i to the resting level. Despite extensive studies, the mechanism underlying the catch state is not yet fully understood. This article briefly deals with (1) anatomical and ultrastructural aspects of the ABRM, (2) mechanical studies on the transition from the active to the catch state in the isotonic condition, (3) electron microscopic and histochemical studies on the intracellular translocation of Ca ions during the transition from the active to the catch state, and (4) biochemical studies on the catch state, with special reference to a high molecular mass protein, twitchin, which is known to occur in molluscan catch muscles.

Stepwise Artificial Yarn Muscles with Energy-Free Catch States Driven by Aluminum-Ion Insertion

“…The mussel can remain in a close and open state with low energy consumption due to the Ca 2+ -regulated bonding between actin filaments and myosin filaments. When the Ca 2+ binds to the myosin neck, the myosin attaches to the actin filament and dephosphorylated twitchin, and a trimeric compound is formed resulting in the catch state …”

“…When the Ca 2+ binds to the myosin neck, the myosin attaches to the actin filament and dephosphorylated twitchin, and a trimeric compound is formed resulting in the catch state. 2 Inspired by the trimeric compounds-enabled catch state, we introduce an intercalation compound formed by AlCl 4 − anions and collapsed CNT yarn to allow stepwise actuation and actuation catch state in an artificial muscle. Figure 1b shows the presently utilized reaction system for actuation, which is an electrochemically reversible insertion and extraction reaction.…”

“…Bivalve mollusks can keep their hard shells tightly closed while consuming very low energy. This muscle behavior is known as the catch state, which is enabled by Ca 2+ -regulated trimeric compounds formed by actin filaments and myosin filaments in the anterior byssus retractor muscle. , Endowing artificial muscles with a catch state is extremely important because it allows the retention of tensioned actuation states without continuous stimulations and energy consumption and programmable stepwise actuation according to control profiles. To date, various artificial muscles that can reversibly contract, bend, expand, or rotate when subjected to external stimuli have been developed. − However, such a catch state featuring energy-free high actuation retention and stepwise actuation has rarely been achieved.…”

Role of the Neuroendocrine System of Marine Bivalves in Their Response to Hypoxia

“…The catch state is established only after the removal of ACh, producing the maximum tension. This indicates that the development of ACh-induced tension to the maximum tension is the necessary prerequisite for the establishment of the catch state [ 148 ]. In bivalve mollusks, catch muscles such as the ABRM show an increased demand for energy during the first hours of recovery after valve closure, which is met by the activation of glycolysis [ 12 , 149 ].…”

Myosin assembly of smooth muscle: from ribbons and side polarity to a row polar helical model

“…11E) because these filaments are not only extremely large (in their length and diameter) but build up with two additional rod-like proteins. The first protein is called "paramyosin" (Sugi et al 2020) and the other one has been named "myorod" (Shelud'ko et al 1999). As it is apparent from the former review, the backbone architecture of these large myosin filaments is still not understood, nevertheless, the supra-coiled-coil assembly of the molluscan myosin on their surfaces appears to be similar to that described in the study by AS in 1973(Sobieszek 1973.…”