Introductory Remarks

1980 ◽  
Vol 38 ◽  
pp. 598-599
Author(s):  
H. Mohri
Keyword(s):  
Muscle Contraction ◽  
Experimental Evidence ◽  
Sea Urchin ◽  
Constant Length ◽  
Thin Filaments ◽  
Bridge Formation ◽  
Thick Filaments ◽  
Sliding Mechanism ◽  
Radial Spokes ◽  
Cilia And Flagella

In 1959, Afzelius observed the presence of two rows of arms projecting from each outer doublet microtubule of the so-called 9 + 2 pattern of cilia and flagella, and suggested a possibility that the outer doublet microtubules slide with respect to each other with the aid of these arms during ciliary and flagellar movement. The identification of the arms as an ATPase, dynein, by Gibbons (1963)strengthened this hypothesis, since the ATPase-bearing heads of myosin molecules projecting from the thick filaments pull the thin filaments by cross-bridge formation during muscle contraction. The first experimental evidence for the sliding mechanism in cilia and flagella was obtained by examining the tip patterns of molluscan gill cilia by Satir (1965) who observed constant length of the microtubules during ciliary bending. Further evidence for the sliding-tubule mechanism was given by Summers and Gibbons (1971), using trypsin-treated axonemal fragments of sea urchin spermatozoa. Upon the addition of ATP, the outer doublets telescoped out from these fragments and the total length reached up to seven or more times that of the original fragment. Thus, the arms on a certain doublet microtubule can walk along the adjacent doublet when the doublet microtubules are disconnected by digestion of the interdoublet links which connect them with each other, or the radial spokes which connect them with the central pair-central sheath complex as illustrated in Fig. 1. On the basis of these pioneer works, the sliding-tubule mechanism has been established as one of the basic mechanisms for ciliary and flagellar movement.

scholarly journals Comparative Biomechanics of Thick Filaments and Thin Filaments with Functional Consequences for Muscle Contraction

2010 ◽  
Vol 2010 ◽  
pp. 1-14 ◽  
Author(s):  
Mark S. Miller ◽  
Bertrand C. W. Tanner ◽  
Lori R. Nyland ◽  
Jim O. Vigoreaux
Keyword(s):  
Mechanical Properties ◽  
Muscle Contraction ◽  
Material Properties ◽  
Muscle Function ◽  
Striated Muscle ◽  
Muscle Performance ◽  
Thin Filaments ◽  
Thick Filaments ◽  
Functional Consequences

The scaffold of striated muscle is predominantly comprised of myosin and actin polymers known as thick filaments and thin filaments, respectively. The roles these filaments play in muscle contraction are well known, but the extent to which variations in filament mechanical properties influence muscle function is not fully understood. Here we review information on the material properties of thick filaments, thin filaments, and their primary constituents; we also discuss ways in which mechanical properties of filaments impact muscle performance.

scholarly journals ULTRASTRUCTURAL STUDIES ON THE CONTRACTILE MECHANISM OF SMOOTH MUSCLE

1969 ◽  
Vol 42 (3) ◽  
pp. 683-694 ◽  
Author(s):  
Robert E. Kelly ◽  
Robert V. Rice
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
Striated Muscle ◽  
Smooth Muscle Contraction ◽  
Nuclear Chromatin ◽  
Taenia Coli ◽  
Thin Filaments ◽  
Ultrastructural Studies ◽  
Thick Filaments ◽  
Morphological Differences

Fresh taenia coli and chicken gizzard smooth muscle were studied in the contracted and relaxed states. Thick and thin filaments were observed in certain (but not all) cells fixed in contraction. Relaxed smooth muscle contained only thin filaments. Several other morphological differences were observed between contracted and relaxed smooth muscle. The nuclear chromatin is clumped in contraction and evenly dispersed in the relaxed state. The sarcolemma is more highly vesiculated in contraction than in relaxation. In contraction, the sarcoplasm also appears more electron opaque. Over-all morphological differences between cells fixed in isometric and in unloaded contraction were also noticeable. The results suggest a sliding filament mechanism of smooth muscle contraction; however, in smooth muscle, unlike striated muscle, the thick filaments appear to be in a highly labile condition in the contractile process. The relation between contraction and a possible change in pH is also discussed.

scholarly journals Urinary Titin N-Fragment as a Biomarker of Muscle Atrophy, Intensive Care Unit-Acquired Weakness, and Possible Application for Post-Intensive Care Syndrome

2021 ◽  
Vol 10 (4) ◽  
pp. 614 ◽  
Author(s):  
Nobuto Nakanishi ◽  
Rie Tsutsumi ◽  
Kanako Hara ◽  
Masafumi Matsuo ◽  
Hiroshi Sakaue ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Muscle Atrophy ◽  
Critically Ill Patients ◽  
Chronic Illnesses ◽  
Rehabilitation Management ◽  
Muscle Dystrophy ◽  
Thin Filaments ◽  
Thick Filaments ◽  
Post Intensive Care Syndrome

Titin is a giant protein that functions as a molecular spring in sarcomeres. Titin interconnects the contraction of actin-containing thin filaments and myosin-containing thick filaments. Titin breaks down to form urinary titin N-fragments, which are measurable in urine. Urinary titin N-fragment was originally reported to be a useful biomarker in the diagnosis of muscle dystrophy. Recently, the urinary titin N-fragment has been increasingly gaining attention as a novel biomarker of muscle atrophy and intensive care unit-acquired weakness in critically ill patients, in whom titin loss is a possible pathophysiology. Furthermore, several studies have reported that the urinary titin N-fragment also reflected muscle atrophy and weakness in patients with chronic illnesses. It may be used to predict the risk of post-intensive care syndrome or to monitor patients’ condition after hospital discharge for better nutritional and rehabilitation management. We provide several tips on the use of this promising biomarker in post-intensive care syndrome.

scholarly journals Dimeric heat shock protein 40 binds radial spokes for generating coupled power strokes and recovery strokes of 9 + 2 flagella

2008 ◽  
Vol 180 (2) ◽  
pp. 403-415 ◽  
Author(s):  
Chun Yang ◽  
Heather A. Owen ◽  
Pinfen Yang
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Adenosine Triphosphatase ◽  
Stable Conformation ◽  
Initiation And Propagation ◽  
Evolutionarily Conserved ◽  
Radial Spokes ◽  
Cilia And Flagella ◽  
Hsp 40

T-shape radial spokes regulate flagellar beating. However, the precise function and molecular mechanism of these spokes remain unclear. Interestingly, Chlamydomonas reinhardtii flagella lacking a dimeric heat shock protein (HSP) 40 at the spokehead–spokestalk juncture appear normal in length and composition but twitch actively while cells jiggle without procession, resembling a central pair (CP) mutant. HSP40− cells begin swimming upon electroporation with recombinant HSP40. Surprisingly, the rescue doesn't require the signature DnaJ domain. Furthermore, the His-Pro-Asp tripeptide that is essential for stimulating HSP70 adenosine triphosphatase diverges in candidate orthologues, including human DnaJB13. Video microscopy reveals hesitance in bend initiation and propagation as well as irregular stalling and stroke switching despite fairly normal waveform. The in vivo evidence suggests that the evolutionarily conserved HSP40 specifically transforms multiple spoke proteins into stable conformation capable of mechanically coupling the CP with dynein motors. This enables 9 + 2 cilia and flagella to bend and switch to generate alternate power strokes and recovery strokes.

The Filament Lattice of Striated Muscle

1998 ◽  
Vol 78 (2) ◽  
pp. 359-391 ◽  
Author(s):  
BARRY M. MILLMAN
Keyword(s):  
Muscle Contraction ◽  
Structural Changes ◽  
Striated Muscle ◽  
Muscle Fibers ◽  
Lattice Stability ◽  
X Ray Diffraction ◽  
Thin Filaments ◽  
Intact Muscle ◽  
Radial Forces ◽  
Speed Of Shortening

Millman, Barry M. The Filament Lattice of Striated Muscle. Physiol. Rev. 78: 359–391, 1998. — The filament lattice of striated muscle is an overlapping hexagonal array of thick and thin filaments within which muscle contraction takes place. Its structure can be studied by electron microscopy or X-ray diffraction. With the latter technique, structural changes can be monitored during contraction and other physiological conditions. The lattice of intact muscle fibers can change size through osmotic swelling or shrinking or by changing the sarcomere length of the muscle. Similarly, muscle fibers that have been chemically or mechanically skinned can be compressed with bathing solutions containing very large inert polymeric molecules. The effects of lattice change on muscle contraction in vertebrate skeletal and cardiac muscle and in invertebrate striated muscle are reviewed. The force developed, the speed of shortening, and stiffness are compared with structural changes occurring within the lattice. Radial forces between the filaments in the lattice, which can include electrostatic, Van der Waals, entropic, structural, and cross bridge, are assessed for their contributions to lattice stability and to the contraction process.

scholarly journals Regulation of flagellar motility by the conserved flagellar protein CG34110/Ccdc135/FAP50

2011 ◽  
Vol 22 (7) ◽  
pp. 976-987 ◽  
Author(s):  
Yong Yang ◽  
Deborah A. Cochran ◽  
Mary D. Gargano ◽  
Iryna King ◽  
Nayef K. Samhat ◽  
...  
Keyword(s):  
Flagellar Motility ◽  
Genetic Screens ◽  
Sperm Flagellum ◽  
Respiratory Epithelia ◽  
Downstream Effectors ◽  
Radial Spokes ◽  
Flagellar Proteins ◽  
Flagellar Protein ◽  
Cilia And Flagella ◽  
Lost Boys

Eukaryotic cilia and flagella are vital sensory and motile organelles. The calcium channel PKD2 mediates sensory perception on cilia and flagella, and defects in this can contribute to ciliopathic diseases. Signaling from Pkd2-dependent Ca2+ rise in the cilium to downstream effectors may require intermediary proteins that are largely unknown. To identify these proteins, we carried out genetic screens for mutations affecting Drosophila melanogaster sperm storage, a process mediated by Drosophila Pkd2. Here we show that a new mutation lost boys (lobo) encodes a conserved flagellar protein CG34110, which corresponds to vertebrate Ccdc135 (E = 6e-78) highly expressed in ciliated respiratory epithelia and sperm, and to FAP50 (E = 1e-28) in the Chlamydomonas reinhardtii flagellar proteome. CG34110 localizes along the fly sperm flagellum. FAP50 is tightly associated with the outer doublet microtubules of the axoneme and appears not to be a component of the central pair, radial spokes, dynein arms, or structures defined by the mbo waveform mutants. Phenotypic analyses indicate that both Pkd2 and lobo specifically affect sperm movement into the female storage receptacle. We hypothesize that the CG34110/Ccdc135/FAP50 family of conserved flagellar proteins functions within the axoneme to mediate Pkd2-dependent processes in the sperm flagellum and other motile cilia.

Natural Variability in the Length of Thin and Thick Filaments in Single Fibres From a Crab, Portunus Depurator

1970 ◽  
Vol 6 (2) ◽  
pp. 559-592
Author(s):  
CLARA FRANZINI-ARMSTRONG
Keyword(s):  
Thick Filament ◽  
Natural Variability ◽  
Thin Filaments ◽  
Thick Filaments ◽  
Striation Spacing ◽  
Free Region ◽  
Cross Striation ◽  
Single Fibres ◽  
Length Changes ◽  
Medium Type

The carpopodite flexor of the walking legs of the crab Portunus depurator contains fibres belonging to 3 groups. These are characterized by differences in the cross-striation spacing. Fibres having sarcomeres of approximately 4, 5 and 7 µm are here called short, medium and long sarcomere types, respectively. Within individual fibres belonging to any of the groups the length of the A band is not constant. Up to 25 % length differences have been measured in A bands belonging even to the same fibril. The bridge-free regions of the thick filaments are not always in the centre, so that the filaments are often asymmetric. Analogally, the L line, resulting from the alignment of the bridge-free regions of the thick filaments, may be asymmetrically placed in the Z band. The length of the bridge-free region in crab thick filaments is 60 nm, while the corresponding region in vertebrate thick filaments is 120 nm. This is discussed in terms of a possible model of the filament. The length of the thin filaments is proportional to that of the thick filaments in the corresponding portion of the sarcomere. When two A bands of different length occur in adjacent positions along the fibril, the Z line is not a centre of symmetry. The ratio of thin to thick filament number is variable in individual fibrils. In general, the ratio is higher in the medium sarcomere type fibres than in the short sarcomere type. Stretched and shorter portions of single fibres of the medium type have been examined and the A-band length populations compared. From such a study it can be deduced that passive length changes occur in crab fibres by sliding of thin and thick filaments.

scholarly journals LOCALIZATION OF MYOSIN FILAMENTS IN SMOOTH MUSCLE

1968 ◽  
Vol 37 (1) ◽  
pp. 105-116 ◽  
Author(s):  
Robert E. Kelly ◽  
Robert V. Rice
Keyword(s):  
Smooth Muscle ◽  
Cross Section ◽  
Striated Muscle ◽  
Thick Filament ◽  
Longitudinal Axis ◽  
Thin Filaments ◽  
Chicken Gizzard ◽  
Thick Filaments ◽  
Myosin Filaments ◽  
Muscle Myosin

Thick myosin filaments, in addition to actin filaments, were found in sections of glycerinated chicken gizzard smooth muscle when fixed at a pH below 6.6. The thick filaments were often grouped into bundles and run in the longitudinal axis of the smooth muscle cell. Each thick filament was surrounded by a number of thin filaments, giving the filament arrangement a rosette appearance in cross-section. The exact ratio of thick filaments to thin filaments could not be determined since most arrays were not so regular as those commonly found in striated muscle. Some rosettes had seven or eight thin filaments surrounding a single thick filament. Homogenates of smooth muscle of chicken gizzard also showed both thick and thin filaments when the isolation was carried out at a pH below 6.6, but only thin filaments were found at pH 7.4. No Z or M lines were observed in chicken gizzard muscle containing both thick and thin filaments. The lack of these organizing structures may allow smooth muscle myosin to disaggregate readily at pH 7.4.

scholarly journals Changes in thick filament length in Limulus striated muscle.

1977 ◽  
Vol 75 (2) ◽  
pp. 366-380 ◽  
Author(s):  
M M Dewey ◽  
B Walcott ◽  
D E Colflesh ◽  
H Terry ◽  
R J Levine
Keyword(s):  
Horseshoe Crab ◽  
Striated Muscle ◽  
Thick Filament ◽  
Filament Length ◽  
Thin Filaments ◽  
Thick Filaments ◽  
Wide Range ◽  
The Difference

Here we describe the change in thick filament length in striated muscle of Limulus, the horseshoe crab. Long thick filaments (4.0 microns) are isolated from living, unstimulated Limulus striated muscle while those isolated from either electrically or K+-stimulated fibers are significantly shorter (3.1 microns) (P less than 0.001). Filaments isolated from muscle glycerinated at long sarcomere lengths are long (4.4 microns) while those isolated from muscle glycerinated at short sarcomere lengths are short (2.9 microns) and the difference is significant (P less than 0.001). Thin filaments are 2.4 microns in length. The shortening of thick filaments is related to the wide range of sarcomere lengths exhibited by Limulus telson striated muscle.

scholarly journals PROPERTIES OF FLAGELLAR "RIGOR WAVES" FORMED BY ABRUPT REMOVAL OF ADENOSINE TRIPHOSPHATE FROM ACTIVELY SWIMMING SEA URCHIN SPERM

1974 ◽  
Vol 63 (3) ◽  
pp. 970-985 ◽  
Author(s):  
Barbara H. Gibbons ◽  
I. R. Gibbons
Keyword(s):  
Sea Urchin ◽  
Sperm Suspension ◽  
Complete Relaxation ◽  
Viscous Shear ◽  
Radial Spokes ◽  
Wave Forms ◽  
Cross Bridges ◽  
Triton X ◽  
The Waves ◽  
Sea Urchin Sperm

Sea urchin sperm were demembranated and reactivated with a solution containing 0.04% Triton X-100 and 0.03 mM ATP. The ATP concentration was then lowered abruptly by diluting the sperm suspension 50-fold into reactivating solution containing no ATP. The flagella of the sperm in the diluted suspension were not motile, but they were bent into a variety of stationary rigor wave forms closely resembling the wave forms occurring at different stages of the flagellar bending cycle during normal movement. The form of these rigor waves was unchanged upon storage for several hours in the presence of dithiothreitol and EDTA. Addition of 1 µM ATP induced slow relaxation of the waves, with most of the sperm becoming partially straightened over a period of about 30 min; somewhat higher concentrations gave a more rapid and complete relaxation. Concentrations of ATP above 10 µM induced resumption of normal beating movements. Addition of ITP, GTP, or GDP (up to 1 mM) produced no relaxation of the rigor waves. Digestion with trypsin to an extent sufficient to disrupt the radial spokes and the nexin links caused no change in the rigor wave forms, suggesting that these wave forms could be maintained by the dynein cross-bridges between the outer doublet tubules of the flagellar axoneme. Study of the effects of viscous shear on the rigor wave axonemes has shown that they are resistant to distortion by bending, although they can be twisted relatively easily.

Sign in / Sign up

Export Citation Format

Share Document