Substructures in the core of thick filaments: Arrangement and number in relation to the paramyosin content of insect flight muscles

Asynchronous insect flight muscles produce oscillatory contractions and can contract at high frequency because they are activated by stretch as well as by Ca2+. Stretch activation depends on the high stiffness of the fibres and the regular structure of the filament lattice. Cytoskeletal proteins may be important in stabilising the lattice. Two proteins, zeelin 1 (35 kDa) and zeelin 2 (23 kDa), have been isolated from the cytoskeletal fraction of Lethocerus flight muscle. Both zeelins have multiple isoforms of the same molecular mass and different charge. Zeelin 1 forms micelles and zeelin 2 forms filaments when renatured in low ionic strength solutions. Filaments of zeelin 2 are ribbons 10 nm wide and 3 nm thick. The position of zeelins in fibres from Lethocerus flight and leg muscle was determined by immunofluorescence and immunoelectron microscopy. Zeelin 1 is found in flight and leg fibres and zeelin 2 only in flight fibres. In flight myofibrils, both zeelins are in discrete regions of the A-band in each half sarcomere. Zeelin 1 is across the whole A-band in leg myofibrils. Zeelins are not in the Z-disc, as was thought previously, but migrate to the Z-disc in glycerinated fibres. Zeelins are associated with thick filaments and analysis of oblique sections showed that zeelin 1 is closer to the filament shaft than zeelin 2. The antibody labelling pattern is consistent with zeelin molecules associated with myosin near the end of the rod region. Alternatively, the position of zeelins may be determined by other A-band proteins. There are about 2.0 to 2.5 moles of myosin per mole of each zeelin. The function of these cytoskeletal proteins may be to maintain the ordered structure of the thick filament.

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THE FILAMENT LATTICE OF COCKROACH THORACIC MUSCLE

The Journal of Cell Biology ◽

10.1083/jcb.36.3.433 ◽

1968 ◽

Vol 36 (3) ◽

pp. 433-442 ◽

Cited By ~ 21

Author(s):

Martin Hagopian ◽

David Spiro

Keyword(s):

Fine Structure ◽

Electron Microscope ◽

Flight Muscle ◽

Insect Flight ◽

Thick Filament ◽

Leucophaea Maderae ◽

Thick Filaments ◽

Femoral Muscle ◽

Flight Muscles ◽

Characteristic 3

The fine structure of the tergo-coxal muscle of the cockroach, Leucophaea maderae, has been studied with the electron microscope. This muscle differs from some other types of insect flight muscles inasmuch as the ratio of thin to thick filaments is 4 instead of the characteristic 3. The cockroach flight muscle also differs from the cockroach femoral muscle in thin to thick filament ratios and diameters and in lengths of thick filaments. A comparison of these latter three parameters in a number of vertebrate and invertebrate muscles suggests in general that the diameters and lengths of the thick filaments and thin to thick filament ratios are related.

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In vitro stability and protein composition of thick filaments from insect flight muscles

Cellular and Molecular Life Sciences ◽

10.1007/bf01923609 ◽

1992 ◽

Vol 48 (1) ◽

pp. 60-62 ◽

Cited By ~ 1

Author(s):

C. Ziegler ◽

U. Hinterding ◽

G. Beinbrech

Keyword(s):

Insect Flight ◽

Protein Composition ◽

Thick Filaments ◽

Flight Muscles ◽

In Vitro Stability

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Characterization of components of Z-bands in the fibrillar flight muscle of Drosophila melanogaster.

The Journal of Cell Biology ◽

10.1083/jcb.109.5.2157 ◽

1989 ◽

Vol 109 (5) ◽

pp. 2157-2167 ◽

Cited By ~ 78

Author(s):

J D Saide ◽

S Chin-Bow ◽

J Hogan-Sheldon ◽

L Busquets-Turner ◽

J O Vigoreaux ◽

...

Keyword(s):

Drosophila Melanogaster ◽

Monoclonal Antibodies ◽

Flight Muscle ◽

Cross Reactivity ◽

Antigenic Determinants ◽

Immunogold Staining ◽

Thick Filaments ◽

The Matrix ◽

Flight Muscles

Twelve monoclonal antibodies have been raised against proteins in preparations of Z-disks isolated from Drosophila melanogaster flight muscle. The monoclonal antibodies that recognized Z-band components were identified by immunofluorescence microscopy of flight muscle myofibrils. These antibodies have identified three Z-disk antigens on immunoblots of myofibrillar proteins. Monoclonal antibodies alpha:1-4 recognize a 90-100-kD protein which we identify as alpha-actinin on the basis of cross-reactivity with antibodies raised against honeybee and vertebrate alpha-actinins. Monoclonal antibodies P:1-4 bind to the high molecular mass protein, projectin, a component of connecting filaments that link the ends of thick filaments to the Z-band in insect asynchronous flight muscles. The anti-projectin antibodies also stain synchronous muscle, but, surprisingly, the epitopes here are within the A-bands, not between the A- and Z-bands, as in flight muscle. Monoclonal antibodies Z(210):1-4 recognize a 210-kD protein that has not been previously shown to be a Z-band structural component. A fourth antigen, resolved as a doublet (approximately 400/600 kD) on immunoblots of Drosophila fibrillar proteins, is detected by a cross reacting antibody, Z(400):2, raised against a protein in isolated honeybee Z-disks. On Lowicryl sections of asynchronous flight muscle, indirect immunogold staining has localized alpha-actinin and the 210-kD protein throughout the matrix of the Z-band, projectin between the Z- and A-bands, and the 400/600-kD components at the I-band/Z-band junction. Drosophila alpha-actinin, projectin, and the 400/600-kD components share some antigenic determinants with corresponding honeybee proteins, but no honeybee protein interacts with any of the Z(210) antibodies.

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Calcium-Dependent Myosin from Insect Flight Muscles

The Journal of General Physiology ◽

10.1085/jgp.63.5.553 ◽

1974 ◽

Vol 63 (5) ◽

pp. 553-563 ◽

Cited By ~ 38

Author(s):

William Lehman ◽

Belinda Bullard ◽

Kathleen Hammond

Keyword(s):

Atpase Activity ◽

Insect Flight ◽

Calcium Regulation ◽

Regulatory Proteins ◽

Myosin Molecule ◽

Thin Filaments ◽

Actomyosin Atpase ◽

Calcium Dependent ◽

Regulatory Systems ◽

Flight Muscles

Calcium regulation of the insect actomyosin ATPase is associated with the thin filaments as in vertebrate muscles, and also with the myosin molecule as in mollusks. This dual regulation is demonstrated using combinations of locust thin filaments with rabbit myosin and locust myosin with rabbit actin; in each case the ATPase of the hybrid actomyosin is calcium dependent. The two regulatory systems are synergistic, the calcium dependency of the locust actomyosin ATPase being at least 10 times that of the hybrid actomyosins described above. Likewise Lethocerus myosin also contains regulatory proteins. The ATPase activity of Lethocerus myosin is labile and is stabilized by the presence of rabbit actin. Tropomyosin activates the ATPase of insect actomyosin and the activation occurs irrespective of whether the myosin is calcium dependent or rendered independent of calcium.

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The activities of lipases and carnitine palmitoyl-transferase in muscles from vertebrates and invertebrates

Biochemical Journal ◽

10.1042/bj1300697 ◽

1972 ◽

Vol 130 (3) ◽

pp. 697-705 ◽

Cited By ~ 95

Author(s):

B. Crabtree ◽

E. A. Newsholme

Keyword(s):

Insect Flight ◽

Glycerol Kinase ◽

O2 Uptake ◽

Carnitine Palmitoyl Transferase ◽

Fat Utilization ◽

Metabolic Role ◽

Intact Muscle ◽

Flight Muscles ◽

Hydrolysis Of

1. The activities of tri-, di- and mono-glyceride lipase and carnitine palmitoyltransferase were measured in homogenates of a variety of muscles. These activities were used to estimate the rate of utilization of glycerides and fatty acids by muscle. In muscles whose estimated rates of fat utilization can be compared with rates calculated for the intact muscle from such information as O2 uptake, there is reasonable agreement between the estimated and calculated rates. 2. In all muscles investigated the maximum rates of hydrolysis of glycerides increase in the order triglyceride, diglyceride, monoglyceride. The activity of diglyceride lipase is highest in the flight muscles of insects such as the locust, waterbug and some moths and is lowest in the flight muscles of flies, bees and the wasp. These results are consistent with the utilization of diglyceride as a fuel for some insect flight muscles. 3. In many muscles from both vertebrates and invertebrates the activity of glycerol kinase is similar to that of lipase. It is concluded that in these muscles the metabolic role of glycerol kinase is the removal of glycerol produced during lipolysis. However, in some insect flight muscles the activity of glycerol kinase is much greater than that of lipase, which suggests a different role for glycerol kinase in these muscles.

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ELECTRON MICROSCOPIC STUDIES ON THE INDIRECT FLIGHT MUSCLES OF DROSOPHILA MELANOGASTER

The Journal of Cell Biology ◽

10.1083/jcb.17.2.351 ◽

1963 ◽

Vol 17 (2) ◽

pp. 351-362 ◽

Cited By ~ 58

Author(s):

S. Ahmad Shafiq

Keyword(s):

Drosophila Melanogaster ◽

Epidermal Cells ◽

Uniform Density ◽

Electron Microscopic ◽

Thick Filaments ◽

Irregular Pattern ◽

Regular Arrangement ◽

Microscopic Studies ◽

Hexagonal Arrangement ◽

Flight Muscles

The myofibrils in Drosophila have thick and thin types of myofilaments arranged in the hexagonal pattern described for Calliphora by Huxley and Hanson (15). The thick filaments, along most of their length in the A band, seem to be binary in structure, consisting of a dense cortex and a lighter medulla. In the H zone, however, they show more uniform density; lateral projections (bridges) also appear to be absent in this region. The M band has a varying number of granules (probably of glycogen) distributed between the myofilaments. The myofilaments on reaching the Z region appear to change their hexagonal arrangement and become connected to one another by Z filaments. The regular arrangement of the filaments found in most regions of the fibrils is not seen in the terminal sarcomeres of some flight muscles; the two types of filaments appear to be intermingled in an irregular pattern in these parts of the fibrils. The attachment of myofibrils to the cuticle through the epidermal cells is described.

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Activities of citrate synthase and NAD+-linked and NADP+-linked isocitrate dehydrogenase in muscle from vertebrates and invertebrates

Biochemical Journal ◽

10.1042/bj1540689 ◽

1976 ◽

Vol 154 (3) ◽

pp. 689-700 ◽

Cited By ~ 247

Author(s):

P R. Alp ◽

E A. Newsholme ◽

V A. Zammit

Keyword(s):

Citric Acid ◽

Isocitrate Dehydrogenase ◽

Citric Acid Cycle ◽

Citrate Synthase ◽

Insect Flight ◽

Mechanical Activity ◽

Activity Data ◽

Acid Cycle ◽

Equilibrium Reaction ◽

Flight Muscles

1. The activities of citrate synthase, NAD+-linked and NADP+-linked isocitrate dehydrogenase were measured in muscles from a large number of animals, in order to provide some indication of the importance of the citric acid cycle in these muscles. According to the differences in enzyme activities, the muscles can be divided into three classes. First, in a number of both vertebrate and invertebrate muscles, the activities of all three enzymes are very low. It is suggested that either the muscles use energy at a very low rate or they rely largely on anaerobic glycolysis for higher rates of energy formation. Second, most insect flight muscles contain high activities of citrate synthase and NAD+-linked isocitrate dehydrogenase, but the activities of the NADP+-linked enzyme are very low. The high activities indicate the dependence of insect flight on energy generated via the citric acid cycle. The flight muscles of the beetles investigated contain high activities of both isocitrate dehydrogenases. Third, other muscles of both vertebrates and invertebrates contain high activities of citrate synthase and NADP+-liniked isocitrate dehydrogenase. Many, if not all, of these muscles are capable of sustained periods of mechanical activity (e.g. heart muscle, pectoral muscles of some birds). Consequently, to support this activity fuel must be supplied continually to the muscle via the circulatory system which, in most animals, also transports oxygen so that energy can be generated by complete oxidation of the fuel. It is suggested that the low activities of NAD+-linked isocitrate dehydrogenase in these muscles may be involved in oxidation of isocitrate in the cycle when the muscles are at rest. 2. A comparison of the maximal activities of the enzymes with the maximal flux through the cycle suggests that, in insect flight muscle, NAD+-linked isocitrate dehydrogenase catalyses a non-equilibrium reaction and citrate synthease catalyses a near-equilibrium reaction. In other muscles, the enzyme-activity data suggest that both citrate synthase and the isocitrate dehydrogenase reactions are near-equilibrium.

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