scholarly journals Flight Muscle and Wing Mechanical Properties are Involved in Flightlessness of the Domestic Silkmoth, Bombyx mori

Insects ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 220
Author(s):  
Kunpeng Lu ◽  
Shubo Liang ◽  
Minjin Han ◽  
Chunman Wu ◽  
Jiangbo Song ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bombyx Mori ◽  
Molecular Mechanisms ◽  
Flight Muscle ◽  
Weight Ratio ◽  
Morphological Characteristics ◽  
Wing Loading ◽  
Flexible Wings ◽  
Muscle Weight ◽  
Flight Muscles

Flight loss has occurred in many winged insect taxa. The flightless silkmoth Bombyx mori, is domesticated from the wild silkmoth, Bombyx mandarina, which can fly. In this paper, we studied morphological characteristics attributed to flightlessness in silkmoths. Three domestic flightless B. mori strains and one B. mandarina population were used to compare morphological components of the flight apparatus, including wing characteristics (shape, forewing area, loading, and stiffness), flight muscle (weight, ratio, and microscopic detail) and body mass. Compared with B. mandarina, B. mori strains have a larger body, greater wing loading, more flexible wings and a lower flight muscle ratio. The arrangement in microscopy of dorsal longitudinal flight muscles (DLFMs) of B. mori was irregular. Comparative analysis of the sexes suggests that degeneration of flight muscles and reduction of wing mechanical properties (stiffness) are associated with silkmoth flightlessness. The findings provide important clues for further research of the molecular mechanisms of B. mori flight loss.

Exercise and clenbuterol as strategies to decrease the progression of muscular dystrophy in mdx mice

1996 ◽  
Vol 80 (3) ◽  
pp. 734-741 ◽  
Author(s):  
E. E. Dupont-Versteegden
Keyword(s):  
Body Weight ◽  
Muscular Dystrophy ◽  
Weight Ratio ◽  
Morphological Characteristics ◽  
Mdx Mice ◽  
Body Weight Ratio ◽  
Muscle Weight ◽  
Sedentary Group ◽  
Running Activity ◽  
Tetanic Tension

The effects of exercise and the combination of exercise and clenbuterol on progression of muscular dystrophy were studied in mdx mice. At 3 wk of age, mdx mice were randomly assigned to sedentary (MS), exercise (ME), or combined exercise and clenbuterol (MEC) groups. Clenbuterol was given in the drinking water (1.0-1.5 mg . kg body weight-1 . day-1), and exercise consisted of spontaneous running activity on exercise wheels. At 3 mo or 1 yr of age, ventilatory function, contractile properties, and morphological characteristics of the soleus (Sol) and diaphragm (Dia) muscles were measured. The mdx mice receiving clenbuterol ran less than the mice without clenbuterol. The combination of clenbuterol and exercise was associated with an increase in Sol muscle weight and a muscle weight-to-body weight ratio of 30-35% compared with the sedentary group and approximately 20% compared to exercise alone. Myosin and total protein concentrations of the Sol and Dia increased in the MEC group at 1 yr of age only. Normalized active tension was increased in the Dia at 1 yr of age in both the ME and MEC groups by approximately 30%. Absolute tetanic tension of the Sol was increased at both 3 mo and 1 yr of age in the MEC compared with the MS group. At 1 yr of age, there was an additional 23% increase compared with the ME group. Fatigability increased in the MEC group by approximately 25% in the Sol and Dia muscles at both ages compared with the MS and ME groups. Results indicate that exercise and exercise plus clenbuterol decrease the progression of muscular dystrophy. However, different mechanisms may be involved because the combination of clenbuterol and exercise resulted in increased fatigability and the development of deformities, whereas exercise alone did not. Therefore, clenbuterol may not be suitable for use in patients with muscular dystrophy.

scholarly journals Host plant defense produces species-specific alterations to flight muscle protein structure and flight-related fitness traits of two armyworms

2020 ◽  
Vol 223 (16) ◽  
pp. jeb224907 ◽  
Author(s):  
Scott L. Portman ◽  
Gary W. Felton ◽  
Rupesh R. Kariyat ◽  
James H. Marden
Keyword(s):  
Plant Defense ◽  
Host Plant ◽  
Host Plants ◽  
Molecular Mechanisms ◽  
Flight Muscle ◽  
Troponin T ◽  
Muscle Protein ◽  
Muscle Metabolism ◽  
Spodoptera Eridania ◽  
Flight Muscles

ABSTRACTInsects manifest phenotypic plasticity in their development and behavior in response to plant defenses, via molecular mechanisms that produce tissue-specific changes. Phenotypic changes might vary between species that differ in their preferred hosts and these effects could extend beyond larval stages. To test this, we manipulated the diet of southern armyworm (SAW; Spodoptera eridania) and fall armyworm (FAW; Spodoptera frugiperda) using a tomato mutant for jasmonic acid plant defense pathway (def1), and wild-type plants, and then quantified gene expression of Troponin t (Tnt) and flight muscle metabolism of the adult insects. Differences in Tnt spliceform ratios in insect flight muscles correlate with changes to flight muscle metabolism and flight muscle output. We found that SAW adults reared on induced def1 plants had a higher relative abundance (RA) of the A isoform of Troponin t (Tnt A) in their flight muscles; in contrast, FAW adults reared on induced def1 plants had a lower RA of Tnt A in their flight muscles compared with adults reared on def1 and controls. Although mass-adjusted flight metabolic rate showed no independent host plant effects in either species, higher flight metabolic rates in SAW correlated with increased RA of Tnt A. Flight muscle metabolism also showed an interaction of host plants with Tnt A in both species, suggesting that host plants might be influencing flight muscle metabolic output by altering Tnt. This study illustrates how insects respond to variation in host plant chemical defense by phenotypic modifications to their flight muscle proteins, with possible implications for dispersal.

Structural Limitations on the Power Output of the Pigeon'S Flight Muscles

1966 ◽  
Vol 45 (3) ◽  
pp. 489-498
Author(s):  
C. J. PENNYCUICK ◽  
G. A. PARKER
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Flight Muscle ◽  
Compressive Load ◽  
Bending Moment ◽  
Specific Power ◽  
Wingbeat Frequency ◽  
Flight Muscles ◽  
Centre Of Rotation

1. The tensile strength of the flight-muscle tendons, the distances through which they move and the wingbeat frequency set a maximum of 48 W on the power which could conceivably be transmitted to the pigeon's wings. 2. A minimum of 9·1 W is required to account for observed climbing performance. 3. The safety factor on tension of the muscle insertions cannot exceed 5·2 and is probably substantially less than this. 4. The maximum possible average specific power over one complete cycle is 0·58 W/g.wt. for the pectoralis and 0·28 W/g.wt. for the supracoracoideus. The maximum possible peak specific power during shortening is 0·86 W/g.wt. for both muscles. The minimum average specific power for the flight muscles as a whole is 0·10 W/g.wt. (from rate of climb measurements). 5. These figures do not imply any unusual mechanical properties in the muscles, as compared to other vertebrate muscles. 6. The coracoid can bear a compressive load of over 40 kg. wt., which appears to be about 3·7 times as much as could ever be applied to it in life. 7. The greatest bending moment (about the centre of rotation of the head of the humerus) which the pectoralis could apply to the humerus is 10·2 kg. wt. cm. The supracoracoideus could apply a maximum of 0·88 kg. wt. cm. 8. The tensile strength of supracoracoideus tendon is about 250 kg. wt./cm.2. The compressive strength of coracoid bone is about 1140 kg. wt./cm.2.

scholarly journals Mechanical Properties of Demembranated Flight Muscle Fibres from a Dragonfly

1991 ◽  
Vol 159 (1) ◽  
pp. 135-147
Author(s):  
M. PECKHAM ◽  
D.C. S. WHITE
Keyword(s):  
Mechanical Properties ◽  
Flight Muscle ◽  
Muscle Length ◽  
Psoas Muscle ◽  
Muscle Fibres ◽  
Active Tension ◽  
Rabbit Psoas ◽  
King's College ◽  
Flight Muscles ◽  
Drury Lane

The mechanical properties of demembranated muscle fibres of synchronous flight muscle from a dragonfly Libellula quadrimaculata, asynchronous flight muscle from the giant waterbug Lethocerus indicus and synchronous psoas muscle from rabbit were compared in relaxed, active and rigor conditions. The properties were compared to the known structure and protein compositions of these muscles. We found that active tension of L. indicus flight muscles was stretch-activated (tension was low and was significantly increased following a rapid stretch of 1 % of muscle length), whereas both dragonfly flight muscle and rabbit psoas muscle were not (active tension was high and did not significantly increase following a rapid stretch of 1%). Three different properties have been suggested to give rise to stretch activation in asynchronous muscles: (1) a matching of the helix periodicities of actin target sites to myosin crossbridge heads, (2) a special form of troponin subunit called troponin-H, and (3) the high resting stiffness of these muscles inducing strain in the thick filaments. Rabbit psoas muscle has none of these properties. Dragonfly flight muscles do not have the helix matching, but they do have a form of troponin-H and a high resting stiffness. It seems most likely that dragonfly flight muscles are not stretch-activated because they do not have the helix matching. Note: Present address: Department of Biophysics, King's College London, 26–29 Drury Lane, London, WC2B 5RL, UK.

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

1989 ◽  
Vol 109 (5) ◽  
pp. 2157-2167 ◽  
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.

scholarly journals Fabrication and Characterization of Electrospun Polycaprolactone Blended with Chitosan-Gelatin Complex Nanofibrous Mats

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Yongfang Qian ◽  
Zhen Zhang ◽  
Laijiu Zheng ◽  
Ruoyuan Song ◽  
Yuping Zhao
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Weight Ratio ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Tissue Engineering Scaffolds ◽  
Elongation At Break ◽  
Nanofibrous Scaffolds ◽  
Two Peaks

Design and fabrication of nanofibrous scaffolds should mimic the native extracellular matrix. This study is aimed at investigating electrospinning of polycaprolactone (PCL) blended with chitosan-gelatin complex. The morphologies were observed from scanning electron microscope. As-spun blended mats had thinner fibers than pure PCL. X-ray diffraction was used to analyze the degree of crystallinity. The intensity at two peaks at 2θof 21° and 23.5° gradually decreased with the percentage of chitosan-gelatin complex increasing. Moreover, incorporation of the complex could obviously improve the hydrophilicity of as-spun blended mats. Mechanical properties of as-spun nanofibrous mats were also tested. The elongation at break of fibrous mats increased with the PCL content increasing and the ultimate tensile strength varied with different weight ratios. The as-spun mats had higher tensile strength when the weight ratio of PCL to CS-Gel was 75/25 compared to pure PCL. Both as-spun PCL scaffolds and PCL/CS-Gel scaffolds supported the proliferation of porcine iliac endothelial cells, and PCL/CS-Gel had better cell viability than pure PCL. Therefore, electrospun PCL/Chitosan-gelatin nanofibrous mats with weight ratio of 75/25 have better hydrophilicity mechanical properties, and cell proliferation and thus would be a promising candidate for tissue engineering scaffolds.

Characterization of Hot-Pressed Silicon Nitride Ceramics with Alkoxide-Derived Oxide Mixtures As the Sintering Aid

1992 ◽  
Vol 287 ◽  
Author(s):  
Y. Sato ◽  
C. Sakurai ◽  
M. Ueki ◽  
K. Sugita
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Weight Ratio ◽  
Sintering Aids ◽  
Sintering Aid ◽  
Oxide Powders ◽  
Nitride Ceramics ◽  
Final Weight ◽  
Alkoxide Method

ABSTRACTA homogeneous mixture of Y2O3, CeO2 and MgO with a final weight ratio of 3:1: 2 was prepared by the alkoxide method. The powder mixture was then added into Si3N4 powder in amounts ranging from 4 to 12 wt%, andconsolidated by hot-pressing. Microstructure and mechanical properties of the sintered bodies were determined and compared to those of materials prepared by the conventional route of mixing the oxide powders as sintering aids individually in essentially same composition. The β-fraction (modification ratio) in same composition was higher in thesintered bodies made through the alkoxide method than those made through the conventional one. The room temperature flexural strength was maximized with 6wt% addition of the alkoxide derived oxide, whereas, 12wt% addition of the total oxide was required to maximize the strength by conventional processing.

Muscle regeneration during hindlimb unloading results in a reduction in muscle size after reloading

2001 ◽  
Vol 91 (1) ◽  
pp. 183-190 ◽  
Author(s):  
P. E. Mozdziak ◽  
P. M. Pulvermacher ◽  
E. Schultz
Keyword(s):  
Mitotic Activity ◽  
Satellite Cell ◽  
Soleus Muscle ◽  
Weight Bearing ◽  
Weight Ratio ◽  
The Body ◽  
Hindlimb Unloading ◽  
Muscle Size ◽  
Unit Size ◽  
Muscle Weight

The hindlimb-unloading model was used to study the ability of muscle injured in a weightless environment to recover after reloading. Satellite cell mitotic activity and DNA unit size were determined in injured and intact soleus muscles from hindlimb-unloaded and age-matched weight-bearing rats at the conclusion of 28 days of hindlimb unloading, 2 wk after reloading, and 9 wk after reloading. The body weights of hindlimb-unloaded rats were significantly ( P < 0.05) less than those of weight-bearing rats at the conclusion of hindlimb unloading, but they were the same ( P > 0.05) as those of weight-bearing rats 2 and 9 wk after reloading. The soleus muscle weight, soleus muscle weight-to-body weight ratio, myofiber diameter, number of nuclei per millimeter, and DNA unit size were significantly ( P< 0.05) smaller for the injured soleus muscles from hindlimb-unloaded rats than for the soleus muscles from weight-bearing rats at each recovery time. Satellite cell mitotic activity was significantly ( P < 0.05) higher in the injured soleus muscles from hindlimb-unloaded rats than from weight-bearing rats 2 wk after reloading, but it was the same ( P > 0.05) as in the injured soleus muscles from weight-bearing rats 9 wk after reloading. The injured soleus muscles from hindlimb-unloaded rats failed to achieve weight-bearing muscle size 9 wk after reloading, because incomplete compensation for the decrease in myonuclear accretion and DNA unit size expansion occurred during the unloading period.

scholarly journals The Hippo pathway controls myofibril assembly and muscle fiber growth by regulating sarcomeric gene expression

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Aynur Kaya-Çopur ◽  
Fabio Marchiano ◽  
Marco Y Hein ◽  
Daniel Alpern ◽  
Julie Russeil ◽  
...  
Keyword(s):  
Gene Expression ◽  
Muscle Fiber ◽  
Flight Muscle ◽  
Hippo Pathway ◽  
Muscle Fibers ◽  
Muscle Growth ◽  
Fiber Growth ◽  
Flight Muscles ◽  
Sarcomeric Gene ◽  
The Hippo Pathway

Skeletal muscles are composed of gigantic cells called muscle fibers, packed with force-producing myofibrils. During development the size of individual muscle fibers must dramatically enlarge to match with skeletal growth. How muscle growth is coordinated with growth of the contractile apparatus is not understood. Here, we use the large Drosophila flight muscles to mechanistically decipher how muscle fiber growth is controlled. We find that regulated activity of core members of the Hippo pathway is required to support flight muscle growth. Interestingly, we identify Dlg5 and Slmap as regulators of the STRIPAK phosphatase, which negatively regulates Hippo to enable post-mitotic muscle growth. Mechanistically, we show that the Hippo pathway controls timing and levels of sarcomeric gene expression during development and thus regulates the key components that physically mediate muscle growth. Since Dlg5, STRIPAK and the Hippo pathway are conserved a similar mechanism may contribute to muscle or cardiomyocyte growth in humans.

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