scholarly journals Myosin Heavy Chains IIa and IId Are Functionally Distinct in the Mouse

1998 ◽  
Vol 141 (4) ◽  
pp. 943-953 ◽  
Author(s):  
Carol A. Sartorius ◽  
Brian D. Lu ◽  
Leslie Acakpo-Satchivi ◽  
Renee P. Jacobsen ◽  
William C. Byrnes ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid Level ◽  
Spinal Curvature ◽  
Developmental Expression ◽  
Cross Sectional ◽  
Fast Myosin ◽  
Fast Myosin Heavy Chain ◽  
Fiber Number ◽  
Murine Skeletal Muscle ◽  
And Function

Myosin in adult murine skeletal muscle is composed primarily of three adult fast myosin heavy chain (MyHC) isoforms. These isoforms, MyHC-IIa, -IId, and -IIb, are >93% identical at the amino acid level and are broadly expressed in numerous muscles, and their genes are tightly linked. Mice with a null mutation in the MyHC-IId gene have phenotypes that include growth inhibition, muscle weakness, histological abnormalities, kyphosis (spinal curvature), and aberrant kinetics of muscle contraction and relaxation. Despite the lack of MyHC-IId, IId null mice have normal amounts of myosin in their muscles because of compensation by the MyHC-IIa gene. In each muscle examined from IId null mice, there was an increase in MyHC-IIa– containing fibers. MyHC-IIb content was unaffected in all muscles except the masseter, where its expression was extinguished in the IId null mice. Cross-sectional fiber areas, total muscle cross-sectional area, and total fiber number were affected in ways particular to each muscle. Developmental expression of adult MyHC genes remained unchanged in IId null mice. Despite this universal compensation of MyHC-IIa expression, IId null mice have severe phenotypes. We conclude that despite the similarity in sequence, MyHC-IIa and -IId have unique roles in the development and function of skeletal muscle.

Absence of a growth hormone effect on rat soleus atrophy during a 4-day spaceflight

1993 ◽  
Vol 74 (2) ◽  
pp. 527-531 ◽  
Author(s):  
B. Jiang ◽  
R. R. Roy ◽  
C. Navarro ◽  
V. R. Edgerton
Keyword(s):  
Growth Hormone ◽  
Succinate Dehydrogenase ◽  
Cross Sections ◽  
Fiber Type ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Fast Myosin ◽  
Hormone Effect ◽  
Fast Myosin Heavy Chain

The objectives of the present study were to determine the size and enzyme properties of soleus fibers of rats subjected to a 4-day spaceflight (National Aeronautics and Space Administration, STS-41) and the effects of exogenous growth hormone (GH) on the atrophic response of the muscle. Four groups of rats were studied: 1) control (Con), 2) Con plus GH treated (Con + GH), 3) flight (Fl), and 4) F1 plus GH treated (Fl + GH). Cross-sectional area and the activities of succinate dehydrogenase and myofibrillar adenosinetriphosphatase (ATPase) were determined in fibers identified in frozen serial cross sections. Fibers were categorized immunohistochemically as slow, fast, or slow-fast on the basis of their reaction with slow and fast myosin heavy-chain (MHC) monoclonal antibodies. Fibers also were categorized as light or dark on the basis of their staining for ATPase at pH 8.6. After the 4-day flight, mean body weight was significantly decreased compared with control. The absolute and relative (muscle wt/body wt) soleus weights were significantly smaller in the Fl and Fl + GH rats compared with their respective ground-based controls. In both flight groups, the cross-sectional area of the light ATPase fibers was significantly smaller (approximately 30%) than control. Three of 11 flight rats had a higher proportion of fibers expressing both slow and fast MHCs than expected on the basis of the fiber type distribution in the 11 control rats. Mean fiber succinate dehydrogenase and ATPase activities were similar among the four groups.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Automatic and unbiased segmentation and quantification of myofibers in skeletal muscle

2021 ◽  
Author(s):  
Ariel Waisman ◽  
Alessandra Norris ◽  
Martín Elías Costa ◽  
Daniel Kopinke
Keyword(s):  
Skeletal Muscle ◽  
Primary Cilia ◽  
Learning Algorithm ◽  
Fixed Tissue ◽  
Deep Learning Algorithm ◽  
Ability To Regenerate ◽  
Murine Skeletal Muscle ◽  
And Function ◽  
Injury Models ◽  
Imagej Plugin

ABSTRACTSkeletal muscle has the remarkable ability to regenerate. However, with age and disease muscle strength and function decline. Myofiber size, which is affected by injury and disease, is a critical measurement to assess muscle health. Here, we test and apply Cellpose, a recently developed deep learning algorithm, to automatically segment myofibers within murine skeletal muscle. We first show that tissue fixation is necessary to preserve cellular structures such as primary cilia, small cellular antennae, and adipocyte lipid droplets. However, fixation generates heterogeneous myofiber labeling, which impedes intensity-based segmentation. We demonstrate that Cellpose efficiently delineates thousands of individual myofibers outlined by a variety of markers, even within fixed tissue with highly uneven myofiber staining. We created a novel ImageJ plugin (LabelsToRois) that allows processing multiple Cellpose segmentation images in batch. The plugin also contains a semi-automatic erosion function to correct for the area bias introduced by the different stainings, identifying myofibers as accurately as human experts. We successfully applied our segmentation pipeline to uncover myofiber size differences between two different muscle injury models, cardiotoxin and glycerol. Thus, Cellpose combined with LabelsToRois allows for fast, unbiased, and reproducible myofiber quantification for a variety of staining and fixation conditions.

scholarly journals De-phosphorylation of MyoD is linking nerve-evoked activity to fast myosin heavy chain expression in rodent adult skeletal muscle

2007 ◽  
Vol 584 (2) ◽  
pp. 637-650 ◽  
Author(s):  
Merete Ekmark ◽  
Zaheer Ahmad Rana ◽  
Greg Stewart ◽  
D. Grahame Hardie ◽  
Kristian Gundersen
Keyword(s):  
Skeletal Muscle ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Adult Skeletal Muscle ◽  
Fast Myosin ◽  
Fast Myosin Heavy Chain ◽  
Evoked Activity

scholarly journals MyoVision: software for automated high-content analysis of skeletal muscle immunohistochemistry

2018 ◽  
Vol 124 (1) ◽  
pp. 40-51 ◽  
Author(s):  
Yuan Wen ◽  
Kevin A. Murach ◽  
Ivan J. Vechetti ◽  
Christopher S. Fry ◽  
Chase Vickery ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Content Analysis ◽  
Cross Sections ◽  
Fiber Type ◽  
Cellular Level ◽  
Image Quantification ◽  
Cross Sectional ◽  
Fiber Number ◽  
Muscle Biology ◽  
High Content Analysis

Analysis of skeletal muscle cross sections is an important experimental technique in muscle biology. Many aspects of immunohistochemistry and fluorescence microscopy can now be automated, but most image quantification techniques still require extensive human input, slowing progress and introducing the possibility of user bias. MyoVision is a new software package that was developed to overcome these limitations. The software improves upon previously reported automatic techniques and analyzes images without requiring significant human input and correction. When compared with data derived by manual quantification, MyoVision achieves an accuracy of ≥94% for basic measurements such as fiber number, fiber type distribution, fiber cross-sectional area, and myonuclear number. Scientists can download the software free from www.MyoVision.org and use it to automate the analysis of their own experimental data. This will improve the efficiency and consistency of the analysis of muscle cross sections and help to reduce the burden of routine image quantification in muscle biology. NEW & NOTEWORTHY Scientists currently analyze images of immunofluorescently labeled skeletal muscle using time-consuming techniques that require sustained human supervision. As well as being inefficient, these techniques can increase variability in studies that quantify morphological adaptations of skeletal muscle at the cellular level. MyoVision is new software that overcomes these limitations by performing high-content analysis of muscle cross sections with minimal manual input. It is open source and freely available.

scholarly journals Effects of aging, exercise, and disease on force transfer in skeletal muscle

2015 ◽  
Vol 309 (1) ◽  
pp. E1-E10 ◽  
Author(s):  
David C. Hughes ◽  
Marita A. Wallace ◽  
Keith Baar
Keyword(s):  
Skeletal Muscle ◽  
Muscle Protein ◽  
Injury Rate ◽  
Cytoskeletal Proteins ◽  
Neural Activation ◽  
Force Transmission ◽  
Cross Sectional ◽  
Force Transfer ◽  
Effects Of Aging ◽  
And Function

The loss of muscle strength and increased injury rate in aging skeletal muscle has previously been attributed to loss of muscle protein (cross-sectional area) and/or decreased neural activation. However, it is becoming clear that force transfer within and between fibers plays a significant role in this process as well. Force transfer involves a secondary matrix of proteins that align and transmit the force produced by the thick and thin filaments along muscle fibers and out to the extracellular matrix. These specialized networks of cytoskeletal proteins aid in passing force through the muscle and also serve to protect individual fibers from injury. This review discusses the cytoskeleton proteins that have been identified as playing a role in muscle force transmission, both longitudinally and laterally, and where possible highlights how disease, aging, and exercise influence the expression and function of these proteins.

Evidence for three adult fast myosin heavy chain isoforms in type II skeletal muscle fibers in pigs.

1998 ◽  
Vol 76 (6) ◽  
pp. 1584 ◽  
Author(s):  
L Lefaucheur ◽  
R K Hoffman ◽  
D E Gerrard ◽  
C S Okamura ◽  
N Rubinstein ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Muscle Fibers ◽  
Myosin Heavy Chain Isoforms ◽  
Type Ii ◽  
Fast Myosin ◽  
Skeletal Muscle Fibers ◽  
Fast Myosin Heavy Chain

Adaptation of fibers in fast-twitch muscles of rats to spaceflight and hindlimb suspension

1992 ◽  
Vol 73 (2) ◽  
pp. S58-S65 ◽  
Author(s):  
B. Jiang ◽  
Y. Ohira ◽  
R. R. Roy ◽  
Q. Nguyen ◽  
E. I. Ilyina-Kakueva ◽  
...  
Keyword(s):  
Cross Sections ◽  
Medial Gastrocnemius ◽  
Hindlimb Suspension ◽  
Cross Sectional ◽  
Heavy Chains ◽  
Fast Myosin ◽  
Glycerophosphate Dehydrogenase ◽  
Close Relationship ◽  
Fast Myosin Heavy Chain ◽  
Fast Twitch

The adaptation of single fibers in medial gastrocnemius (MG), a fast-twitch extensor, and tibialis anterior (TA), a fast-twitch flexor, was studied after 14 days of spaceflight (COSMOS 2044) or hindlimb suspension. Cross-sectional area (CSA) and succinate dehydrogenase (SDH), alpha-glycerophosphate dehydrogenase (GPD), and myofibrillar adenosinetriphosphatase (ATPase) activities were determined in fibers identified in frozen serial cross sections. Fibers were categorized as light, dark, or intermediate on the basis of myosin ATPase staining and alkaline preincubation and immunohistochemically as reacting with slow, fast, or both slow and fast myosin heavy chain monoclonal antibodies. Because there was a close relationship between these two means of categorizing fibers, all fibers were categorized on the basis of the immunohistochemical reaction. The percentage of slow- and fast-twitch fibers of the MG and TA were unchanged in either group. Mean fiber size of all fibers, irrespective of type, was unaffected in either muscle after flight or suspension. The fibers that expressed both fast and slow myosin heavy chains were smaller than control in the MG of both experimental groups. Compared with control, the SDH and total SDH activities in the MG were significantly less in suspended rats, with the fast-twitch fibers showing the largest difference. The ATPase activity in the MG was higher in flight than in control or suspended rats. There were no significant effects of flight on fibers of the TA. In contrast, the TA in suspended rats had higher GPD activities than either control or flight rats.(ABSTRACT TRUNCATED AT 250 WORDS)

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