Related Experiment Video
Updated: May 3, 2026
10:53
Author Spotlight: Mitochondrial Remodeling in Skeletal Muscle
Published on: December 1, 2023
4.2K
Mitochondrial Activity Localization in the Skeletal Muscle and Its Individual Fibers Across Tetrapods
Unmod Senapati1, Subhasmita Rout1, Sunil Pani1
1School of Biotechnology, KIIT University, Bhubaneswar, Odisha, India.
Biology of the Cell
|May 2, 2026
Summary
Mitochondrial activity in skeletal muscle varies across tetrapod species, showing unique patterns related to fiber type and evolutionary adaptations. This research maps mitochondrial distribution to understand muscle functional heterogeneity.
Area of Science:
- Muscle physiology
- Mitochondrial biology
- Comparative anatomy
Background:
- Mitochondria are crucial for muscle energy production and are spatially organized to meet ATP demands.
- Mitochondrial distribution varies within muscle fibers and across different muscle types.
- Succinate dehydrogenase (SDH) activity is a key indicator of mitochondrial capacity and can be localized within muscle fibers.
Purpose of the Study:
- To investigate the distribution of mitochondrial activity within individual muscle fibers and their composition within fascicles across diverse tetrapod taxa.
- To compare mitochondrial distribution patterns in pectoralis and gastrocnemius muscles between amphibians, reptiles, birds, and mammals.
- To explore potential evolutionary implications of observed mitochondrial distribution patterns.
Main Methods:
- Analysis of pectoralis and gastrocnemius muscles from various tetrapod species including amphibians, reptiles, birds, and mammals.
- Histochemical staining to assess succinate dehydrogenase (SDH) activity, categorizing fibers into SDHHigh, SDHInt, and SDHLow.
- Microscopic examination to determine fiber composition and mitochondrial activity distribution at the single-fiber and fascicular levels.
Main Results:
- Significant variations in mitochondrial activity distribution were observed across tetrapod muscles.
- Amphibian and reptile muscles predominantly featured fibers with intermediate SDH activity (SDHInt).
- Birds and mammals exhibited fibers with negligible SDH activity (SDHLow), potentially indicating recent evolutionary development.
- Avian pectoralis muscles displayed a unique fiber composition compared to the mosaic pattern seen in mammals.
- Mammalian muscle fiber composition correlated with locomotion strategies: slow-grazers had more SDHHigh/SDHInt fibers, while sprint-runners had more SDHLow fibers.
Conclusions:
- Localized mitochondrial enrichment is an adaptive strategy contributing to muscle group heterogeneity across tetrapods.
- The presence of SDHLow fibers in birds and mammals suggests an evolutionary trend in muscle specialization.
- Comparative analysis of mitochondrial distribution provides insights into the functional adaptations of skeletal muscle in different vertebrate lineages.
More Related Videos
Related Concept Videos
01:48Classification of Skeletal Muscle Fibers
48.5K
Skeletal muscles continuously produce ATP to provide the energy that enables muscle contractions. Skeletal muscle fibers can be categorized into three types based on differences in their contraction speed and how they produce ATP, as well as physical differences related to these factors. Most human muscles contain all three muscle fiber types, albeit in varying proportions.
Slow-Twitch Muscle Fibers
Slow oxidative, muscle fibers appear red due to large numbers of capillaries and high levels of...
Slow-Twitch Muscle Fibers
Slow oxidative, muscle fibers appear red due to large numbers of capillaries and high levels of...
48.5K
01:13Microscopic Anatomy of Skeletal Muscles
22.5K
Skeletal muscle cells, also called muscle fibers, are distinctly elongated, multi-nucleated, slender biological units. They are packed with specialized structures designed to facilitate their primary function, which is contraction.
The muscle sarcolemma is a plasma membrane enclosing each muscle cell that conducts electrical signals called action potentials. The sarcolemma extends into the cell to form T-tubules, ensuring the neural impulses are uniformly distributed across the entire muscle...
The muscle sarcolemma is a plasma membrane enclosing each muscle cell that conducts electrical signals called action potentials. The sarcolemma extends into the cell to form T-tubules, ensuring the neural impulses are uniformly distributed across the entire muscle...
22.5K
01:16Actin and Myosin in Muscle Contraction
26.6K
Actin and myosin are contractile proteins that form the sarcomere found in skeletal muscle tissues for regulating muscle contraction. Actin, a globular contractile protein, interacts with myosin for muscle contraction. The skeletal tissue appears striped or striated under a microscope due to the repeated arrangement of contractile proteins actin and myosin along the length of myofibrils. Dark A bands and light I bands repeat along myofibrils, and the alignment of myofibrils in the cell causes...
26.6K
01:15Overview of Skeletal Muscle
12.7K
Skeletal muscles are composed of a bundle of muscle fibers and are attached to bones through tendons. Each skeletal muscle fiber is a single muscle cell. The sarcolemma, the plasma membrane of a skeletal muscle cell, consists of a lipid bilayer and glycocalyx that supports muscle fibers. The sarcolemma extends into the muscle cells to form tubular structures called transverse or T-tubules. Each side of the T-tubules consists of a membrane-bound structure called the sarcoplasmic reticulum,...
12.7K
01:13Formation of Muscle Fibers from Myoblasts
5.8K
De novo myogenesis, or the formation of muscle fibers, begins during the early embryonic stages. The skeletal muscle is formed from somites– blocks of embryonic cell layers. The somites are further divided into dermatomes, myotomes, sclerotomes, and syndetomes. Among these, the myotomes give rise to muscle fibers.
Muscle progenitor cells (MPCs) are formed from the myotomes. MPCs express genes that encode the transcription factors Pax3 and Pax7. Along with Pax 3/7, other transcription...
Muscle progenitor cells (MPCs) are formed from the myotomes. MPCs express genes that encode the transcription factors Pax3 and Pax7. Along with Pax 3/7, other transcription...
5.8K