Effects of the gravity on maintenance of muscle mass in zebrafish (Zebrafish Muscle ) - 07.15.14
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Science Objectives for Everyone
Physical exercise and control of posture are important for maintaining muscle mass and strength. In microgravity conditions, the postural, known as anti-gravity muscles, undergo atrophy because of prominent decrease in their gravity-dependent activity. The main question of the Zebrafish Muscle experiment is whether atrophy of muscles under microgravity also occurs in zebrafish, and why that muscle atrophy occurs in microgravity.
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OpNom Zebrafish Muscle
Space Environment Utilization Center, Human Space Systems and Utilization Mission Directorate, Tsukuba-City, , Japan
Sponsoring Space Agency
Japan Aerospace Exploration Agency (JAXA)
ISS Expedition Duration
March 2014 - March 2015
Previous ISS Missions
- Physical exercise and control of posture are important for maintaining muscle mass and strength. In simulated or actual microgravity, postural or anti-gravity muscles undergo substantial atrophy because of prominent decrease in the gravity-dependent reflection activity. The question is whether atrophy of muscles under the condition of microgravity also occurs in zebrafish and why their atrophy occurs in the microgravity.
- Proposed experiments that examine the gravity-dependence of skeletal muscles in zebrafish using the transgenic fish expressing GFP-labeled muscles and RFP-labeled cells interact with muscles, and revealed that the intensity of RFP is dependent on interaction with myotubes. First, we will investigate the effect of the microgravity on muscle mass and fiber morphology of the transgenic zebrafish. Second, we will trace recovery processes of muscle mass and functions after the exposure of zebrafish in microgravity. We then examine whether growth factors are required for the recovery process. Among growth factors that are known to be involved in the increase of muscle mass, we will focus on growth factors that increase by physical exercise.
- It is hoped that this research enables the determination of the dependence of functional and morphological recovery of muscle, after the exposure in microgravity on the growth factor by the treatment of zebrafish with growth factor inhibitors. This research should clarify whether physical exercise, and anti-gravity reaction, share common growth factor signalings, or not, through these experiments.
Physical exercise and control of posture are important for maintaining muscle mass and strength. In simulated or actual microgravity, postural or anti-gravity muscles undergo substantial atrophy because of prominent decrease in the gravity-dependent reflection activity. The question is whether atrophy of muscles under the condition of microgravity also occurs in zebrafish, and why their atrophy occurs in the microgravity.
Research has recently identified novel tendon-like cells that are located adjacent to skeletal muscle cells in the zebrafish trunk. In this study, the research team proposes experiments that examine the gravity-dependence of skeletal muscles in zebrafish by monitoring a transgenic zebrafish line, in which those tendon-like, and muscle cells, are labeled with red and green fluorescent protein (GFP and RFP), respectively. It is noted that the intensity of GFP is dependent on interaction with myotubes.
The research team will also investigate the effect of the microgravity on muscle mass and fiber morphology, and on morphology and intensity of GFP of the transgenic zebrafish. Second, the team investigates the expression of mRNAs and proteins in skeletal muscle, and tendon-like cells, after the exposure of zebrafish to microgravity. The team then examines which growth factors are involved in the sensitivity to gravity. Among growth factors that are known to be involved in the increase of muscle mass, the research focuses on growth factors that increase by physical exercise. This should help to clarify whether physical exercise and anti-gravity reaction share common growth factor signaling events, or not, through these experiments.
[Hardware]The Aquatic Habitat is installed in the Multi-purpose Small Payload Rack (MSPR) Work Volume, and is utilized for experiments with fish. It is composed of a closed water circulation system with two aquariums. Each aquarium is equipped with LED light and CCD camera, and the aquarium environment is maintained by water flow and temperature control, dissolved gas exchange, and biological filtration. The Aquatic Habitat has on-orbit maintenance capabilities, such as water quality check, and water exchange, to achieve long-term experiments up to 90 days.
Results from the investigation provides insight into the molecular changes that cause muscles to atrophy in microgravity. Understanding the chemical signals, proteins and other cellular activity involved in muscle atrophy could help researchers develop countermeasures to keep astronauts physically strong in space during long-duration missions.
Results from Zebrafish Muscle investigations could identify the molecular changes involved in muscle atrophy, which could lead to new drugs or treatments for weakened muscles. The research could benefit patients on extended bed rest or those with limited mobility.
Eighteen zebrafish are launched, and the 1.5 month experiment is started using the Aquatic Habitat (twelve zebrafish). Fourteen zebrafish will be chemically fixed. Four zebrafish will be returned alive to ground.
Assemble the Aquatic Habitat in the MSPR Work Volume and perform checkout.
Fish transfer to the Aquatic Habitat and experiment start (breed for approximately 1.5 months).
Fish sampled and chemically fixed for return.
Fixed samples should be stowed in refrigerated/freeze conditions.
Fish (live samples) place in containers for return.
Live samples are retrieved at ambient, and fixed samples in refrigerated/frozen conditions.
Disassemble and Stow the Aquatic Habitat.