Tag: spaceflight

Categories : GeneticsTags :

Muscle Atrophy Gene Identified from Mice Sent into Space

On By ModernMedia
Dragon cargo capsule arriving at the International Space Station. Image by SpaceX-Imagery from Pixabay

Researchers from the University of Tsukuba have found a new gene involved in muscle atrophy when they sent mice into space to explore effects of weightlessness on skeletal muscles.

Extended periods of skeletal muscle inactivity or mechanical unloading (bed rest, immobilisation, spaceflight and reduced step) can result in a significant loss of muscle mass and strength which ultimately lead to muscle atrophy. Spaceflight is one of the leading models of understanding muscle atrophy from disuse.

As the molecular and cellular mechanisms involved in disuse skeletal muscle atrophy have been studied, several different signaling pathways have been studied to understand their regulatory role in this process. However, large gaps exist in the understanding of the regulatory mechanisms involved, as well as their functional significance.

Prior studies examining the effects of reduced gravity on muscle mass and function have used a ground control group which cannot be directly compared to the space experimental group. Researchers from the University of Tsukuba set out to explore the effects of gravity in mice subjected to the same housing conditions, such as the stresses of launch, landing and cosmic radiation. “In humans, spaceflight causes muscle atrophy and can lead to serious medical problems after return to Earth” says senior author Professor Satoru Takahashi. “This study was designed based on the critical need to understand the molecular mechanisms through which muscle atrophy occurs in conditions of microgravity and artificial gravity.”

Two groups of six mice each were housed onboard the International Space Station for 35 days. One group was subjected to artificial gravity (1g) and the other was left in microgravity. All mice were returned to Earth aboard a Dragon capsule and the team compared the effects of the different onboard environments on skeletal muscles. “To understand what was happening inside the muscles and cells, at the molecular level, we examined the muscle fibers. Our results show that artificial gravity prevents the changes observed in mice subjected to microgravity, including muscle atrophy and changes in gene expression,” explained Prof Takahashi. 

Transcriptional analysis of gene expression showed that the artificial gravity environment prevented altered expression of atrophy-related genes, and also identified other genes possibly associated with atrophy. Specifically, a gene called Cacng1 was identified as possibly having a functional role in myotube atrophy, which previously had no known function, and was shown to have increased activity when muscle atrophy was present.

When muscle fibres were cultured in vitro, ones which had Cacng1 expression upregulated were decreased in diameter by 27.5%. A similar effect was seen in newborn mice with upregulated Cacng1.

This work validated the use of 1g artificial gravity environments in spaceflight for examining the effects of microgravity in muscles. These studies add to the body of knowledge surrounding the mechanisms of muscle atrophy, possibly improving the treatment of related diseases.

Source: Tsukuba University

Journal information: Okada, R., et al. (2021) Transcriptome analysis of gravitational effects on mouse skeletal muscles under microgravity and artificial 1 g onboard environment. Scientific Reports. doi.org/10.1038/s41598-021-88392-4.

Categories : COVID Immune SystemTags :

COVID Tracking in Space Company Employees Yields Antibody Clues

On By ModernMedia

SpaceX, an aerospace manufacturing company currently providing satellite launch services as well as transport of crew  to the International Space Station, collaborated with researchers from MIT to monitor the spread of COVID amongst its employees. 

Unusually, the paper included SpaceX CEO Elon Musk as a byline author. The technology entrepreneur is known to be quite hands-on in his company’s projects. However, he has also courted controversy by openly questioning COVID tests and saying he and his family would not take COVID vaccines, saying that achieving herd immunity naturally was a better strategy.

SpaceX was seeking data-driven methods to safeguard its essential workforce. The collaboration allowed the researchers to track the emergence of mild and asymptomatic cases in a cohort of adults as early as April, when data for such cases were rare.

“Essentially, this study indicates that it’s not simply the presence or absence of antibodies that matter; rather, the amount and type of antibodies may play a defining role in the development of a protective immune response,” said Professor Galit Alter, Harvard Medical School and Immunologist, Division of Infectious Diseases, Massachusetts General Hospital. 

The study was originally aimed at measuring antibody levels over time, but when reinfections began to be reported, the team realised their samples had some valuable information.

“In early spring, we weren’t sure if asymptomatic infection could drive long-lived antibodies,” said Prof Alter, “nor whether they possessed the capability to neutralise or kill the virus.”

The researchers knew that 120 participants had mild or asymptomatic COVID infections, resulting in their bodies producing antibodies. Using sophisticated techniques to analyse those antibodies, they found that individuals with stronger symptoms in mild COVID, had a larger number of antibodies and developed immune functions associated with natural immune protection. 

The study found that although the presence of antibodies was sufficient to determine whether an individual had experienced a COVID infection, they did not automatically mean that individual is protected against the virus in the long term.

Antibody effector functions (on the ‘long arm’ of the antibody) linked to long-term protection, such as T cell activation and virus neutralisation were only seen in certain immune responses. These involved high levels of antibodies targetting a part of the virus known as the receptor binding domain.

“Once you hit a certain threshold of these antibodies, it’s like a switch turns on and we can observe antibody effector functions,” said first author Yannic Bartsch, PhD. “These functions were not observed in individuals with lower antibody binding titers, and the level of protection from reinfections is uncertain in these individuals.”

Source: News-Medical.Net

Journal information: Bartsch, Y. C., et al. (2021) Discrete SARS-CoV-2 antibody titers track with functional humoral stability. Nature Communications. doi.org/10.1038/s41467-021-21336-8.