[JPG-RR/MHU-8]
Effects of Partial Gravity on Mammals and their Next Generations (Joint Partial-gravity Rodent Research (JPG-RR)/Mouse Habitat Unit-8 - Takahashi)

RESEARCH OVERVIEW

• Transcriptome analysis and germ-cell development analysis of mice in the space (Mouse Epigenetics) investigation looks at the long-term effects of the space environment on gene expression patterns, and on epigenetic changes of DNA in different organs.
• The impact of the space environment on mammalian germ cells is to be clarified by the production of offspring using the sperm cells exposed to the space environment. The Effects of Partial Gravity on Mammals and their Next Generations investigations studies these offspring in depth.

DESCRIPTION

The NASA-JAXA Joint Partial-gravity Rodent Research (JPG-RR) Mouse Habitat Unit-8 (MHU-8) mission is an investigation into mammalian responses to 30 days of partial gravity similar to what would be experienced on the Moon or Mars using a small centrifuge on the International Space Station (ISS). The JAXA Multiple Artificial-gravity Research System (MARS) facility induces gravity levels (0 g, 0.33 g, 0.67 g, and 1 g) and responses across multiple biological systems in mice, including musculoskeletal and neuromotor performance, circadian rhythm, reproduction, gastrointestinal microbiome, and metabolism. JPG-RR MHU-8 is a collaboration between Japan Aerospace Exploration Agency (JAXA), NASA’s Human Research Program, and NASA’s Space Biology Program under Japan-U.S. Open Platform Partnership Program (JP-US OP3).

This investigation, Effects of Partial Gravity on Mammals and their Next Generations, examines if partial gravity induced by centrifugation affects epigenomic changes in DNA during spaceflight. The following hypotheses and specific aims are addressed:

• Hypothesis: Partial gravity alters the transcriptomics, proteomics, and epigenomics in mammalian tissues in a dose-dependent manner.
• Specific Aim: To identify the effects of partial gravity in the space environment on epigenomic changes in DNA. Transcriptomic, proteomic, and epigenomic analyses are utilized for a systems biology comparison of data from prior JAXA Flight missions (MHU-1, 4, and 5).

SPACE APPLICATIONS

The investigation examines the long-term effects of space travel at a molecular level, including changes to gene expression and changes in DNA that may be inherited (epigenetic modification). Results could support development of countermeasures to help protect crew members on future missions, and their offspring.

EARTH APPLICATIONS

By providing insight into the long-term effects of spaceflight on genetic activity, this investigation could improve understanding of how environmental conditions on Earth may cause changes in gene expression and changes in DNA that can be passed on to future generations.

OPERATIONAL REQUIREMENTS AND PROTOCOLS

Twenty-four (24) mice (male, C57BL/6J, 12 ± 1 weeks old), are launched in JAXA Transportation Cage Units (TCU). Each TCU individually houses 12 mice for vehicle ascent and descent. Once aboard the space station the mice are transferred into Habitat Cage Units (HCU) and maintained for ~30 days. The mice are individually housed and exposed to one of four gravity conditions (n = 6) for the duration of the investigation: 0 G as the in-flight control, 0.33 G, 0.67 G, and 1 G. All mice are returned to Earth alive for Live Animal Return (LAR) and post-flight processing.

TAKAHASHI Satoru [University of Tsukuba]

• Dose-Response Study of Musculoskeletal Outcomes Following Centrifugation in Adult Mice on ISS (Joint Partial-gravity Rodent Research (JPG-RR)/Mouse Habitat Unit 8 - Bouxsein)
• Adaptation of Mouse Systems Physiology to Artificial Gravity via Centripetal Acceleration: Timing, Metabolism & Aging (Joint Partial-gravity Rodent Research (JPG-RR)/Mouse Habitat Unit-8 - Fuller)
• Effects of Partial Gravity on Multi-system Mammalian Physiology: Microbiome and Related Systems (Joint Partial-gravity Rodent Research (JPG-RR)/Mouse Habitat Unit-8 - Vitaterna)