RESUMO
The bone mineral density (BMD) of astronauts decreases specifically in the weight-bearing sites during spaceflight. It seems that osteoclasts would be affected by a change in gravity; however, the molecular mechanism involved remains unclear. Here, we show that the mineral density of the pharyngeal bone and teeth region of TRAP-GFP/Osterix-DsRed double transgenic medaka fish was decreased and that osteoclasts were activated when the fish were reared for 56 days at the international space station. In addition, electron microscopy observation revealed a low degree of roundness of mitochondria in osteoclasts. In the whole transcriptome analysis, fkbp5 and ddit4 genes were strongly up-regulated in the flight group. The fish were filmed for abnormal behavior; and, interestingly, the medaka tended to become motionless in the late stage of exposure. These results reveal impaired physiological function with a change in mechanical force under microgravity, which impairment was accompanied by osteoclast activation.
Assuntos
Densidade Óssea/fisiologia , Reabsorção Óssea/fisiopatologia , Osteoclastos/fisiologia , Osteogênese/fisiologia , Ausência de Peso , Animais , Animais Geneticamente Modificados , Osso e Ossos/fisiologia , Meio Ambiente Extraterreno , Mitocôndrias/fisiologia , Oryzias , Osteoblastos/fisiologia , Voo Espacial , Astronave , Proteínas de Ligação a Tacrolimo/biossíntese , Proteínas de Ligação a Tacrolimo/genética , Dente/fisiologia , Fatores de Transcrição/biossíntese , Fatores de Transcrição/genética , Regulação para CimaRESUMO
Mitsubishi Heavy Industries (MHI) and Japan Aerospace Exploration Agency (JAXA) have been studying Aquatic Animal Experiment Facility, Aquatic Habitat (AQH), for International Space Station (ISS). The AQH will have the capabilities to accommodate small freshwater fish and amphibian for maximum 90 days on orbit. Three-generations of small freshwater fish (medaka and zebrafish), and egg through metamorphosis of amphibian (African clawed toad) could be experimented by AQH. Various experimental functions such as automatic feeding, air-water interface, day/night cycle, video observation, and specimen sampling mechanism will be also equipped in AQH. The water circulation system was improved from the past aquatic facilities for Space Shuttle experiments under the consideration of the long life-time, and a brand-new specimen chamber was developed to equip the above various experimental functions. Currently the prototype model of water circulation system and specimen chambers have been manufactured and biological compatibility tests are being conducted with medaka. The current developmental status of AQH is summarized.
