太空环境对哺乳动物植入前胚胎发育影响的分子机制研究

Abstract: Space environment is very unlike earth, which includes microgravity and cosmic rays. Does gravity affected the mammalian reproductive system and the normal embryonic development? Although attempts have been made in the past few decades to develop mammalian early embryos in space, none have been successful. Thus, the potential effects of weightlessness on the mammalian development are still unclear. In 2016, China launched the country’s first microgravity satellite, SJ-10, on April 6. High-resolution photographs of early embryo development were obtained from SJ-10. The results crucial from experiments aboard China's SJ-10 recoverable satellite prove for the first time that early-stage mammal embryos can develop in space. However, the morphological features and the development rate of embryos from the returned samples in fixing culture units need further investigation. In addition, the potential mechanism that affect the development of mammal preimplantation embryos in space should be further research. In this study, we will detect the developmental status of mouse early embryos in space, we also use immunostaining and single cell DNA sequence methods to analyze those embryos’ quality. This study will be critical in understanding the beginning of mammalian life in space, as well as the first step in understanding the entire process of preimplantation development in space. This will become increasingly important as humans look to carry out long-duration spaceflights and colonise other planets.

摘要：空间环境作为一种完全区别于地球的特殊环境，包含了微重力和太空高能粒子辐射。微重力效应是否影响哺乳动物生殖和胚胎发育还不清楚。尽管在过去的几十年里，人类尝试开展了几次空间哺乳动物早期胚胎方面的研究，但都以失败告终。2016年4月6日，中国发射了SJ-10返回式科学卫星。我们从SJ-10卫星上获得了高清晰的小鼠早期胚胎在太空发育过程的图片，此外， 卫星返回后还回收到了空间发育的小鼠胚胎，这项研究首次证明了哺乳动物早期胚胎能够在太空发育。然而，我们还需要对返回后的胚胎进行形态和质量的进一步分析并且就微重力影响胚胎发育的分子机理还需要进一步的探讨。本研究将对回收的胚胎进行详细的分析，通过免疫荧光和基因测序等手段对发育后的胚胎的质量和状态进行全面的检测。总之，本项目的研究为人类认识哺乳动物在太空中生命的起过程走出了重要一步，也为人类今后开展哺乳动物早期胚胎的太空发育研究奠定了理论和实验基础。

哺乳动物能否在太空完成生命孕育和后代繁衍成为科学界及公众关注的问题。前期的研究提示, 太空飞行会对哺乳动物胚胎发育造成某些潜在的危害,造成这些危害的因素与宇宙辐射和重力变化相关。我们团队前期在SJ-10卫星首次完成了小鼠植入前胚胎在太空发育的过程，并且回收到了空间发育的小鼠胚胎。本研究我们对回收的胚胎进行详细的分析，结果显示：太空发育的小鼠胚胎与地面的两个对照组相比，囊胚发育率和囊胚质量有所下降。此外我们还发现太空发育的囊胚存在严重的DNA损伤的现象，并且还呈现出全基因组整体低甲基化现象。进一步利用地基辐射和模拟微重力平台开展了一系列实验。研究发现地基模拟的低剂量辐射实验得到与太空实验类似的表型，即胚胎发育下降、DNA损伤和全基因组DNA甲基化的下降，而地面模拟的微重力实验结果显示与对照组相比囊胚发育率、胚胎DNA的损伤和全基因组DNA甲基化水平未发生显著地变化，这说明辐射可能是引起太空胚胎发育损伤的主要因素。总之，本项目的研究促进了对胚胎在太空中发育的理解，并揭示了长期的极低剂量辐射是哺乳动物繁殖的危险因素。