Reply to Ferlazzo and Foray: About the Space Pup project.
Reply to Ferlazzo and Foray: About the Space Pup project.
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回复 Ferlazzo 和 Foray：关于 Space Pup 项目。
DOI：
10.1073/pnas.1711468114
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Wakayama T.
中科院分区：
文献类型：
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作者：
Wakayama S;Kamada Y;Yamanaka K;Kohda T;Suzuki H;Shimazu T;Tada MN;Osada I;Nagamatsu A;Kamimura S;Nagatomo H;Mizutani E;Ishino F;Yano S;Wakayama T.
Ferlazzo和Maray(1)的一个担忧是，我们的对照实验需要暴露在日本的地面辐射中，而不是暴露在高自然辐射本底(NRB)中，如拉姆萨尔。正如作者所建议的，将我们的对照样本同时暴露给拉姆萨尔和日本将是一个好主意。当控制辐射水平从0.5mSv/y(日本)增加到70mSv/y(Ramsar)时，空间辐射与地面辐射之间的差异将大大缩小。正如我们在论文中提到的，我们的结论是，关于在太空和低NRB地点(日本)之间使用较高的辐射差异，“它不会影响在国际空间站上至少储存9个月后可存活后代的产生。”(2)因此，即使我们使用高NRB地点作为控制，我们的结论可能也不会改变。费拉佐和福雷(1)还指出：“因此，当作者报告太空中的低剂量率比地球上高100倍时，他们省略了没有重大危险证据的最高NRB。”我们很遗憾不知道地点。然而，为了找出空间辐射产生的微小影响，最好是将低净辐射比位置与空间进行比较。作者还担心，如何才能从9个月的任务中获得的无关紧要的数据中推断出2.7年任务的风险，这可能是危险的。我们很遗憾没有在我们的论文中很好地解释这一点。我们原本计划在更长的时间内进行我们的太空Pup项目。然而，正如美国宇航局网页(https://www.)所示，我们的任务仍在进行中美国宇航局。Gov/mission_pages/station/research/experiments/893.)，我们的样本将在较长时间暴露于太空辐射后返回地球。由于使用国际空间站的限制，我们必须证明我们的项目进展顺利，没有任何问题。出于这个原因，我们需要立即公布我们的第一个数据，以证明将另一个太空样本在国际空间站上保留更长时间是合理的。另一个令人担忧的问题是太空保存的精子的可育性。作者提出，“超过2000mGy后，无精子症可能是永久性的”，而“暴露在109.5 mSv的剂量与这些剂量相去甚远。”我们感谢他们的这一建议。已知辐射对活体动物和冷冻细胞的影响是不同的。冷冻干燥的精子不能修复太空飞行中的DNA损伤，因此，损伤将比活体动物更大。然而，我们的数据(178毫西弗)不足以预测空间辐射的实际影响。因此，作者的以下担忧是完全有道理的：“因此，要评估太空辐射对生育力的影响，更重要的是进行更长时间的任务。”如上所述，我们已经在进行更长时间的保存实验，并将在实验完成后公布我们的结论。
One concern of Ferlazzo and Foray (1) is that our control experiment entailed exposure to the ground radiation of Japan, rather than to a high natural radiation background (NRB), such as Ramsar. As the authors suggest, it would have been a good idea to expose our control sample to both Ramsar and Japan. When the control radiation level increases from 0.5 mSv/y (Japan) to 70 mSv/y (Ramsar) the difference between space and ground radiation will largely decrease. As mentioned in our paper, we concluded that regarding the use of a higher difference in radiation between space and a low-NRB location (Japan)“it does not affect the production of viable offspring after at least 9 mo of storage on the ISS [International Space Station].”(2) Thus, even if we use a high-NRB location as a control our conclusion will probably not change. Ferlazzo and Foray (1) also point out the following:“Hence, when the authors report that the low dose rate in space is 100 times higher than on Earth, they omit the highest NRB where there is no evidence of significant hazard.” We regret not knowing the location. However, to find small effects derived from space radiation it might be better to make a comparison between a low-NRB location and space. The authors were also concerned about how one can “extrapolate the risks for a 2.7-y mission that may be hazardous from the nonsignificant data obtained for a 9-mo mission.” We regret not being able to explain it very well in our paper. We had planned to conduct our Space Pup project for a longer period. However, our mission is still ongoing, as shown on a NASA web page (https://www. nasa. gov/mission_pages/station/research/experiments/893. html), and our sample will be returned to Earth after a longer exposure to space radiation. Due to the restrictions placed on using the ISS we must demonstrate that our project is going well without any problems. For this reason, we need to publish our first data immediately to justify keeping the other space sample on the ISS for a longer period. Another concern is the fertility of space-preserved sperm. The authors suggested that “aspermia may be permanent after more than 2,000 mGy” and that “exposure to 109.5 mSv is very far from these doses.” We thank them for this suggestion. The effects of radiation on live animals and frozen cells are known to be different (3). Freeze-dried sperm cannot repair DNA damage during space flight; therefore, the damage will be greater than that in live animals. Nevertheless, our data (178 mSv) are inadequate to predict the actual effects of space radiation. Therefore, the authors’ following concern is perfectly valid:“Hence, to evaluate the impact of space radiation upon fertility, a much longer mission would have been more relevant.” As mentioned above, we are already conducting a longer preservation experiment and will publish our conclusion upon completing the experiment.