Space radiation may cause DNA damage to cells and concern for the inheritance of mutations in offspring after deep space exploration. However, there is no way to study the long-term effects of space radiation using biological materials. Here, we developed a method to evaluate the biological effect of space radiation and examined the reproductive potential of mouse freeze-dried spermatozoa stored on the International Space Station (ISS) for the longest period in biological research. The space radiation did not affect sperm DNA or fertility after preservation on ISS, and many genetically normal offspring were obtained without reducing the success rate compared to the ground-preserved control. The results of ground x-ray experiments showed that sperm can be stored for more than 200 years in space. These results suggest that the effect of deep space radiation on mammalian reproduction can be evaluated using spermatozoa, even without being monitored by astronauts in Gateway.
Random integration is a phenomenon in which transfected DNA molecules integrate into (random sites of) the host genome via non-homologous recombination. Although it is assumed that repair of DNA double-strand breaks leads to random integration events, how these endogenous DNA lesions are generated in living cells is poorly understood. In this study, we present evidence that DNA topoisomerase IIα (Top2α) and reactive oxygen species (ROS) are responsible for causing genomic DNA damage that leads to random integration. Specifically, we employed a human pre-B lymphocyte cell line to examine the effects of cellular Top2 expression levels and oxygen concentrations during cell culture. We find that treating cells with Top2α siRNA significantly reduces random integration frequency, while the absence of Top2β had little or no impact. We also show that cells continuously cultured under low (3%) oxygen culture conditions after electroporation display reduced random integration frequency compared to that under normal (21%) oxygen conditions. These findings support the notion that Top2α protein and ROS are endogenous factors that can produce DNA damage leading to random integration of transfected DNA in human cells.
Our previous spaceflight experiment CERISE showed that gene and protein expression levels of muscular components, cytoskeleton, and mitochondrial enzymes are altered in space flown wild-type C. elegans. To confirm and clarify whether the C. elegans muscle fibers and mitochondrial network are physically altered in response to microgravity, this Nematode Muscles project was designed with wild-type and several mutant lines with GFP expression. This investigation also studied whether microgravity could affect the insulin/ IGF-1 (Insulin-like growth factor -1) and/or TGF-β signaling by imaging DAF-16::GFP fusion protein. Wild-type and several mutants were grown in a culture bag kept under microgravity or 1G centrifuge conditions on board ISS for 4 days starting from L1 larva. All samples were fixed on board and recovered, to be analyzed on the earth. The worms did not grow well in the μG culture bag probably due to unexpected air bubbles. Therefore, DAF-16 activation observed in larval worms in μG and not in 1G may be attributed to starvation instead of μG response. In 1G samples, we could successfully find normal mitochondrial network. We also found that chemical fixation using CFA is an effective method for preservation of GFP containing C. elegans in space environment.
Whether mammalian embryos develop normally under microgravity remains to be determined. However, embryos are too small to be handled by inexperienced astronauts who orbit Earth on the International Space Station (ISS). Here we describe the development of a new device that allows astronauts to thaw and culture frozen mouse 2-cell embryos on the ISS without directly contacting the embryos. First, we developed several new devices using a hollow fiber tube that allows thawing embryo without practice and observations of embryonic development. The recovery rate of embryos was over 90%, and its developmental rate to the blastocyst were over 80%. However, the general vitrification method requires liquid nitrogen, which is not available on the ISS. Therefore, we developed another new device, Embryo Thawing and Culturing unit (ETC) employing a high osmolarity vitrification method, which preserves frozen embryos at −80°C for several months. Embryos flushed out of the ETC during thawing and washing were protected using a mesh sheet. Although the recovery rate of embryos after thawing were not high (24%-78%) and embryonic development in ETC could not be observed, thawed embryos formed blastocysts after 4 days of culture (29%-100%) without direct contact. Thus, this ETC could be used for untrained astronauts to thaw and culture frozen embryos on the ISS. In addition, this ETC will be an important advance in fields such as clinical infertility and animal biotechnology when recovery rate of embryos were improved nearly 100%.
Whether mammalian embryos develop normally under microgravity remains to be determined. However, embryos are too small to be handled by inexperienced astronauts who orbit Earth on the International Space Station (ISS). Here we describe the development of a new device that allows astronauts to thaw and culture frozen mouse 2-cell embryos on the ISS without directly contacting the embryos. First, we developed several new devices using a hollow fiber tube that allows thawing embryo without practice and observations of embryonic development. However, the general vitrification method requires liquid nitrogen, which is not available on the ISS. Therefore, we developed another new device, Embryo Thawing and Culturing unit (ETC) employing a high osmolarity vitrification method, which preserves frozen embryos at −80°C for several months. Embryos flushed out of the ETC during thawing and washing were protected using a mesh sheet. Although embryonic development could not be observed in the ETC, thawed embryos formed blastocysts after 4 days of culture without direct contact. This ETC will enable untrained astronauts to thaw and culture frozen embryos on the ISS, as well as to serve as an important advance in fields such as clinical infertility and animal biotechnology.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.