Table S2.

Brightness of male pronuclei fertilized with ground or space-preserved spermatozoa and immunostained with anti–gamma-H2AX antibody

Mouse strain	Condition of preservation*	No. of zygotes	Average brightness of male pronucleus†	SD	P value, t test
C57BL/6	Ground	21	1.123	0.101
	Space	18	1.170	0.096	>0.1
BDF1	Ground	23	1.147	0.108
	Space	24	1.165	0.117	>0.1
BCF1	Ground	22	1.149	0.095
	Space	22	1.253	0.178	<0.05
129B6F1-GFP	Ground	21	1.150	0.146
	Space	19	1.210	0.095	>0.1

^*Ground: At the same times and for the same durations as when launching and storing the sample case, a control sample case was exposed to room temperature, then frozen at –95 °C and stored in a freezer at the Tsukuba Space Center in Japan. These are referred to as ground control sperm samples. Space: Samples were launched and stored on the ISS for 9 mo.

^†The brightness of the whole male pronucleus was assayed using ImageJ, and then subtracted from the brightness of the zygote cytoplasm.