Male mice, caged in the International Space Station for 35 days, sire healthy offspring

Abstract

The effect on the reproductive system and fertility of living in a space environment remains unclear. Here, we caged 12 male mice under artificial gravity (≈1 gravity) (AG) or microgravity (MG) in the International Space Station (ISS) for 35 days, and characterized the male reproductive organs (testes, epididymides, and accessory glands) after their return to earth. Mice caged on earth during the 35 days served as a “ground” control (GC). Only a decrease in accessory gland weight was detected in AG and MG males; however, none of the reproductive organs showed any overt microscopic defects or changes in gene expression as determined by RNA-seq. The cauda epididymal spermatozoa from AG and MG mice could fertilize oocytes in vitro at comparable levels as GC males. When the fertilized eggs were transferred into pseudo-pregnant females, there was no significant difference in pups delivered (pups/transferred eggs) among GC, AG, and MG spermatozoa. In addition, the growth rates and fecundity of the obtained pups were comparable among all groups. We conclude that short-term stays in outer space do not cause overt defects in the physiological function of male reproductive organs, sperm function, and offspring viability.

Intergenerational effect of short-term spaceflight in mice

“…We also observed differences in gene expression profiles in the spleen and retina between GC and MG treatments (Horie et al, 2019;Mao et al, 2018). On the other hand, spermatozoa collected from MG and AG mice had normal morphology and reproduction abilities (Matsumura et al, 2019).…”

Sperm membrane proteins DCST1 and DCST2 are required for the sperm-egg fusion process in mice and fish

“…Cauda epididymal spermatozoa were squeezed out and dispersed in PBS (for sperm morphology) and TYH (for sperm motility and IVF) 34 . After incubation of 10 and 120 minutes in TYH, sperm motility patterns were examined using the CEROS II sperm analysis system 35–37 . IVF was conducted as described previously 38 .…”

Sperm proteins SOF1, TMEM95, and SPACA6 are required for sperm−oocyte fusion in mice

“…Cauda epididymal spermatozoa were dispersed in phosphate-buffered saline (PBS) (for sperm morphology) or TYH drops (for sperm motility and IVF) (41). After an incubation period of 10 and 120 min in TYH, sperm motility patterns were examined using the CEROS I and II sperm analysis system (42)(43)(44). IVF was performed as described previously (45).…”