Transgenerational Effects on Calf Spermatogenesis and Metabolome Associated with Paternal Exposure to the Fukushima Nuclear Power Plant Accident

The Fukushima nuclear power plant (FNPP) accident raised worldwide attention to the health risk of radiation exposure and to its potential transgenerational effects. Here, we analysed transgenerational effects on calf spermatogenesis and on blood plasma metabolome in order to detect alterations associated with paternal exposure to low-dose-rate (LDR) radiation. Sperm was collected from a bull exposed to radiation for 2 years abandoned in the ex-evacuation zone of the FNPP accident (the abandoned bull) and was used for artificial insemination (AI) into a non-radiocontaminated cow. Haematoxylin and eosin stained sections of the testis of a 13-month-old calf revealed spermatogonia, spermatocytes, spermatids, and sperm in normal morphology. Nuclear and acrosomal morphology of sperm was generally normal. Metabolomic profiling of plasma using capillary electrophoresis– mass spectrometry resulted in 104 peaks of candidate compounds suggestive of paternal exposure. A calf was delivered by AI using sperm from the abandoned bull. Regarding glycolysis, the contents of nucleotide sugars tended to be lower in the delivered calf than in the control calf. Among energy carries, AMP and ATP showed different tendency between non-radiocontaminated and delivered calf. In conclusion, there were no apparent transgenerational effects on both spermatogenesis and blood plasma metabolome in a calf obtained by AI using sperm from the abandoned bull exposed to LDR in the ex-evacuation zone of the FNPP accident for about 2 years.