Parental exposure to gamma radiation causes progressively altered transcriptomes that are linked to adverse effects in zebrafish offspring

In zebrafish, parental exposure to ionizing radiation has been associated with effects in offspring, such as increased DNA damage and reactive oxygen species. Here, we assessed short (one month) and long term effects (one year) on gene expression in embryonic offspring (5.5 hours post fertilization) from zebrafish exposed during gametogenesis to gamma radiation (8.7 or 53 mGy/h for 27 days, total dose 5.2 or 31 Gy). One month after exposure, a global change in gene expression was observed in offspring from the 53 mGy/h group, followed by embryonic death at late gastrula, whereas offspring from the 8.7 mGy/h group was unaffected. One year after exposure, embryos from the 8.7 mGy/h group exhibited 2455(61.8% downregulated) differentially expressed genes. Overlaps in differentially expressed genes and enriched biological pathways were evident between the 53 mGy/h group one month and 8.7 mGy/h one year after exposure, which could be linked to effects in adults and offspring, such as DNA damage and lipid peroxidation. Interestingly, pathways between the two groups were oppositely regulated. Our results indicate latent effects following ionizing radiation exposure in parents that can be transmitted to offspring and warrants monitoring effects over subsequent generations. One month after exposure, mRNA from F1 5.5 hpf embryos from parents exposed to 8.7 and 53 mGy/h gamma radiation during gametogenesis was sequenced on the Illumina 4000 platform with three replicas per treatment. One year after exposure, mRNA from F1 embryos from the same parents exposed to 8.7 mGy/h was sequenced with three biological replicates. In both cases, F1 embryos from non-exposed parents were used as control and mRNA sequenced in triplicates, taken at the same time points as the exposed samples.