Day 55 has 29 protein-coding genes (browser view), including XRCC5 (X-ray repair complementing defective repair in Chinese hamster cells 5). As the name implies, XRCC5 was discovered through experiments that used X-rays to damage cells from the Chinese hamster.
Radiation and carcinogens can cause DNA to suffer double-stranded breaks. XRCC5 helps repair these through the non-homologous end joining process.
Click here to see the sequence of Day 55 with your XRCC5 gene underlined.