Temperature-induced embryonic diapause in blue-breasted quail (Coturnix chinensis) correlates with decreased mitochondrial-respiratory network and increased stress-response network

Blue-breasted quail has been recognized as a potential model animal. The aim of this study is to investigate the low-temperature-induced embryonic diapause in blue-breasted quail. To this end, the early embryonic staging in blue-breasted quail was briefly described and various incubation temperatures were tested. While the embryonic diapause in early blue-breasted quail embryos can be induced when the eggs were stored at 21°C, a lower temperature such as 16°C yielded a significantly better hatchability (P = 0.0231). Additionally, prolonged storage duration from 3, 7 to 14 d significantly reduced the hatchability (P < 0.0001). Visual examination on the unhatched eggs revealed that reduced hatchability in prolonged storage was significantly correlated with embryonic mortality during the first half of incubation period (R2 = 0.9999, P = 0.0055). High-throughput RNA sequencing with de novo assembly showed that a gene network cluster consisted of ND4, ND5, ND6, and COX3, which are components of mitochondrial respiratory complexes, was down-regulated in the cold-stored embryos, while a stress-responsive gene network cluster consisted of JUN, ATF3, and DUSP1 was up-regulated. Accordingly, cell death in the blastoderm was significantly increased as the storage duration prolonged from 3 to 10 d. Taken together, our study provided basic information on the temperature-induced embryonic diapause in blue-breasted quail. Furthermore, transcriptomic analysis sheds light for the molecular basis on how blastoderm cells respond to the prolonged cold-stress and stay diapause.