Inhibition of Late Apoptosis and Cell Cycle Arrest at G2/M Phase During Avian Blastoderm Dormancy

However, very little is known about dormant avian embryos at the cellular level. To investigate the molecular processes that occur in chicken blastoderm during cold torpor, we performed transcriptome analysis and investigated cellular responses in dormant embryos.

In embryos stored at low temperature, we observed up-regulation of genes and proteins related to ER stress and SAPK signaling. In addition, the proportion of early apoptotic cells rose dramatically during torpor, whereas the proportion of late apoptotic cells was unchanged. Cell cycle analysis revealed that mitotic arrest occurred at G2/M phase in a DNA damage–independent manner, and that the arrest was alleviated after incubation at 37°C. Collectively, our data suggest that the dormant avian embryo tolerates cold stress by inducing stress-tolerance pathways, inhibiting late apoptosis, and triggering cell cycle arrest at G2/M phase.