The Potential Roles of the Apoptosis-Related Protein PDRG1 in Diapause Embryo Restarting of Artemia sinica

High salinity and low temperatures can induce Artemia sinica to enter the diapause stage during embryonic development. Diapause embryos stop at the gastrula stage, allowing them to resist apoptosis and regulate cell cycle activity to guarantee normal development after diapause termination. P53 and DNA damage-regulated gene 1 (pdrg1) is involved in cellular physiological activities, such as apoptosis, DNA damage repair, cell cycle regulation, and promotion of programmed cell death. However, the role of pdrg1 in diapause and diapause termination in A. sinica remains unknown. Here, the full-length A. sinica pdrg1 cDNA (As-pdrg1) was obtained and found to contain 1119 nucleotides, including a 228 bp open reading frame (ORF), a 233 bp 5'-untranslated region (UTR), and a 658-bp 3'-UTR, which encodes a 75 amino acid protein. In situ hybridization showed no tissue specific expression of As-pdrg1. Quantitative real-time PCR and western blotting analyses of As-pdrg1 gene and protein expression showed high levels at 15-20 h of embryo development and a subsequent downward trend. Low temperatures upregulated As-pdrg1 expression. RNA interference for the pdrg1 gene in Artemia embryos caused significant developmental hysteresis. Thus, PDRG1 plays an important role in diapause termination and cell cycle regulation in early embryonic development of A. sinica.