APC/CCDC20 and APC/C play pivotal roles in the process of embryonic development in Artemia sinica

EBF1 Gene mRNA Levels in Maternal Blood and Spontaneous Preterm Birth

Genetic variants of six genes (EBF1, EEFSEC, AGTR2, WNT4, ADCY5, and RAP2C) have been linked recently to gestational duration and/or spontaneous preterm birth (sPTB). Our goal was to examine sPTB in relation to maternal blood mRNA levels of these genes. We used a public gene expression dataset (GSE59491) derived from maternal blood in trimesters 2 and 3 that included women with sPTB (n = 51) and term births (n = 106) matched for maternal age, race/ethnicity, pre-pregnancy body mass index, smoking during pregnancy, and parity. T tests were used to examine mRNA mean differences (sPTB vs term) within and across trimesters, and logistic regression models with mRNA quartiles were applied to assess associations between candidate gene mRNA levels and sPTB. Based on these analyses, one significant candidate gene was used in a Gene Set Enrichment Analysis (GSEA) to identify related gene sets. These gene sets were then compared with the ones previously linked to sPTB in the same samples. Our results indicated that among women in the lowest quartile of EBF1 mRNA in the 2nd or 3rd trimester, the odds ratio for sPTB was 2.86 (95%CI 1.08, 7.58) (p = 0.0349, false discovery rate (FDR) = 0.18) and 4.43 (95%CI 1.57, 12.50) (p = 0.0049, FDR = 0.06), respectively. No other candidate gene mRNAs were significantly associated with sPTB. In GSEA, 24 downregulated gene sets were correlated with 2nd trimester low EBF1 mRNA and part of previous sPTB-associated gene sets. In conclusion, mRNA levels of EBF1 in maternal blood may be useful in detecting increased risk of sPTB as early as 2nd trimester. The potential underlying mechanism might involve maternal-fetal immune and cell cycle/apoptosis pathways.

Investigation of the Possible Role of RAD9 in Post-Diapaused Embryonic Development of the Brine Shrimp Artemia sinica

Background: The cell cycle checkpoint protein RAD9 is a vital cell cycle regulator in eukaryotic cells. RAD9 is involved in diverse cellular functions by oligomer or monomer. However, the specific mechanism of its activity remains unknown in crustaceans, especially in embryonic diapause resumption of the brine shrimp Artemia sinica. Methods and Results: In the present article, a 1238 bp full-length cDNA of As–RAD9 gene, encoding 376 amino acids, was obtained from A. sinica. The expression pattern of As–RAD9 was analyzed by qPCR and Western blot. The mRNA expression level climbs to the top at the 10 h stage of embryo development, while the protein expression pattern is generally consistent with qPCR results. Moreover, the As–RADd9 related signaling proteins, As–RAD1, As–HUS1, As–RAD17, and As–CHK1, were also detected. Immunofluorescence assay showed that the location of As–RAD9 did not show tissue or organ specificity, and the intracellular expression was concentrated in the cytoplasm more than in the nucleus. We also explored the amount of As–RAD9 under the stresses of cold and high salinity, and the results indicate that As–RAD9 is a stress-related factor, though the mechanisms may be different in response to different stresses. Knocking down of the As–RAD9 gene led to embryonic development delay in A. sinica. Conclusions: All these results reveal that As–RAD9 is necessary for post-diapaused embryonic development in A. sinica.

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.