Molecular characterization and expression of MAP2K1 gene in Hyriopsis cumingii

In order to study the role of the MAP2K1 (MEK1) gene in the sex determination of Hyriopsis cumingii, we applied RACE (Rapid-amplification of cDNA ends) method to clone the MAP2K1 gene sequence. We conducted a real-time fluorescence quantitative analysis to compare MAP2K1 gene in six tissues (Gonads, adductor muscle, hepatopancreas, gills, mantle, foot), gonads at early developmental stage (1−8 month old) and the 1−3 years' level of expression in male and female glands of H. cumingii. We determined the location of MAP2K1 gene in the gonads of 2-year-old H.cumingii by in situ hybridization. The results show that the ORF region of MAP2K1 gene was 1 194 bp in length and encoded 397 amino acids. MAP2K1 gene was highly expressed in the ovary; the expression level was the highest at 2 months of age at early developmental stage; the expression results from 1−3 years of age show that the expression of MAP2K1 gene in the ovary was higher than that in the spermatozoa for the same period (P<0.05). The in situ hybridization results show that the MAP2K1 gene had a significant hybridization signal in the oocytes and eggs of female H. cumingii. RNAi results show that the expression of the downstream gene MAP2K1 gene decreased by 82.31% in females and 73.60% in males after interfering with the upstream gene C-MOS gene of MAP2K1 gene. In conclusion, MAP2K1 gene may be involved in the ovarian development process and is a female-biased gene in H. cumingii, and C-MOS gene affects its expression.