Abstract:  EF\|hand domain\|containing protein of pearl oyster played an important role in the regulation of calcium metabolism in pearl formation. Strengthening the study of the EF\|hand protein was very important to cultivate large high\|quality pearls. In this study， seven EF\|hand genes were screened from transcriptome of Hyriopsis cumingii， then bioinformatics analysis of them was performed. Expression trends and levels of these seven EF\|hand genes were analyzed at different periods in the mantle and visceral mass after inserted nucleus through the digital gene expression profiling （DGE） and real\|time quantitative PCR. The results showed that these seven EF\|hand genes had classic conservative EF\|hand module. Phylogenetic analysis showed that EFCB1 and EFCB6， EFCB7 and N\|EFCB1， EFCBD2 and RASEFCB had closer representation than the others. DGE analysis showed that EF\|hand genes at different culturing period had different expression levels in mantle and visceral mass organizations of Hyriopsis cumingii， suggesting that these seven genes had different functions during the formation of pearl. Fluorescence quantitative PCR results of these seven genes in mantle and visceral mass at different periods after inserting nucleus showed the same trend as DGE analysis. EFCB1 showed the highest expression level in mantle at 20 days after nucleus inserting （P<0.05）， EFCB6 and EFCB7 showed the highest expression level in visceral mass at 20 days after nucleus inserting （P<0.05）， suggesting that these 3 genes might play important roles in the initial phase of nacre secretion forming process. This study provided useful information for further study on the regulation of calcium metabolism and pearl formation.

Key words: Hyriopsis cumingii, EF\, hand gene, mantle pallial, visceral mass, nucleated pearl