IDENTIFICATION OF DIFFERENT SPLICE VARIANTS AND FLUCTUATION EXPRESSION OF ECDYSONE RECEPTOR GENE FROM Eriocheir sinensis

Alternative splicing is a normal phenomenon in eukaryotes, it could greatly increases the biodiversity of proteins that can be encoded by the genome. It is believed to be an important mechanism of post-translational modifications. Ecdysone receptor (EcR), an essential nuclear receptor, played essentials roles in molting, growth, development, reproduction, and regeneration of crustaceans. In this study, different alternative isoforms of EcR gene in Eriocheir sinensis were amplified, and isoforms expression were evaluated in different molting stages, developmental stages, and tissues.

Our results indicated five transcripts were identified for EcR gene, (EsEcR-1 to EsEcR-5) (Figure 1), with two splicing events, exon skipping and intron retention.  

Significant higher expression were identified in premolt stage for EsEcR-3 and EsEcR-5, especially the expression of the EsEcR-3 was 7 times higher (fold change) than that of intermolt stage. However, there was no significant expression change for EsEcR-2 and EsEcR-4 between premolt and intermolt stages. During different developmental stages, dramatic expression changes were presented for EsEcR-5 for two metamorphosis development stage (zoea to megalopa and megalopa to juvenile crab). The expression of the EsEcR-2, EsEcR-4, and EsEcR-5 in ovary were relative smaller than that of the hepatopancreas, but higher than that of testis.

In conclusion, five alternative isoforms were identified in this study, all these isoforms have participated in the growth and developmental process of E. sinensis. EsEcR-3 likely to be the essential isoforms, which regulate molting of E. sinensis. EsEcR-5 may play important roles in the metamorphosis process, and EcR gene was strongly associated with ovary development. More work need to be conducted to study the specific functions of each isoforms of EcR gene for E. sinensis in future.