Molecular Characterization, Structure and Expression Analysis of a Ras- Related Nuclear (Ran) Gene in Pacific White Shrimp, Litopenaeus vannamei

Ras-related nuclear (Ran) gene is widely expressed and predominantly localized in the nucleus of eukaryotic cells.It has been shown to function in nucleo-cytoplasmic transport, mitotic spindle formation and nuclear envelope reformation.Pacific white shrimp (Litopenaeus vannamei, Boone, 1931) is an economic culture species all over the world.With the rapid development of shrimp cultures, bacterial and viral diseases become serious problems in its aquaculture.However, little is known about the role of Ran gene in L. vannamei against viral or bacterial infection.The present study showed that full-length of L. vannamei Ran cDNA was 1104 bp, including a 5'-terminal untranslated region (UTR; 71 bp), 3'-UTR (387 bp) and 645 bp of open reading frame encoding 215 amino acids.Ran gene was well conserved among shrimp, bee and ant species.This protein contains an ATP/GTP binding domain and an effector molecule binding motif.Like human Ran, L. vannamei Ran was consisted of multiple -helix and -sheets structures, and ATP/GTP binding motifs were located on the surface of structure.Quantitative RT-PCR analysis demonstrated that Ran was expressed highly in lymphoid organs and gills, followed in hepatopancreas and hemocytes.Time-course expression analysis indicated that Ran transcript was up-regulated in groups infected with both Vibrio anguillarum and white spot syndrome virus (WSSV).It suggests that Ran may play roles in L. vannamei immunity against both viral and bacterial infections, which provided valuable information for further studying the functions and regulation mechanism of Ran in L. vannamei.