Molecular Cloning And Expression Of A Full Length CDNA Encoding Vitellogenin(Vg) In Oratosquilla Oratoria

Oratosquilla oratoria is an important marine crustaceans with a high economic value that li ves along the coast of China. In recent years, due to overfishing and marine environment damagi ng, the amount of Oratosquilla oratoria resources is reducing decreasingly, breeding and conser vation of resources are now used by artificial mearsures. We expected the vitellogenin gene cloni ng and expression as a starting point to solve the reproductive problem.In oviparous animals, vitellin(Vn) is the major egg yolk protein which is produced by a precursor protein called Vitellogenin(Vg). Vg not only provides some proteins, carbohydrates, lipids, and other nutritional supplies to the maturing oocytes for resources of the developing embryo, but also combines with metallic ions(such as Zn2+, Fe3+, Cu2+, Mg2+, Ca2+) and takes them into oocytes as a carrier. In addition, carotenoid, thyroxine, retinol and riboflavin can be taken into oocytes during vitellogenesis by the carrier of Vg. Furthermore, Vg has a function of immunoprophylaxis. Until now, many researches mainly focus on the decapods crustaceans, not on stomatopoda crustaceans. Considering the important role of Oratosquilla oratoria vitellogenin in reproduction and development, it is very important to analyze the cloning and expression of vitellogenin gene.The complete vitellogenin(Vg) c DNA sequence cloned from Oratosquilla oratoria using RACE method and the expressions of Vg m RNA in different ovarian development stages measured by q PCR for the first time. The result was showed that the full-length c DNA of Vg gene was consisted of 7727 nucleotides, including a 5’-untranslated region(UTR) of 29 bp and a 3’UTR of 170 bp. A 7521 bp open reading flame(ORF) encoded 2506 amino acid residues was found by ORF finding program. Phylogenetic tree analysis was demonstrated that O. oratoria Vg and decapods Vg formed two branches on the same group of the tree. The deduced amino acid sequence showed 46%-52% identity with other known decapods Vg amino acid sequence by using BLASTP. O. oratoria Vg sequence was contained 4 kinds of structural domains including the N-terminal domain of vitellogenin, the N-terminal domain of lipoprotein, and the 2 kinds of von Willebrand factor D-type domain. The results of q PCR was showed that the level of m RNA increased significantly to the maximum followed by decreasing significantly to the minimum from immature stage to mature stage. It was indicated by the expression pattern of Vg gene that ovary entered into the stage of rest to prepare for the next reproduction cycle after a period of strong vitellogenin synthesis.