Cloning And Preliminary Study On Function Of VLDLR-coding Gene From Branchiostoma Belcheri From Zhang Jiang

Amphioxus, a cephalochordate, is a kind of transitional species between invertebrates and vertebrates. Although, amphioxus lacks vertebrate adaptive immune system, it already has the relative perfect innate immune system. Amphioxus lives normally until now relying on the efficient specific immune system and it has been an important resource to study the origin of the immune system of vertebrate. The Very Low Density Lipoprotein Receptor(VLDLR) is one of the Low Density Lipoprotein Receptor. It mainly locates in the fat tissue, the brains and the hearts etc of many animals besides human. Recently, VLDLR not only has function on the metabolism of fats but also has many functions in the sence of the pathology and physiology. Presently, we find that the Lipophorin receptor of the mosquito Aedes aegypt has immune function in the Mosquito Aedes aegypti. It is a good question: does the VLDLR also have the immune function as a relative of the Lipophorin receptor?Our research based on amphioxus in the Zhan Jiang, Guang Zhou as the object, we imply to study the immune offense function of VLDLR through the means of molecular.The results of the research as follows:1) A full-length VLDLR cDNA of 3217bp was cloned by RACE, and the VLDLR cDNA revealed a 103-bp 5'-untranslated region (UTR), a 537-bp 3'-UTR and a 2577-bp open reading frame.2) By the bioinformatic analysis, the ORF encodes a protein of 858 amino acids, and in the N-terminal there is a putative signal peptide of 26 amino acids. The predicted molecular weight is 95.0kDa, theoretical isoelectric point is 4.47, the theoretical half life is 30h, the instabe quotiety is 41.30, which belongs the instabe protein in theory.3) By making the phylogenetic tree, we can imply that the VLDLR may have the common ancient with the VLDLR of Chordata and the LpR of Insect, and it has even closer relationship with the LpR of Insect, therefore it may have the potential function in immunity.4) Branchiostoma belcheri from Zhan Jiang was injected with the Gram-negative bacteria(Vibrio parahaemolyticus) and the Gram-positive baceria(Staphylococcus aureus). The result indicated that the Very Low Density Lipoprotein Receptor which was in the amphioxus infected with the Gram-positive baceria and the Gram-negative baceria has a significant increase. Significant differences has been found that the amphioxus was injected with the Staphylococcus aureus after 10h. It may tell us that the very low density lipoprotein receptor in amphioxus has immune function. It may provide the reference for researching the immunity of amphioxus.