Molecular Cloning、expression And Application Of Vitellogeningene In Geocoris Pallidipennis

The Geocoris pallidipennis(Costa) is one of the most important predaceous insects. It has very broad prospects in biological control application. In recent years, the morphology, biology, ecology and predaceous function of G. pallidipennis were studied; however, the molecular features of vitellogenin(Vg) in this species are unknown. The current studies cloned and studied molecular features of the Vg gene in G. pallidipennis. At the same time, the expression of 37 KDa protein and the physiological function of the protein in G. pallidipennis were conducted. The research will provid theoretical basis for the improvement of the artificial diet and large-scale rearing of G. pallidipennis.The results were summarized as following:1. The Vg gene c DNA of G.pallidipennis was cloned and sequenced using RT-PCR and RACE. The full-length c DNA of the Vg gene is 5667bp(Gen Bank accession No. KP688587), encoding 1848 amino acids residues, and there is a signal peptide of 19 residues. The conserved motifs and RXXR cleavage site of Vg were found through sequence analysis. The deduced amino acid sequence of Vg from G.pallidipennis showed a high level of similarity with the Vg sequences from other Hemipterainsects. The results indicated that the c DNA obtained was Vg gene in G.pallidipennis.2. The Vg detected by ELISA gradually increased and reached the peak on the 22 th day after adult emergence. In this study, the specific primers were designed based on the known sequences of Vgs, the c DNA was used as a template for PCR amplification. Structured recombinant expression plasmid was transformed into host cell. The protein was inducted to be expressed at different conditions, and then target protein was separated and purified. The results showed that the recombinant expression vector was successfully structured, and the induced fusion protein was expressed in host cell.3. The effects of 37 KDa protein on the developmental and reproduction of G. pallidepennis were determined. The results indicated that the developmental time of 5th instar and pre-oviposition in the treatment containing the 37 KDa protein were significantly shorter than the control containing the purified water or the PBS buffer. The total egg production in first fourteendays of per G. pallidipennis female in the treatmemt was significantly higher than the controls. In addition, the hatching rate of eggs laid by females in treatment increased by 18.95 % for the control of purified water and 15.92 % for the PBS buffer, respectively. 37 KDa protein can significantly promote the growth and reproduction of G. pallidipennis.