The Function Research And Application Of Bombyx Mori Polycomb Proteins

Polycomb group proteins are highly conserved regulatory proteins that were first found in the development of Drosophila embryos, and they usually play roles by forming complex proteins. PcG proteins are involved in the control of the cell program, cancer, cell apoptosis, chromosome X-inactivation, cell type decision and stem cell differentiation and other cellular pathways. With the completion of the whole genome sequence of silkworm, it is possible for us to identify the components and function of PcG protein in silkworm. It will provide a clue to understand the regulatory function of Pc G protein in insects by studying on the common and special characteristics of PcG protein in silkworm.In this theis, we use silkworm as the research materials. In order to study the function of PcG proteins in vitro, the expression vectors were constructed and the proteins were expressed in prokaryotic system and purified. The results showed that BmEZ, BmESC, BmSU(z)12 protein were expressed successfully and existed in the form of inclusion body. Then the proteins were purified from the gel and were used to prepare polyclonal antibody. Q-PCR was applied to analyse the expression pattern of PcG genes in the different stages of silkworm. The results showed that the expression of PcG in the developmental stages of silkworm embryo were regular, but significantly different between the diapause and nondiapause eggs. The expression of 1 to 5 d in the early stage of nondiapause eggs was higher than the later stage, but lower than that of non diapause eggs. On the contrary, the expression of 6 to 9 d in the late stage of diapause was much higher than that of non diapause eggs. The expression level of 1st to 4th in the silkworm larvae was lower, and the expression quantity was higher at the initial stage and the last stage of the 5th instars. The expression level in the early stage of the female pupa was maintained at a stable level, and was the highest at 5 d, but the expression level of the male pupa has no significantly different. The effects of PC and PSC on the development of silkworm embryos were detected by dsRNA interference. The results showed that there was no obvious change on the phenotype and molecular level of the silkworm.In conclusion, it is suggested that PcG proteins have a role in early embryo development and the diapause of silkworm eggs. Through further construction of the interference and over expression transgenic vector of the silkworm PcG genes, studying their effects on silkworm embryo development will also provided theoretical basis for the cultivation of new varieties of silkworm and the control of Lepidoptera pests.