[Cloning and characterization of BmBrat in silkworm, Bombyx mori]

NHL proteins, which play important roles in regulation of cell proliferation and differentiation, have been extensively studied on mammals. Here, we cloned a member of NHL protein family namely BmBrat in silkworm. The full-length cDNA sequence of BmB rat was obtained by means of the rapid amplification of cDNA ends (RACE), including 3 614 bp. The ORF is 2 580 bp long, encoding a protein with 859 amino acid residues. The molecular weight is 94.3 kDa and the isoeledtric point (pI) is 6.65. The BmBrat expression profile was detected by RT-PCR at L5D3 larval stage, and it was expressed in all tissues, including silk gland, midgut, fat body and malpighian tubule. However, it was highly expressed in ovary and head. The expression profile was also detected at different stage of embryo development, and reached a peak at the 4th and 5th days of the embryonic period. Anti-BmBrat polyclonal antibody was generated f6llowing prokaryotic expression, protein purification and mice immunization, which is highly specific and effective for recognizing BmBrat protein through Western blotting and immunofluorescence staining. Subcellular localization of BmBrat in hemocytes revealed that it was specifically expressed in cytoplasm. This study provides a foundation for further research of the biological function of BmBrat gene.