Abstract: The large subunit and small subunit of vitellogenin in Bombyx mandarina were identified through SDS-PAGE and Western blot, with molecular weight about 175 kD and 42 kD respectively based on high molecular weight marker. Several primers were designed according to cDNA sequence of vitellogenin in Bombyx mori and conservatism of insect vitellogenin. The cDNA sequence of vitellogenin in Bombyx mandarina (GenBank accession number: AY309967) was obtained through RT-PCR of the total RNA and RACE amplification of 3′end and 5′end. This sequence contains 5 754 bases, an open reading frame which encodes 1 780 amino acids, and the putative cleavage sites RSRR for the proteases of the subtilisin family at position 364－367 where provitellogenin is cleaved into two subunits. The molecular weights of the two subunits are 161.571 kD and 40.794 kD respectively based on amino acids, which are in accordance with the SDS-PAGE results if modification after translation is considered. The results of homology analysis suggested that amino acid sequence of insect vitellogenin be highly conserved within the same order for insects.

Key words: Bombyx mandarina, vitellogenin, cDNA sequence, cluster analysis, homology comparison