Abstract:

The storage proteins in Mythimna separata were studied by means of native PAGE, SDS-PAGE and Western blot. The results indicated that there were two storage proteins (SP-1 and SP-3) in M. separata. SP-1 was detected on the 2nd day of the 6th instar of M. separata, and its concentration in the hemolymphincreased with the age and reached to a peak on the last day of the 6th instar. SP-1 disappeared in the hemolymph when the larva ceased feeding. In the adult stage only SP-3 was found. SP-3 as persistent storage protein appeared in the fat body of pupa, and was continuously expressed till the adult stage. SP-1 was composed of two subunits of the molecular size of 94 kD and 100 kD respectively. SP-3 was composed of one subunit in size of 94 kD. The native molecular weights of these two storage proteins were all 550 kD. Analysis of the amino acid compositions of SP-1 showed that the content of aromatic acids (Phe and Tyr) was 8.16% and the content of methionine 3.06%. The contents of the storage proteins in 2nd, 3rd, 4th day of the last instar larvae treated with celangulin Ⅴ in the sublethal dosage were markedly lower than that in the control group. But beyond the 5th day of the last instar, no difference was tested in the contents of the storage proteins and the number of eggs laid per female adult between the group treated with celangulin Ⅴ and the control.

Key words: Mythimna separata, celangulin Ⅴ, storage protein, hemolymph, fat body, sublethal dosage, PAGE