Quantitative Changes of Storage Proteins and Vitellogenin during the Pupal-Adult Development in the Silkworm, Bombyx mori (Lepidoptera: Bombycidae)

Abstract

Accumulation and distribution of two storage proteins, SP-1 (female-specific) and SP-2, and vitellogenin in the silkworm, Bornbyx mori, were studied during the pupal period by means of Oudin' single diffusion tests using antisera specific to these proteins. In females SP-1 and SP-2 account for approximately one fourth of the total protein in the newly ecdysed pupa, while in males which lack SP-1, SP-2 comprises one twentieth of the total protein. Both proteins decrease slightly in the early half of the pupal stage, and then rapidly decline so as to disappear shortly before adult emergence. During the metamorphosis, most of them are found in the fat body, negligible amounts in the haemolymph and essentially none in other tissues. The content of vitellogenin is 5% of the total protein in the newly pupated female, but increases gradually in the early pupal stage, and then during pharate adult development it accumulates sharply up to several times the initial amount, attaining to 40% of the total protein in the newly ecdysed adult. In the early half of the pupal stage, vitellogenin is detectable only in the haemolymph, but in the latter half it increases rapidly in the ovary while maintaining its level in the haemolymph. The amino acid composition of vitellogenin is similar to that of SP-1 except that the former is higher in glutamate and serine, but lacks the exceptionally high methionine of the latter. © 1981, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.