Developmental changes and hormonal regulation of mRNA of Bombyx mori larval serum protein (BmLSP)
1998
Fujiwara, Y. (Nagoya Univ. (Japan). Faculty of Agriculture) | Yamashita, O.
Bombyx mori larval Serum protein (BmLSP) is a major hemolymph protein until the early fifth instar larval period. In order to understand the regulatory mechanisms of gene expression for BmLSP, the developmental changes in the BmLSP concentration of hemolymph, the mRNA content in the fat body, and the effects of allatectomy on mRNA content and ecdysteroid application were compared with a 30K protein. BmLSP concentration in hemolymph increased gradually up to day 2 of the fifth instar, and then decreased steeply thereafter. BmLSP mRNA content in the fat body was high during the feeding period of the fourth instar, undetectable during the molting period, and low during the fifth instar. Allatectomy decreased levels of BmLSP mRNA and increased levels of the 30K protein mRNA. These effects were abolished by application of a juvenile hormone analog. The BmLSP mRNA content was repressed by 20-hydroxyecdysone injected into the separated abdomen in fourth and fifth instar larvae. The expression of the BmLSP gene reflects the condition of pupal commitment and, thus, the BmLSP gene is a suitable model system forstudying the molecular mechanisms associated with metamorphosis
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