Keiji Kurata

Purification and characterization of a juvenile hormone binding protein from hemolymph of the silkworm, Bombyx mori

A juvenile hormone binding protein (JHBP) has been isolated from Bombyx mori hemolymph by gel filtration, ion-exchange chromatography, chromatofocusing and hydroxyapatite column chromatography. Gel electrophoresis indicates that the isolated protein is homogeneous in the presence or absence of a denaturing agent. The JHBP in question has a relative molecular mass of 32 kDa, determined by denaturing gel electrophoresis. Chromatofocusing analysis indicated that the JHBP is an acidic protein with pI 4.9. The protein exhibits a dissociation constant of 9.0 x 10(-8) M for JH I, 1.14 x 10(-7) M for JH II and 3.9 x 10(-7) M for JH III, and thus its affinity for JH analogues is in the order of JH I > JH II > JH III. Its amino acid composition indicates that the protein consists of 297 residues of 18 kinds of amino acids. The sequence of the N-terminus of the polypeptide chain was determined for 34 of the first 36 residues: Asp-Gln-Asp-Ala-Leu-Leu- Lys-Pro-?-Lys-Leu-Gly-Asp-Met-Gln-Ser-Leu-Ser-Ser-Ala-Thr-Gln-Gln-Phe-Le u-Glu- Lys-Thr-Ser-Lys-Gly-Ile-Pro-?-Tyr-His-.

Nucleic acids accumulation of silk gland of Bombyx mori in relation to silk protein

1. 1. Productivity of silk, properly fibroin, of the silkworm Bombyx mori was in proportion to the amount of RNA accumulation in the posterior division of silk gland. 2. 2. DNA content of the silk gland of a line of high silk productivity was twice as much as that of low productivity. A DNA molecule can transcribe RNA, ranged from 3 × 106 to 6 × 106 molecules. 3. 3. An application of actinomycin to larvae lowered an accumulation of RNA in the silk gland and resulted in a decrease of silk production. 4. 4. Even under the upper limit of starvation by which the larvae complete their life, the silk gland kept a normal level of the DNA content, except that it lost the synthesizing activity of RNA. 5. 5. Treatment of larvae with juvenile hormone occasionally induced another DNA replication of the silk gland.