Hybridization-selected translation of Bombyx mori high-cysteine chorion proteins in Xenopus laevis oocytes.

Abstract

Xenopus laevis oocytes were injected with poly(A)+-mRNA isolated from chorionating follicular epithelium of the domesticated silk moth (Bombyx mori). On two-dimensional gel electrophoresis, the resultant translation products comigrated with authentic, secreted, chorion standards, demonstrating that the frog oocyte system synthesizes and correctly processes virtually all major chorion components. A cDNA clone has been shown to contain sequences complementary to those of mRNAs encoding B.monr high-cysteine (Hc) chorion proteins Hc6-HclI. mRNAs were selected by hybridization to plasmid m5000 DNA bound to diazobenzyloxymethyl-cellulose and subsequently translated in X. laevis oocytes into forms that comigrated with authentic chorion standards. The selection of a distinct subset of Hc mRNAs under stringent hybridization conditions (70% formamide/0.2 M NaCl, 600C) suggests that they are encoded by related genes. This is consistent with the pattern obtained by hybridizing radioactive m5000 DNA to Southern blots prepared from EcoRI-cleaved B. mori chromosomal DNA.

Novel B family sequence from an early chorion cDNA library of Bombyx mori.

“…2c shows that when moth DNA was blotted after digestion with EcoRI (an enzyme that does not cut 6A2), a total of seven bands hybridized with 6A2, three strongly and four weakly. In similar experiments (unpublished data), 11 bands hybridized with m5000, a member of the Hc-B family (6,22), and approximately 25 bands hybridized with m1602, a typical member of the B family (23 Developmental Specificity of 6A2. Choriogenesis in B. monri is a favorable system for precisely determining the developmental period of expression of specific genes.…”