Isolation and characterization of fibroin mRNAs from the saturniid silkworms, Antheraea yamamai, Antheraea pernyi and Philosamia cynthia ricini

Abstract

Fibroin mRNAs of the saturniid silkworms, Antheraea yamamai, Antheraea pernyi and Philosamia cynthia ricini, were isolated and characterized. First, the total cellular RNAs of the posterior silk glands of the saturniid larvae at the wandering stage were extracted by SDS-phenol method. Then, the high molecular weight RNA was isolated by Sepharose 2B column chromatography and sucrose gradient centrifugation. These high molecular weight RNAs were found to be the fibroin mRNAs of the saturniid silkworms based on the following characteristics: (1) each RNA preparation displayed a single band in an agarose gel and its molecular weight determined by the gel agreed with the expected size calculated from each fibroin polypeptide; (2) these RNAs contained about 60% G + C as expected since the fibroins contain large amounts of glycine and alanine, whose codons are GGX and GCX, respectively; (3) the RNAs bound to an oligo d(T) column, indicating that the RNAs possess a poly A tail, and were translated into an array of polypeptides by a rabbit reticulocyte lysate.