Submitted to: Developmental Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 19, 1997
Publication Date: N/A
Interpretive Summary: New methods are needed to protect stored commodities from insect pests because of the loss of many insecticides as a result of acquired resistance or environmental regulations. Scientists at the USDA, ARS, Center for Medical and Veterinary Entomology are developing genetic and physiologically based methods of control for integrated pest management programs. To find a method to produce sterile insects, the gene for a germ cell specific protein was identified and isolated from the Indianmeal moth. The gene is structurally similar with alpha-crystallin proteins from vertebrates and the protein functions as a chaperon which protects yolk proteins in the eggs of this insect. DNA regulatory sequences for this gene will be used to develop methods to sterilize the Indianmeal moth.
Alpha-crystallin protein cognates were found in germ cells of the Indianmeal moth, Plodia interpunctella (Shirk and Zimowska, in press). A cDNA clone was isolated for a 25,000 kDa molecular weight polypeptide member of this family, aCP25. Both the DNA sequence and predicted amino acid sequence showed considerable homology with the embryonic lethal gene, l(2)efl, in Drosophila melanogaster. The predicted amino acid sequence for the acp25 gene, as well as l(2)efl, also showed significant sequence similarity with the alpha-crystallin A chain polypeptides from the lenses of vertebrate eyes. An N-terminal hydrophobic aggregation site and a C-terminal protective binding site common to alpha-crystallin proteins were present in the predicted acp25 amino acid sequence. On the other hand, the cDNA sequence for acp25 showed more similarity to small heat shock proteins in D. melanogaster. This evidence suggests that although the alpha-crystallin protein cognates in P. interpunctella evolve from a gene common with small heat shock protein genes, the amino acid sequence has converged on a structure similar to that of alpha-crystallin proteins. An electroblot binding assay was used to show that the germ-cell alpha-crystallins of P. interpunctella bind specifically with the follicular epithelium yolk protein (FEYP) and that the binding was reversible in the presence of ATP or low pH. Thus, the alpha-crystallin cognates appear to function as chaperones for the follicular epithelium yolk proteins in the embryos of P. interpunctella.