Submitted to: Insect Molecular Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/9/2003
Publication Date: 6/9/2003
Citation: Cheon, H.M., Kim, H.J., Yun, C.Y., Lee, H.J., Lee, I.H., Shirk, P.D., Seo, S.J. Fat body expressed yolk protein genes in Hyphantria cunea are related to the YP4 follicular epithelium yolk protein subunit gene of pyralid moths. Insect Molecular Biology. 2003. v.12(4). p.383-392. Interpretive Summary: The protection of crops and stored commodities from insect pests is in jeopardy. The expected loss of most insecticides because of acquired resistance or environmental hazard has left the industry with fewer options for pest control. Scientists at the USDA ARS, Center from Medical, Agricultural and Veterinary Entomology in collaboration with scientists in Korea cloned the genes for two of the major yolk proteins from the fall webworm moth (FWM), a major crop pest of Asia. The predicted proteins were related to a protein in the Indianmeal moth and the greater wax moth that is packaged in the yolk spheres of the eggs. While the protein of the Indianmeal and greater wax moths are produced in the ovaries, the two yolk proteins of the FWM are produced in the fat body. This suggests that the evolution of these proteins resulted in a change in tissue expression similar to that observed in the higher flies. These findings relate to the identification of sex specific genes that can be genetically modified in pest insects for use in sterile insect release as part of integrated pest management programs.
Technical Abstract: cDNA clones for two of the yolk proteins, YP1 and YP2, produced by the fat body of the moth, Hyphantria cunea, were sequenced and found to have homology with the follicular epithelium yolk proteins of Pyralid moths. The sequence identity between YP1 and YP2 was very high (79.9%) and both cDNA clones coded for polypeptides of 290 residues. Analysis of the secondary structure of the predicted polypeptides suggests that YP1 and YP2 do not form heteromeric proteins because of differences in secondary structure due to the lack of alpha helix in YP1. Northern blot analysis showed that the transcripts for YP1 (1.2 kb) and YP2 (1.1 kb) were present primarily in the female fat body with only trace levels detectable in the ovary of the adult female. In a developmental study, the YP1 and YP2 transcripts were first detectable in 10-day-old pupae and increased into the adult stage. These results suggest that the YP1 and YP2 genes in H. cunea have been recruited to replace the vitellogenin gene as the primary source of yolk proteins. During this process they have acquired a modified pattern of expression that is different from homologous genes reported in pyralid moths. The assessment of the evolution of proteinacious yolk in these moths should serve as an excellent model for the evolution of gene recruitment.