Location: Crop Genetics and Breeding ResearchTitle: Natural history and intragenomic dynamics of the Transib transposon Hztransib in the cotton bollworm Helicoverpa zea Author
Submitted to: Insect Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2010
Publication Date: 12/16/2010
Citation: Du, E., Ni, X., Zhao, H., Li, X. 2010. Natural history and intragenomic dynamics of the Transib transposon Hztransib in the cotton bollworm Helicoverpa zea. Insect Molecular Biology. 20:291-301. Interpretive Summary: A previously characterized jumping gene (that is, Hztransib) from the corn earworm (also known as the cotton bollworm) is the first intact member of a novel superfamily of jumping genes - Transib. Jumping genes are fragments of deoxyribonucleic acid (or DNA) capable of moving around in the genetic makeup (or genome) of a living organism. In this study, two molecular detection methods (transposon display and genomic PCR-gel analyses) were used to address 1) when the jumping gene entered into the corn earworm genetic makeup; and 2) whether it is still active in the genetic makeup of the corn earworm. The counterpart of the transposable element was detected in the genetic makeup of the immediate ancestral species (i.e. Helicoverpa armigera) of the corn earworm (Helicoverpa zea), but not in the genetic makeup of their common ancestral species (i.e. Helicoverpa assulta). A total of 39 locations where jumping gene was inserted in the corn earworm genome were detected from eight populations of the corn earworm. However, both the number of copies and the locations where copies of the jumping gene inserted were highly variable among the 128 caterpillars (16 larvae from each of the 8 populations) tested in this study. We therefore conclude that the jumping gene - Hztransib had probably inherited from its most closely-related ancestral species and still remains active as part of the genetic makeup of the corn earworm.
Technical Abstract: Hztransib recently identified from Helicoverpa zea represents the first intact and transcriptionally active Transib element. Its open reading frame was detected in H. armigera, from which H. zea evolved, and H. assulta, the common ancestor of H. zea and H. armigera. But its remaining parts were found only in H. armigera. Thirty nine Hztransib insertion sites, all of which are polymorphic, were detected from eight populations of H. zea. Out of the 39 insertion sites, 35 were not frequently occupied, with 1 to 33 occurrences in a total of 128 individuals from the 8 populations (16 larvae per population). Its copy number ranged from 5.8 to 14.2 per individual, with putative intact copies always more abundant than internally-deleted ones. In conclusion, Hztransib had probably transferred to H. zea from H. armigera and most likely still retains its capacity to maintain structural integrity, increase copy number and remobilize in H. zea.