|Handler, Alfred - Al|
Submitted to: Insect Molecular Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/8/2008
Publication Date: 7/1/2008
Citation: Handler, A.M., Zimowska, G., Armstrong, K.F. 2008. Highly similar piggyBac elements in Bactrocera that share a common lineage with elements in noctuid moths. Insect Molecular Biology. 17(4):387-393 Interpretive Summary: The creation of transgenic strains of economically important insects for the development of more effective biological control programs is a major goal of our laboratory at Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL. Development of this methods to effectively and safely utilize transgenic insects for biological control will depend upon a comprehensive analysis of various potential risks. These relate to the stability of the transgenic strain so that it maintains effectiveness over many generations, typically under mass-rearing. Of equal importance is ecological safety in terms of the potential for movement of the transgene from the original host into other species with which it interacts. These risks are directly affected by the existence of the transposon used for transformation, in the host species. If the transposon or closely related element exists in the host, it may have the ability to restrict vector integrations or re-mobilize them once integrated. This may preclude our ability to use particular vectors in some species, or may result in transgenic strains that are unstable and/or subject to inter-species transfer resulting in potential ecological risks. This study shows that closely related sequences to the piggyBac transposon, discovered originally in a noctuid moth, exist throughout the Oriental fruit fly species complex. Many of these species have high agricultural importance, and the presence of piggyBac must be taken into consideration if piggyBac vectors are used to create transgenic strains for their biological control.
Technical Abstract: The piggyBac IFP2 transposable element, originally discovered in a Trichoplusia ni cell line, also exists as nearly identical elements in other noctuid lepidopteran species and in mutant and wild type strains of the oriental fruit fly, Bactrocera dorsalis. To further define the distribution of piggyBac in Bactrocera, a survey by PCR amplification was performed in a wide range of Bactrocera species including several within the B. dorsalis species complex and other closely related species. Highly conserved piggyBac sequences were found in all of the B. dorsalis complex species and several closely related species in the B. zonata and B. frauenfeldi complexes. All nucleotide sequences had > 96% identity to corresponding sequences in the T. ni IFP2 element, and > 92% identity among the sequences. The conserved primers used did not detect any distantly related sequences that have been found by computational searches in a wider range of insect and non-insect species. Notably, 53 nucleotide substitutions relative to IFP2 were conserved in all the Bactrocera sequences and the piggyBacs previously sequenced from moths, with 18 resulting in amino acid substitutions. This provides additional support for the notion that IFP2 is a variant of a predecessor element.