BIOLOGICALLY-BASED TECHNOLOGIES FOR MANAGEMENT OF CROP INSECT PESTS IN LOCAL AND AREA-WIDE PROGRAMS
Location: Insect Behavior and Biocontrol Research Unit
Title: Recombination technologies for enhanced transgene stability in bioengineered insects
Submitted to: Genetica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 16, 2010
Publication Date: January 1, 2011
Citation: Schetelig, M.A., Gotschel, F., Viktorinova, I., Handler, A.M., Wimmer, E. 2011. Recombination technologies for enhanced transgene stability in bioengineered insects. Genetica. 139:71-78.
Interpretive Summary: The ability to create transgenic strains of economically and medically important insect species has the potential to greatly improve existing biological control methods, which is a major goal of our laboratory at the Center for Medical, Agricultural and Veterinary Entomology, USDA, Agricultural Research Service, Gainesville, FL. Development of this methodology and strategies to effectively and safely utilize transgenic insects for biological control will depend upon new vector systems that can be targeted to specific genomic integration sites and then stabilized to minimize strain breakdown and ecological risks related to unintended movement of the transgenes to other organisms.
The technologies reviewed and discussed in here are important to establish stabilized transgenic systems for a safe environmental-friendly biological control. In particular, methods for stabilizing transgenic systems by deleting or rearranging transposable elements in Drosophila melanogaster and Ceratitis capitata are compared and discussed. Recent development in generating and testing stabilized transgenic insects for an environmental-friendly Sterile Insect Technique are outlined.
Transgenic technology is able to improve several aspects of biological control on its own and combined with other control methods in an integrated pest management (IPM). The technologies reviewed in here show the ability of generating safe transgenic insects. The pros and cons for the development and safety of transgenic insect strains intended for field release are discussed.
Transposon-based vectors currently provide the most suitable gene transfer systems for insect germ-line transformation and are used for molecular improvement of the Sterile Insect Technique. However, the long time stability of genome-integrated transposon constructs depends on the absence of transposase activity that could remobilize the vector and associated transgenes. To achieve transgene stability, transposon vectors are usually non-autonomous, lacking a functional transposase gene, and chosen so that endogenous or related transposon activities are not present in the host. Nevertheless, the non-autonomous transposon vector could become instable by the unintended presence of a mobilizing transposase that may have been undetected or subsequently entered the host species by horizontal gene transfer. Since the field release of transgenic insects will present environmental concerns relating to large populations and high mobility, it will be important to ensure that transgene constructs are stably integrated for maintaining strain integrity and eliminating the possibility for unintentional transfer into the genome of another organism. Here we review efficient methods to delete or rearrange terminal repeat sequences of transposon vectors necessary for their mobility, subsequent to their initial genomic integration. These procedures should prevent transposase-mediated remobilization of the vector and associated genes, ensuring their genomic stability.