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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Insect Behavior and Biocontrol Research » Research » Publications at this Location » Publication #303593
Title: Pro-apoptotic gene regulation and its activation by gamma-irradiation in the Caribbean fruit fly, Anastrepha suspensa

Author
item NIRMALA, XAVIER - University Of Florida
item SCHETELIG, MARC - Justus-Liebig University
item ZIMOWSKA, GRAZYNA - Former ARS Employee
item Handler, Alfred - Al
item ZHOU, LEI - University Of Florida

Submitted to: Apoptosis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2014
Publication Date: 1/1/2015
Citation: Nirmala, X., Schetelig, M.F., Zimowska, G.J., Handler, A.M., Zhou, L. 2015. Pro-apoptotic gene regulation and its activation by gamma-irradiation in the Caribbean fruit fly, Anastrepha suspensa. Apoptosis. 20(1):1-9.

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 effective and safe transgenic insect strains for biological control will depend on robust and reliable expression of lethal effectors isolated from specific pest insects. Previously we identified and isolated two pro-apoptotic cell death genes, Ashid and Asrpr, which are potential lethal effectors from the Caribbean fruit fly, Anastrepha suspensa. Here we further characterize these genes in terms of their developmental regulation, and their response to '-irradiation, in comparison to their homologs in Drosophila melanogaster. Both the regulation of the Ashid and Asrpr genes and their induced gene expression in response to irradiation are quite similar to D. melanogaster, indicating a a conserved molecular mechanism for the programmed cell death pathway in insects. This suggests that the tephritid pro-apoptotic genes will be effective as lethal effectors for the development of conditional lethality strains for more efficient biologically-based population control programs of tephritid pest species.

Technical Abstract: Transcriptional activation of pro-apoptotic genes in response to cytotoxic stimuli is a conserved feature of the cell death pathway proposed for metazoans. However, understanding the extent of this conservation in insects, as well as other organisms, has been limited by the lack of known pro-apoptotic genes in non-drosophilids. Recently, we described the pro-apoptotic genes, Asrpr and Ashid, from the tephritid, Anastrepha suspensa, that now allow us to fully explore the conservation of pro-apoptotic gene regulation during development and in response to ionizing radiation, between a tephritid and drosophilids. Developmental profiles of Asrpr and Ashid transcript levels during embryogenesis and in embryos exposed to '-irradiation were assessed by qRT-PCR and correlated to apoptosis visualized by acridine orange staining. Transcript levels from both genes were moderately low throughout embryogenesis, with strong expression of Ashid during early to mid-embryogenesis while Asrpr expression peaked in late embryogenesis. This correlated to visually identified apoptotic cells first appearing at 17h, with increasing cell death over time. However, embryos irradiated at 16h post-oviposition exhibited significant high levels of apoptosis 2h later consistent with strong induction of Asrpr and Ashid transcript levels by '-irradiation until 24-32h post-oviposition. Further, embryos irradiated <24h post-oviposition failed to hatch, while those irradiated between 24-32h had increased hatching rates which peaked to non-irradiated control levels of 48-72h post-oviposition irradiated embryos. This indicated a transition of embryos from irradiation-sensitivity to resistance between 24-32h. The two pro-apoptotic genes, known to act cooperatively in both Drosophila and Anastrepha, generally shared similar patterns of up-regulated gene expression throughout post-embryonic development, which correlated well to ecdysone-induced developmental events, especially during metamorphosis. Together these results provide the first direct evidence for a conserved molecular mechanism of the programmed cell death pathway in insects.