Submitted to: Peptides
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/16/2005
Publication Date: 3/1/2006
Citation: Nachman, R.J., Strey, A.A., Zubrzak, P., Zdarek, J. 2006. A comparison of the pupariation acceleration activity of pyrokinin-like peptides native to the flesh fly: Which peptide represents the primary pupariation factor? Peptides. 27:527-533. Interpretive Summary: Because of problems with the development of resistance to conventional pesticides, there is a critical need for new concepts and alternative approaches in controlling insect pests. The basic premise of this research is that neuropeptides (short chains of amino acids) serve as potent messengers in insects to regulate vital functions. New, selective control measures may be developed by designing metabolically stable mimics of these neuropeptides that actively inhibit or over-stimulate functions regulated by them, resulting in disruption of the internal environment of the insect. We report on a comparison of the activity of native peptides to elicit the transformation of an immature stage of the flesh fly to the adult form. In addition, the effects of these peptides on the underlying muscular patterns that accompany this maturation process were studied in detailed fashion via a specialized technique that monitors changes in internal pressure. A deeper understanding of how these neuropeptides regulate critical processes in insects will aid in the design of strategies to disrupt insect maturation. The work brings us one step closer to the development of practical neuropeptide-like substances that will be effective in controlling pest insects in an environmentally friendly fashion.
Technical Abstract: Five native pyrokinin-like peptides (Neb-PK-1, Neb-PK-2, Neb-PVK-1, [L9]Neb-PVK-2, [I9]Neb-PVK-2) identified in the neuropeptidome of the flesh fly Neobellieria bullata were compared for their quantitative and/or qualitative effects on puparium formation (pupariation). In a standard pupariation bioassay, both Neb-PVK-1 and [I9]Neb-PVK-2 proved inactive, whereas [L9]Neb-PVK-2 demonstrated only weak activity. In contrast, both Neb-PK-1 and Neb-PK-2 demonstrated potent threshold doses, with Neb-PK-2 about 10 fold more active than Neb-PK-1. Analysis of neuromuscular activity during pupariation using a tensiometric technique demonstrates that the two native Neb-PKs accelerate the onset of immobilization and cuticular shrinkage more than motor programs associated with retraction of the anterior segments and longitudinal body contraction. It was further determined that the sensitivity of various components of the pupariation process to these peptides decreases in the following order: immobilization > cuticular shrinkage > motor program for anterior retraction > motor program for longitudinal contraction = tanning of cuticle of the newly formed puparium. A paradoxical situation was observed whereby the motor programs of pupariation are temporally dissociated from actual morphogenesis of the puparium. The tensiometric data suggest that the most likely candidate for a primary pupariation factor is Neb-PK-2, rather than Neb-PK-1.