Wednesday, 20 November 2002

This presentation is part of : Display Presentations, Section B. Physiology, Biochemistry, Toxicology, and Molecular Biology

Identification of antennal proteins of the red imported fire ant

Robert Renthal, Kalyani Guntur, Daniel Velasquez, and J. Aaron Cassill. University of Texas at San Antonio, Department of Biology, 6900 N. Loop 1604 W, San Antonio, TX

      It is not clear whether pheromone-binding proteins (PBPs) can be readily isolated from antennal extracts of social insects, since they are expected to have complex chemical communication systems. We have analyzed urea extracts of antennae of the red imported fire ant, Solenopsis invicta, using two-dimensional gel electrophoresis. Worker antennae have many low-abundance proteins with isoelectric points between 4 and 5 and molecular weights below 20 kDa (the range expected for PBPs). N-terminal amino acid sequence analysis of the major protein in this region, W2, shows 62% identity to an RR-1 soft cuticle protein from Drosophila (gb AAF58518). Consistent with this assignment, gels of individual antennal segments contain W2 when the dissected segment includes the non-sclerotized joints, but not when the segment is dissected to exclude the joints.       Because male fire ants do not forage or work in the nest, we expect that their olfactory repertoire is more limited than workers. Two dimensional gel electrophoresis of urea extracts of male fire ant antennae show only two major acidic low molecular weight proteins, (18 kDa and 15 kDa). We determined the N-terminal amino acid sequence of the 18 kDa protein, which did not match any known sequence. We prepared degenerate 5' PCR primers based on this sequence. After 2-step PCR amplification and cloning, we obtained one sequence consistent with the isoelectric point and size of the 18 kDa protein. The derived protein sequence is 25% identical to apolipophorin-III from Derobrachus geminatus (Coleoptera, Cerambycidae) (gb AAA64736). Apolipophorin-III has not been previously identified in insect antennae, and its function in the antenna is unknown.  

Species 1: Hymenoptera Formicidae Solenopsis invicta (red imported fire ant)
Species 2: Coleoptera Cerambycidae Derobrachus geminatus (palo verde root borer)
Species 3: Diptera Drosophilidae Drosophila melanogaster (fruit fly)
Keywords: soft cuticle, apolipophorin-III

Back to Display Presentations, Section B. Physiology, Biochemistry, Toxicology, and Molecular Biology
Back to Posters
Back to The 2002 ESA Annual Meeting and Exhibition