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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Imported Fire Ant and Household Insects Research » Research » Publications at this Location » Publication #178166
Title: SOLENOPSIS INVICTA TRANSFERRIN: CDNA CLONING, GENE ARCHITECTURE, AND UP-REGULATION IN RESPONSE TO BEAUVERIA BASSIANA INFECTION

Author
item Valles, Steven
item Pereira, Roberto

Submitted to: Gene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2005
Publication Date: 7/21/2005
Citation: Valles, S.M., Pereira, R.M. 2005. Solenopsis invicta transferrin: cDNA cloning, gene architecture, and up-regulation in response to Beauveria bassiana infection. Gene. 358:60-66.

Interpretive Summary: The red imported fire ant was introduced into the United States in the 1930s and currently infests about 300 million acres. It causes significant economic losses in livestock and agricultural production and poses a serious threat to human health. A method to identify fire ant nests under attack by pathogens would be very useful in finding new pathogens that could be exploited for fire ant control. USDA-ARS scientists at the Center for Medical, Agricultural and Veterinary Entomology (Gainesville, FL) have identified a fire ant gene (SiTf) that responds to fungal infection. The induction of SiTf suggests that this gene plays a role in the immune response of the ant. This line of research has several potentially promising aspects, including the development of methods to specifically target this gene rendering the ants more susceptible to pathogens and use of this gene as a method to identify new fire ant pathogens.

Technical Abstract: Transferrin genes from several insects have been shown to be induced in response to bacterial or fungal infection. We were interested to know whether transferrin genes in the red imported fire ant, Solenopsis invicta, are similarly induced by microbial challenge. Hence, the cDNA and structure of a gene exhibiting significant homology to insect transferrins were elucidated for S. invicta. The cDNA was comprised of 2417 nucleotides, excluding the poly(A) tail, with a large open reading frame of 2106 nucleotides. The predicted translation product of the S. invicta tranferrin (SiTf) gene was a 702 amino acid polypeptide with an estimated molecular mass of 77.3 kDa and a pI value of 5.66, characteristics consistent with transferrin proteins. Comparative analysis of genomic and cDNA sequences revealed that the SiTf gene was comprised of 8 exons. Quantitative real-time PCR was used to examine the expression of SiTf. Among different developmental stages selected, early pupae exhibited the highest expression level, with significantly lower expression levels in late larvae, queens, and workers. Expression of SiTf was induced in worker ants exposed to Beauveria bassiana conidia. Autoclave-killed conidia did not elicit a SiTf induction response from worker ants. Worker ants exposed to a juvenile hormone-treated glass surface exhibited a significantly lower relative expression of SiTf compared with an untreated control. Genes, like SiTf, responding to microbe attack or infection may provide a unique approach to assist in the discovery of microbial control organisms for the target insect pest.