4 research outputs found

    Short Neuropeptide F Receptor in the Worker Brain of the Red Imported Fire Ant (Solenopsis invicta Buren) and Methodology for RNA Interference

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    The red imported fire ant (Solenopsis invicta Buren) is one of the worst invasive species in the United States. Investigating their physiology to understand its molecular basis could lead to the discovery of new gene targets for fire ant control. Neuropeptides are involved in the regulation of important physiological processes, and in insects the short neuropeptide F (sNPF) plays an important role as regulator of feeding, and involved in mechanisms of nutrient sensing, growth and reproduction. This study is focused into unveiling the physiological role of the sNPF and its receptor (sNPFR) in fire ants. In workers, we found a total of nine clusters of immunoreactive-sNPFR cells located near important neuropiles in the brain. These sNPFR-expressing cells are sensitive to the presence/absent of brood, perhaps in correlation with changes in the nutritional status of the colony. Also, these cell clusters are differentially expressed among worker subcastes, suggesting the sNPF/sNPFR pathway could be associated with mechanisms of division of labor. To discover where sNPF is synthesized, we attempted to localize the sNPF-expressing cells in the brain of queens and workers through in situ hybridization, unfortunately without success; thus, the site of synthesis of sNPF in the brain still remains unknown. Finally, we tried to elucidate the role of the sNPFR in social context by silencing its gene expression trough feeding of dsRNA using small laboratory colonies. We found differential effects when delivering the sNPFR-dsRNA through heat-killed dsRNA-producing bacteria or by delivering dsRNA purified from these bacterial cultures. Also, the type of food used as carrier and the concentration of dsRNA were crucial for gene silencing success. Our results showed that feeding a large concentration of dsRNA in liquid and solid foods is required to induce RNAi in the queen midgut; and that the silencing of the sNPFR in this organ did not induce mortality in these queens, but instead it appears to increase larval mortality. In summary, our results are consistent with the sNPF/sNPFR signaling pathway in fire ants being involved in the regulation of division of labor and in sensing the nutritional status, and suggest its function is fundamental for larval development

    Short Neuropeptide F Receptor in the Worker Brain of the Red Imported Fire Ant (Solenopsis invicta Buren) and Methodology for RNA Interference

    Get PDF
    The red imported fire ant (Solenopsis invicta Buren) is one of the worst invasive species in the United States. Investigating their physiology to understand its molecular basis could lead to the discovery of new gene targets for fire ant control. Neuropeptides are involved in the regulation of important physiological processes, and in insects the short neuropeptide F (sNPF) plays an important role as regulator of feeding, and involved in mechanisms of nutrient sensing, growth and reproduction. This study is focused into unveiling the physiological role of the sNPF and its receptor (sNPFR) in fire ants. In workers, we found a total of nine clusters of immunoreactive-sNPFR cells located near important neuropiles in the brain. These sNPFR-expressing cells are sensitive to the presence/absent of brood, perhaps in correlation with changes in the nutritional status of the colony. Also, these cell clusters are differentially expressed among worker subcastes, suggesting the sNPF/sNPFR pathway could be associated with mechanisms of division of labor. To discover where sNPF is synthesized, we attempted to localize the sNPF-expressing cells in the brain of queens and workers through in situ hybridization, unfortunately without success; thus, the site of synthesis of sNPF in the brain still remains unknown. Finally, we tried to elucidate the role of the sNPFR in social context by silencing its gene expression trough feeding of dsRNA using small laboratory colonies. We found differential effects when delivering the sNPFR-dsRNA through heat-killed dsRNA-producing bacteria or by delivering dsRNA purified from these bacterial cultures. Also, the type of food used as carrier and the concentration of dsRNA were crucial for gene silencing success. Our results showed that feeding a large concentration of dsRNA in liquid and solid foods is required to induce RNAi in the queen midgut; and that the silencing of the sNPFR in this organ did not induce mortality in these queens, but instead it appears to increase larval mortality. In summary, our results are consistent with the sNPF/sNPFR signaling pathway in fire ants being involved in the regulation of division of labor and in sensing the nutritional status, and suggest its function is fundamental for larval development

    The Red Imported Fire Ant (<i>Solenopsis invicta</i> Buren) Kept Y not F: Predicted sNPY Endogenous Ligands Deorphanize the Short NPF (sNPF) Receptor

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    <div><p>Neuropeptides and their receptors play vital roles in controlling the physiology and behavior of animals. Short neuropeptide F (sNPF) signaling regulates several physiological processes in insects such as feeding, locomotion, circadian rhythm and reproduction, among others. Previously, the red imported fire ant (<i>Solenopsis invicta</i>) sNPF receptor (<i>S. invicta</i> sNPFR), a G protein-coupled receptor, was immunolocalized in queen and worker brain and queen ovaries. Differential distribution patterns of <i>S. invicta</i> sNPFR protein in fire ant worker brain were associated both with worker subcastes and with presence or absence of brood in the colony. However, the cognate ligand for this sNPFR has not been characterized and attempts to deorphanize the receptor with sNPF peptides from other insect species which ended in the canonical sequence LRLRFamide, failed. Receptor deorphanization is an important step to understand the neuropeptide receptor downstream signaling cascade. We cloned the full length cDNA of the putative <i>S. invicta</i> sNPF prepropeptide and identified the putative “sNPF” ligand within its sequence. The peptide ends with an amidated Tyr residue whereas in other insect species sNPFs have an amidated Phe or Trp residue at the C-terminus. We stably expressed the HA-tagged <i>S. invicta</i> sNPFR in CHO-K1 cells. Two <i>S. invicta</i> sNPFs differing at their N-terminus were synthesized that equally activated the sNPFR, SLRSALAAGHLRYa (EC<sub>50</sub> = 3.2 nM) and SALAAGHLRYa (EC<sub>50</sub> = 8.6 nM). Both peptides decreased the intracellular cAMP concentration, indicating signaling through the G<sub>αi</sub>-subunit. The receptor was not activated by sNPF peptides from other insect species, honey bee long NPF (NPY) or mammalian PYY. Further, a synthesized peptide otherwise identical to the fire ant sequence but in which the C-terminal amidated amino acid residue ‘Y’ was switched to ‘F’, failed to activate the sNPFR. This discovery will now allow us to investigate the function of sNPY and its cognate receptor in fire ant biology.</p></div
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