RNA Taste Is Conserved in Dipteran Insects.

Area of Science:

• Insect biology
• Molecular evolution
• Sensory neuroscience

Background:

• Ribonucleosides and RNA are vital nutrients for insect larval development.
• The Gr28 gene family encodes taste receptors essential for detecting these nutrients in Drosophila.
• These receptors are among the most conserved insect taste receptor subfamilies.

Purpose of the Study:

• To investigate RNA and ribose taste perception in blow fly and mosquito larvae.
• To determine if mosquito Gr28 homologs can function as RNA receptors when expressed in Drosophila.
• To understand the evolutionary origins of RNA taste sensing in insects.

Main Methods:

• Utilized a 2-choice preference assay adapted for blow fly larvae.
• Developed a novel aquatic 2-choice preference assay for mosquito larvae.
• Identified and expressed Gr28 homologs from mosquitoes in transgenic Drosophila larvae.

Main Results:

• Blow fly larvae (Cochliomyia macellaria, Lucilia cuprina) showed strong attraction to RNA.
• Aedes aegypti mosquito larvae exhibited a significant preference for RNA in aquatic assays.
• Expressing mosquito Gr28 homologs rescued RNA and ribose preference in Drosophila lacking their own Gr28 genes.

Conclusions:

• The ability to taste RNA and ribonucleosides evolved approximately 260 million years ago, coinciding with the divergence of mosquitoes and fruit flies.
• Conserved RNA taste receptors suggest RNA is a critical nutrient for rapidly growing insect larvae.
• This conserved sensory mechanism highlights the evolutionary importance of RNA as a nutrient source for insects.