Identification and characterization of two sensory neuron membrane proteins from Cnaphalocrocis medinalis...

Sensory neuron membrane proteins (SNMPs), which are located on the dendritic membrane of olfactory neurons, were considered as important components involved in pheromone reception in insects. In Drosophila melanogaster, mutants without SNMP are unable to evoke neuronal activities in the presence of pheromone cis-vaccenyl acetate (cVA). So deeply understanding the SNMPs functions may help to develop pheromone-mediated insect pest management tactics. The present study reports the identification and characterization of CmedSNMP1 and CmedSNMP2, two candidate SNMPs in the rice leaffolder, Cnaphalocrocis medinalis, one of the serious rice insect pests in Asia. The comparison of amino acid sequences shows that CmedSNMP1 and CmedSNMP2 are very similar to the previously reported SNMPs isolated from moths such as Ostrinia nubilalis and O. furnacalis, respectively, but the two CmedSNMPs share low identity with each other. The distribution patterns of two CmedSNMPs in different tissues of adult moths were examined using RT-PCR and quantitative real-time PCR. Although the two genes are expressed not only in antennae but also in nonolfactory tissues such as wings, legs, and body; the relative transcription level shows both CmedSNMP1 and CmedSNMP2 are highly enriched in antennae. The dN/dS ratios of the two CmedSNMPs indicate that the two genes are all subject to purifying selection and evolved to be functional genes. This work presents for the first time a study on the SNMPs of C. medinalis, which may help in providing guidance to future functional research of moth SNMPs.