Identification and characterization of a novel nuclear noncoding RNA, Fben-1, which is preferentially expressed in the higher brain center of the female silkworm moth, Bombyx mori.

Sexually dimorphic neural circuits are essential for the reproductive behavior. The molecular basis underling the sexual dimorphism, however, is still elusive in the brains of insects. To identify genes with sex-differential expression in the brain of silkworm moths, we performed fluorescent differential display screening and identified a novel gene, termed Fben-1 (Female-brain expressed noncoding RNA-1), whose expression is preferential to the female brain. Fben-1 cDNA sequences contained no significant open-reading frames and comprised a sex-differential transcript composition. Expression of Fben-1 was developmentally regulated and predominant in adult female moth brains. In situ hybridization revealed that Fben-1 is mainly expressed in the cells around the mushroom bodies, a higher brain center of the insect brain. In addition, Fben-1 transcripts were localized exclusively in the nuclei of these cells. This is the first report that a long nuclear noncoding RNA is expressed in a sex-differential manner in the higher center of insect brains. Our results suggest the possible involvement of nuclear noncoding RNA in sexually dimorphic brain functions.