Identification and characterisation of ROS modulator 1 in Lampetra japonica

•An evolutionarily conserved Romo1 gene was identified in Lampetra japonica.•The level of Lj-Romo1 mRNA was markedly up-regulated after stimulation by LPS.•Lj-Romo1 was localised to the mitochondria and can increase the ROS level in cells.•Romo1 plays important role in innate immune responses in lamprey.

Reactive oxygen species (ROS) are a heterogeneous group of highly reactive molecules that oxidise targets in biological systems. ROS are also considered important immune regulators. In this study, we identified a homologue of reactive oxygen species modulator 1 (Romo1) in the Japanese lamprey (Lampetra japonica). The L japonica Romo1 (Lj-Romo1) gene shares high sequence homology with the Romo1 genes of jawed vertebrates. Real-time quantitative PCR demonstrated the wide distribution of Lj-Romo1 in lamprey tissues. Furthermore, after the lampreys were stimulated with lipopolysaccharide (LPS), the level of Lj-Romo1 mRNA was markedly up-regulated in the liver, gill, kidney, and intestine tissues. Lj-Romo1 was localised to the mitochondria and has the capacity to increase the ROS level in cells. The results obtained in the present study will help us to understand the roles of Romo1 in ROS production and innate immune responses in jawless vertebrates.