A genomic survey on the immune differences among Sinocyclocheilus fishes

In our previous work, we reported comparative genomics studies on 3 Sinocyclocheilus fishes, including the surface-dwelling S. graham (Sg), the semi-cave-dewlling S. rhinocerous (Sr) and the cave-restricted S. anshuiensis (Sa). Here, we performed a genomic survey on the immunity differences among the 3 fishes by combination of the genome and transcriptome data. Our results demonstrate that immune-related genetic pathways in Sa and Sr present more similarities than Sg. The innate immune activity in Sa seems to be higher than Sg and Sr, while Sr owns more copy numbers of MHC-related genes (related with the acquired immune system) than Sg and Sa. These differential immune activities in the 3 Sinocyclocheilus species may be due to their differential habitats. Generally speaking, most immunity genes transcribe the lowest levels in Sa when compared with Sg and Sr, which may be associate with a less various microbial environment in the cave-restricted habitat. However, Sr has more members of MHC-related genes than those in Sg and Sa, suggesting a great contribution from the semi-cave-dwelling condition.