Submitted to: PLoS One
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/6/2013
Publication Date: 9/4/2013
Citation: Liu, L.G., Li, C., Su, B., Beck, B.H., Peatman, E. 2013. Short-term feed deprivation alters immune status of surface mucosa in channel catfish (Ictalurus punctatus). PLoS One. 8(9):e74581. doi:10.1371/journal.pone.0074581.t004. Interpretive Summary: Short-term feed deprivation (or fasting) is a common occurrence in aquacultured fish species and can be brought about by seasonal changes, production strategies, or as a means to combat certain disease outbreaks. In channel catfish, periods of fasting seem to increase the susceptibility of fish to columnaris disease (caused by the bacterium Flavobacterium columnare). Because columnaris primarily affects the gill and skin, we examined changes at the genetic level in these tissues in fish that were subjected to a 7 day period of fasting. In comparison to fish fed daily, fasted fish showed changes in the levels of over 1,500 genes. Many of these changes involved a decrease in the levels of important genes of the immune system and suggest that fasted fish may have impaired immunity which leads to an increased susceptibility to disease. These findings enhance our understanding of the effects of fasting on the immune system of channel catfish, and will ultimately help catfish producers reduce costly losses to columnaris disease.
Technical Abstract: Short-term feed deprivation (or fasting) is a common occurrence in aquacultured fish species whether due to season, production strategies, or disease. In channel catfish (Ictalurus punctatus) fasting impacts susceptibility to several bacterial pathogens including Flavobacterium columnare, the causative agent of columnaris disease. As columnaris gains entry through the gills and skin of fish, we examined here changes in transcriptional regulation induced in these surface mucosal tissues due to short-term (7 day) fasting. RNA-seq expression analysis revealed a total of 1,545 genes perturbed by fasting. Fasting significantly altered expression of critical innate immune factors in a manner consistent with lower immune fitness as well as dysregulating key genes involved in energy metabolism and cellcycling/proliferation. Downregulation of innate immune actors such as iNOS2b Lysozyme C, and peptidoglycan recognition protein 6 is predicted to impact the delicate recognition/tolerance balance for commensal and pathogenic bacteria on the skin and gill. The highlighted expression profiles reveal potential mechanistic similarities between gut and surface mucosa and underscore the complex interrelationships between nutrition, mucosal integrity, and immunity in teleost fish.