Submitted to: Developmental and Comparative Immunology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/21/2013
Publication Date: 12/28/2013
Citation: Li, C., Beck, B.H., Peatman, E. 2014. Nutritional impacts on gene expression in the surface mucosa of blue catfish (Ictalurus furcatus). Developmental and Comparative Immunology. 44(1):226-234. Interpretive Summary: Short-term feed deprivation (or fasting) is a common occurrence in farmed fish species and can be brought about by seasonal changes, production strategies, or as a means to combat certain disease outbreaks. Fasting can have serious consequences on fish health including increasing the susceptibility of fish to diseases such as columnaris disease, a highly lethal disease that plagues the catfish industry. Culture and selection of blue catfish (Ictalurus furcatus) has gained importance as the production of the channel catfish x blue catfish (I. punctatus x I. furcatus) hybrid has increased substantially in recent years in the Southeastern US. However, very little is known about the immune system of the blue catfish, and how the immune system responds to periods of fasting. In the present study, we examined changes at the genetic level in the gill and skin of blue catfish 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 500 genes. Many of these genes were involved in the immune response, mucus production, and metabolism. These findings suggest that fasted fish may have an impaired immune system which may lead to an increased susceptibility to disease. These findings enhance our understanding of the effects of fasting on the immune system of blue catfish, and will ultimately help catfish producers better manage feeding regimens and disease outbreaks on farms.
Technical Abstract: Short-term feed deprivation is a common occurrence in both wild and farmed fish species, due to reproductive processes, seasonal variations in temperature, or in response to a disease outbreak. Fasting can have dramatic physiological and biological onsequences for fish, including impacts on mucosal immunity which can, in turn, change host susceptibility to pathogens. Culture and selection of blue catfish (Ictalurus furcatus) has gained importance as the production of a channel catfish x blue catfish (I. punctatus x I. furcatus) hybrid has increased in the Southeast US. Following a recent examination of fasting-induced impacts on mucosal immunity in channel catfish, here we utilized Illumina-based RNA-seq expression profiling to compare changes in blue catfish gill and skin after a brief (7 day) period of fasting. Transcriptome sequencing and de novo assembly of over 194 million 100 base-pair transcript reads was followed by differential expression analysis. Fasting altered a total of 530 genes in the surface mucosa, including genes regulating the immune response, energy metabolism, mucus production, cellular cytoskeletal structure, cell proliferation, and antioxidant responses. In particular, fasting perturbed arginine synthesis and metabolism pathways in a manner likely altering macrophage activation states and immune readiness. Our findings highlight key mediators of the critical interaction between nutrition and immunity at points of pathogen adherence and entry.