Bio-Mos®: An effective inducer of dicentracin gene expression in European sea bass (Dicentrarchus labrax)

Concern over the use of dietary antibiotics in aquaculture has encouraged the industry to search for alternatives that both enhance performance and afford protection from disease. Bio-Mos®, derived from the outer cell wall of a specific strain of yeast Saccharomyces cerevisiae (Alltech Inc, USA) is a product that fits these criteria. Here, we present data on the impact of a Bio-Mos® supplemented diet on the mRNA copy number of the antimicrobial peptide dicentracin, whose transcript regulation has not yet been explored in fish. We analyzed Bio-Mos®-induced changes in the expression of sea bass (Dicentrarchus labrax) dicentracin, using a one-tube two-temperature real-time RT-PCR with which the gene expression can be absolutely quantified using the standard curve method. Our results revealed that 30 days of feeding fish with diets containing Bio-Mos® supplemented at either 3‰ or 5‰ significantly increased the dicentracin mRNA copy number in the head kidney. Furthermore, the mRNA copy number in fish fed at 3‰ was significantly higher than that of the group fed at 5‰ for the same period of feeding Bio-Mos®. A longer feeding period (60 days) did not further increase the dicentracin transcript levels as compared to the values recorded after 30 days of feeding either in the group fed at 3‰ or in the one fed at 5‰ diet. However, the transcript levels in fish fed at 3‰ proved to be significantly higher than those of the controls after 60 days of feeding. These findings offer new information about the response of antimicrobial peptides at the transcriptional level to diets supplemented with immune response modulators, and support a role of Bio-Mos® in promoting sea bass nonspecific immune system.