Approximately 2.5% of young children are allergic to cow milk. In this study, milk protein hydrolysates made from full-cream milk via enzymatic hydrolysis played a positive role in regulating the immune system of ICR mice. Milk protein hydrolysates enhanced immunity in mice by stimulating host immunity, probably by increasing the weight of certain immune system organs, improving the level of hemolysin in serum, and enhancing the phagocytosis of macrophages. Milk protein hydrolysates have the capability to reduce type I hypersensitivity by decreasing IgE levels, IL-4 in serum, and the release of histamine and bicarbonate in peritoneal mast cells, as well as enhancing transforming growth factor-β levels in the serum of ovalbumin-sensitized mice.

Taurine is usually included in fish feed as a nutritional supplement, and it can also improve feed performance. To assess the potential use of taurine as a feed attractant in plant protein-based diets, we examined four different concentrations of taurine to determine the optimal levels for attracting large yellow croaker (Larimichthys crocea). The fish displayed the most significant attractive responses to 3.5% taurine and showed good feed performance with an all-plant protein diet supplying 3.5% taurine. Next, deep sequencing of the olfactory epithelium was conducted to identify genes differentially expressed in the taurine group (Tau) versus controls.We found that 11,793 unigenes were differentially expressed: 10,795 were upregulated and 998 were down-regulated unigenes. We detected 77 olfactory receptor genes, including 37 up-regulated unigenes, and validated the expression dynamics of eight genes using quantitative reverse transcription-PCR (RT-qPCR). We utilized Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) to analyse the function of the differentially expressed genes, which were mainly involved in signaling and cell communication (GO) and olfactory transduction (KEGG). Cumulatively, our results indicate that taurine could be a good phagostimulant for plant protein-based diets for L. crocea. Furthermore, improved understanding via olfactory epithelium transcriptomic analysis would inform the development of an all-plant protein diet for L. crocea. K E Y W O R D S all-plant protein diets, Larimichthys crocea, olfactory-related genes, taurine, transcriptomic analysis for Zhejiang Marine High-Efficiency and

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Fish produce and release bile salts as chemical signalling substances that act as sensitive olfactory stimuli. To investigate how bile salts affect olfactory signal transduction in large yellow croaker (Larimichthy crocea), deep sequencing of olfactory epithelium was conducted to analyse olfactory-related genes in olfactory transduction. Sodium cholates (SAS) have typical bile salt chemical structures, hence we used four different concentrations of SAS to stimulate L. crocea, and the fish displayed a significant behavioural preference for 0.30% SAS. We then sequenced olfactory epithelium tissues, and identified 9938 unigenes that were significantly differentially expressed between SAS-stimulated and control groups, including 9055 up-regulated and 883 down-regulated unigenes. Subsequent Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses found eight categories linked to the olfactory transduction pathway that was highly enriched with some differentially expressed genes (DEGs), including the olfactory receptor (OR), Adenylate cyclase type 3 (ADCY3) and Calmodulin (CALM). Genes in these categories were analysed by RT-qPCR, which revealed aspects of the pathway transformation between odor detection, and recovery and adaptation. The results provide new insight into the effects of bile salt stimulation in olfactory molecular mechanisms in fishes, and expands our knowledge of olfactory transduction, and signal generation and decline.