The effects of dietary leucine on the growth performances, body composition, metabolic abilities and innate immune responses in black carp Mylopharyngodon piceus.

The present study was focused on the growth, body composition, metabolic abilities and innate immune responses in juvenile black carp Mylopharyngodon piceus fed with six levels of dietary leucine (7.3, 12.4, 16.2, 21.9, 28.3 and 34.5 g kg-1) for 9 weeks. Results showed that the highest weight gain (WG) and the lowest feed conversion ratio (FCR) was obtained at 23.5 and 23.9 g kg-1 dietary leucine using second-order polynomial model, respectively. Adequate dietary leucine content (21.9 and 28.3 g kg-1) could significantly up-regulate the expression levels of neuropeptide Y (NPY) and ghrelin (GRL) in the brain of black carp juveniles. The protein efficiency ratio (PER), feed efficiency ratio (FER) and protein deposition ratio (PDR) were also significantly increased by adequate dietary leucine content (21.9 and 28.3 g kg-1) (p < 0.05). Adequate dietary leucine content (21.9 and 28.3 g kg-1) could significantly up-regulate the activities of metabolic enzymes, such as α amylase, trypsin, chymotrypsin and elastase in the liver of Black carp (p < 0.05). However, the activities of alanine transaminase (ALT), aspartate aminotransferase (AST) and leucine aminopeptidase (LAP) were significantly reduced in the fish serum by adequate dietary leucine content (21.9 and 28.3 g kg-1) compared with leucine-deficient diet (7.3 and 12.4 g kg-1). In addition, 21.9 and 28.3 g kg-1 dietary leucine could significantly increase complement component 3 (C3) and C4 contents, lysozyme (LYZ) activities in the serum compared with the leucine-deficient diet (7.3 and 12.4 g kg-1) (p < 0.05). Furthermore, optimal dietary leucine could also significantly up-regulate the mRNA expression levels of LYZ, interferon α (IFN-α), hepcidin (HEPC), natural resistance-associated macrophage protein (NRAMP), C3 and C9 in the blood of juvenile black carp compared with the leucine-deficient diets (7.3 and 12.4 g kg-1) (p < 0.05). In conclusion, these results suggest that adequate dietary leucine (21.9 and 28.3 g kg-1) could increase growth performances, improve metabolic abilities and then enhance non-specific immunities in black carp juveniles.

[Effects of PUVA on expression of Fas and FasL in inducing apoptosis of NB4 and K562 cells].

OBJECTIVE: To explore the effects of psoralen (PSO) and long wave ultraviolet A (PUVA) on expression of Fas and FasL in apoptosis of NB4 and K562 leukemia cells. METHODS: The NB4 and K562 cells were taken as the study objects and their apoptosis ratios, ultrastructure changes and the expression of Fas and FasL were detected in order to observe the effects of PSO and UVA of wave length 360 nm on human leukemia cells. The factorial design and analysis of variance were used to analyze the interaction among the factors. RESULTS: All of PSO, UVA and PUVA could induce the apoptosis of NB4 and K562 cells, and the effects of PUVA were stronger than the other two. After treated with PUVA, the NB4 and K562 cells all showed obvious ultrastruture changes about apoptsis under the electron microscope. All of PSO, UVA and PUVA could increase the expression of Fas gene and protein, and decrease the expression of FasL gene and protein. Moreover, the effects of PUVA were stronger than the other two. CONCLUSION: PUVA can induce the apoptosis of NB4 and K562 cells and the effects are the strongest, one of the pathway of PUVA to induce apoptosis is to upregulate the expression of Fas gene and downregulate the expression of FasL gene.