Effect of an Established Nutritional Level of Selenium on Energy Metabolism and Gene Expression in the Liver of Rainbow Trout.

The nutritional selenium (Se) has been demonstrated to have health-boosting effects on fish. However, its effect on fish energy metabolism remains unclear. This study explores the effect and underlying mechanism of the action of nutritional Se on energy metabolism in fish. Rainbow trout (Oncorhynchus mykiss) were fed a basal diet (0 mg Se/kg diet) and a diet containing an already established nutritional Se level (2 mg Se/kg diet, based on Se-yeast) for 30 days. After the feeding experiment, the plasma and liver biochemical profiles and liver transcriptome were analyzed. The results showed that the present nutritional level of Se significantly increased liver triglyceride, total cholesterol, and plasma total cholesterol contents (P < 0.05) compared with the control. Transcriptome analysis showed that 336 and 219 genes were significantly upregulated and downregulated, respectively. Gene enrichment analysis showed that many differentially expressed genes (DEGs) were associated with lipid metabolism pathways (fatty acid biosynthesis, fatty acid elongation, and unsaturated fatty acid biosynthesis), carbohydrate metabolism pathways (glycolysis, the pentose phosphate pathway, and the citrate cycle), and the oxidative phosphorylation pathway. Real-time quantitative PCR (Q-PCR) validation results showed that the expression profiles of 15 genes exhibited similar trends both in RNA sequencing (RNA-seq) and Q-PCR analysis. These results reveal that optimum dietary Se activates glucose catabolic processes, fatty acid biosynthetic processes, and energy production and hence produces higher liver lipid content. This study concludes that the previously established level of nutritional Se (Se-yeast) (2 mg/kg diet, fed basis) for rainbow trout promotes energy storage in the liver, which may benefit fish growth to some extent.

Dietary Selenium Promotes Somatic Growth of Rainbow Trout (Oncorhynchus mykiss) by Accelerating the Hypertrophic Growth of White Muscle.

As a nutritionally essential trace element, selenium (Se) is crucial for fish growth. However, the underlying mechanisms remain unclear. Fish somatic growth relies on the white muscle growth. This study aimed to explore the effects and underlying mechanisms of Se on fish white muscle growth using a juvenile rainbow trout (Oncorhynchus mykiss) model. Fish were fed a basal diet unsupplemented or supplemented with selenium yeast at nutritional dietary Se levels (2 and 4 mg/kg Se, respectively) for 30 days. Results showed that dietary Se supplementation significantly enhanced trout somatic growth. Histological and molecular analysis of trout white muscle tissues at the vent level showed that dietary Se supplementation elevated the total cross-sectional area of white muscle, mean diameter of white muscle fibers, protein content, nuclei number, and DNA content of individual muscle fiber, and suppressed the activities of calpain system and ubiquitin-proteasome pathway. Overall, this study demonstrated that dietary Se within the nutritional range inhibits calpain- and ubiquitin-mediated protein degradation and promotes the fusion of myoblasts into the existed muscle fibers to promote the hypertrophic growth of white muscle, thereby accelerating the somatic growth of rainbow trout. Our results provide a mechanistic insight into the regulatory role of Se in fish growth.

Effect of dietary selenium on postprandial protein deposition in the muscle of juvenile rainbow trout (Oncorhynchus mykiss).

Se, an essential biological trace element, is required for fish growth. However, the underlying mechanisms remain unclear. Protein deposition in muscle is an important determinant for fish growth. This study was conducted on juvenile rainbow trout (Oncorhynchus mykiss) to explore the nutritional effects of Se on protein deposition in fish muscle by analysing the postprandial dynamics of both protein synthesis and protein degradation. Trout were fed a basal diet supplemented with or without 4 mg/kg Se (as Se yeast), which has been previously demonstrated as the optimal supplemental level for rainbow trout growth. After 6 weeks of feeding, dietary Se supplementation exerted no influence on fish feed intake, whereas it increased fish growth rate, feed efficiency, protein retention rate and muscle protein content. Results of postprandial dynamics (within 24 h after feeding) of protein synthesis and degradation in trout muscle showed that dietary Se supplementation led to a persistently hyperactivated target of rapamycin complex 1 pathway and the suppressive expression of numerous genes related to the ubiquitin-proteasome system and the autophagy-lysosome system after the feeding. However, the ubiquitinated proteins and microtubule-associated light chain 3B (LC3)-II:LC3-I ratio, biomarkers for ubiquitination and autophagy activities, respectively, exhibited no significant differences among the fish fed different experimental diets throughout the whole postprandial period. Overall, this study demonstrated a promoting effect of nutritional level of dietary Se on protein deposition in fish muscle by accelerating postprandial protein synthesis. These results provide important insights about the regulatory role of dietary Se in fish growth.

A comparison of accumulation and depuration effect of dissolved hexavalent chromium (Cr6+) in head and muscle of bighead carp (Aristichthys nobilis) and assessment of the potential health risk for consumers.

In this study, bighead carp (Aristichthys nobilis) were exposed to waterborne Cr6+ of 0.01, 0.1, 1 and 5 mg/L for 14 days and subsequently transferred to clean water for another 14 days. The Cr6+ contents in some edible parts, such as dorsal muscle, ventral muscle and head were detected. The Cr6+ concentrations in the three parts were in the order of: head > ventral muscle > dorsal muscle with significant increase during exposure period and remarkable decrease when kept at clean water during depuration stage. The head contained higher fat than that of muscle and the Cr6+ levels of these parts showed significantly positive correlation with fat content, however, the Cr6+ contents in the separated fat were extremely low. The Cr6+ levels determined in tissues can tell a real story rather than the correlation coefficient. Fish head poses a higher potential health risk than muscle due to heavy metals pollution.

Arginine affects growth and integrity of grass carp enterocytes by regulating TOR signaling pathway and tight junction proteins.

Dietary arginine (Arg) could improve the intestinal structure and absorption of grass carp (Ctenopharyngodon idellus); however, the mechanism of Arg on intestinal morphology improvement was unclear. The present study aimed to explain the possible mechanism of the positive effect of Arg on intestinal epithelial cells of grass carp. An in vitro study was conducted through a primary culture model to assess the growth, cell viability, mRNA expressions of TOR signal pathway, and tight junction proteins of enterocytes after culture in the medium with 6 levels of Arg (0, 0.1, 0.2, 0.5, 1.0, and 2.0 mmol/L). The results showed that 0.5 mmol/L Arg improved the cell number and decreased the lactate dehydrogenase and creatine kinase activities in culture medium (P < 0.05). The alkaline phosphatase activity in cell lysis buffer was depressed by 1 and 2 mmol/L Arg (P < 0.05). The nitric oxide (NO) content showed an increasing trend with the Arg content (P < 0.05), whereas the NO synthase activity showed an opposite trend to NO. TOR expression was higher in 0.2 and 0.5 mmol/L groups, whereas S6K1 expression in 1.0 mmol/L and 2.0 mmol/L groups were lower (P < 0.05). The mRNA expressions of occludin, claudin 3, and claudin c in 0.5 mmol/L group were the highest, while ZO-1 and claudin b expressions were higher in 0.2 and 0.5 mmol/L groups (P < 0.05). This study indicated that Arg enhanced the growth and integrity of intestinal epithelial cells of grass carp through upregulation of mRNA expression of TOR signal pathway and tight junction proteins at an optimal Arg content of 0.2-0.5 mmol/L.

[Clinical Efficacy of L-Asparaginasum Combined with CHOP for Treating Patients with Extranodal Natural Killer/T Cell Lymphoma].

OBJECTIVE: To investigate the clinical efficacy of L-asparginasum, ASP) combined with CHOP for treating patients with extranodal natural killer/T-cell lymphoma. METHODS: A total of 68 patients with extranodal natural killer/T-cell lymphoma in our hospital from August 2007 to May 2009 were enrolled in this study, out of them 34 patients received CHOP regimen (CHOP group) and other 34 patients received CHOP regimen combined with L-Asparaginasum (ASP+CHOP group). The clinical efficacy of both groups was analyzed and compared after treatment. RESULTS: In CHOP group 16 patients achieved CR+PR, the total remission rate (TRR) was 47.06%; in ASP+CHOP group 24 patients achieved CR+PR, the TRR was 70.58%, and the TRR in ASP+CHOP group was higher than that in CHOP group, there was statistical significance between these 2 groups (X(2) = 3.886, P < 0.05). The time of PFS in CHOP group was 24.7 months, and the time of PFS in ASP+CHOP group was 47.5 months which was significantly longer than that in CHOP group, and there was statistical siguificance between these 2 groups (P < 0.05). The incidence of anemia with grade I-II and III-IV blood cell reduction in ASP+CHOP group was higher than that in CHOP group (P < 0.05). The incidence of fever with grade I-II and albumin decrease in ASP+CHOP group was higher than that in CHOP group (P < 0.05). The abnormality of coagulation function in ASP+CHOP group was higher than that in CHOP group (P < 0.05). The anaphylactic reaction was found in 6 cases. The increase of serum amylase was observed in 1 case of aggressive NK/T cell lymphoma, the acute pancreatitis occured in 1 case who was inproved after treatment, but this patients died due to rapid progression of disease caused by poor general condition and untolerance to chemotherapy. The incomplete intestinal obstruction was found in 3 patients who recovered after conservative treatment. The grade II serum creatinine was elevated in 2 cases of ASP+CHOP group and in 1 case of CHOP group who was inproved after symptomatic therapy. CONCLUSION: L-Asparaginasum combined with CHOP for treating patients with extranodal natural killer/T-cell lymphoma is effective, and may be used in clinic.

[Effects of salvianolate on cardiomyocytes apoptosis and heart function in a swine model of acute myocardial infarction].

OBJECTIVE: To observe the effects of salvianolate on cardiomyocytes apoptosis and heart function in a swine model of acute myocardial infarction (AMI). METHODS: A total of 21 young swine were randomly divided into untreated group, low-dose salvianolate (LS) group and high-dose salvianolate (HS) group (7 in each group). AMI was induced by ligaturing left anterior descending coronary artery. After the operation, 400 or 200 mg salvianolate dissolved in 250 mL 5% glucose saline was administered by intravenous drip to swine in the HS group and the LS group respectively for 7 days. The swine in the untreated group were administered with 250 mL 5% glucose saline. The left ventricular ejection fraction (LVEF) and myocardial perfusion were measured by gated myocardial perfusion imaging at the end of the 4th week after operation. And myocardial apoptosis was detected by TdT-mediated dUTP-biotin nick end labeling (TUNEL) method. Apoptosis index was calculated under an optical microscope. RESULTS: Myocardial apoptotic index in the edge of myocardial infarction was decreased in the HS group and the LS group, which in the HS group was lower than that in the untreated group (P<0.05). Radioactive defect regions were found by gated myocardial perfusion imaging in all the three groups, but those in the HS group and the LS group were less than those in the untreated group (P<0.05). And the levels of myocardial perfusion and LVEF in the HS group were significantly higher than those in the untreated group (P<0.05). CONCLUSION: Salvianolate administered by intravenous drip can inhibit the cardiomyocytes apoptosis and improve the function of heart after AMI in swine.