Dietary choline prevents high fat-induced disorder of hepatic cholesterol metabolism through SREBP-2/HNF-4α/CYP7A1 pathway in a freshwater teleost yellow catfish Pelteobagrus fulvidraco

The transcription factors HNF-4α and NF-κB activate the CDO gene to promote taurine biosynthesis in the golden pompano Trachinotus ovatus (Linnaeus 1758)

Cysteine dioxygenase (CDO) is a rate-limiting enzyme in taurine biosynthesis. Taurine synthesis is limited in marine fish, and most taurine is provided by their diet. Although a nutritional study indicated that the transcription of ToCDO was significantly altered by treatment with 10.5 g/kg taurine in food, the regulatory mechanism of this biosynthesis has not been fully elucidated. In the present study, we identified the sequence features of Trachinotus ovatus cysteine dioxygenase (ToCDO), which consists of 201 amino acids. It is characterized by being a member of the cupin superfamily with two conserved cupin motifs located at amino acids 82-102 and 131-145 and with a glutamate residue substituted by a cysteine in its first motif. Moreover, phylogenetic analysis revealed that the similarity of the amino acid sequences between ToCDO and other species ranged from 84.58 % to 91.54 %. Furthermore, a high-performance liquid-phase assay of the activity of recombinantly purified ToCDO protein showed that ToCDO could catalyse the oxidation of cysteine to produce cysteine sulphite. Furthermore, the core promoter region of CDO was identified as -1182∼+1 bp. Mutational analysis revealed that the HNF4α and NF-κB sites significantly and actively affected the transcription of CDO. To further investigate the binding of these two loci to the CDO promoter, an electrophoretic shift assay (EMSA) was performed to verify that HNF4α-1 and NF-κB-1 interact with the binding sites of the promoter and promote CDO gene expression, respectively. Additionally, cotransfection experiments showed that HNF4α or both HNF4α and NF-κB can significantly influence CDO promoter activity, and HNF4α was the dominant factor. Thus, HNF4α and NF-κB play important roles in CDO expression and may influence taurine biosynthesis within T. ovatus by regulating CDO expression.

Whole grain germinated brown rice intake modulates the gut microbiota and alleviates hypertriglyceridemia and hypercholesterolemia in high fat diet-fed mice

Hyperlipidemia is a common clinical disorder of lipid metabolism in modern society and is considered to be one of the major risk factors leading to cardiovascular-related diseases. Germinated brown rice (GBR) is a typical whole grain food. The lipid-lowering effect of GBR has received increasing attention, but its mechanism of action is not fully understood. The gut microbiota has been proposed as a novel target for the treatment of hyperlipidemia. The aim of this study was to investigate the effects of GBR on the gut microbiota and lipid metabolism in high-fat diet (HFD)-fed C57BL/6J mice. The effect of GBR on hyperlipidemia was evaluated by measuring blood lipid levels and by pathological examination. The gut microbiota was detected by 16S rRNA sequencing, and the protein and mRNA expression levels involved in cholesterol metabolism were detected by western blotting and RT-qPCR to find potential correlations. The results showed that GBR supplementation could effectively reduce the levels of TC, TG, LDL-C and HDL-C in the serum and alleviate the excessive accumulation of fat droplets caused by HFD. Moreover, GBR intervention improved HFD-fed gut microbiota disorder via increasing the diversity of the gut microbiota, reducing the Firmicutes/Bacteroidetes ratio, and improving gut barrier damage. In addition, GBR could inhibit endogenous cholesterol synthesis and promote cholesterol transport and excretion. These findings suggest that GBR may be a competitive candidate for the development of functional foods to prevent abnormal lipid metabolism.

Insight into the differences of meat quality between Qinghai white Tibetan sheep and black Tibetan sheep from the perspective of metabolomics and rumen microbiota

The purpose of this study was to investigate the differences in meat quality between two local breeds of Tibetan sheep, the White Tibetan sheep and the Black Tibetan sheep in Qinghai, and to search for metabolic mechanisms that produce meat quality differences by analyzing differential metabolites and key rumen microorganisms. The meat quality results showed that one breed, SG73, was superior to the other (WG). Further investigation identified differences in the composition of muscle metabolites and rumen microorganisms between the two Tibetan sheep breeds. It also regulates muscle tenderness, water retention, fat content and the composition and content of AA and FA through two major metabolic pathways, AA metabolism and carbohydrate metabolism. These findings could be beneficial for the development of breeding strategies for Tibetan sheep in Qinghai in the future.