Proteomics and Its Combined Analysis with Transcriptomics: Liver Fat-Lowering Effect of Taurine in High-Fat Fed Grouper (Epinephelus coioides).

In order to understand the intervention effect of taurine on liver fat deposition induced by high fat intake in the orange-spotted grouper (Epinephelus coioides), we performed proteomic analysis and association analysis with previously obtained transcriptomic data. Three isoproteic (47% crude protein) diets were designed to contain two levels of fat and were named as the 10% fat diet (10F), 15% fat diet (15F), and 15% fat with 1% taurine (15FT). The 10F diet was used as the control diet. After 8 weeks of feeding, the 15F diet exhibited comparable weight gain, feed conversion ratio, and hepatosomatic index as the 10F diet, but the former increased liver fat content vs. the latter. Feeding with the 15FT diet resulted in an improvement in weight gain and a reduction in feed conversion ratio, hepatosomatic index, and liver fat content compared with feeding the 15F diet. When comparing liver proteomic data between the 15F and 15FT groups, a total of 133 differentially expressed proteins (DEPs) were identified, of which 51 were upregulated DEPs and 82 were downregulated DEPs. Among these DEPs, cholesterol 27-hydroxylase, phosphatidate phosphatase LPIN, phosphatidylinositol phospholipase C, and 6-phosphofructo-2-kinase were further screened out and were involved in primary bile acid biosynthesis, glycerolipid metabolism, the phosphatidylinositol signaling system, and the AMPK signaling pathway as key DEPs in terms of alleviating liver fat deposition of taurine in high-fat fed fish. With the association analysis of transcriptomic and proteomic data through KEGG, three differentially expressed genes (atp1a, arf1_2, and plcd) and four DEPs (CYP27α1, LPIN, PLCD, and PTK2B) were co-enriched into five pathways related to fat metabolism including primary bile acid synthesis, bile secretion, glycerolipid metabolism, phospholipid D signaling, or/and phosphatidylinositol signaling. The results showed that dietary taurine intervention could trigger activation of bile acid biosynthesis and inhibition of triglyceride biosynthesis, thereby mediating the liver fat-lowering effects in high-fat fed orange-spotted grouper. The present study contributes some novel insight into the liver fat-lowering effects of dietary taurine in high-fat fed groupers.

Hepatic Transcriptome Analysis Provides New Insight into the Lipid-Reducing Effect of Dietary Taurine in High-Fat Fed Groupers (Epinephelus coioides).

A transcriptome analysis was conducted to provide the first detailed overview of dietary taurine intervention on liver lipid accumulation caused by high-fat in groupers. After an eight-week feeding, the fish fed 15% fat diet (High-fat diet) had higher liver lipid contents vs. fish fed 10% fat diet (Control diet). 15% fat diet with 1% taurine (Taurine diet) improved weight gain and feed utilization, and decreased hepatosomatic index and liver lipid contents vs. the High-fat diet. In the comparison of the Control vs. High-fat groups, a total of 160 differentially expressed genes (DEGs) were identified, of which up- and down-regulated genes were 72 and 88, respectively. There were 49 identified DEGs with 26 and 23 of up- and down-regulated in the comparison to High-fat vs. Taurine. Several key genes, such as cysteine dioxygenase (CDO1), ADP-ribosylation factor 1/2 (ARF1_2), sodium/potassium-transporting ATPase subunit alpha (ATP1A), carnitine/acylcarnitine translocase (CACT), and calcium/calmodulin-dependent protein kinase II (CAMK) were obtained by enrichment for the above DEGs. These genes were enriched in taurine and hypotaurine metabolism, bile secretion, insulin secretion, phospholipase D signaling pathway, and thermogenesis pathways, respectively. The present study will also provide a new insight into the nutritional physiological function of taurine in farmed fish.

Microbial Quality of Ready-to-Eat Foods Sold in School Cafeterias in Chongqing, China.

ABSTRACT: The microbiological quality of ready-to-eat (RTE) foods from school cafeterias in Chongqing, People's Republic of China, was evaluated and compared with a guideline published by a provincial health commission. These RTE foods were divided into five types based on their preparation processes and potential risks: 1, general cooked and hot-held foods; 2, cooked meats; 3, heated aquatic products; 4, fresh fruits or vegetables; and 5, cooked foods with postcooking handling (e.g., cutting, cooling, or addition of ingredients or condiments). Food types 1 through 3 (subjected to thermal processes and hot-held) were microbiologically safer than types 4 and 5 (prepared by nonthermal process or with postcooking processes). None of the samples of types 1 through 3 were unsatisfactory based on their aerobic plate counts (APC) and total coliforms (TC), whereas 43.1% of type 4 and 8.3 and 71.7% of type 5 samples were unsatisfactory due to high counts of TC and high APC and TC, respectively. Two, 12, and 50 samples of types 2, 4, and 5, respectively, were unacceptable due to high levels of Staphylococcus aureus. Bacillus cereus and Vibrio parahaemolyticus were detected, but levels were below the unacceptable limits. None of the samples were positive for Salmonella, Listeria monocytogenes, or Escherichia coli O157. The bacterial profile can be used by policy makers and epidemiologists for microbiological risk assessments, which may be conducive to developing interventions to control hazards, improve food hygiene, and develop safety management systems for school cafeterias in China.