Association between type 2 diabetes mellitus and body composition based on MRI fat fraction mapping.

Purpose: To explore the association between type 2 diabetes mellitus (T2DM) and body composition based on magnetic resonance fat fraction (FF) mapping. Methods: A total of 341 subjects, who underwent abdominal MRI examination with FF mapping were enrolled in this study, including 68 T2DM patients and 273 non-T2DM patients. The FFs and areas of visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and abdominal muscle (AM) were measured at the level of the L1-L2 vertebral. The FF of bone marrow adipose tissue (BMAT) was determined by the averaged FF values measured at the level of T12 and L1 vertebral, respectively. The whole hepatic fat fraction (HFF) and pancreatic fat fraction (PFF) were measured based on 3D semi-automatic segmentation on the FF mapping. All data were analyzed by GraphPad Prism and MedCalc. Results: VAT area, VAT FF, HFF, PFF of T2DM group were higher than those of non-T2DM group after adjusting for age and sex (P < 0.05). However, there was no differences in SAT area, SAT FF, BMAT FF, AM area and AM FF between the two groups (P > 0.05). VAT area and PFF were independent risk factors of T2DM (all P < 0.05). The area under the curve (AUC) of the receiver operating characteristic (ROC) for VAT area and PFF in differentiating between T2DM and non-T2DM were 0.685 and 0.787, respectively, and the AUC of PFF was higher than VAT area (P < 0.05). Additionally, in seemingly healthy individuals, the SAT area, VAT area, and AM area were found to be significantly associated with being overweight and/or obese (BMI ≥ 25) (all P < 0.05). Conclusions: In this study, it was found that there were significant associations between T2DM and VAT area, VAT FF, HFF and PFF. In addition, VAT area and PFF were the independent risk factors of T2DM. Especially, PFF showed a high diagnostic performance in discrimination between T2DM and non-T2DM. These findings may highlight the crucial role of PFF in the pathophysiology of T2DM, and it might be served as a potential imaging biomarker of the prevention and treatment of T2DM. Additionally, in individuals without diabetes, focusing on SAT area, VAT area and AM area may help identify potential health risks and provide a basis for targeted weight management and prevention measures.

Pparα activation stimulates autophagic flux through lipid catabolism-independent route.

Autophagy is a cellular process that involves the fusion of autophagosomes and lysosomes to degrade damaged proteins or organelles. Triglycerides are hydrolyzed by autophagy, releasing fatty acids for energy through mitochondrial fatty acid oxidation (FAO). Inhibited mitochondrial FAO induces autophagy, establishing a crosstalk between lipid catabolism and autophagy. Peroxisome proliferator-activated receptor α (PPARα), a transcription factor, stimulates lipid catabolism genes, including fatty acid transport and mitochondrial FAO, while also inducing autophagy through transcriptional regulation of transcription factor EB (TFEB). Therefore, the study explores whether PPARα regulates autophagy through TFEB transcriptional control or mitochondrial FAO. In aquaculture, addressing liver lipid accumulation in fish is crucial. Investigating the link between lipid catabolism and autophagy is significant for devising lipid-lowering strategies and maintaining fish health. The present study investigated the impact of dietary fenofibrate and L-carnitine on autophagy by activating Pparα and enhancing FAO in Nile tilapia (Oreochromis niloticus), respectively. The dietary fenofibrate and L-carnitine reduced liver lipid content and enhanced ATP production, particularly fenofibrate. FAO enhancement by L-carnitine showed no changes in autophagic protein levels and autophagic flux. Moreover, fenofibrate-activated Pparα promoted the expression and nuclear translocation of Tfeb, upregulating autophagic initiation and lysosomal biogenesis genes. Pparα activation exhibited an increasing trend of LC3II protein at the basal autophagy and cumulative p62 protein trends after autophagy inhibition in zebrafish liver cells. These data show that Pparα activation-induced autophagic flux should be independent of lipid catabolism.

Effects of methionine deficiency on B7H3-DAP12-CAR-T cells in the treatment of lung squamous cell carcinoma.

Lung squamous cell carcinoma (LUSC) is a subtype of lung cancer for which precision therapy is lacking. Chimeric antigen receptor T-cells (CAR-T) have the potential to eliminate cancer cells by targeting specific antigens. However, the tumor microenvironment (TME), characterized by abnormal metabolism could inhibit CAR-T function. Therefore, the aim of this study was to improve CAR-T efficacy in solid TME by investigating the effects of amino acid metabolism. We found that B7H3 was highly expressed in LUSC and developed DAP12-CAR-T targeting B7H3 based on our previous findings. When co-cultured with B7H3-overexpressing LUSC cells, B7H3-DAP12-CAR-T showed significant cell killing effects and released cytokines including IFN-γ and IL-2. However, LUSC cells consumed methionine (Met) in a competitive manner to induce a Met deficiency. CAR-T showed suppressed cell killing capacity, reduced cytokine release and less central memory T phenotype in medium with lower Met, while the exhaustion markers were up-regulated. Furthermore, the gene NKG7, responsible for T cell cytotoxicity, was downregulated in CAR-T cells at low Met concentration due to a decrease in m5C modification. NKG7 overexpression could partially restore the cytotoxicity of CAR-T in low Met. In addition, the anti-tumor efficacy of CAR-T was significantly enhanced when co-cultured with SLC7A5 knockdown LUSC cells at low Met concentration. In conclusion, B7H3 is a prospective target for LUSC, and B7H3-DAP12-CAR-T cells are promising for LUSC treatment. Maintaining Met levels in CAR-T may help overcome TME suppression and improve its clinical application potential.

Improving thermo-tolerance of Saccharomyces cerevisiae by precise regulation of the expression of small HSP.

The level of heat resistance in microbial cells is an important factor in determining the energy consumption and product synthesis efficiency of fermentation processes. Current research generally believes that heat shock proteins (HSPs) are the most closely related functional molecules to heat resistance inside cells. They can stabilize cell structures and allow cells to perform their normal physiological functions. Based on our previous transcriptome data, this study applies synthetic biology methods to validate the functionality of heat-resistant elements. The researchers introduced gene circuits expressing small HSPs (sHSP-HB8, HSP12, HSP26, HSP30, HSP42, and ibpa-MB4) with different promoter strengths (TDH3p, YNL247wp) into Saccharomyces cerevisiae strains for functional verification. All engineered strains, with the exception of No. 3 and No. 8, demonstrated a significantly higher growth rate and cell viability at 42 °C. Among them, No. 7 (YNL247wp-HSP12-SLM5t) and No. 11 (YNL247wp-sHSP-HB8-SLM5t), the two best performing engineered strains, exhibited a 19.8% and 17.2% increase in cell density, respectively, compared to the control strain. Additionally, the analysis of pyruvate kinase (PK) and malate dehydrogenase (MDH) enzyme activities indicated that the engineered strains enhanced protein quality at higher temperatures. The research methods and ideas presented in this paper have significant scientific reference value for exploring and applying other stress-resistant gene circuits.

[Spatiotemporal Simulation and Prediction of Grassland Carbon Budget in Gansu Under Different Climate Scenarios].

Under the background of carbon peak and carbon neutrality, grassland carbon sinks are a key pathway to carbon neutrality. Based on the Coupled Model Intercomparison Project Phase 6 (CMIP6) climate scenario data, the Daycent model was used to simulate the carbon budget of Gansu grasslands from 2015 to 2100, and the trend analysis was used to study the spatial and temporal changes in grassland carbon budget in the next 78 years. The results revealed that, under the future climate scenario of SSP245, the net ecosystem productivity (NEP) indicated a non-significant fluctuating downward trend with a rate of -0.20 g·(m2·a)-1(in C, the same below), and the grassland carbon sink was in a declining state. Under the future climate scenario of SSP585, the grassland NEP indicated a significant fluctuating increase trend with a growth rate of 1.36 g·(m2·a)-1, and the grassland carbon sink gradually increased under this scenario; the spatial distribution of grassland carbon budget increased from northwest to southeast. The increase in temperature and precipitation under the SSP585 climate scenario was higher than that under the SSP245 climate scenario, and the grassland carbon budget strongly correlated positively with precipitation. However, a negative correlation was observed between grassland carbon budget and temperature. We identified the carbon sink intensity in Gansu grasslands under different climate conditions, which provides a reference for and contribution to effective carbon sequestration.

Modulating the organic photovoltaic properties of non-fullerene acceptors by molecular modification based on Y6: a theoretical study.

Developing non-fullerene acceptors (NFAs) by modifying the backbone, side chains and end groups is the most important strategy to improve the power conversion efficiency of organic solar cells (OSCs). Among numerous developed NFAs, Y6 and its derivatives are famous NFAs in the OSC field due to their good performance. Herein, in order to understand the mechanism of tuning the photovoltaic performance by modifying the Y6's center backbone, π-spacer and side-chains, we selected the PM6:Y6 OSC as a reference and systematically studied PM6:AQx-2, PM6:Y6-T, PM6:Y6-2T, PM6:Y6-O, PM6:Y6-1O and PM6:Y6-2O OSC systems based on extensive quantum chemistry calculations. The results indicate that introducing quinoxaline to substitute thiadiazole in the backbone induces a blue-shift of absorption spectra, reduces the charge transfer (CT) distance (Δd) and average electrostatic potential (ESP), and increases the singlet-triplet energy gap (ΔEST), CT excitation energy and the number of CT states in low-lying excitations. Inserting thienyl and dithiophenyl as π spacers generates a red-shift of absorption spectra, enlarges Δd and average ESP, and reduces ΔEST and the number of CT states. Introducing furo[3,2-b]furan for substituting one thieno[3,2-b]thiophene unit in the Y6's backbone causes a red-shift of absorption spectra and increases ΔEST, Δd and average ESP as well as CT excitation energy. Introducing alkoxyl as a side chain results in a blue-shift of absorption spectra, and increases ΔEST, Δd, average ESP, CT excitation energy and the number of CT states. The rate constants calculated using Marcus theory suggest that all the molecular modifications of Y6 reduce the exciton dissociation and charge recombination rates at the heterojunction interface, while introducing furo[3,2-b]furan and alkoxyl enlarges CT rates.

Hypoxia tolerance in fish depends on catabolic preference between lipids and carbohydrates.

Hypoxia is a common environmental stress factor in aquatic organisms, which varies among fish species. However, the mechanisms underlying the ability of fish species to tolerate hypoxia are not well known. Here, we showed that hypoxia response in different fish species was affected by lipid catabolism and preference for lipid or carbohydrate energy sources. Activation of biochemical lipid catabolism through peroxisome proliferator-activated receptor alpha (Pparα) or increasing mitochondrial fat oxidation in tilapia decreased tolerance to acute hypoxia by increasing oxygen consumption and oxidative damage and reducing carbohydrate catabolism as an energy source. Conversely, lipid catabolism inhibition by suppressing entry of lipids into mitochondria in tilapia or individually knocking out three key genes of lipid catabolism in zebrafish increased tolerance to acute hypoxia by decreasing oxygen consumption and oxidative damage and promoting carbohydrate catabolism. However, anaerobic glycolysis suppression eliminated lipid catabolism inhibition-promoted hypoxia tolerance in adipose triglyceride lipase (atgl) mutant zebrafish. Using 14 fish species with different trophic levels and taxonomic status, the fish preferentially using lipids for energy were more intolerant to acute hypoxia than those preferentially using carbohydrates. Our study shows that hypoxia tolerance in fish depends on catabolic preference for lipids or carbohydrates, which can be modified by regulating lipid catabolism.

Inhibition of mitochondrial fatty acid ß-oxidation activates mTORC1 pathway and protein synthesis via Gcn5-dependent acetylation of Raptor in zebrafish.

Pharmacological inhibition of mitochondrial fatty acid oxidation (FAO) has been clinically used to alleviate certain metabolic diseases by remodeling cellular metabolism. However, mitochondrial FAO inhibition also leads to mechanistic target of rapamycin complex 1 (mTORC1) activation-related protein synthesis and tissue hypertrophy, but the mechanism remains unclear. Here, by using a mitochondrial FAO inhibitor (mildronate or etomoxir) or knocking out carnitine palmitoyltransferase-1, we revealed that mitochondrial FAO inhibition activated the mTORC1 pathway through general control nondepressible 5-dependent Raptor acetylation. Mitochondrial FAO inhibition significantly promoted glucose catabolism and increased intracellular acetyl-CoA levels. In response to the increased intracellular acetyl-CoA, acetyltransferase general control nondepressible 5 activated mTORC1 by catalyzing Raptor acetylation through direct interaction. Further investigation also screened Raptor deacetylase histone deacetylase class II and identified histone deacetylase 7 as a potential regulator of Raptor. These results provide a possible mechanistic explanation for the mTORC1 activation after mitochondrial FAO inhibition and also bring light to reveal the roles of nutrient metabolic remodeling in regulating protein acetylation by affecting acetyl-CoA production.

Double-edged effect of sodium citrate in Nile tilapia (Oreochromis niloticus): Promoting lipid and protein deposition vs. causing hyperglycemia and insulin resistance.

Citrate is an essential substrate for energy metabolism that plays critical roles in regulating glucose and lipid metabolic homeostasis. However, the action of citrate in regulating nutrient metabolism in fish remains poorly understood. Here, we investigated the effects of dietary sodium citrate on growth performance and systematic energy metabolism in juvenile Nile tilapia (Oreochromis niloticus). A total of 270 Nile tilapia (2.81 ± 0.01 g) were randomly divided into three groups (3 replicates per group, 30 fish per replicate) and fed with control diet (35% protein and 6% lipid), 2% and 4% sodium citrate diets, respectively, for 8 weeks. The results showed that sodium citrate exhibited no effect on growth performance (P > 0.05). The whole-body crude protein, serum triglyceride and hepatic glycogen contents were significantly increased in the 4% sodium citrate group (P < 0.05), but not in the 2% sodium citrate group (P > 0.05). The 4% sodium citrate treatment significantly increased the serum glucose and insulin levels at the end of feeding trial and also in the glucose tolerance test (P < 0.05). The 4% sodium citrate significantly enhanced the hepatic phosphofructokinase activity and inhibited the expression of pyruvate dehydrogenase kinase isozyme 2 and phosphor-pyruvate dehydrogenase E1 component subunit alpha proteins (P < 0.05). Additionally, the 4% sodium citrate significantly increased hepatic triglyceride and acetyl-CoA levels, while the expressions of carnitine palmitoyl transferase 1a protein were significantly down-regulated by the 4% sodium citrate (P < 0.05). Besides, the 4% sodium citrate induced crude protein deposition in muscle by activating mTOR signaling and inhibiting AMPK signaling (P < 0.05). Furthermore, the 4% sodium citrate significantly suppressed serum aspartate aminotransferase and alanine aminotransferase activities, along with the lowered expression of pro-inflammatory genes, such as nfκb, tnfα and il8 (P < 0.05). Although the 4% sodium citrate significantly increased phosphor-nuclear factor-kB p65 protein expression (P < 0.05), no significant tissue damage or inflammation occurred. Taken together, dietary supplementation of sodium citrate could exhibit a double-edged effect in Nile tilapia, with the positive aspect in promoting nutrient deposition and the negative aspect in causing hyperglycemia and insulin resistance.

Endofungal Bacterial Microbiota Promotes the Absorption of Chelated Inorganic Phosphorus by Host Pine through the Ectomycorrhizal System.

Ectomycorrhizal fungi play an irreplaceable role in phosphorus cycling. However, ectomycorrhizal fungi have a limited ability to dissolve chelated inorganic phosphorus, which is the main component of soil phosphorus. Endofungal bacteria in ectomycorrhizal fruiting bodies are always closely related to the ecological function of ectomycorrhizal fungi. In this study, we explore endofungal bacteria in the fruiting body of Tylopilus neofelleus and their function during the absorption of chelated inorganic phosphorus by host pine through the ectomycorrhizal system. The results showed that the endofungal bacterial microbiota in the fruiting body of T. neofelleus might be related to the dissolution of chelated inorganic phosphorus in soil. The soluble phosphorus content in the combined system of T. neofelleus and endofungal bacteria Bacillus sp. strain B5 was five times higher than the sum of T. neofelleus-only treatment and Bacillus sp. strain B5-only treatment in the dissolution experiment of chelated inorganic phosphorus. The results showed that T. neofelleus not only promoted the proliferation of Bacillus sp. strain B5 in the combined system but also improved the expression of genes related to organic acid metabolism, as assesed by transcriptomic analysis. Lactic acid content was five times higher in the combined system than the sum of T. neofelleus-only treatment and Bacillus sp. strain B5-only treatment. Two essential genes related to lactate metabolism of Bacillus sp. strain B5, gapA and pckA, were significantly upregulated. Finally, in a pot experiment, we verified that T. neofelleus and Bacillus sp. strain B5 could synergistically promote the absorption of chelated inorganic phosphorus by Pinus sylvestris in a ternary symbiotic system. IMPORTANCE Ectomycorrhizal fungi (ECMF) have a limited ability to dissolve chelated inorganic phosphorus, which is the main component of soil phosphorus. In the natural environment, the extraradical hyphae of ECMF alone may not satisfy the phosphorus demand of the plant ectomycorrhizal system. In this study, our results innovatively show that the ectomycorrhizal system might be a ternary symbiont in which ectomycorrhizal fungi might recruit endofungal bacteria that could synergistically promote the mineralization of chelated inorganic phosphorus, which ultimately promotes plant phosphorus absorption by the ectomycorrhizal system.

PDK inhibition promotes glucose utilization, reduces hepatic lipid deposition, and improves oxidative stress in largemouth bass (Micropterus salmoides) by increasing pyruvate oxidative phosphorylation.

In omnivorous fish, the pyruvate dehydrogenase kinases (PDKs)-pyruvate dehydrogenase E1α subunit (PDHE1α) axis is essential in the regulation of carbohydrate oxidative catabolism. Among the existing research, the role of the PDKs-PDHE1α axis in carnivorous fish with poor glucose utilization is unclear. In the present study, we determined the effects of PDK inhibition on the liver glycolipid metabolism of largemouth bass (Micropterus salmoides). DCA is a PDK-specific inhibitor that inhibits PDK by binding the allosteric sites. A total of 160 juvenile largemouth bass were randomly divided into two groups, with four replicates of 20 fish each, fed a control diet and a control diet supplemented with dichloroacetate (DCA) for 8 weeks. The present results showed that DCA supplementation significantly decreased the hepatosomatic index, triglycerides in liver and serum, and total liver lipids of largemouth bass compared with the control group. In addition, compared with the control group, DCA treatment significantly down-regulated gene expression associated with lipogenesis. Furthermore, DCA supplementation significantly decreased the mRNA expression of pdk3a and increased PDHE1α activity. In addition, DCA supplementation improved glucose oxidative catabolism and pyruvate oxidative phosphorylation (OXPHOS) in the liver, as evidenced by low pyruvate content in the liver and up-regulated expressions of glycolysis-related and TCA cycle/OXPHOS-related genes. Moreover, DCA consumption decreased hepatic malondialdehyde (MDA) content, enhanced the activities of superoxide dismutase (SOD), and increased transforming growth factor beta (tgf-ß), glutathione S-transferase (gst), and superoxide dismutase 1 (sod1) gene expression compared with the control diet. This study demonstrated that inhibition of PDKs by DCA promoted glucose utilization, reduced hepatic lipid deposition, and improved oxidative stress in largemouth bass by increasing pyruvate OXPHOS. Our findings contribute to the understanding of the underlying mechanism of the PDKs-PDHE1α axis in glucose metabolism and improve the utilization of dietary carbohydrates in farmed carnivorous fish.

THOC3 interacts with YBX1 to promote lung squamous cell carcinoma progression through PFKFB4 mRNA modification.

The THO complex (THOC) is ubiquitously involved in RNA modification and various THOC proteins have been reported to regulate tumor development. However, the role of THOC3 in lung cancer remains unknown. In this study, we identified that THOC3 was highly expressed in lung squamous cell carcinoma (LUSC) and negatively associated with prognosis. THOC3 knockdown inhibited LUSC cell growth, migration, and glycolysis. THOC3 expression was regulated by TRiC proteins, such as CCT8 and CCT6A, which supported protein folding. Furthermore, THOC3 could form a complex with YBX1 to promote PFKFB4 transcription. THOC3 was responsible for exporting PFKFB4 mRNA to the cytoplasm, while YBX1 ensured the stability of PFKFB4 mRNA by recognizing m5C sites in its 3'UTR. Downregulation of PFKFB4 suppressed the biological activities of LUSC. Collectively, these findings suggest that THOC3, folded by CCT proteins can collaborate with YBX1 to maintain PFKFB4 expression and facilitate LUSC development. Therefore, THOC3 could be considered as a novel promising therapeutic target for LUSC.

Uridine alleviates high-carbohydrate diet-induced metabolic syndromes by activating sirt1/AMPK signaling pathway and promoting glycogen synthesis in Nile tilapia (Oreochromis niloticus).

Carbohydrates have a protein sparing effect, but long-term feeding of a high-carbohydrate diet (HCD) leads to metabolic disorders due to the limited utilization efficiency of carbohydrates in fish. How to mitigate the negative effects induced by HCD is crucial for the rapid development of aquaculture. Uridine is a pyrimidine nucleoside that plays a vital role in regulating lipid and glucose metabolism, but whether uridine can alleviate metabolic syndromes induced by HCD remains unknown. In this study, a total of 480 Nile tilapia (Oreochromis niloticus) (average initial weight 5.02 ± 0.03 g) were fed with 4 diets, including a control diet (CON), HCD, HCD + 500 mg/kg uridine (HCUL) and HCD + 5,000 mg/kg uridine (HCUH), for 8 weeks. The results showed that addition of uridine decreased hepatic lipid, serum glucose, triglyceride and cholesterol (P < 0.05). Further analysis indicated that higher concentration of uridine activated the sirtuin1 (sirt1)/adenosine 5-monophosphate-activated protein kinase (AMPK) signaling pathway to increase lipid catabolism and glycolysis while decreasing lipogenesis (P < 0.05). Besides, uridine increased the activity of glycogen synthesis-related enzymes (P < 0.05). This study suggested that uridine could alleviate HCD-induced metabolic syndrome by activating the sirt1/AMPK signaling pathway and promoting glycogen synthesis. This finding reveals the function of uridine in fish metabolism and facilitates the development of new additives in aquatic feeds.

High cholesterol intake remodels cholesterol turnover and energy homeostasis in Nile tilapia (Oreochromis niloticus).

The roles of dietary cholesterol in fish physiology are currently contradictory. The issue reflects the limited studies on the metabolic consequences of cholesterol intake in fish. The present study investigated the metabolic responses to high cholesterol intake in Nile tilapia (Oreochromis niloticus), which were fed with four cholesterol-contained diets (0.8, 1.6, 2.4 and 3.2%) and a control diet for eight weeks. All fish-fed cholesterol diets showed increased body weight, but accumulated cholesterol (the peak level was in the 1.6% cholesterol group). Then, we selected 1.6% cholesterol and control diets for further analysis. The high cholesterol diet impaired liver function and reduced mitochondria number in fish. Furthermore, high cholesterol intake triggered protective adaptation via (1) inhibiting endogenous cholesterol synthesis, (2) elevating the expression of genes related to cholesterol esterification and efflux, and (3) promoting chenodeoxycholic acid synthesis and efflux. Accordingly, high cholesterol intake reshaped the fish gut microbiome by increasing the abundance of Lactobacillus spp. and Mycobacterium spp., both of which are involved in cholesterol and/or bile acids catabolism. Moreover, high cholesterol intake inhibited lipid catabolic activities through mitochondrial ß-oxidation, and lysosome-mediated lipophagy, and depressed insulin signaling sensitivity. Protein catabolism was elevated as a compulsory response to maintain energy homeostasis. Therefore, although high cholesterol intake promoted growth, it led to metabolic disorders in fish. For the first time, this study provides evidence for the systemic metabolic response to high cholesterol intake in fish. This knowledge contributes to an understanding of the metabolic syndromes caused by high cholesterol intake or deposition in fish. Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-022-00158-7.

Bacillus cereus Alters Bile Acid Composition and Alleviates High-Carbohydrate Diet-Induced Hepatic Lipid Accumulation in Nile Tilapia (Oreochromis niloticus).

A high-carbohydrate diet (HCD) can induce excessive fat accumulation in fish, and intestinal microbiota are thought to play important roles in host metabolism. Whether and how intestinal bacteria alleviate the HCD-induced metabolic disorders in fish have attracted more attention. Bacillus cereus was isolated from the intestine content of Nile tilapia. The control diet, high-carbohydrate diet (HC), and HC supplemented with B. cereus Su1 (HCS) were used to feed juvenile Nile tilapia for 8 weeks. The results of the present study showed that B. cereus Su1 supplementation decreased the serum glucose, triglycerides (TG), and reduced hepatic lipid accumulation compared with the HC group. The intestinal bacterial composition analysis suggested that HCS elevated bacterial diversity and the enriched bacteria were closely related to bile acid (BA) metabolism. Higher bile salt hydrolase (BSH) activity was found in the HCS group and B-targeted metabolomic analysis revealed that HCS increased BA content in the intestine and liver compared with HC, including unconjugated BAs (CA and CDCA) and conjugated BAs (TCA, GCA, TCDCA, GCDCA, TDCA, and TUDCA). Furthermore, a high-carbohydrate diet supplemented with B. cereus Su1 significantly enhanced the protein expression of the BA receptor farnesoid X receptor in the liver and decreased significantly the expression level of lipid synthesis-related genes and proteins, while it had no significant effect on lipolysis-related genes and proteins. This study found that B. cereus Su1 altered the intestinal microbiota and bile acid content and composition to regulate the lipid metabolism, revealing the function of the crosstalk among probiotics, intestinal microbiota, and BAs in ameliorating lipid accumulation induced by a high-carbohydrate diet in fish.

Dietary docosahexaenoic acid reduces fat deposition and alleviates liver damage induced by D-galactosamine and lipopolysaccharides in Nile tilapia (Oreochromis niloticus).

Liver health is important to maintain survival and growth of fish. Currently, the role of dietary docosahexaenoic acid (DHA) in improving fish liver health is largely unknown. This study investigated the role of DHA supplementation in fat deposition and liver damage caused by D-galactosamine (D-GalN) and lipopolysaccharides (LPS) in Nile tilapia (Oreochromis niloticus). Four diets were formulated as control diet (Con), Con supplemented with 1 % DHA, 2 % DHA and 4 % DHA diets, respectively. The diets were fed to 25 Nile tilapia (2.0 ± 0.1 g, average initial weight) in triplicates for four weeks. After the four weeks, 20 fish in each treatment were randomly selected and injected with a mixture of 500 mg D-GalN and 10 µL LPS per mL to induce acute liver injury. The results showed that the Nile tilapia fed on DHA diets decreased visceral somatic index, liver lipid content and serum and liver triglyceride concentrations than those fed on the Con diet. Moreover, after D-GalN/LPS injection, the fish fed on DHA diets decreased alanine aminotransferase and aspartate transaminase activities in the serum. The results of liver qPCR and transcriptomics assays together showed that the DHA diets feeding improved liver health by downregulating the expression of the genes related to toll-like receptor 4 (TLR4) signaling pathway, inflammation and apoptosis. This study indicates that DHA supplementation in Nile tilapia alleviates the liver damage caused by D-GalN/LPS through increasing lipid catabolism, decreasing lipogenesis, TLR4 signaling pathway, inflammation, and apoptosis. Our study provides novel knowledge on the role of DHA in improving liver health in cultured aquatic animals for sustainable aquaculture.

Partial replacement of soybean meal by yellow mealworm (Tenebrio molitor) meal influences the flesh quality of Nile tilapia (Oreochromis niloticus).

This study investigated the effects of yellow mealworm meal (YM) replacing soybean meal (SBM) at different proportions (0%, 15%, 30% and 45%, referred as YM0, YM15, YM30 and YM45, respectively) on the flesh quality of Nile tilapia. A total of 360 fish (70.0 ± 0.12 g) were randomly divided into 4 groups (3 tanks per group). Fish were fed the experimental diet twice daily for 10 wk. The results showed that muscle protein content significantly decreased in YM30 and YM45, while the lipid content significantly decreased in YM45 (P < 0.05). The essential amino acids and flavor amino acids of the muscle were not affected by the YM substitution, while saturated fatty acid content decreased in YM30 and YM45 compared with YM0 (P < 0.05). Fillets in YM45 had higher hardness, gumminess, and a higher proportion of thin myofibers (≤100 µm, P < 0.05) than those in other groups. Further analysis revealed that apoptosis and atrophy related genes were up-regulated, while the muscle antioxidant capacity decreased significantly in YM45 (P < 0.05), which may be related to the high acid value in YM45 diet. Our findings indicated that YM could replace up to 30% SBM without substantially altering the flesh quality. When the replacement ratio increased to 45%, the flesh quality would change. Special attention should be paid to avoid feed rancidity which may affect the flesh quality of fish.

High dissolved oxygen exacerbates ammonia toxicity with sex-dependent manner in zebrafish.

Ammonia nitrogen is one of the important environmental factors, and causes negative effects for fish health in ecosystem and aquaculture. The toxic effects and mechanisms of ammonia in fish deserve further investigation. In the present study, we exposed female and male zebrafish (Danio rerio) to ammonia (50 mg/L NH4Cl) with oxygenated (7.5-7.8 mg/L) or non­oxygenated (3.8-4.5 mg/L) water, to identify the combined effects of dissolved oxygen and ammonia on fish with gender difference. The results showed that oxygenated ammonia exposure increased fish mortality, gill secondary lamellas damage and gill tissue spaces, gene expressions of proinflammatory interleukin 1 beta (il-1ß) and apoptotic caspase8 as compared with non­oxygenated ammonia. Besides, oxygenated ammonia elevated plasma ammonia contents, and decreased the discharge of body ammonia through gills by depressing the enzyme activity of Na+/K+-ATPase. Notably, when zebrafish were subjected to ammonia stress, more severe mortality, gill damage and tissue inflammatory response were observed in males than females. This is the first study to clarify the gender-dependent impacts of ammonia toxicity, and the adverse effects of oxygenation on ammonia resistance in zebrafish.

Vitellogenin 1 is essential for fish reproduction by transporting DHA-containing phosphatidylcholine from liver to ovary.

Vitellogenins (Vtgs) are essential for female reproduction in oviparous animals, yet the exact roles and mechanisms remain unknown. In the present study, we knocked out vtg1, which is the most abundant Vtg in zebrafish, Danio rerio via the CRISPR/Cas 9 technology. We aimed to identify the roles of Vtg1 and related mechanisms in reproduction and development. We found that, the Vtg1-deficient female zebrafish reduced gonadosomatic index, egg production, yolk granules and mature follicles in ovary compared to the wide type (WT). Moreover, the Vtg1-deficient zebrafish diminished hatching rates, cumulative survival rate, swimming capacity and food intake, but increased malformation rate, and delayed swim bladder development during embryo and early-larval phases. The Vtg1-deficiency in female broodstock inhibited docosahexaenoic acid-enriched phosphatidylcholine (DHA-PC) transportation from liver to ovary, which lowered DHA-PC content in ovary and offspring during larval stage. However, the Vtg1-deficient zebrafish increased gradually the total DHA-PC content via exogeneous food intake, and the differences in swimming capacity and food intake returned to normal as they matured. Furthermore, supplementing Vtg1-deficient zebrafish with dietary PC and DHA partly ameliorated the impaired female reproductive capacity and larval development during early phases. This study indicates that, DHA and PC carried by Vtg1 are crucial for female fecundity, and affect embryo and larval development through maternal-nutrition effects. This is the first study elucidating the nutrient and physiological functions of Vtg1 and the underlying biochemical mechanisms in fish reproduction and development.

Isopropyl 3-(3, 4-dihydroxyphenyl)-2-hydroxypropanoate protects lipopolysaccharide-induced acute lung injury in mice by attenuating pyroptosis.

Isopropyl 3-(3,4-dihydroxyphenyl)-2-hydroxypropanoate (IDHP) is one of the main bioactive metabolites of the Chinese medicinal herb Danshen, which can be absorbed into blood compounds by oral administration of Compound Danshen dripping pills (CDDPs). Previous study showed that IDHP exerted anti-inflammatory effects by abolishing the secretion of proinflammatory factors stimulated by lipopolysaccharide (LPS). However, the effects of IDHP on LPS-induced acute lung injury (ALI) are not fully understood. In the present study, we observed the effects of IDHP on mortality and lung injury in LPS-treated mice and on LPS-induced THP-1 macrophages. Pretreatment with high dose of IDHP was found to reduce the mortality of ALI mice, significantly improve LPS-induced pathological changes, and reduce protein leakage and inhibited myeloperoxidase (MPO) activity in lung tissue. IDHP also inhibited the release of inflammatory factors in bronchoalveolar lavage fluid (BALF) and lung tissue. Meanwhile, IDHP treatment significantly reduced the expression of active-caspase1, Nlrp3, Asc speck formation, Gsdmd (part of the canonical pyroptosis pathway), caspase4 (part of the non-canonical pyroptosis pathway), therefore decreasing IL-1ß, IL-18, and ROS secretion in LPS-stimulated THP-1 macrophages. Moreover, after co-culturing endothelial/epithelial cells with conditioned medium (CM) from LPS-stimulated THP-1 macrophages, we found that the protein levels of occludin and Zonula occludens-1 (Zo-1) were increased in IDHP CM-treated endothelial cells compared to those that were LPS CM-treated. Lactic dehydrogenase (LDH) assay shows that IDHP also alleviated LPS-induced endothelial/epithelial cell injury. These findings indicate that the protective effect of IDHP on LPS-induced lung injury may be partly due to the inhibition of pyroptosis pathways.