Implications of ultrasound-based deep learning model for preoperatively differentiating combined hepatocellular-cholangiocarcinoma from hepatocellular carcinoma and intrahepatic cholangiocarcinoma.

OBJECTIVES: The current study developed an ultrasound-based deep learning model to make preoperative differentiation among hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC), and combined hepatocellular-cholangiocarcinoma (cHCC-ICC). METHODS: The B-mode ultrasound images of 465 patients with primary liver cancer were enrolled in model construction, comprising 264 HCCs, 105 ICCs, and 96 cHCC-ICCs, of which 50 cases were randomly selected to form an independent test cohort, and the rest of study population was assigned to a training and validation cohorts at the ratio of 4:1. Four deep learning models (Resnet18, MobileNet, DenseNet121, and Inception V3) were constructed, and the fivefold cross-validation was adopted to train and validate the performance of these models. The following indexes were calculated to determine the differential diagnosis performance of the models, including sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV), F-1 score, and area under the receiver operating characteristic curve (AUC) based on images in the independent test cohort. RESULTS: Based on the fivefold cross-validation, the Resnet18 outperformed other models in terms of accuracy and robustness, with the overall training and validation accuracy as 99.73% (± 0.07%) and 99.35% (± 0.53%), respectively. Furthers validation based on the independent test cohort suggested that Resnet 18 yielded the best diagnostic performance in identifying HCC, ICC, and cHCC-ICC, with the sensitivity, specificity, accuracy, PPV, NPV, F1-score, and AUC of 84.59%, 92.65%, 86.00%, 85.82%, 92.99%, 92.37%, 85.07%, and 0.9237 (95% CI 0.8633, 0.9840). CONCLUSION: Ultrasound-based deep learning algorithm appeared a promising diagnostic method for identifying cHCC-ICC, HCC, and ICC, which might play a role in clinical decision making and evaluation of prognosis.

Clinical application of preoperative shear wave dispersion for prediction of post liver failure in patients with hepatocellular carcinoma after hepatectomy.

OBJECTIVE: The aim in this study was to determine the efficacy of shear wave dispersion (SWD) technique for the prediction of post hepatectomy liver failure (PHLF) in patients with hepatocellular carcinoma after hepatectomy and develop an SWD based risk prediction model. METHODS & MATERIALS: We prospectively enrolled 205 consecutive patients who were scheduled to undergo hepatectomy for hepatocellular carcinoma (HCC), pre-operative SWD examination, laboratory data and some other clinicopathological tests were collected. The risk factors of PHLF were identified according to univariate and multivariate analysis, a predictive model was established based on logistic regression analyses. RESULTS: SWD examination was successfully performed in 205 patients. PHLF occurred in 51 patients (24.9%), including 37/11/3 patients with Grade A/B/C, respectively. There was a high correlation between SWD value of liver and liver fibrosis stage (r = 0.873, p < 0.05). Patients with PHLF has a higher median SWD value of liver than patients without PHLF [17.4 vs 14.7 (m/s)/kHz, p < 0.05]. The SWD value of liver, total bilirubin (TB), international normalized ratio of prothrombin time (INR) and splenomegaly were significantly related to PHLF based on the multivariate analysis. A new prediction model (PM) for PHLF was established (PM = -12.918 + 0.183× SWD + 6.668× INR +0.100×TB+1.240×splenomegaly). The optimal cutoff value of SWD for predicting PHLF was 16.7 (m/s)/kHz. The area under the curve (AUC) of the PM for PHLF was 0.833, which was higher than that of SWD, INR, Forns, FIB4, APRI (p < 0.005, respectively). CONCLUSION: SWD is a promising and reliable method for PHLF prediction in patients with HCC who were undergoing hepatectomy. Compared with SWD, Forns, APRI and FIB-4, PM demonstrate better efficacy for preoperative PHLF prediction.

A Comparative Study of Ultrasound Attenuation Imaging, Controlled Attenuation Parameters, and Magnetic Resonance Spectroscopy for the Detection of Hepatic Steatosis.

OBJECTIVES: To investigate the methodology and clinical application of ultrasound attenuation imaging (ATI) and comparative analyze the diagnostic performance of ATI and controlled attenuation parameters (CAP) for detecting and grading hepatic steatosis. METHODS: A total of 159 patients with NAFLD were prospectively enrolled. CAP and ATI examinations were performed within a week before proton magnetic resonance spectroscopy (1 H-MRS). Ten liver attenuation coefficient (AC) measurements by ATI were obtained in each patient. The interclass correlation coefficients (ICCs) of the intraobserver consistencies and the ICCs between the median of the first two through the first nine measurements and all 10 measurements were calculated. The correlations between 1 H-MRS, CAP, biological data, and ATI were evaluated. The significant factors associated with ATI and the diagnostic performance of ATI and CAP for detecting hepatic steatosis was evaluated. RESULTS: The median value of AC for detecting hepatic steatosis was 0.831 dB/cm/MHz. For the intraobserver consistency of ATI, the ICC was 0.931. Compared with 10 measurements, a minimum of four ATI measurements was required. The correlation of AC with hepatic fat fraction (HFF) was significantly higher than that of CAP (0.603 vs 0.326, P = .0015). The HFF and triglyceride (TG) were the significant factors for the ATI. The area under the receiver operating characteristics (ROC) curves of ATI and CAP were 0.939 and 0.788 for detecting ≥10% hepatic steatosis; 0.751 and 0.572 for detecting >33% hepatic steatosis. The cutoff values of ATI and CAP were 0.697 dB/cm/MHz and 310 dB/m for detecting ≥10% hepatic steatosis; 0.793 dB/cm/MHz and 328 dB/m for detecting >33% hepatic steatosis. The sensitivity of ATI and CAP were 85.92% and 52.11% for detecting ≥10% hepatic steatosis; 87.50% and 82.14% for detecting >33% hepatic steatosis. The specificity of ATI and CAP were 94.12% and 100% for detecting ≥10% hepatic steatosis; 54.37% and 43.69% for detecting >33% hepatic steatosis. CONCLUSIONS: ATI technology showed excellent intraobserver consistency and the optimal minimum number of ATI measurements was 4. ATI is a promising noninvasive, quantitative and convenient tool for assessing hepatic steatosis.

Clinical application of two dimensional shear wave elastography with a propagation map in evaluating liver fibrosis in patients with liver tumors.

OBJECTIVE: This study aimed to evaluate the diagnostic performance of two-dimensional shear wave elastography (2D-SWE) with a propagation map in evaluating the degree of hepatic fibrosis in patients with liver tumors before resection. METHODS AND MATERIALS: From January 2020 to April 2021, 128 patients with liver tumors were prospectively enrolled, including 20 benign liver tumors and 108 malignant liver tumors. 2D-SWE with a propagation map technology was used to measure the stiffness of liver parenchyma 2 cm away from the tumor. The median value of five measurements was used in this study. The stage of hepatic fibrosis was graded in accordance with Scheuer standard. Spearman correlation was used to analyze the correlation between liver fibrosis stage and the liver stiffness. Univariate and multivariate linear regression analyses were used to determine significant affecting factors for liver stiffness value. The diagnostic performance of 2D-SWE with a propagation map in predicting fibrosis stage was evaluated by receiver operating characteristic curve analysis. RESULTS: The median liver stiffness value in patients with benign liver tumors was lower than that in patients with malignant liver tumors (6.0 kPa vs. 9.4 kPa, p < 0.05). The median liver stiffness values in patients with primary liver cancer were higher than that in patients with benign liver tumors and other types of malignant liver tumors (9.6 kPa vs. 6.0 kPa, p < 0.05). The liver stiffness measured by 2D-SWE was highly correlated with the fibrosis stage confirmed by postoperative pathology (r = 0.834, p < 0.05). For the liver stiffness value, PLT,TB,ALB and fibrosis stage are significantly associated with liver stiffness. The median liver stiffness values in stages S0-S4 of fibrosis were 6.0, 7.2, 8.0, 9.4, and 12.6 kPa, respectively. The areas under the ROC curve of S≥1, S≥2, S≥3, and S = 4 as predicted by SWE were 0.932, 0.945, 0.945, and 0.916, respectively. According to the Youden index, the optimal critical values for predicting fibrosis S≥1, S≥2, S≥3, and S = 4 were 6.8 (sensitivity of 89.69% and specificity of 93.55%), 7.5 (sensitivity of 87.50 % and specificity of 95.00 %), 8.3 (sensitivity of 87.14 % and specificity of 87.93 %) and 9.8 (sensitivity of 79.55 % and specificity of 86.90 %) kPa. CONCLUSION: 2D-SWE with a propagation map could noninvasively and accurately predict the staging of liver fibrosis in patients with liver tumors before resection.

Transcriptome profiling reveals differential expression of immune-related genes in gills of hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂) under hypoxic stress: Potential NLR-mediated immune response.

Fish gills are the primary organ that respond to sudden changes in the dissolved oxygen (DO) level in the aquatic environment. Hypoxic stress impairs the normal function of gill tissues. However, little is known about the mechanisms of the response of yellow catfish gills to hypoxic stress. In this study, we compared transcriptomic and physiological changes in gill tissues of hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂) between a hypoxia-treated group (DO: 1.5 mg/L) and a control group (DO: 6.5 mg/L). In fish in the hypoxia-treated group, gill filaments underwent adaptive changes, and the number of vacuoles in gill tissues increased. Exposure to hypoxic conditions for 96 h resulted in increased anaerobic metabolism and decreased antioxidant and immune capacity in gill tissues. Transcriptome analyses revealed 1556 differentially expressed genes, including 316 up-regulated and 1240 down-regulated genes, between fish in the hypoxia-treated and control groups. Functional analyses indicated that the main pathway enriched with differentially expressed genes was immune response, followed by energy metabolism and signal transduction. Under hypoxic stress, the transcript levels of genes involved in the NOD-like receptor signaling pathway initially increased rapidly but then decreased over time, suggesting that the NOD-like receptor-mediated immune response plays an essential role in hypoxia tolerance and resistance in hybrid yellow catfish. Our results provide novel insights into which immune-related genes and pathways are activated under hypoxic stress, and reveal details of early adaptation of the immune response and defense mechanisms under hypoxic stress.

Differentiation between hepatocellular carcinoma and intrahepatic cholangiocarcinoma using contrast-enhanced ultrasound: A systematic review and meta-analysis.

AIM: To explore the diagnostic ability of contrast-enhanced ultrasound (CEUS) in distinguishing intrahepatic cholangiocarcinoma (ICC) from hepatocellular carcinoma (HCC). MATERIALS AND METHODS: PubMed, EMBASE, Cochrane Library, and Web of Science were systematically searched for studies reporting the diagnostic accuracy of CEUS in differentiating ICC from HCC. The diagnostic ability of CEUS was assessed based on the pooled sensitivity, specificity, diagnostic odds ratio (DOR), positive likelihood ratio (PLR), negative likelihood ratio (NLR) and area under the curve (AUC) with 95% confidence intervals (CIs). The methodologic quality was assessed by the QUADAS-2 tool. Subgroup analyses, meta-regression and investigation of publication bias were performed to identify the source of heterogeneity. RESULTS: A total of eight studies were included, consisting of 1,116 patients with HCC and 529 with ICC. The general diagnostic performance of CEUS in distinguishing ICC and HCC were as follows: pooled sensitivity, 0.92 (95% CI: 0.84-0.96); pooled specificity, 0.87 (95% CI: 0.79-0.92); pooled PLR, 7.1 (95% CI: 4.1-12.0); pooled NLR, 0.09 (95% CI: 0.05-0.19); pooled DOR, 76 (95% CI: 26-220) and AUC, 0.95 (95% CI: 0.93-0.97). Different liver background may be a potential factor that influenced the diagnostic accuracy of CEUS according to the subgroup analysis, with the pooled DOR of 89.67 in the mixed liver background group and 46.87 in the cirrhosis group, respectively. Six informative CEUS features that may help differentiate HCC from ICC were extracted. The three CEUS features favoring HCC were arterial phase hyperenhancement (APHE), mild washout and late washout (>60s); the three CEUS favoring ICC were arterial rim enhancement, marked washout and early washout (<60s). No potential publication bias was observed. CONCLUSION: CEUS showed great diagnostic ability in differentiating ICC from HCC, which may be promising for noninvasive evaluation of these diseases.

Multi-omics analysis reveals the glycolipid metabolism response mechanism in the liver of genetically improved farmed Tilapia (GIFT, Oreochromis niloticus) under hypoxia stress.

BACKGROUND: Dissolved oxygen (DO) in the water is a vital abiotic factor in aquatic animal farming. A hypoxic environment affects the growth, metabolism, and immune system of fish. Glycolipid metabolism is a vital energy pathway under acute hypoxic stress, and it plays a significant role in the adaptation of fish to stressful environments. In this study, we used multi-omics integrative analyses to explore the mechanisms of hypoxia adaptation in Genetically Improved Farmed Tilapia (GIFT, Oreochromis niloticus). RESULTS: The 96 h median lethal hypoxia (96 h-LH50) for GIFT was determined by linear interpolation. We established control (DO: 5.00 mg/L) groups (CG) and hypoxic stress (96 h-LH50: 0.55 mg/L) groups (HG) and extracted liver tissues for high-throughput transcriptome and metabolome sequencing. A total of 581 differentially expressed (DE) genes and 93 DE metabolites were detected between the CG and the HG. Combined analyses of the transcriptome and metabolome revealed that glycolysis/gluconeogenesis and the insulin signaling pathway were down-regulated, the pentose phosphate pathway was activated, and the biosynthesis of unsaturated fatty acids and fatty acid metabolism were up-regulated in GIFT under hypoxia stress. CONCLUSIONS: The results show that lipid metabolism became the primary pathway in GIFT under acute hypoxia stress. Our findings reveal the changes in metabolites and gene expression that occur under hypoxia stress, and shed light on the regulatory pathways that function under such conditions. Ultimately, this information will be useful to devise strategies to decrease the damage caused by hypoxia stress in farmed fish.

Physiological parameters and gut microbiome associated with different dietary lipid levels in hybrid yellow catfish (Tachysurus fulvidracoâ™€× Pseudobagrus vachellii♂).

Yellow catfish are intensively farmed in China and are often fed a high-fat diet (HFD) with the aim of using less protein. However, an excess of dietary lipids is likely to affect the gut microflora, which strongly affects immunity and nutrient digestion. To determine the effects of different lipid levels on the growth, physiological parameters and gut microbiome of hybrid yellow catfish, we conducted an 8-week feeding experiment with a low-fat diet (2% lipids, LFD), a normal-fat diet (9% lipids, NFD), and a HFD (15% lipids) (120 fish per group). The HFD group showed higher serum alanine aminotransferase and aspartate transaminase activities, which suggests that excess dietary lipids cause liver damage. A total of 1138 operational taxonomic units, 11 phyla, and 117 genera were identified from fish gut samples. Neither the HFD nor the LFD strongly affected the microbial composition in gut samples. Compared with fish in the NFD, those in the HFD and LFD showed significantly decreased intestinal microbial diversity. The composition of macronutrients in the different diets affected the composition of intestinal microflora, mainly the phyla Fusobacteria, Proteobacteria, and Firmicutes. The HFD and the LFD favored the growth of Fusobacteria, while the HFD and LFD resulted in decreased abundance of Firmicutes and Proteobacteria, respectively. These findings shed light on the complex relationships among diet, intestinal microorganisms, and host metabolism. When using an HFD for farmed fish, its effects on the gut microbiome should be considered to avoid illness and poor growth.

Cloning of the gene encoding acyl-CoA thioesterase 11 and its functional characterization in hybrid yellow catfish (Pelteobagrus fulvidraco ♀ × Pelteobagrus vachelli ♂) under heat stress.

Members of the ACOT (acyl-CoA thioesterase) family hydrolyze fatty acyl-CoA to form free fatty acids (FFAs) and coenzyme A (CoA). These enzymes play important roles in fatty acid metabolism. Here, we report the cloning and functional analysis of acot11ß in hybrid yellow catfish (Pelteobagrus fulvidraco ♀ × P. vachelli ♂). The open reading frame of acot11ß was found to be 594 bp in length, encoding 198 amino acids. We determined the transcript levels of acot11ß in ten tissues of hybrid yellow catfish by qRT-PCR and found that it was highly expressed in the liver, so we chose the liver for further analysis. We determined the transcript levels of acot11ß in hybrid yellow catfish under heat stress conditions, and analyzed the changes in serum biochemical parameters, liver biochemical parameters, and transcript levels of lipid metabolism-related genes. Healthy yellow catfish were subjected to heat stress at 35 °C for 96 h, and the experimental results were compared with those from fish in a control group (28 °C). The levels of glucose (GLU), total cholesterol (TC), and triglyceride (TG) in serum were significantly increased in the heat-stressed group compared with the control group (P < 0.05). Acute heat stress led to decreased liver glycogen contents, but significantly increased TC and TG contents in the liver (P < 0.05). The transcript levels of acot11ß, acc, and fas were significantly reduced, while that of pparα was significantly increased in hybrid yellow catfish exposed to heat stress (P < 0.05). Our results indicate that acot11ß plays an important role in regulating lipid metabolism in hybrid yellow catfish, and this metabolic process is greatly affected by temperature. These results may be useful for developing effective strategies to prevent or reduce metabolic disorders of yellow catfish caused by high temperature.

Physiological and gut microbiome changes associated with low dietary protein level in genetically improved farmed tilapia (GIFT, Oreochromis niloticus) determined by 16S rRNA sequence analysis.

The aim of this study was to determine the effects of different dietary protein levels on the growth, physiological parameters, and gut microbiome of genetically improved farmed tilapia (GIFT, Oreochromis niloticus). Two pellet feed diets with low (25%, LPD) and normal (35%, NPD) protein levels were fed to GIFT in aquaria at 28°C for 8 weeks. The LPD reduced trypsin activity and inhibited the growth of GIFT. The serum alanine amino transferase and aspartate transaminase activities, hepatic malondialdehyde content, and superoxide dismutase, glutathione peroxidase, and catalase activities were significantly higher in LPD GIFT than in NPD GIFT (p < .05). The LPD led to decreased lysozyme activity and increased levels of C3 (p < .05). A 16S rRNA gene profiling analysis showed that the LPD significantly affected the gut microbial composition. Compared with the NPD, the LPD significantly decreased intestinal microbial diversity (p < .05). The macronutrient distribution affected the taxonomic profile of gut bacteria, mainly the phyla Bacteroidetes, Proteobacteria, and Firmicutes. The LPD favored growth of the genus Bacteroides. The NPD appeared to increase the abundance of the genera Lawsonia, Romboutsia, and Sphingomonas. Our results showed that, compared with NPD GIFT, the LPD GIFT had weakened nonspecific immune function, altered microbial community structure, and decreased gut microbial diversity.

Changes in Physiological Parameters, Lipid Metabolism, and Expression of MicroRNAs in Genetically Improved Farmed Tilapia (Oreochromis niloticus) With Fatty Liver Induced by a High-Fat Diet.

Tilapia is susceptible to hepatic steatosis when grown in intensive farming systems. The aim of this study was to explore the mechanism of fatty liver induced by a high-fat diet (HFD) in genetically improved farmed tilapia (GIFT, Oreochromis niloticus). Juvenile GIFT were fed with HFD or a normal-fat diet (NFD) for 60 days. Substantial fat deposition in the liver of HFD-fed GIFT on days 20, 40, and 60 was observed using hematoxylin - eosin staining and oil red O staining. The increased fat deposition was consistent with increased triglyceride (TG) and total cholesterol (TC) levels in the liver of HFD-fed GIFT. There were significant differences (P < 0.05) in serum biochemical indexes (TG, TC, low density lipoprotein-cholesterol, and insulin contents, and alanine aminotransferase activity) between GIFT fed a HFD and GIFT fed a NFD on days 20, 40, and 60. Furthermore, 60 days of a HFD significantly changed (P < 0.05) the hepatic fatty acid composition, and led to increased polyunsaturated fatty acid levels and decreased saturated fatty acid and monounsaturated fatty acid levels. Hepatic antioxidant enzyme activities increased by day 20 and then declined, which led to an increase in malondialdehyde contents in the liver of HFD-fed GIFT. Molecular analyses revealed that the microRNAs miR-122, miR-29a, and miR-145-5p were upregulated, whereas miR-34a was downregulated in HFD-fed GIFT. SCD, ELOVL6, and SRD5A2 encode three important enzymes in lipid metabolism, and were identified as potential targets of miRNAs. The transcript levels of hepatic SCD and ELOVL6 were decreased and that of hepatic SRD5A2 was increased in GIFT fed a HFD. Overall, the results of this study revealed a potential link between miRNAs and fatty liver induced by HFD, and suggest that a HFD could lead to excess fat deposition in the GIFT liver, which may disrupt hepatic lipid metabolism and reduce the antioxidant defense capacity.

Responses of blood biochemistry, fatty acid composition and expression of microRNAs to heat stress in genetically improved farmed tilapia (Oreochromis niloticus).

We investigated the effects of heat stress on genetically improved farmed tilapia, focusing on metabolic and immune responses. Differences in blood parameters, serum biochemistry, muscle fatty acid composition, and microRNA (miRNA) expression were analyzed in fish under heat stress. Fish were exposed to heat stress at 35 °C and sampled at 0, 6, 12, 24, and 48 h after exposure and compared with a control group maintained at 28 °C. The results showed that red and white blood cell counts, hemoglobin levels, and hematocrit values tended to increase (P < 0.05) and reached their maximum levels after 24 h, then declined. Acute heat stress enhanced serum glucose, total protein, and total cholesterol levels, and muscle fatty acid components were also altered. Serum alanine aminotransferase (ALT) activity was significantly increased after heat stress for 6 and 12 h. Polyunsaturated fatty acids levels were increased after heat stress for 12 and 24 h, whereas levels of monounsaturated fatty acids decreased in response to heat stress. Expression of hepatic miR-1 and miR-122 was significantly upregulated, and expression of miR-10c was significantly increased (P < 0.05) only after heat stress for 48 h. Acute heat stress altered metabolism closely related to the immune system and the liver of tilapia. These findings contribute to a theoretical framework for tilapia breeding at high temperatures.

miR-205-5p negatively regulates hepatic acetyl-CoA carboxylase ß mRNA in lipid metabolism of Oreochromis niloticus.

MicroRNAs (miRNAs) are non-coding RNAs that function as post-transcriptional gene regulators and that play vital roles controlling lipid metabolism. miR-205 is an important miRNA related to adipogenesis and lipid metabolism. However, little is known about the potential role of miR-205-5p in genetically improved farmed tilapia (GIFT, Oreochromis niloticus). In this study, we used miRanda software to search for potential miR-205-5p target genes and found a lipid-metabolism-related gene called acetyl-CoA carboxylase ß (ACACß). Quantitative real-time polymerase chain reaction data indicated that there may be a negative regulation relationship between miR-205-5p and ACACß gene expression under HFD rearing. Using luciferase reporter assays, we verified the binding site of miR-205-5p in the 3'-untranslated region of the ACACß mRNA. Furthermore, an in vivo functional analysis of miR-205-5p was performed by injecting GIFT juveniles with a miR-205-5p antagomir. Reduced levels of miR-205-5p in GIFT liver increased ACACß mRNA expression 12 h post-injection. miR-205-5p suppression also increased fatty acid synthase and peroxisome proliferator-activated receptor-α mRNA levels 48 h and 120 h post-injection, respectively. Taken together, our results indicate that miR-205-5p negative regulates hepatic ACACß mRNA expression, and may serve as an important regulator in controlling hepatic lipid metabolism in GIFT.

CCD and RSM optimization approach for antioxidative activity and immune regulation in head kidney of yellow catfish (Pelteobagrus fulvidraco) based on different lipid levels and temperatures.

Yellow catfish (Pelteobagrus fulvidraco) is an important economic cultured fish in China. Here we report antioxidative activity and immune regulation in head kidney using a central composite design based on water temperature (20-34 °C) and dietary lipid (2-17%). Response values were optimized using response surface methodology to maximize the immune response and relieve oxidative stress. The experiment was conducted under laboratory conditions and lasted for seven weeks. The results showed that the linear effects of lipid level on superoxide dismutase (SOD, and lysozyme (LYZ) activity, and malondialdehyde (MDA) content in head kidney, respiratory burst activity (RBA) of head kidney macrophages, and cumulative mortality of fish infected by Streptococcus iniae (S. iniae) were significant (P < 0.05). Similarly, the linear effects of water temperature on SOD activity, MDA content, and cumulative mortality were significant (P < 0.05). In addition, the quadratic effects of water temperature and lipid level on all experimental response values were significant (P < 0.05), and no interactive effect was found between water temperature and lipid level (P > 0.05). High water temperature and high lipid diet significantly reduced the antioxidative activity and immune response in head kidney, and increased MDA content, which caused increased mortality of the S. iniae-infected fish. The adjusted R2 values for SOD activity, MDA content, LYZ activity, RBA, phagocytic activity, and cumulative mortality regression models were 0.76, 0.85, 0.87, 0.79, 0.64, and 0.87, respectively. The optimal combination of water temperature and lipid level was 26.9 °C and 7.7%, at which good antioxidative activity and immune regulation were achieved, with reliability of 0.878. This combination was close to the optimal combination of water temperature and lipid level for growth performance (27.5 °C and 9.2%) reported previously. Thus, the optimal combination may not only promote growth, but also enhance antioxidant and immune levels.

Identification and characterization of lipid metabolism-related microRNAs in the liver of genetically improved farmed tilapia (GIFT, Oreochromis niloticus) by deep sequencing.

MicroRNAs (miRNAs) play vital roles in modulating diverse metabolic processes in the liver, including lipid metabolism. Genetically improved farmed tilapia (GIFT, Oreochromis niloticus), an important aquaculture species in China, is susceptible to hepatic steatosis when reared in intensive culture systems. To investigate the miRNAs involved in GIFT lipid metabolism, two hepatic small RNA libraries from high-fat diet-fed and normal-fat diet-fed GIFT were constructed and sequenced using high-throughput sequencing technology. A total of 204 known and 56 novel miRNAs were identified by aligning the sequencing data with known Danio rerio miRNAs listed in miRBase 21.0. Six known miRNAs (miR-30a-5p, miR-34a, miR-145-5p, miR-29a, miR-205-5p, and miR-23a-3p) that were differentially expressed between the high-fat diet and normal-fat diet groups were validated by quantitative real-time PCR. Bioinformatics tools were used to predict the potential target genes of these differentially expressed miRNAs, and Gene Ontology enrichment analysis indicated that these miRNAs may play important roles in diet-induced hepatic steatosis in GIFT. Our results provide a foundation for further studies of the role of miRNAs in tilapia lipid homeostasis regulation, and may help to identify novel targets for therapeutic interventions to reduce the occurrence of fatty liver disease in farmed tilapia.