Dietary palm oil enhances Sterol regulatory element-binding protein 2-mediated cholesterol biosynthesis through inducing endoplasmic reticulum stress in muscle of large yellow croaker (Larimichthys crocea).

Sterol regulatory element-binding protein 2 (SREBP2) is considered to be a major regulator to control cholesterol homoeostasis in mammals. However, the role of SREBP2 in teleost remains poorly understand. Here, we explored the molecular characterisation of SREBP2 and identified SREBP2 as a key modulator for 3-hydroxy-3-methylglutaryl-coenzyme A reductase and 7-dehydrocholesterol reductase, which were rate-limiting enzymes of cholesterol biosynthesis. Moreover, dietary palm oil in vivo or palmitic acid (PA) treatment in vitro elevated cholesterol content through triggering SREBP2-mediated cholesterol biosynthesis in large yellow croaker. Furthermore, our results also found that PA-induced activation of SREBP2 was dependent on the stimulating of endoplasmic reticulum stress (ERS) in croaker myocytes and inhibition of ERS by 4-Phenylbutyric acid alleviated PA-induced SREBP2 activation and cholesterol biosynthesis. In summary, our findings reveal a novel insight for understanding the role of SREBP2 in the regulation of cholesterol metabolism in fish and may deepen the link between dietary fatty acid and cholesterol biosynthesis.

Molecular cloning, tissue expression pattern, responses to different fatty acids and potential functions of lysophosphatidylcholine acyltransferase 1 (LPCAT1) in large yellow croaker (Larimichthys crocea).

In farmed fish, diets rich in palm oil have been observed to promote abnormal lipid build-up in the liver, subsequently leading to physiological harm and disease onset. Emerging research suggests that integrating phospholipids into the feed could serve as a potent countermeasure against hepatic impairments induced by vegetable oil consumption. Phosphatidylcholine is the most abundant type among phospholipids. In the metabolic processes of mammal, lysophosphatidylcholine acyltransferase 1 (LPCAT1), crucial for phosphatidylcholine remodeling, demonstrates a marked affinity towards palmitic acid (PA). Nonetheless, aspects concerning the cloning, tissue-specific distribution, and affinity of the LPCAT1 gene to diverse oil sources have yet to be elucidated in the large yellow croaker (Larimichthys crocea). Within the scope of this study, we successfully isolated and cloned the cDNA of the LPCAT1 gene from the large yellow croaker. Subsequent analysis revealed distinct gene expression patterns of LPCAT1 across ten different tissues of the species. The fully sequenced coding DNA sequence (CDS) of LPCAT1 spans 1503 bp and encodes a sequence of 500 amino acids. Comparative sequence alignment indicates that LPCAT1 shares a 69.75 % amino acid similarity with its counterparts in other species. Although LPCAT1 manifests across various tissues of the large yellow croaker, its predominance is markedly evident in the liver and gills. Furthermore, post exposure of the large yellow croaker's hepatocytes to varied fatty acids, PA has a strong response to LPCAT1. Upon the addition of appropriate lysolecithin to palm oil feed, the mRNA expression of LPCAT1 in the liver cells of the large yellow croaker showed significant variations compared to other subtypes. Concurrently, the mRNA expression of pro-inflammatory genes il-1ß, il-6, il-8, tnf-α and ifn-γ in the liver tissue of the large yellow croaker decreased. Interestingly, they exhibit the same trend of change. In conclusion, we have cloned the LPCAT1 gene on fish successfully and find the augmented gene response of LPCAT1 in hepatocytes under PA treatment first. The results of this study suggest that LPCAT1 may be associated with liver inflammation in fish and offer new insights into mitigating liver diseases in fish caused by palm oil feed.

Oral intake of collagen hydrolysate from mackerel scad (Decapterus macarellus) attenuates skin photoaging by suppressing the UVB-induced expression of MMP-1 and IL-6.

OBJECTIVES: Excessive skin exposure to UVB radiation can induce photoaging caused by an imbalance in oxidative stress and inflammatory responses, damaging the skin's structure and surface layer. A previous study revealed that collagen hydrolisate extracted from the skin of mackarel scads (Decapterus macarellus) had antiaging properties that were tested in vitro, which serves as a foundation for a subsequent study of its use in vivo. This study aimed at investigating the repair effect of the mackerel scad's skin collagen hydrolysate (MSS-CH) in photoaging conditions in a mouse model. METHODS: MSS-CH was given orally in mice model of skin photoaging under chronic exposure to UVB irradiation for 12 weeks. Morphological and histological changes on the skin were evaluated using SEM and HE staining, along with the measurement of the expression of matrix metalloproteinases (MMP-1) and cytokine pro-inflammatory interleukin 6 (IL-6) using ELISA. RESULTS: MSS-CH inhibits the occurrence of epidermal thickening and damage to the dermal layer of the skin. As a result, it restores the epidermis' barrier function and reduces surface damage caused by photoaging. The skin of the MSS-CH treated group exhibited improved physical appearance with reduced fine lines, wrinkles, and enhanced smoothness. Additionally, administering MSS-CH to the mice groups reduced the expression of MMP-1 and IL-6 in UVB-exposed skin. CONCLUSIONS: Altogether, this in vivo study demonstrates the photoaging-protective properties of CH-MSS, aligning with previous in vitro data. Thus, MSS-CH emerges as a strong candidate for use as an ingredient in nutraceuticals and biocosmetics.

Proteomics and phosphoproteomics analysis identifies liver immune protein markers in large yellow croakers (Larimichthys crocea) fed a soybean oil-based diet.

Dietary fish oil (FO) replacement has led to an inflammatory response in fish species. This study aimed to identify immune-related proteins in the liver tissue of fish fed a FO-based or soybean oil (SO)-based diet. By conducting proteomics and phosphoproteomics analyses, a total of 1601 differentially expressed proteins (DEPs) and 460 differentially abundant phosphorylated proteins (DAPs) were identified, respectively. Enrichment analysis revealed immune-related proteins involved in bacterial infection, pathogen identification, cytokine production, and cell chemotaxis. The mitogen-activated protein kinase (MAPK) pathway exhibited significant alterations in both protein and phosphorylation levels, with several hub DEPs and DAPs associated with MAPK pathway and leukocyte transendothelial migration being notable. In vitro experiments indicated that linolenic acid (LNA), derived from SO, inhibited the expression of NF-E2-related factor 2 (Nrf2), but increased the expression of signaling proteins linked to nuclear factor κB (NF-κB) and MAPK pathways. Transwell assays indicated that treatment of liver cells with LNA promoted macrophage migration. Collectively, the results showed that the SO-based diet upregulated the expression of NF-κB signaling-related proteins and activated the MAPK pathway, promoting immune cell migration. These findings provide novel insights for developing effective solutions to alleviate health problems caused by dietary high levels of SO inclusion.

Physicochemical characteristics and gel-forming properties of mandarin fish (Siniperca chuatsi) protein during the fish fermentation with Lactobacillus sake SMF-L5: The formation of garlic-cloves shaped protein gel.

Mandarin fish (Siniperca chuatsi) during fermentation presents a unique elastic texture. In this investigation, the physicochemical and gel-forming properties of fish proteins were evaluated to explain the formation of elastic characteristics. During fermentation, the combined effects of acidification by Lactobacillus sake SMF-L5, increased sodium chloride, and decreased moisture content in the fish protein generated a suitable microenvironment for gelation. The mass transfer of sodium chloride was accompanied by NMR relaxation of the immobilized water. The ripening fermented fish had a functionally available MHC, a higher fractal dimension, and a stable α-helical structure. Also, it exhibited excellent gel-forming performances, mainly including garlic-cloves shaped protein gel, stronger springiness, and enhanced L* and whiteness. Correlation analysis showed that the gel's physical properties were differently related to the protein's physicochemical characteristics except for total free amino acids. These results could lay a theoretical foundation for the gel formation mechanism of fermented mandarin fish.

Detoxification effects of ascorbic acid on the oxidative stress, neurotoxicity, and metallothionein (MT) gene expression in juvenile rockfish, Sebastes schlegelii by the dietary chromium exposure.

Juvenile rockfish Sebastes schlegelii (mean length 10.8 ± 1.4 cm, and mean weight 31.7 ± 3.6 g) were exposed for 4 weeks with the different levels of dietary chromium (Cr6+) at 0, 120 and 240 mg/L and ascorbic acids (AsA) at 100, 200 and 400 mg/L. Superoxide dismutase (SOD) activity, glutathione S-transferase (GST) activity, and glutathione (GSH) level of liver and gill were evaluated as antioxidant response indicators for the 4 weeks exposure. The SOD and GST activity of liver and gill were substantially increased by the high concentrations of dietary Cr exposure, whereas a significant decrease was observed in the GSH levels of liver and gill. Metallothionein (MT) gene in liver was significant stimulated in the response to the dietary Cr exposure. In neurotoxicity, AChE activity was considerably inhibited in brain and muscle tissues by dietary Cr exposure. The high levels of AsA supplementation were highly effective to attenuate the alterations in the antioxidant responses, MT gene expression, and AChE activity by the dietary Cr exposure.

Evaluation on the effect of ice glazing with different compound additives on the quality of frozen stored (-23 °C) large yellow croaker (Pseudosciaena crocea).

BACKGROUND: Compounded ice glazing has been used in large yellow croaker to improve its quality during frozen storage. The ice glazing liquid is prepared by compound use of trehalose and tea polyphenols, and the moisture, protein-related properties and freshness of the fish have been evaluated during 300 days of frozen storage. RESULTS: The results showed that the addition of trehalose effectively reduced the loss of water. At the same time, it was difficult for ice crystals to grow under the action of trehalose, the average diameter could still be maintained at 111.25-119.85 µm. The combination with tea polyphenols could effectively maintain the protein structure and keep the total volatile base nitrogen (TVB-N) and K value within 11.84 mg/100 g and 13.18%, so that the freshness of the fish was always at the first level. CONCLUSION: In a word, the ice glazing with 5% trehalose and 8% tea polyphenols had the best preservation effect, which was recommended for the frozen storage. © 2022 Society of Chemical Industry.

Palmitic acid induces intestinal lipid metabolism disorder, endoplasmic reticulum stress and inflammation by affecting phosphatidylethanolamine content in large yellow croaker Larimichthys crocea.

In the 21st century, intestinal homeostatic imbalance has emerged as a growing health challenge worldwide. Accumulating evidence reveals that excessive intake of saturated fatty acid (SFA) induces intestinal homeostatic imbalance. However, the potential molecular mechanism is still unclear. In the present study, we found that palm oil or palmitic acid (PA) treatment disturbed lipid metabolism homeostasis and triggered endoplasmic reticulum (ER) stress and inflammation in the intestine or intestinal cells of large yellow croaker (Larimichthys crocea). Interestingly, PA treatment significantly decreased phosphatidylethanolamine (PE) content in the intestinal cells. PE supplementation decreased triglyceride content in the intestinal cells induced by PA treatment by inhibiting fatty acid uptake and lipogenesis. PE supplementation suppressed ER stress. Meanwhile, PE supplementation alleviated inflammatory response through p38 MAPK-p65 pathway, reducing the damage of intestinal cells caused by PA treatment to some extent. Our work revealed that intestinal homeostatic imbalance caused by PA treatment was partly due to the decrease of PE content. PE consumption might be a nutritional strategy to regulate intestinal homeostasis in fish and even human beings.

Gum tragacanth-sodium alginate active coatings containing epigallocatechin gallate reduce hydrogen peroxide content and inhibit lipid and protein oxidations of large yellow croaker (Larimichthys crocea) during superchilling storage.

The active coatings supplemented with epigallocatechin gallate (EGCG) (0.16 %, 0.32 %, and 0.64 %, respectively) combined with superchilling storage (-3 ± 0.2 °C) were used to reduce hydrogen peroxide (H2O2) content, and inhibit lipid and protein oxidations of large yellow croaker during 42 days of superchilling storage. EGCG coatings delayed lipid and protein oxidations by inhibiting the generation of H2O2, malondialdehyde (MDA) and carbonyl groups, and maintaining a higher Ca2+-ATPase activity and sulfhydryl content. We also observed that EGCG treatments maintained myofibrillar organized secondary structure by keeping higher α-helix content, and also stabilized tertiary structure during superchilling storage. Low-field nuclear magnetic resonance (LF-NMR) revealed that EGCG treatments might improve the association of water molecules with protein for fixed water. In addition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and scanning electron microscope (SEM) images both showed that these treatments could delay the myofibrillar degradation of fresh fish. Overall, we report that the active coatings containing EGCG treatments protect the lipid and protein of large yellow croaker during superchilling storage.

Serum proteomic analysis reveals possible mechanism underlying physiological hemostasis of swim bladder.

The hemostatic effect of isinglass (dried swim bladder) in traditional Chinese medicine is well known. But its mechanism of action remains unclear. Here, mice were gavaged with the dried swim bladder of the chu's croaker (Nibea coibor). The hemostatic effect of swim bladder was investigated, tandem mass tag (TMT)-based quantitative proteomics analysis was performed to screen differentially abundant proteins associated with hemostasis in mouse serum. Results indicated that isinglass significantly shorten bleeding time and promoted coagulation after acute trauma (cut out mouse tail). In total, 57 differentially expressed proteins were identified in the sera between control and swim bladder group, of which 31 were up-regulated and 26 were down-regulated in swim bladder group. KEGG pathway enrichment analysis further demonstrated that the Neutrophil extracellular trap formation pathway was significantly affected. Combined with RT-qPCR verification, our findings further suggested that five candidate proteins in the pathway may be involved in the onset of hemostasis after swim bladder gavage, indicating their important role during the hemostasis process promoting by swim bladder. SIGNIFICANCE: Serum proteomics after swim bladder gavage described differentially enriched proteins related to hemostasis, and enriched pathways were validated. This study revealed the possible pathways involved in the hemostatic effect of swim bladder, which may provide a new effector target for the development of new hemostatic drugs.

Effects of dietary lysolecithin on growth performance, serum biochemical indexes, antioxidant capacity, lipid metabolism and inflammation-related genes expression of juvenile large yellow croaker (Larimichthys crocea).

A 70-day feeding trial was conducted to investigate effects of dietary lysolecithin on growth performance, serum biochemical indexes, antioxidant capacity, lipid metabolism and inflammation-related genes expression of juvenile large yellow croaker (Larimichthys crocea) with initial weight of 6.04 ± 0.08 g. A formulated diet containing approximately 42% crude protein and 12.5% crude lipid was used as the control diet (CON). The other three experimental diets were formulated with supplementation of 0.2%, 0.4% and 0.6% lysolecithin based on the control diet, respectively. Results showed that weight gain rate (WGR) and specific growth rate (SGR) significantly increased in fish fed diets with lysolecithin compared with those in the control diet (P < 0.05). Fish fed diets with 0.4% and 0.6% lysolecithin had notably higher lipid content in muscle than that in the control diet (P < 0.05). When fish were fed diets with lysolecithin, serum high-density lipoprotein cholesterol (HDL-c) content was notably higher than that in the control diet (P < 0.05), while fish fed the diet with 0.6% lysolecithin had a significant lower serum low-density lipoprotein cholesterol (LDL-c) content than that in the control diet (P < 0.05). Meanwhile, serum aspartate transaminase (AST) and alanine transaminase (ALT) activities in fish fed diets with lysolecithin were remarkably lower than those in the control diet (P < 0.05). With the increase of dietary lysolecithin from 0.2% to 0.6%, mRNA expression of stearoyl-coenzyme A desaturase 1 (scd1), diacylglycerol acyltransferase 2 (dgat2) and sterol-regulatory element binding protein 1 (srebp1) showed decreasing trends. Furthermore, mRNA expression of carnitine palmitoyl transferase 1 (cpt1) and lipoprotein lipase (lpl) among each dietary lysolecithin treatment were significantly higher than those in the control diet (P < 0.05). In terms of inflammation, mRNA expression of tumor necrosis factor α (tnf-α) and interleukin-1 ß (il-1ß) were significantly down-regulated in fish fed diets with lysolecithin compared with those in the control diet (P < 0.05), while the mRNA expression of interleukin-10 (il-10) was significantly higher than that in the control diet (P < 0.05). In conclusion, dietary lysolecithin could promote the growth performance, improve hepatic lipid metabolism and regulate inflammation response in juvenile large yellow croaker, and the optimal supplement level of lysolecithin was approximately 0.4% in this study.

The effects of tea polyphenol-ozonated slurry ice treatment on the quality of large yellow croaker (Pseudosciaena crocea) during chilled storage.

BACKGROUND: The aim of the current study was to evaluate the synergistic effects of tea polyphenol-ozonated slurry ice on the quality, physicochemical and protein characteristics of large yellow croaker (Pseudosciaena crocea) during chilled (4 °C) storage. To 0.3% tea polyphenol combined with ozone water was added sodium chloride until the salt concentration reached 3.3% and with the use of an ice machine the mixture formed the tea polyphenol-ozonated slurry ice. Microbial [total viable count (TVC)], physicochemical [total volatile basic nitrogen (TVB-N), K value], myofibrillar fragmentation index (MFI), Ca2+ -ATPase activity, total sulfhydryl content, intrinsic fluorescence intensity (IFI), Fourier-transform infrared (FTIR), scanning electron microscopy (SEM) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were analyzed during chilled (4 °C) storage for up to 20 days. RESULTS: The results showed that tea polyphenol-ozonated slurry ice could effectively inhibit the increase of TVC and TVB-N, reduce the degree of adenosine triphosphate (ATP) degradation. In addition, the tea polyphenol-ozonated slurry ice treatment could protect the integrity of myosin in myofibrillar proteins (MPs) by inhibiting the decrease of Ca2+ -ATPase activity and the content of total sulfhydryl. Furthermore, the tea polyphenol-ozonated slurry ice presented a superiorly protective effect on protein structure in MPs as manifested by the results of IFI, FTIR and SDS-PAGE. It was possible that due to the addition of tea polyphenol, the antioxidant activity of this complex was significantly improved. CONCLUSION: The tea polyphenol-ozonated slurry ice treatment can maintain the quality of large yellow croaker by decreasing the damage of MP caused by the interaction between microorganisms and endogenous enzymes. © 2022 Society of Chemical Industry.

Nrf2 pathway in vegetable oil-induced inflammation of large yellow croaker (Larimichthys crocea).

This study was conducted to investigate the effects and regulation of dietary vegetable oil (VO, enriched with α-linolenic acid [ALA] and linoleic acid [LNA]) on the nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-κB (NF-κB) pathways in large yellow croaker. In vivo study showed that the VO diet significantly decreased the activity of antioxidant enzymes and antioxidant enzyme-related mRNA expression in the liver tissue, in comparison with the fish oil (FO) diet (P < 0.05). The suppression of antioxidant capacity might be due to the decrease of nuclear Nrf2 protein translocation, Nrf2 binding to antioxidant response element (ARE) sequences, and subsequently, antioxidant genes transcription as electrophoretic mobility shift assay (EMSA) and luciferase assay showed. VO-derivated ALA and LNA exerted a lower antioxidant capacity than FO-derivated DHA and EPA, characterized by significantly lower nucleus Nfr2 protein expression but significantly higher ROS production values in primary hepatocytes (P < 0.05). The pro-inflammatory genes (tumor necrosis factor α [TNFα] and interleukin 1ß [IL1ß]) expression was significantly higher in the liver tissue of fish fed the VO diet which might be due to the activation of the NF-κB pathway (P < 0.05). Knockdown of the Nrf2 gene negatively affected the anti-inflammatory effect of fatty acids by increasing the expression of TNFα and the IL1ß gene and nuclear p65 protein (P < 0.05). In general, the results indicated that dietary vegetable oil decreased antioxidant capacity but induced inflammatory responses through the Nrf2/NF-κB pathway.

Regulation of Δ6Fads2 Gene Involved in LC-PUFA Biosynthesis Subjected to Fatty Acid in Large Yellow Croaker (Larimichthys crocea) and Rainbow Trout (Oncorhynchus mykiss).

Δ6 fatty acyl desaturase (Δ6Fads2) is regarded as the first rate-limiting desaturase that catalyzes the biosynthesis of long-chain polyunsaturated fatty acids (LC-PUFA) from 18-carbon fatty acid in vertebrates, but the underlying regulatory mechanism of fads2 has not been comprehensively understood. This study aimed to investigate the regulation role of fads2 subjected to fatty acid in large yellow croaker and rainbow trout. In vivo, large yellow croaker and rainbow trout were fed a fish oil (FO) diet, a soybean oil (SO) diet or a linseed oil (LO) diet for 10 weeks. The results show that LO and SO can significantly increase fads2 expression (p < 0.05). In vitro experiments were conducted in HEK293T cells or primary hepatocytes to determine the transcriptional regulation of fads2. The results show that CCAAT/enhancer-binding protein α (C/EBPα) can up-regulate fads2 expression. GATA binding protein 3 (GATA3) can up-regulate fads2 expression in rainbow trout but showed opposite effect in large yellow croaker. Furthermore, C/EBPα protein levels were significantly increased by LO and SO (p < 0.05), gata3 expression was increased in rainbow trout by LO but decreased in large yellow croaker by LO and SO. In conclusion, we revealed that FO replaced by LO and SO increased fads2 expression through a C/EBPα and GATA3 dependent mechanism in large yellow croaker and rainbow trout. This study might provide critical insights into the regulatory mechanisms of fads2 expression and LC-PUFA biosynthesis.

Dietary calcium pyruvate could improve growth performance and reduce excessive lipid deposition in juvenile golden pompano (Trachinotus ovatus) fed a high fat diet.

Excessive lipid deposition in farmed fish is a challenge in the aquaculture industry. To study the effect of dietary calcium pyruvate (CaP) on lipid accumulation in fish, we used a high fat diet (HFD) to establish a lipid accumulation model in juvenile golden pompano (Trachinotus ovatus) and supplemented with 0%, 0.25%, 0.50%, 0.75% and 1.0% CaP (diets D0-D4, respectively). After 8-week feeding in floating cages, dietary CaP significantly improved growth performance, which peaked in fish fed diet D3. Supplementation of CaP significantly decreased whole body lipid content in fish fed D2-D4 and hepatosomatic index and liver lipid content in fish fed D3 and D4. Serum and hepatic antioxidant indices, including glutathione, catalase and superoxide dismutase, showed generally increasing trends in fish fed diets with CaP. In addition, increasing dietary CaP increasingly reduced hepatic activities of hexokinase, phosphofructokinase and pyruvate kinase involved in glycolysis, and increased glycogen contents of the liver and muscle. Dietary CaP up-regulated the liver mRNA expression of pparα, cpt1, hsl and fabp1, but down-regulated expression of srebp-1, fas and acc. In conclusion, 0.75% CaP improved growth performance and reduced excessive lipid deposition by affecting fatty acid synthesis and lipolysis in juvenile T. ovatus fed HFD.

Evaluating dynamic effects of dietary glycerol monolaurate on the productive performance and flesh quality of large yellow croaker (Larimichthys crocea).

The effects of GML (Glycerol monolaurate) supplementation with two level (0.5 and 1.0 g kg-1) on the productive performance and flesh quality of large yellow croaker (360 per group) were investigated during feeding (23,50-days) and fasting stage (23,70-days). The GML supplementation significantly increased body weight after 23-days and crude protein, inosinic acid, and yellowness after 50-days. Moreover, it increased hardness, springiness, and chewiness by increasing the collagen content, myofiber density, and decreasing myofiber diameter. The high GML supplementation increased the total free amino acids, delicate amino acids, monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (n-3 PUFA), and EPA + DHA, whereas it decreased the content of saturated fatty acids/unsaturated fatty acids (SFA/UFA). During fasting, better body shape and color were shown were shown at high GML supplementation. Conclusively, high dose GML supplementation exerted promising effects on the productive performance and flesh quality of large yellow croaker.

Dispersed Crude Oil Induces Dysbiosis in the Red Snapper Lutjanus campechanus External Microbiota.

The fish external microbiota competitively excludes primary pathogens and prevents the proliferation of opportunists. A shift from healthy microbiota composition, known as dysbiosis, may be triggered by environmental stressors and increases host susceptibility to disease. The Deepwater Horizon (DWH) oil spill was a significant stressor event in the Gulf of Mexico. Despite anecdotal reports of skin lesions on fishes following the oil spill, little information is available on the impact of dispersed oil on the fish external microbiota. In this study, juvenile red snapper (Lutjanus campechanus) were exposed to a chemically enhanced water-accommodated fraction (CEWAF) of Corexit 9500/DWH oil (CEWAF) and/or the bacterial pathogen Vibrio anguillarum in treatments designed to detect changes in and recovery of the external microbiota. In fish chronically exposed to CEWAF, immunoglobulin M (IgM) expression significantly decreased between 2 and 4 weeks of exposure, coinciding with elevated liver total polycyclic aromatic hydrocarbons (PAHs). Dysbiosis was detected on fish chronically exposed to CEWAF compared to seawater controls, and addition of a pathogen challenge altered the final microbiota composition. Dysbiosis was prevented by returning fish to clean seawater for 21 days after 1 week of CEWAF exposure. Four fish exhibited lesions during the trial, all of which were exposed to CEWAF but not all of which were exposed to V. anguillarum. This study indicates that month-long exposure to dispersed oil leads to dysbiosis in the external microbiota. As the microbiota is vital to host health, these effects should be considered when determining the total impacts of pollutants in aquatic ecosystems. IMPORTANCE Fish skin is an immunologically active tissue. It harbors a complex community of microorganisms vital to host homeostasis as, in healthy fish, they competitively exclude pathogens found in the surrounding aquatic environment. Crude oil exposure results in immunosuppression in marine animals, altering the relationship between the host and its microbial community. An alteration of the healthy microbiota, a condition known as dysbiosis, increases host susceptibility to pathogens. Despite reports of external lesions on fishes following the DWH oil spill and the importance of the external microbiota to fish health, there is little information on the effect of dispersed oil on the external microbiota of fishes. This research provides insight into the impact of a stressor event such as an oil spill on dysbiosis and enhances understanding of long-term sublethal effects of exposure to aid in regulatory decisions for protecting fish populations during recovery.

Polyphenolic Extracts from Spent Coffee Grounds Prevent H2O2-Induced Oxidative Stress in Centropomus viridis Brain Cells.

Oxidative stress in aquatic organisms might suppress the immune system and propagate infectious diseases. This study aimed to investigate the protective effect of polyphenolic extracts from spent coffee grounds (SCG) against oxidative stress, induced by H2O2, in C. viridis brain cells, through an in vitro model. Hydrophilic extracts from SCG are rich in quinic, ferulic and caffeic acids and showed antioxidant capacity in DPPH, ORAC and FRAP assays. Furthermore, pretreatment of C. viridis brain cells with the polyphenolic extracts from SCG (230 and 460 µg/mL) for 24 h prior to 100 µM H2O2 exposure (1 h) significantly increased antioxidant enzymes activity (superoxide dismutase and catalase) and reduced lipid peroxidation (measured by MDA levels). These results suggest that polyphenols found in SCG extracts exert an antioxidative protective effect against oxidative stress in C. viridis brain cells by stimulating the activity of SOD and CAT.

Simultaneous Determination and Comprehensive Evaluation of Mineral Elements in Yellow Croaker Ear-Stone on Sale in China.

Yellow Croaker Ear-stone or Yunaoshi, is actually two kinds of fish otolith in China and has received increased attention in recent years as important folk medicine. For better understanding of this crude drug, a chaotic market circulation status investigation was carried out and seventeen samples with different varieties or producing areas were collected. In this study, pharmacodynamic components of nineteen varieties mineral elements of the seventeen samples were simultaneously determined by Inductively coupled plasma mass spectrometry (ICP-MS) method. The detected elements were categorized into the beneficial (Na, Mg, Ca, K, Fe, Mn, Zn, Sr, B) and unbeneficial elements (Cu, As, Cd, Hg, Al, Pb, Co, Ba, Cr and Ni) kinds and their concentrations were quantified. Then the principal component analysis (PCA) and hierarchical clustering analysis (HCA) were further applied to launch an exploratory analysis for Yunaoshi samples. The results showed that samples 1-3, 15-8, 15-3 ranked the top three from the perspective of beneficial elements and samples 1-3, 1-4, 15-2 ranked the top three based on the unbeneficial elements sides. Combined with HCA results, all samples can be used as the substitutes for Yunaoshi except for samples 1-3, 1-4 and 15-2 only judging from the perspective of mineral elements concentrations. In conclusion, simultaneous determination of mineral elements accompanied with PCA and HCA can not only provide pharmacogenetic reference for the medicinal material of Yunaoshi, but also establish a feasibility for exploring new crude resources or substitutes to this medicine.

DHA-enriched phospholipids from large yellow croaker roe regulate lipid metabolic disorders and gut microbiota imbalance in SD rats with a high-fat diet.

Large yellow croaker roe phospholipids (LYCRPLs) have great nutritional value because they are rich in docosahexaenoic acid (DHA), which is an n-3 polyunsaturated fatty acid (n-3 PUFA). In previous research, we studied the effect of LYCRPLs on the inhibition of triglyceride accumulation at the cellular level. However, its lipid regulation effect in rats on a high-fat diet and its influence on the gut microbiota has not yet been clarified. In this study, a high-fat diet was used to induce the lipid metabolism disorder in SD rats, and simvastatin, low-dose, medium-dose and high-dose LYCRPLs were given by intragastric administration for 8 weeks. The rats' body weight, food intake, organ index, blood biochemical indicators, epididymal fat tissue and liver histopathology were compared and analyzed. High-throughput 16S rRNA gene sequencing technology and bioinformatics analysis technology were also used to analyze the diversity of gut microbiota in rats. We found that LYCRPLs can significantly regulate lipid metabolism, and improve the gut microbiota disorder induced in rats by a high-fat diet. These results can lay a foundation for the study of the regulation mechanism of LYCRPLs lipid metabolism, and also provide a theoretical basis for the development of LYCRPLs as functional food additives and excipients with hypolipidemic effects.