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Various reduced graphene oxide supported CuS (RGO-CuS) composites were obtained via a hydrothermal way in this work. The as-obtained RGO-CuS with a low bandgap of ~1.24 eV showed significant light absorption in near-infrared (NIR) region. In acidic media, the optimized 0.1RGO-CuS needed an overpotential of 179 mV (at 10 mA cm−2) to trigger the hydrogen evolution reaction under NIR light. And the lowest Tafel slope of 0.1RGO-CuS (61 mV dec−1), suggesting that the photoelectrocatalytic hydrogen evolution was performed under the Volmer-Heyrovsky mechanism. The 0.1RGO-CuS displayed a good durability after 5000 cycles in acid. According to the results of EIS measurement, both NIR irradiation and RGO modification could effectively lower charge transfer resistance and improve charge transport rate of the photoelectrochemical process. The introduction of RGO could improve the electron and hole separation ability of the photoelectrochemical process, which resulted in an enhanced photoelectrocatalytic HER performance.

This study was designed to evaluate whether the administration of commensal Shewanella sp. MR-7 (MR-7) could ameliorate lipopolysaccharide (LPS)-induced intestine dysfunction in turbot. Fish (body weight: 70.00 ± 2.00 g) were randomly divided into three groups including the control group treated with dough, the LPS group treated with dough plus LPS, and the LPS+MR-7 (LMR) group treated with dough plus LPS and MR-7. These three groups with 24 fish each were force-fed with 1 g dough daily for 7 continuous days. The results revealed that MR-7 administration ameliorated LPS-induced intestinal injury, showing higher intestinal villus and microvillus height. Further results showed that MR-7 could inhibit LPS-induced activation of TLR-NF-κB signaling thus maintaining the normal expression levels of cytokines and finally ameliorate the intestinal inflammatory response in turbot. Compared with the LPS group, LMR group had less goblet cells and lower mucin-2 expression level. Moreover, MR-7 restored LPS-induced down-regulation of tight junction protein-related gene expression (zonula occluden-1, occludin, tricellulin and claudin-3). Further investigations indicated that MR-7 partially counteracted LPS-induced changes in gut microbiota composition, enhanced the beneficial bacteria Lactobacillus and reduced the Pseudomonas, thus maintaining the overall microbiota balance. Taken together, the administration of MR-7 could effectively restore LPS-induced intestine function disorder in turbot by ameliorating inflammatory response, mucosal barrier dysfunction and microbiota dysbiosis.

A continuous fibroblast-like cell line, TMF (turbot muscle fibroblasts), was established from juvenile turbot Scophthalmus maximus muscle with the method of trypsin digestion. It has been subcultured more than 60 passages for over 150 days. The TMF cells were cultured in L-15 medium supplemented with HEPES, fetal bovine serum (FBS), GlutaMAX, and basic fibroblast growth factor (bFGF). The optimal temperature for TMF culture was 24 °C. TMF cells were predominantly composed of fibroblastic-like cells, and the transcription factor 4 (TCF-4) was highly expressed in TMF cells. Chromosome analysis revealed that it had a diploid chromosome number of 2n = 44. The transfection efficiency achieved 54.95 ± 6.59%, and the cell mortality rate was about 8.70% when transfected with the nucleofection method. Meanwhile, the TMF cells showed a sensitive response to amino acid levels and activation target of rapamycin (TOR) signaling pathway. These results indicate that TMF was a potential tool to explore the signal transduction of teleost in vitro.

Methionine is one of the most limited factors in plant-based feed for fish. It plays critical roles in fish growth performance and feed utilization. However, little is known about its effects on amino acid metabolism and intestinal homeostasis in turbot. In this study, an 8-week feeding trial was conducted to examine the nutritional physiology of turbot fed with diets containing deficient (0.85%, LM), adequate (1.82%, MM) or excess (2.80%, HM) levels of methionine respectively. After the feeding trial, fish growth and feed efficiency were significantly reduced by LM diet while no significant difference was observed between MM group and HM group. Methionine deficiency diet also led to a reduction of free Met, Cys, Thr, Arg and His levels in plasma, while an elevation of Gly, Lys and Ala concentrations. The Asp and Gly levels in HM group were significantly lower than other groups. The mRNA expression of cystathionine β-synthase (cbs) and s-adenosylmethionine decarboxylase (samdc) in LM group were up-regulated while the expression of methionine synthase (ms) in LM group was depressed. The expression of ornithine decarboxylase (odc) was not affected by dietary methionine levels. Furthermore, methionine deficiency decreased the height of intestinal villus and microvilli, as well as the number of goblet cells. The mRNA expression of proliferating cell nuclear antigen (pcna) and mucin-2 (muc-2), as well as the content of glutathione, were also induced with the methionine level in the diets. These results provide important new clues in methionine function in teleost.

A Fe-N-C catalyst is supposed to drive commercialization of microbial fuel cells (MFCs) because of its remarkable catalytic performance on oxygen reduction reaction (ORR). However, the catalyst suffers from unclear active site structure and unknown responses of the cathodic microbial community. Here, we prepared a mesoporous core-shell structure catalyst with a nitrogen doped matrix carbon shell, and a Fe3O4 core (Fe3O4@N-mC) as efficient cathode catalysts for the oxygen reduction reaction (ORR). The resulting hybrid electrocatalyst (Fe3O4@N-mC) showed higher limiting current density (2.94 mA cm−2), lower H2O2 yield (7.2–12.7%), and a higher electron transfer number (3.74–3.85) for ORR activity than its intermediates, including Fe3O4, polyaniline (PANI), nitrogen doped carbon (N-C), and magnetic polyaniline composite (Fe3O4@PANI). In MFC tests, Fe3O4@N-mC produced a power density of 0.73 W m−2, which was 2.14 times of N-C (0.34 W m−2), 3.84 times of Fe3O4@PANI (0.19 W m−2), and more than four times of Fe3O4 (4.29, 0.17 W m−2) and PANI (4.87, 0.15 W m−2). Illumina sequencing of 16S rRNA gene amplicons and non-metric multi-dimensional scaling (NMDS) indicated distinct separation of the cathode biofilm bacterial communities between MFCs with different cathodic catalysts. MFCs with the Fe3O4@N-mC cathode facilitated the enrichment of putative exoelectrogenic Dietzia. Our findings suggest that enhancing ORR performance of Fe3O4@N-mC in MFCs can be attributed to the co-effects of Fe and N, the core-mesoporous shell structure, and various nitrogen functionalities.

Climate change and food shortage are two of the defining challenges in the coming decades. Considering that conventional approaches for protein production may associate with negative environmental impacts and greenhouse gas emissions, alternative protein sources that rely on inexhaustible substrates/energy should be pursued. In this proof-of-concept study, we propose a two-stage bioinorganic electrosynthesis process that can first convert CO2 and excessive electricity into methane and then synthesize single-cell protein. With an external voltage of 3.5 V and a CO2 inflow rate of 50 mL·d−1, it was possible to produce methanotrophic biomass of 118.7 ± 9.2 mg·L−1 with an amino acids mass content of 54.6% ± 8.3%, resulting in nitrogen assimilation and CO2 conversion efficiency of 91.0% ± 1.3% and 71.0%. The applied voltages, CO2 inflow rates, and O2 supply were found to affect the process significantly. This process using renewable feedstocks was proved independent of conventional agriculture for protein production.

The development of an effective biocathode with high catalytic ability and dense biomass is a major challenge for the industrial applications of electromethanogenesis (EM) process. In our previous study, intact anaerobic granular sludge (AnGS) biocathode and EM hybrid system (AnGS-EM) showed superior ability and stability when treating raw biogas, but its maximum CO2-to-CH4 conversion potential and the response to different operating conditions are still unknown. Herein, we optimized the performance of the AnGS-EM system and explored its maximum CH4 production capacity. The AnGS-EM system achieved a maximum methane production rate of 202.15 L CH4/m2catproj/d, which is over 3 times higher than the maximum value reported so far. Within a certain range, the methane production rate increased with the buffer concentration, applied voltage, and bicarbonate concentration. Excessive applied voltage and carbonate concentration not only led to resource waste but also inhibited methanogen performance. The AnGS biocathode could withstand oxygen exposure for 24 h, the acidic (pH of 5.5), and alkaline conditions (pH over 9). Illumina sequencing results showed that hydrogenotrophic methanogen (especially Methanobacterium) were dominant. This work using AnGS as biocathode for CH4 synthesis offers insight into the development of scalable, efficient, and cost-effective biocathode for biofuels and value-added chemicals production.

Separating copper and arsenic has always been a major problem in the copper slag flotation process, which influences copper slag utilization and the environmental safety. A comparative study of flash smelting furnace (FSF) slag and its flotation products (concentrate and tailing) reveals the factors affecting the separation of copper and arsenic in the beneficiation process from the perspective of mineralogy and morphology. The elemental fractionation in the process shows a positive correlation of As, Cu and Cd and an obvious correlation between speciation transformation of copper and arsenic was observed. The occurrence of arsenic and copper in FSF slag correlate the key phases of arsenic copper alloys, accounted for 88.91 % of total arsenic-bearing phases and 32.28% of copper-bearing phases. Closely-embeded matte and copper-arsenic alloys incerease the difficulty of the separation suggesting the finer grinding is needed for slag. Arsenic is liberated and oxidized into arsenate compounds while the recombination of As-O and Cu-S happened in the process affecting the selectivity of copper and arsenic. Arsenic fixed in silicate minerals is discharged into tailing which suggested to induce and fix arsenic into silicate minerals can facilitate arsenic removal from concentrate. FSF slag and its flotation concnetrate show risks of some of some of HMs which should be cautiously transported, disposed, and utilized.

This study investigated the in vitro effect of various vital dyes in common clinical use on human Muller cell viability, and it compared the toxicity of these dyes using a cell culture model. Muller cells were exposed to a series of concentrations (1 %, 0.5 %, 0.25 %, and 0.125 % or 12.9 mM, 6.45 mM, 3.22 mM and 1.61 mM) of Indocyanine green (ICG) for 2, 24, 48, and 72 h. Similarly, groups of Muller cells were stained with "Heavy" brilliant blue G (HBBG), Trypan blue (TB) (0.15 %, or 1.56 mM), Membrane-blue-dual (MBD), and ICG (0.25 %, or 3.22 mM) or BBG (0.025 %, or 0.3 mM) with glucose (GS) (50 %, 66 % and 75 % or 2.78 M, 3.67 M and 4.17 M) for 30, 60, and 120 s. Cell viability was measured with the Cell Counting Kit-8 (CCK-8) and Lactate Dehydrogenase (LDH) release assays. We found that high stain concentration and long exposure time resulted in increased toxicity to Muller cells. Nevertheless, ICG seemed to be safe at the clinically relevant concentration of 0.25 % (3.22 mM) in the short time of exposure. TB was safer than both HBBG and MBD, especially HBBG. Hypertonic GS as a dilution was not safe for Muller cells, and the negative effect was more obvious in 0.025 % (0.3 mM) BBG than that in 0.25 % (3.22 mM) ICG. This is the first report to observe the cytotoxicity of commonly used stains in clinical on human Muller cells in vitro, and to provide some basis for further studies, including in vivo investigation.

The micro-morphology of leaf epidermises is valuable for the study of leaf development and function, as well as the classification of plant species. There have been few studies comparing different preparation and imaging methods for visualizing the leaf epidermis. Here, four specimen preparation methods were used to investigate the leaf epidermis morphology of Arabidopsis, radish, cucumber, wheat, rice, and maize, under an inverted basic light microscope (LM), a laser scanning confocal microscope (LSCM), or a scanning electron microscope (SEM). Optical microscope specimens were obtained using either the direct isolation method or the chloral hydrate-based clearing method. SEM images were obtained using a standard stage for conventional dehydrated samples or a Coolstage for fresh tissue. Different parts of epidermis peels were well focused under the LM. Investigation of samples cleared by chloral hydrate is convenient and autofluorescence of cell walls can be detected in rice. The resolution of images of conventional SEM leaf samples was generally higher than the Coolstage images at the same magnification, whereas local collapse and shrinkage were observed in leaves with high water content when using the conventional method. However, stomatal apparatuses of Arabidopsis, cucumber, radish, and maize deformed and showed poor appearance when using the Coolstage. Moreover, we usually used glutaraldehyde as an SEM fixative when using t-butanol for freeze-drying, though methanol is considered a better fixative in recent studies. In addition, fresh samples were not stable on the Coolstage. Thus, we compared four different t-butanol freeze-drying methods and two Coolstage methods. The dimension and morphology of tissues were compared using the six different methods. The results indicate that methanol fixative obviously reduced shrinkage of SEM samples compared with glutaraldehyde and formaldehyde alcohol acetic acid (FAA) fixatives. The use of methanol and a graded series of steps improved the preservation of samples. Preparing samples with optimal cutting temperature compound and observing at −30°C helped to increase the stability of Coolstage samples. In summary, our results provide an overview of the shortcomings and merits of four different methods, and might provide some information about choosing an optimal method for visualizing epidermal morphology.

Methane-oxidizing bacteria (MOB) that can use biogas and recycled nitrogen from wastewater as a sustainable feedstock for single cell protein (SCP) synthesis are receiving increasing attention. Though promising, limited knowledge is available on the alternative strains especially the ones that can tolerant to strict environments such as acidic conditions. Furthermore, how would the hydrogen sulfide affect the MOB (especially the alternative strains) for SCP synthesis when crude biogas is used as feedstock is still unknown. In this study, the capability of an acidic-tolerant methanotrophic bacterium Methylocapsa acidiphila for SCP production using raw biogas and the associated inhibitory effect of sulfide on the bioconversion was for the first time investigated. Results showed that the inhibitory effect of sulfide on the growth of M. acidiphila was observed starting from 8.13 mg L−1 Na2S (equivalent to approximately 1000 ppm of H2S in crude biogas). The total amino acid content in the dry biomass decreased more than two times due to sulfide inhibition compared with the control samples without the presence of sulfide (585.96 mg/g dry biomass), while the proportion of essential amino acids in the total amino acid was not affected when the concentration of Na2S was lower than 5.73 mg L−1. The performance of M. acidiphila in a sulfide-rich environment was further studied at different operational conditions. The feeding gas with a CH4/O2 ratio of 6:4 could help to alleviate the sulfide inhibition, compared with other ratios (4:6 and 8:2). Moreover, the sequential supply of the feed gas could also alleviate sulfide inhibition. In addition, the MOB's growth rate was higher when applying a higher mixing rate of 120 rpm, compared with 70 rpm and 0, due to a better gas-liquid mass transfer. The inoculum size of 20% and 10% resulted in a faster growth rate compared with the 5%. Furthermore, M. acidiphila could assimilate either NH4+ or NO3− as nitrogen source with a similar growth rate, giving it the potential to recycle nitrogen from a wide range of wastewaters. The results will not only create new knowledge for better understanding the role of hydrogen sulfide in the assimilation of raw biogas by acid-tolerant M. acidiphila but also provide technical insights into the development of an efficient and robust process for the waste-to-protein conversion.

At present, the bioproduction of short-chain fatty acids (SCFAs) from waste activated sludge (WAS) has attracted worldwide attention due to the demand of carbon neutrality during waste treatment. Calcium peroxide (CaO2) has been reported to be an effective method for the solubilization of WAS and the accumulation of SCFAs, but the high reagent cost limits its industrial application. Therefore, free nitrous acid (FNA) was introduced into the WAS pretreatment system to assist with CaO2 for enhancing the disruption of extracellular polymeric substances (EPS) and the subsequent acidogenesis process. The results showed that FNA and CaO2 synergistically enhanced EPS decomposition and the release of biodegradable organic compounds during pretreatment. The highest soluble chemical oxygen demand (3.1- and 2.6-fold higher compared to individual pretreatments at the same concentrations) after pretreatment and the highest SCFAs accumulation (2.0- and 6.4-fold compared to individual pretreatments at the same concentrations) after a 2-day fermentation period was observed in the FNA + CaO2 (0.15 g/g VSS) co-treated group. Therefore, the FNA + CaO2 (0.15 g/g VSS) co-treatment was determined to be the optimal strategy for ensuring the disintegration of the EPS matrix and enhancing the accumulation of SCFAs in pretreated sludge during anaerobic digestion.

The present study was conducted to evaluate the effects of dietary Eucommia ulmoides (EU) on growth, feed utilization, antioxidant activity and immune responses of turbot fed a basal diet (CON) or EU‐supplemented diets with 5.0 g/kg (EU1), 10.0 g/kg (EU2) and 20.0 g/kg (EU3) EU leaf powder. After 70‐day trial, EU supplementation did not affect nutrient utilization, but reduced feed intake (FI) and specific growth rate (SGR) of fish at doses above 5.0 g/kg. Superoxide dismutase (SOD), catalase (CAT) and total antioxidant capacity (T‐AOC) activities in the EU‐supplemented groups were significantly higher than those in the control group at a dose of 20.0 g/kg. Significantly reduced malondialdehyde (MDA) contents were observed in EU‐supplemented groups at doses over 5.0 g/kg. Furthermore, fish fed 20.0 g/kg EU showed the highest lysozyme (LZM) activity among groups. The EU‐supplemented diets with doses above 5.0 g/kg significantly enhanced the mRNA expressions of cytokines. The expression level of major histocompatibility complex II alpha (MHC IIα) was significantly upregulated compared to that of the control fish when the supplemental level was at 20.0 g/kg. Taken together, the present study indicated that the EU could remarkably enhance the antioxidant activity, non‐specific immunity and maintain an active immune response in turbot.

This study was conducted to investigate protective effects of dietary selenium (Se) on abalone Haliotis discus hannai Ino against the toxicity of cadmium (Cd). A 60‐day feeding trial was conducted with abalone (initial weight: 3.17 ± 0.01 g), which were exposed to 0.34 mg/L of waterborne Cd. During a feeding trial, abalone were fed graded levels of Se at 0.10 (controls), 1.31, and 4.20 mg/kg diet respectively. Results showed that there was no significant difference in specific growth rate and survival rate of abalone among the three treatments. Compared with the controls, dietary Se significantly decreased Cd concentrations in serum, muscle, mantle, gill, mantle, and hepatopancreas of abalone. Besides, compared with the controls, dietary Se significantly increased metallothionein concentration in the hepatopancreas of abalone. Additionally, compared with the controls, dietary Se significantly decreased concentrations of malondiadehyde and protein carbonyl in hepatopancreas of abalone. Meanwhile, compared with the controls, dietary Se significantly increased activities of glutathione peroxidase, thioredoxin reductase, and thioredoxin peroxidase, and concentration of glutathione in the hepatopancreas of abalone. Based on the data above, in abalone, dietary Se showed protective effects against waterborne Cd.

A previous study showed that flesh quality of large yellow croaker (LYC) was improved by feeding dietary hydroxyproline (Hyp, 0·69 %). The aim of the present study was to explore the underlying mechanisms using transcriptomics and metabolomics analysis. The metabolomics analysis showed that muscle metabolite profiles could be clearly separated between the basal diet and Hyp supplementation diet. Metabolites including betaine, Hyp, lactate, glucose-6-phosphate, trimethylamine N-oxide, taurine, creatine, inosine monophosphate, histamine and serine made significant contribution to the separation. Compared with the control diet, the transcriptomics analysis identified a total of 334 different expressed genes, of which 298 genes were up-regulated and thirty-six genes were down-regulated in the Hyp supplementation group. The altered genes of the Hyp supplementation group were involved in collagen metabolism, lipid metabolism and energy metabolism. The integrated results revealed that the increased muscle collagen content in the Hyp supplementation diet was partly because of its enhancement of biosynthesis and the reduction of degradation. The improvement of muscle quality by dietary Hyp supplementation could also be related to a good utilisation of glucose through enhancement of glycolysis. It was concluded that dietary Hyp supplementation could improve flesh quality because of comprehensive metabolism changes including elevated collagen content, glycolysis, lipid metabolism and flesh flavour of LYC. The present study provided a novel strategy to understand the underlying molecular mechanism of flesh quality of LYC fed diet with Hyp supplementation.

A rapid quantification method of glycated hemoglobin (HbA1c) is proposed based on ATR-FTIR spectroscopy in human hemolysate samples. HbA1c, a major clinical diagnostic indicator of diabetes, is a relative content indicator, which was indirectly determined by determining the hemoglobin (Hb) and absolute HbA1c content (Hb·HbA1c) using ATR-FTIR spectroscopy. The equidistant combination partial least squares (EC-PLS) method was employed in wavelength selection to improve the modeling performance. Modeling samples were divided into calibration and prediction sets 50 times repeatedly to increase the model stability. For Hb and Hb·HbA1c, 90 and 198 wavenumbers were screened out by EC-PLS, respectively. The predicted values of HbA1c were calculated based on the predicted Hb and Hb·HbA1c values. The root-mean-square errors (RMSEP) and correlation coefficients of prediction (RP) were 5.9 g L−1 and 0.945 for Hb, 1.32 g L−1 and 0.931 for Hb·HbA1c, and 0.67% and 0.918 for HbA1c, respectively, for the validation samples. The results indicated the feasibility of quantification of HbA1c with ATR-FTIR spectroscopy. This method is simpler and quicker than conventional methods. Thus, this process is a potential diabetes screening tool in large populations.

The low methionine content in plant-based diets is a major limiting factor for feed utilization by animals. However, the molecular consequences triggered by methionine deficiency have not been well characterized, especially in fish species, whose metabolism is unique in many aspects and important for aquaculture industry. In the present study, the primary muscle cells of turbot (Scophthalmus maximus L.) were isolated and treated with or without methionine for 12 h in culture. The responses of nutrient sensing pathways, the proteomic profiling of metabolic processes, and the expressions of key metabolic molecules were systematically examined. Methionine deprivation (MD) suppressed target of rapamycin (TOR) signaling, activated AMP-activated protein kinase (AMPK) and amino acid response (AAR) pathways. Reduced cellular protein synthesis and increased protein degradation by MD led to increased intracellular free amino acid levels and degradations. MD also reduced glycolysis and lipogenesis while stimulated lipolysis, thus resulted in decreased intracellular lipid pool. MD significantly enhanced energy expenditure through stimulated tricarboxylic acid (TCA) cycle and oxidative phosphorylation. Collectively, our results identified a comprehensive set of transcriptional, proteomic, and signaling responses generated by MD and provided the molecular insight into the integration of cell homeostasis and metabolic controls in fish species.

The proper disposal of arsenic-containing smelting dust has been an important challenge in the copper pyrometallurgy industry which is mostly limited by the variability of arsenic content and species in different types of dusts. The eight types of flash smelting dusts produced along the gas line have been extensively characterized and comparatively studied. Arsenic content gradually increases along the flash smelting (FS) and flash converting (FC) parts of the gas line, and a negative correlation with the pH and copper content has been observed. PM10 accounts for 81.65% and 95.02% of the flash copper furnance (FSF) dust pocket dust and FSF electrostatic precipitator (ESP) dust, respectively. The size distribution variation inply the As enrichment in finer particles. The valence state of arsenic tends to migrate to reach higher valence states along both the FSF and FCF gas line, and the formation mechanism of different types of arsenic particles differs. The As(III)-O mainly remains in the WHB convection part dust and most of them are oxidized to arsenate compounds. More than 80% of the arsenic species was present in the ESP as As(V) and As(III)-arsenite. Fragmentation of concentrate particles and rapid condensation by gas phases lateral flushing of the pipe may produce arsenic particles in the waste heat boiler (WHB), while those remaining in the dust pocket and the ESP may result from adsorption, condensation, and chemical reactions. Temperature is the main factor that affects the deposition site of As2O3 particles. Alkali metal oxide particles influence As content and speciation in dusts by promoting the arsenate formation.

This work presents an effective way of enhancing MoS2-mediated electrocatalytic hydrogen evolution, by exploiting the synergistic effect of reduced graphene oxide (rGO) and near-infrared (NIR) light. Various rGO-MoS2 composites were obtained via hydrothermal method. The optimized composite, 0.2rGO-MoS2 exhibited enhanced electrocatalytic hydrogen evolution activity in a wide pH range under NIR irradiation, without adding noble metal. The overpotentials of 0.2rGO-MoS2 at 10 mA cm−2 in acidic and alkaline media were 146 and 314 mV, respectively. The corresponding Tafel slopes in acidic and alkaline media were 51 and 80 mV dec−1, respectively. In both media, the electrocatalytic hydrogen evolution by 0.2rGO-MoS2 under NIR irradiation was attributed to the Volmer-Heyrovsky mechanism. 0.2rGO-MoS2 also had a good reproducibility and durability under NIR light irradiation after 5000 cycles and 24 h of continuous electrolysis in both media. Furthermore, the roles of rGO and NIR irradiation in the electrocatalytic hydrogen evolution by MoS2 were investigated.

Fermentation has been reported to improve the utilization of plant ingredients including soybean meal (SBM) by fish, but the detailed mechanism is still poorly understood. This study compared the effects of partial replacement of fish meal (FM) protein with SBM or Enterococcus faecium fermented SBM (EFSM) on the growth, antioxidant status, intestinal microbiota, morphology, and inflammatory responses in turbot (Scophthalmus maximus L.). The FM-based diet was used as the control (CONT). Two experimental diets were formulated in which 45% of the FM protein was replaced with SBM or EFSM. Each diet was fed to triplicate groups of fish (7.57 ± 0.01 g) twice daily for 79 d. Inferior growth performance was observed in SBM group, however, no significant depression was observed in EFSM group compared to the CONT group. The CONT group had the highest values of lysozyme, complement component 3, total antioxidant capacity, superoxide dismutase and catalase, followed by the EFSM group, and the lowest in SBM group. The malondialdehyde content was lowest in the CONT group, followed by the EFSM group, and was highest in the SBM group. Gut morphology showed that SBM diet induced alterations typical for intestinal inflammation including decreased villus and microvillus height, and increased width and inflammatory cell infiltration of the lamina propria. However, the EFSM group alleviated such SBM-induced intestinal pathological disruption. Paralleled with the morphological symptoms, the inflammatory gene expression levels of tumor necrosis factor alpha, interleukin-1 beta and interleukin-8 were highest in the SBM group, followed by the EFSM group, and were lowest in the CONT group. Furthermore, the intestinal microbiota analysis revealed that EFSM group had an overall more similar microbiota with CONT group than SBM group. Specifically, compared with the SBM group, EFSM group significantly enhanced the probiotics Lactobacillus and anti-inflammatory bacterium Faecalibaculum, and inhibited the Vibrio. Collectively, this study indicated that Enterococcus faecium fermentation effectively counteracted the negative effects of SBM by enhancing antioxidant capacity, suppressing inflammatory responses, and modulating gut microbiota in turbot.

High levels of soybean meal (SBM) in aquafeed leads to detrimental inflammatory response and oxidative stress in fish. In the present study, fermentation with Aspergillus awamori was conducted to explore the potential effects on improving the nutritional quality of soybean meal and the health status of turbot. A 63-day feeding trial (initial weight 8.53 ± 0.11 g) was carried out to evaluate the utilization of fermented soybean meal (FSM) by juvenile turbot. 0% (FM, control), 30% (S30, F30), 45% (S45, F45), and 60% (S60, F60) of fish meal were replaced with SBM or FSM, respectively. As the results showed, fermentation significantly reduced the contents of anti-nutritional factors in SBM, including raffinose (−98.8%), glycinin (−98.5%), β-conglycinin (−97.4%), trypsin inhibitors (−80%) and stachyose (−80%). A depression of fish growth performance and activities of superoxide dismutase and lysozyme were observed in S45 and S60 groups, while these inferiorities were only observed in F60 group. Meanwhile, fermentation also improved the heights of enterocytes and microvillus significantly in the F45 and F60 groups compared with those in SBM. An induced expression of anti-inflammatory cytokine transforming growth factor-β and depression of pro-inflammatory cytokines tumor necrosis factor-α and interleukin-1β in the distal intestine were observed in the F45 and F60 groups. Taken together, this study indicated that fermentation with Aspergillus awamori could improve the replacement level with soybean meal from 30% to 45% in turbot.

Adding immunopotentiators to plant protein based diets has been a feasible way to improve fish growth performance and healthy status. In this study, an 8-week trial was carried out to explore the effects of resveratrol, a natural polyphenolic compound, on growth performance, anti-oxidative capacity and immune responses in turbot fed soybean meal based diet. As the results showed, replacement 45% fish meal with soybean meal (SBM) significantly depressed the fish growth, feed utilization and the heights of villi and microvilli in distal intestine. The mRNA levels of hepatic antioxidant enzymes, including superoxide dismutase (sod), glutathione peroxidase (gsh-px) and peroxiredoxin 6 (prx 6), were highly inhibited in SBM group. The inflammation related genes in intestine were also responsive to soybean meal. Supplying resveratrol showed no effects on fish growth performance but significantly restored the intestinal morphology and improved the mRNA levels of hepatic antioxidant enzymes as well as the activity of SOD. Meanwhile, resveratrol significantly improved the mRNA levels of anti-inflammatory cytokine transforming growth factor-β and inhibited the expression of pro-inflammatory cytokines tumor necrosis factor-α (tnf-ɑ), interleukin-1β (il-1β) and interleukin-8 (il-8). The results indicate that resveratrol could attenuate the oxidative stress and inflammatory response induced by soybean meal in turbot. This study shows resveratrol is an effective immunopotentiator to carnivorous fishes fed plant protein sources.

Transition metal oxides with hierarchical porous nanostructure have attracted tremendous attention in removal organic pollutants and heavy metal due to their high adsorption efficiency and versatile properties. In this work, a CoO/MoO2/Mo2C composite was obtained via a one-pot hydrothermal method. The CoO/MoO2/Mo2C composite showed a core-shell structure with enhanced adsorption performance. Batch adsorption experiments indicated that adsorbent type, solution pH, dosage and pollutant concentration affected the adsorption performance of CoO/MoO2/Mo2C. The adsorption of methyl orange (MO), methylene blue (MB), Congo red (CR) and Cr(VI) fitted the Pseudo-second-order kinetic model. The Langmuir model was more suitable to describe the adsorption isotherm, and the theoretical maximum adsorption capacities were 555.6, 384.6, 219.8 and 294.1 ​mg ​g−1 @ 25 ​°C, respectively, which marched well with the experimental data (472.7, 328.0, 213.0 and 263.9 ​mg ​g−1, respectively). The adsorption capacity of CoO/MoO2/Mo2C maintained more than 80% after three adsorption-desorption cycles, which confirmed that the CoO/MoO2/Mo2C was stable and could be considered to be a potential versatile adsorbent.

Microspheres composed of H2SO4-protonated graphitic carbon nitride (g-C3N4) nanosheets were prepared through a template-free dialysis method. The g-C3N4 microspheres displayed a much larger band gap and greater UV light absorption in the light region of 200–300 nm compared with that of bulk g-C3N4, and thus substantially improved their UV light photocatalytic performance towards the degradation of Rhodamine B (RhB). The present work approached soft solution assembly of g-C3N4 nanosheets in a one pot manner, demonstrating a new strategy for constructing g-C3N4 nanostructures.

In this work, we prepared the polyimide (PI) nanocomposite films containing barium titanate @polydopamine (BT@PDA) nanoparticles within a core-shell structure by solution casting method. The dielectric constant of these nanocomposite films is significantly improved compared to pure PI film, and increases with the increase of BT nanoparticles. And, the breakdown strength of these nanocomposite films is better than that of untreated BT/PI films at the fixed BT content. The PI composite film containing 1 vol% of BT@PDA nanoparticles exhibits the highest energy storage density of 1.94 J/cm3 under an electric field of 315 kV/mm, which is 42% over the pristine PI (1.37 J/cm3 at 295 kV/mm) and about 162% greater than biaxially-oriented polypropylene (BOPP) (≈1.2 J/cm3 at 640 kV/mm). The presence of PDA shell effectively improves the dispersion uniformity and interfacial compatibility of BT nanoparticles in the PI matrix, giving rise to lower local electric field distortion in the composites. Besides, the BT@PDA/PI nanocomposite films have excellent dielectric thermal stability in the temperature range from 25 to 200 °C and thermal stability up to 500 °C. The BT@PDA/PI composites fabricated in this work have a great potential to be used in the high-temperature film capacitors.

In the present study, Lactobacillus plantarum P8 was used to ferment soybean meal (SBM), resulting in a significant reduction in the indigestible oligosaccharides (sucrose, raffinose, and stachyose) and anti-nutritional factors (tannin, trypsin inhibitors, glycinin, and β-conglycinin) in SBM. Nine isonitrogenic and isoenergetic experimental diets were formulated in which SBM or L. plantarum P8 fermented SBM (LPFSBM) replaced fish meal (FM) protein with 0 (control); 15% by SBM (Diet 1), 30% by SBM (Diet 2), 45% by SBM (Diet 3), 60% by SBM (Diet 4), 15% by LPFSBM (Diet 5), 30% by LPFSBM (Diet 6), 45% by LPFSBM (Diet 7), and 60% by LPFSBM (Diet 8). Triplicate groups of 30 fish were fed to apparent satiation twice daily for 66 d in an indoor recycling seawater system. No significant differences were found in survival rate among the different groups. However, 45% SBM, 60% SBM, and 60% LPFSBM (Diets 3, 4, and 8) diets significantly reduced growth performance and feed utilization. The LPFSBM diets did not affect moisture, crude protein, crude lipid, or crude ash contents of whole-body measurements. However, 60% SBM (Diet 4) significantly decreased crude protein and lipid content while increasing moisture and crude ash contents of the whole-body. The activity of serum lysozyme was significantly decreased in the group fed with 60% SBM (Diet 4). Total antioxidant capacity was significantly increased in the group fed the 45% LPFSBM (Diet 7). Apparent digestibility coefficient (ADC) of protein was significantly lower in fish fed diets with 45% and 60% of protein from SBM and 60% of protein from LPFSBM than in the control group. When the substitution level of SBM was equal to or above 45%, the activities of protein metabolism enzymes (alanine aminotransferase, ALT and aspartate aminotransferase, AST) were significantly lower than those in the control group. The level of LPFSBM did not affect the activities of ALT and AST. SBM-induced pathological changes seen in the distal intestine of fish fed 45% and 60% SBM (Diets 3 and 4) were not pronounced in groups fed LPFSBM. The results of the present study suggest that protein from SBM could substitute up to 30% of FM protein, with protein from LPFSBM being able to replace up to 45% of FM protein. Statement of relevance The present study was conducted to investigate the effects of Lactobacillus plantarum P8 fermentation on soybean meal and evaluate LPFSBM as a partial replacement for fish meal in diets of turbot by examining growth, activities of protein metabolism enzymes, intestinal morphology, and immune responses. Our results would be helpful to develop cost effective and sustainable dietary formulations for turbot. The results of this study indicate that LPFSBM could replace up to 45% of fish meal protein in juvenile turbot diet. The ANFs are important factors that affect the growth performance of turbot, damaging the normal structure of intestine and a depression of digestion and absorption function. LPFSBM reduced SBM-induced pathomorphological changes in the distal intestine which partly accounted for the L. plantarum P8 fermentation reduces indigestible oligosaccharides and anti-nutritional factors in soybean meal and enhanced the apparent digestibility coefficients (ADCs) of dry matter and crude protein of soybean meal. The results are reliable and of both theoretical and practical importance. The work described has not been submitted elsewhere for publication, in whole or in part, and all the authors listed have approved the manuscript that is enclosed. I have read and have abided by the statement of ethical standards for manuscript submitted to Aquaculture.

Fluorine-rich nanoporous carbons with tunable porosity and F content have been successfully synthesized from a silane precursor using a solution-based F doping method. The F-rich carbon surface with higher polarity provides stronger affinity and wettability for the organic electrolyte, which is for the first time demonstrated though Gauss computational calculation between F-carbon surface and organic electrolytes. The optimized F-rich nanoporous carbon manifests a high specific capacitance of 168 F g −1 in a symmetric cell with excellent retention at high rates and upon prolonged 10,000 cycles.

Taurine is one of the conditionally essential amino acids for fish. Its metabolism has attracted much attention in fish nutrition due to the substitution fishmeal with plant ingredients, which barely contain taurine. However, little is known about the mechanisms of taurine homoeostasis in turbot (Psetta maxima), an economically valuable carnivorous fish with limited taurine biosynthesis ability. In this study, we obtained the full-length cDNA of turbot taurine transporter (PmTauT) and classified its tissue distribution in juvenile turbot and substrate regulation in isolated turbot muscle cells. Full-length PmTauT cDNA was 2566 bp containing a 58 bp 5′ untranslated region (UTR), a 633 bp 3′UTR and a 1875 bp open reading frame (ORF) encoding 624 amino acid residues. The deduced protein contained 12 putative transmembrane domains and showed highest similarity with taurine transporter from Senegalese sole (Solea senegalensis), another flatfish species. By quantitative real-time PCR analysis, PmTauT transcript was predominantly detected in liver and intestine, while was lesser expressed in gill and stomach. In addition, PmTauT in isolated turbot muscles was down-regulated by taurine in a dose-dependent manner. These results suggested that PmTauT was involved in taurine homoeostasis in turbot.

In this study, a group of nitrogen-doped sludge biochar were prepared by a single-step pyrolysis method and employed as catalysts for the activation of peroxymonosulfate (PMS). The N content of as-synthesized biochar composites was altered by adding a different ratio of melamine with the precursors. The sample characterization results indicated that the N content of sludge-melamine-blended biochar named SM-(0.5:1) significantly increased from 1.91 to 9.93% compared with that of raw sludge biochar. Consequently, the surface area and mesoporosity also enhanced. SM-(0.5:1) exhibited excellent degradation ability of reluctant organic pollutants in PMS/acidic media, which outperformed many previously reported carbocatalysts. Complete color removal of a mixture solution of seven cationic and anionic dyes (10 mg L−1 of each) was achieved within 50 min by using 200 mg L−1 of SM-(0.5:1) and 350 mg L−1 of PMS. A mechanism study indicated that the non-radical process performed by the pyridine N dominated the oxidative degradation of pollutants rather than that of SO4 − and OH radical process governed by graphitic N, C O, and surface metal oxides. This study concurrently provides a facile route of enhancing N functionality of sludge-based carbocatalysts and an efficient way of sludge valorization.

Searching for nutraceuticals and understanding the underlying mechanism that promote fish growth is at high demand for aquaculture industry. In this study, the modulatory effects of soy phosphatidic acids (PA) on cell proliferation, nutrient sensing, and metabolic pathways were systematically examined in primary muscle cells of turbot (Scophthalmus maximus). PA was found to stimulate cell proliferation and promote G1/S phase transition through activation of target of rapamycin signaling pathway. The expression of myogenic regulatory factors, including myoD and follistatin, was upregulated, while that of myogenin and myostatin was downregulated by PA. Furthermore, PA increased intracellular free amino acid levels and enhanced protein synthesis, lipogenesis, and glycolysis, while suppressed amino acid degradation and lipolysis. PA also was found to increased cellular energy production through stimulated tricarboxylic acid cycle and oxidative phosphorylation. Our results identified PA as a potential nutraceutical that stimulates muscle cell proliferation and anabolism in fish.

Aims Dihydroartemisinin has been shown to inhibit the development of pulmonary fibrosis in rats, but its mechanism has yet to be elucidated. This study aimed to determine the mechanisms of dihydroartemisinin in bleomycin-induced pulmonary fibrosis in a rat model. Main methods Morphological changes and collagen deposition were analyzed via hematoxylin-eosin staining and Masson staining and the expression of biotic-factor-related oxidative stress in lung tissues was assayed with standard assay kits. The expressions of α-SMA, E-cadherin, and Nrf2/HO-1 were detected by Western blot and RT-PCR, and the cell morphology and proliferation of cultured type II alveolar epithelial cells (AECs) were assessed via microscopy and immunocytochemical assay. Key findings Dihydroartemisinin treatment significantly decreased the level of oxidative stress and collagen synthesis and inhibited AECs differentiation in bleomycin-induced pulmonary fibrosis compared to the control group (P Significance Our results indicated that dihydroartemisinin might decrease oxidative damage to attenuate lung injury and fibrosis.

A 56-day feeding trial was conducted to evaluate the safety level of 2-hydroxy-4-(methylthio) butanoic acid (HMTBa) as a dietary methionine source for turbot Scophthalmus maximus . Four isonitrogenous and isolipidic diets were formulated with graded levels of HMTBa (0%, 1%, 5% and 10%). These four experimental diets were named as H-0, H-1, H-5 and H-10, respectively. The effects of dietary HMTBa on growth performances, anti-oxidative responses, and liver and intestine conditions of turbot were analyzed. Results showed that the survival rate in H-10 treatment (95.83%) was significantly lower than that in H-1 (99.58%) ( P P P P

This study was conducted to investigate the effect of dietary proline (Pro), and Pro and hydroxyproline (Hyp) in combination on the growth performance, total Hyp and collagen concentrations of tissues, and prolyl 4-hydroxylase α(I) (P4H α(I)) gene expression in juvenile turbot feeding high plant protein diets. A diet containing 50% crude protein and 12% crude lipid was formulated as the basal and control, on which other two protein and lipid contents identical experimental diets were formulated by supplementing the basal with either 0.75% Pro (Pro-0.75) or 0.75% Pro and 0.75% Hyp (Pro+Hyp). Four groups of fish in indoor seawater recirculating systems, 35 individuals each, were fed twice a day to apparent satiation for 10 weeks. The results showed that dietary Pro and Hyp supplementation had no significant effect on growth performance and feed utilization of juvenile turbot (P > 0.05). Total Hyp and collagen concentrations in muscle were significantly increased when dietary Pro and Hyp increased (P

The aim of this study was to compare the effects of waterborne copper (Cu) and cadmium (Cd) on survival, anti-oxidative response, lipid peroxidation and metal accumulation in abalone Haliotis discus hannai. Experimental animals (initial weight: 7.49 g ± 0.01 g) were exposed to graded concentrations of waterborne Cu (0.02, 0.04, 0.06, 0.08 mg L−1) or Cd (0.025, 0.05, 0.25, 0.5 mg L−1) for 28 days, respectively. Activities of the anti-oxidative enzymes (catalase, CAT; superoxide dismutase, SOD; glutathione peroxidases, GPx; glutathione S-transferase, GST), contents of the reduced glutathione (GSH) and malondiadehyde (MDA) in the hepatopancreas, and metal accumulation in hepatopancreas and muscles were analyzed after 0, 1, 3, 6, 10, 15, 21, 28 days of metal exposure, respectively. Results showed that 0.04 mg L−1, 0.06 mg L-−1 and 0.08 mg L−1 Cu caused 100% death of abalone on the 21st, 10th and 6th day, respectively. However, no dead abalone was found during the 28-day waterborne Cd exposure at all experimental concentrations. Generally, activities of SOD and GST in hepatopancreas under all Cu concentrations followed a decrease trend as the exposure time prolonged. However, these activities were firstly increased and then decreased to the control level and increased again during Cd exposure. Activities of CAT in all Cu exposure treatments were higher than those in the control. These activities were firstly increased and then decreased to the control level and increased again during Cd exposure. Contents of MDA in hepatopancreas in all Cu treatments significantly increased first and then decreased to the control level. However, the MDA contents in hepatopancreas were not significantly changed during the 28-day Cd exposure. The metals accumulation in both hepatopancreas and muscles of abalone significantly increased with the increase of waterborne metals concentration and exposure time. These results indicated that H. discus hannai has a positive anti-oxidative defense against Cu or Cd. In conclusion, anti-oxidative mechanism in abalone to resist waterborne Cu did not follow the same pattern as that for waterborne Cd.

This study was designed to assess the protective effects of dietary selenium (Se) on abalone Haliotis discus hannai Ino against the toxicity of waterborne copper (Cu). A 60-day feeding trial was conducted in a static water system for abalone (initial weight: 3.17 ± 0.01 g) exposed to 0.02 mg L−1 of waterborne Cu. The animals were fed one of the three experimental diets with 0.10, 1.31 and 4.20 mg kg−1 of Se from Na2SeO3·5H2O respectively. Results showed that the abalone fed 1.31 mg kg−1 of dietary Se had the lowest Cu concentration in shell, muscle, mantle, gill, hepatopancreas and serum. Meanwhile, the significant lowest contents of malondiadehyde and protein carbonyl in hepatopancreas were also found in the treatment with 1.31 mg kg−1 of dietary Se (P

Fishmeal could only be replaced by plant proteins at limited levels in aquafeeds, especially for carnivorous fish. In this study, an experiment was designed to evaluate the possibility of improving the utilization of plant proteins by maggot meal supplementation in turbot diet. Five diets were formulated: a reference diet (FM) containing 63% fishmeal and four experimental diets (35(0%), 35(3%), 40(0%), 40(3%)) in which fishmeal was substituted at different levels by plant proteins with 0–3% maggot meal. Turbot (4.90 ± 0.03 g) was fed with these diets for 9 weeks. Fishmeal was successfully replaced by plant proteins in turbot diet without growth reduction at 35% but not 40%. However, maggot supplementation (3%) at 40% plant protein replacement level achieved comparable growth performance with that of fishmeal. Maggot meal supplementation improved apparent digestibility coefficients, plasma hydroxyproline levels, intestine trypsin activities and activated target of rapamycin (TOR) signalling, all of which were decreased or down-regulated after high plant protein replacement. Therefore, this study demonstrated maggot meal, a potential valuable protein source for turbot.

The present study was conducted to investigate the effects of reduced glutathione (GSH) supplementation in practical diet on growth performance, anti-oxidative response, disease resistance and intestine morphology of shrimp Litopenaeus vannamei. Two control diets based on the commercial formulation were designed with high level (27%) and low level (22%) of fish meal, respectively. Based on the control diet with low level of fish meal, 75, 150 and 225 mg/kg of GSH were added, respectively, to make the other three experimental diets. The five formulated diets were named as C1, C2, G1, G2 and G3, respectively. The shrimp (initial body weight: 0.30 ± 0.02 g) were fed with the five experimental diets for 8 weeks followed by a challenge test with Vibrio parahaemolyticus. The results showed that the specific growth rate (SGR) of shrimp in the C2 group was significantly lower than that in C1. The SGRs in G1 and G2 had no significant difference with those in C1 and C2. However, the SGR in G3 was significantly lower than that in C1. The serum GSH concentration in C2 was significantly lower than the other groups, but the malondialdehyde concentration was significantly higher. The supplementation of dietary GSH significantly improved the total anti-oxidative capacity and activities of glutathione S-transferase and glutathione peroxidase in serum. The villus height of intestine in the GSH supplemented groups had no significant difference with C1, but was significantly higher than C2. The jejunum wall thickness of intestine in G2 and G3 was significantly higher than those in the other groups. After the challenge test, the cumulative mortalities in G1 and G2 were significantly lower than C1 and C2. However, there was no significant difference in cumulative mortalities among G3, C1 and C2. In conclusion, based on the present experimental conditions, 75–150 mg/kg of GSH was suggested to be supplemented into the practical diet to improve the growth, anti-oxidative capacity, disease resistance and gut health of shrimp L. vannamei.

A 9-week feeding trial was conducted to investigate the effects of dietary astaxanthin and xanthophylls on the growth and skin coloration of large yellow croaker Larimichthys croceus (mean initial weight: 33.33 ± 1.67 g). There were five experimental diets: CD (control diet without carotenoid), AST37.5 (diet with 37.5 mg/kg of astaxanthin), AST75 (diet with 75 mg/kg of astaxanthin), X37.5 (diet with 37.5 mg/kg of xanthophylls) and X75 (diet with 75 mg/kg of xanthophylls). Results showed that the growth and feed efficiency ratio were not significantly affected by dietary treatments (P > 0.05). With the feeding period increased, the lightness (L*) in the dorsal skin showed a slight increase. However, it decreased in the ventral skin (P > 0.05). Treatments of X37.5 and X75 had lower redness (a*) in the dorsal skin. As to a* values in the ventral skin, fish fed with carotenoid supplemented diets were higher than that in the CD group. Yellowness (b*) values in the ventral and dorsal skins of fish fed with the carotenoid supplemented diets were elevated as the feeding period increased. Fish in the X37.5 and X75 groups had higher b* values in the ventral and dorsal skins than those in the AST37.5 and AST75 groups (P

Hydroxyproline (hyp) is one of the bioactive molecules rich in fishmeal but low in plant protein sources. With increased utilization of plant proteins in aquafeeds, a better understanding is warranted for the necessity of hyp supplementation in high plant protein based diets. In the present study, isonitrogenous and isoenergetic turbot diets were formulated with 40%, 50% and 60% fishmeal substituted by plant proteins, with (or without) addition of 0.6% hyp. After an 8-week feeding trial in juvenile turbot, hyp supplementation significantly improved specific growth rate (SGR) and feed efficiency ratio (FER) in fish fed diets with 50% or higher fishmeal replaced, but not in the group with 40% fishmeal replaced by plant proteins. Hyp levels in plasma and tissues were reduced after plant protein substitutions and replenished by dietary supplementation. Dietary hyp significantly increased muscle hardness, springiness and chewiness of fish ( P

A 60-day feeding trial in seawater floating cages (1.5 × 1.5 × 2.0 m) was conducted to investigate the effects of dietary corn gluten meal (CGM) levels on feed intake, growth performance, survival, digestion and protein metabolism in relation to IGF-I gene expression of Japanese seabass (initial body weight 18.09 ± 0.10 g). Six isonitrogenous (crude protein 43%) and isoenergetic (18 kJ g − 1 ) practical diets were formulated by replacing 0 (the control), 15, 30, 45, 60 and 75% of fish meal protein with CGM protein. Each diet was randomly fed to triplicate groups of fish, and each cage was stocked with 30 fish. Fish were fed twice daily (05:30 and 16:30) to apparent satiation. The survival rate ranged from 96 to 100%, and no significant difference was observed among dietary treatments ( P > 0.05). With increasing dietary CGM levels, feed intake (FI) and specific growth rate (SGR) decreased, however, feed efficiency (FE) showed a contrary changing trend. Fish fed the diet with 75% of protein from CGM had significantly lower SGR than the control group ( P P P P > 0.05). When the substitution level was equal to or above 15%, the activities of protein metabolism enzymes (alanine aminotransferase, ALT; aspartate aminotransferase, AST) were significantly lower compared with the control group ( P P

A 10-week growth trial was conducted to examine the effects of dietary cholesterol on feed intake, growth performance and cholesterol metabolism in juvenile turbot ( Scophthalmus maximus L.) (initial body weight 5.18 ± 0.01 g). Five isonitrogenous and isolipidic experimental diets were formulated with supplementation of 0.0, 0.5, 1.0, 1.5 and 2.0% cholesterol, and the final dietary cholesterol concentrations were 0.38, 0.76, 1.30, 1.80 and 2.22%, respectively. WGR of fish fed diets with 1.30, 1.80 and 2.22% cholesterol was significantly higher than that of fish fed the diet with 0.38% cholesterol, but no significant differences of WGR were found among fish fed diets with 1.30, 1.80 and 2.22% cholesterol. Also no significant differences were found in feed intake (FI) in all treatments. With dietary cholesterol increasing, a general upward trend of total cholesterol (TC), free cholesterol (FC), cholesterol ester (CE), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) in serum was exhibited. However, these kinds of cholesterol in serum were plateaued when fish fed diets with approximately over 1.30 to 1.80% cholesterol. The results of TC in liver and feces showed that, with increasing dietary cholesterol, only TC in feces exhibited an increasing trend. Quantitative PCR (qPCR) was used to assess the effects of dietary cholesterol on rate limiting enzyme 3-hydroxy-3-methylglutaryl-Coenzyme A (HMG-CoA) reductase in cholesterol synthesis and cholesterol 7α-hydroxylase (CYP7A1) in bile acid synthesis. HMG-CoA reductase expression in liver was significantly suppressed with increasing dietary cholesterol, while CYP7A1 expression in liver was significantly enhanced as dietary cholesterol increased. There were no significant differences of ghrelin expression in both gut and brain. It can be concluded that moderate dietary cholesterol was beneficial to growth performance, while feed intake promotion effect was limited in juvenile turbot in the present study. Feedback control might exist in the cholesterol metabolism of turbot to keep cholesterol in homeostasis.

Taurine is essential for development and homeostasis in various fish species. However, very limited information was available on the regulation of taurine biosynthesis in fish. In the present study, the effects of dietary sulfur amino acid supplementation on taurine biosynthesis were examined in juvenile turbot. Fish were fed with a casein-based semi-purified basal diet (CON) and diets supplemented with methionine at 0.5% (MM) and 1.5% (HM), cysteine at 0.3% (MC) and 0.6% (HC), or taurine at 1.5% (MT) and 2.5% (HT) separately, twice per day for 2 weeks. Growth performance, taurine concentration in multiple tissues, hepatic activities of cysteine dioxygenase (CDO) and cysteine sulfinic acid decarboxylase (CSD) were measured. Methionine, cysteine and taurine supplementations promoted growth performance in turbot. Methionine and cysteine supplementations stimulated hepatic CDO but not hepatic CSD activities. Dietary supplementation of methionine, cysteine and taurine increased taurine concentration in the liver. These results suggest the possibility that juvenile turbot has taurine biosynthesis capability, but may not be enough for its endogenous requirement.

Long chain polyunsaturated fatty acid (LC-PUFA) biosynthesis is limited in many marine species, normally due to lack of Δ5 fatty acyl desaturase (Fad) activity. Among exceptions, abalone possesses considerable LC-PUFA conversion ability from C18 precursors. However, its characterization and relevant enzyme are not well characterized. Here we successfully cloned and characterized two Δ5 Fads in abalone (Haliotis discus hannai Ino). Two Δ5 Fad mRNA transcripts, Hdhfad1 (GQ 470626) and Hdhfad2 (GQ 466197), were found in abalone sharing 96.82% similarity for cDNA sequence and 96.58% similarity for their deduced amino acid sequences. Hdhfad1 cDNA is 1530 bp in length with an opening reading frame (ORF) coding for 438 amino acids. Hdhfad2 cDNA is 1525 bp in length with an ORF encoding for 439 amino acids. Both have characteristic features of front–end desaturase, including three histidine boxes, an N-terminal cytochrome b5 domain with heme-binding motif and transmembrane regions. Both Hdhfad1 and Hdhfad2 were expressed in tissues of abalone, especially in hepatopancreas and intestine. HdhFad1 possessed higher Δ5 desaturase activity but expressed at a lower level than HdhFad2. Both isoforms preferred 20:4n-3 than 20:3n-6 as substrate. These results should provide valuable information on the molecular evolution of Fads and better understanding of LC-PUFA biosynthesis in abalone.

Gossypol is known to be a polyphenolic compound toxic to animals. However, its molecular targets are far from fully characterized. To evaluate the physiological and molecular effects of gossypol, we chose turbot ( Scophthalmus maximus L.), a carnivorous fish, as our model species. Juvenile turbots (7.83 ± 0.02 g) were fed diets containing gradient levels of gossypol at 0 (G0), 600 (G1), and 1,200 (G2) mg/kg diets for 11 wk. After the feeding trial, fish growth, body protein, and fat contents were significantly reduced in the G2 group compared with those of the G0 group ( P < 0.05). Gossypol had little impact on digestive enzyme activities and intestine morphology. However, gossypol caused liver fibrosis and stimulated chemokine and proinflammatory cytokine secretions. More importantly, gossypol suppressed target of rapamycin (TOR) signaling and induced endoplasmic reticulum (ER) stress pathway in both the feeding experiment and cell cultures. Our results demonstrated that gossypol inhibited TOR signaling and elevated ER stress pathways both in vivo and in vitro, thus providing new mechanism of action of gossypol in nutritional physiology.

Animals have varied taurine biosynthesis capability, which was determined by activities of key enzymes including cysteine dioxygenase (CDO) and cysteine sulfinate decarboxylase (CSD). However, whether CDO and CSD are differentially regulated across species remains unexplored. In the present study, we examined the regulations of CDO and CSD in rainbow trout and Japanese flounder, the two fish species with high and low taurine biosynthesis ability respectively. Our results showed that the expression of CDO was lower in rainbow trout but more responsive to cysteine stimulation compared to that in Japanese flounder. On the other hand, both the expression and catalytic efficiency (kcat) of CSD were higher in rainbow trout than those of Japanese flounder. A three-residue substrate recognition motif in rainbow trout CSD with sequence of F126/S146/Y148 was identified to be responsible for high kcat, while that with sequence of F88/N108/F110 in Japanese flounder led to low kcat, as suggested by site-directed mutagenesis studies. In summary, our results determined new aspects of taurine biosynthesis regulation across species.

Hyaluronic acid has been extensively investigated due to intrinsic properties of natural origin and strong ability to bind ions in water. Hyaluronic acid is an excellent crystal modifier because its abundant negatively charged carboxyl groups can bind the cations protruding from the crystal lattice. In this review, we mainly present the latest work focus on the role of hyaluronic acid in controlling the crystallization, breaking the symmetry of crystal, and the surface funtionalization of nanocrystals.