Integrating larval zebrafish model and network pharmacology for screening and identification of edible herbs with therapeutic potential for MAFLD: A promising drug Smilax glabra Roxb.

Metabolic-associated fatty liver disease (MAFLD) is becoming a prevalent chronic liver disease. Many medicinal and edible herbs exhibit remarkable biological activities in ameliorating MAFLD but lack a comprehensive assessment of their therapeutic efficacy. This study determined total phenolic and flavonoid contents and in vitro antioxidant properties of 34 edible herbs. Smilax glabra Roxb. (SGR), Coreopsis tinctoria Nutt., and Smilax china L. were obtained with the best bioactivity and antioxidant capacity. The high-cholesterol diet-induced larval zebrafish model was established to compare the anti-MAFLD activity of the three herb extracts mentioned above. In vivo experiments revealed that SGR intervention significantly decreased lipid accumulation, alleviated oxidative stress, and modulated intestinal microbiota composition in zebrafish. Furthermore, three potential active components in SGR and their possible mechanisms were explored through network pharmacology and molecular docking. Our study suggested that SGR is a potential candidate for developing new drugs or dietary supplements for MAFLD therapy.

Small grazing angle reflection and the sound siphon effect over a low velocity layer of sediments.

The low-order normal modes with small grazing angles (SGA) often control long-range sound field characteristics in shallow water. The SGA reflection loss from a half-space low-velocity bottom (LVB) is independent of the sound attenuation, except around the angle of complete transmission; the SGA bottom reflection loss (BRL) from a seafloor with a top low-velocity layer is very insensitive to the LVB attenuation also, except around a few selected frequencies. Thus, the "seafloor velocity-attenuation coupling" problem will be more fatal for LVB geo-acoustic inversions. The dispersion equation of the normal modes in the LVB layer is coincidentally the same as the singularity expression of the SGA reflection coefficient in the water column, resulting in a sound siphon effect that causes the abnormally high SGA BRL and transmission loss in the water at the siphon frequencies. The siphon effect is very sensitive to seafloor acoustic parameters, might offer a physical base for geo-acoustic inversion, and show a dim light in a "gray area" for inverting the LVB sound attenuation at low to mid frequencies. As an example, the acoustic siphon effect and related seafloor geophysical parameters forming it in the Yellow Sea are reported in this paper.

Short-term dietary teprenone improved thermal tolerance and mitigated liver damage caused by heat stress in juvenile largemouth bass (Micropterus salmoides).

Heat stress seriously threatens fish survival and health, demanding immediate attention. Teprenone is a gastric mucosal protective agent that can induce heat shock protein expression. This research investigated the effects of teprenone on largemouth bass (Micropterus salmoides) subjected to heat stress. Juvenile fish were assigned to different groups: group C (control group, 0 mg teprenone/kg diet), T0, T200, T400, and T800 (0, 200, 400, and 800 mg teprenone/kg diet, respectively), which were fed for 3 days, followed by a day without the diet. All groups except group C were subjected to acute heat stress (from 24 °C to 35 °C at 1 °C per hour and then maintained at 35 °C for 3 h). The results were as follows: The critical thermal maxima were significantly higher in the T200, T400, and T800 groups compared with the T0 group (P < 0.05). Heat stress caused severe damage to the tissue morphology of the liver, while teprenone significantly reduced this injury (P < 0.05). Serum cortisol concentration decreased gradually as teprenone concentration increased, and the lowest concentration was observed in the T800 group (P < 0.05). Compared with the T0 group, the serum activities of aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase were significantly lower in the T200, T400, and T800 groups (P < 0.05). The liver activities of catalase, total superoxide dismutase, and peroxidase were significantly higher in the T200 group than in the T0 group (P < 0.05). Transcript levels of the heat shock proteins (hsp90, hsp70, hspa5, and hsf1) and caspase family (caspase3 and caspase9) in the liver of the T200 group were significantly higher than those of the T0 group (P < 0.05). Western blot results showed that HSP70 and HSPA5 in the liver were significantly upregulated in the T200 group compared with the T0 group (P < 0.05). In summary, dietary teprenone improved thermal tolerance, alleviated heat stress damage in the liver, enhanced antioxidant capacity, and upregulated heat shock proteins in juvenile largemouth bass. This study offers theoretical support for applying teprenone in aquaculture to reduce financial losses caused by abiotic factors.

Sound attenuation at low to mid frequencies in low velocity seabottoms.

Attenuation is the most difficult seafloor acoustic property to get, particularly at low to mid frequencies. For low velocity bottoms (LVB), it becomes even more challenging, due to its small attenuation and lower velocity (relative to the velocity of the adjacent water). The latter one causes a fatal "seafloor velocity-attenuation couplings" in geo-acoustic inversions. Thus, attenuation inversions for the LVB require an accurate seafloor velocity profile, especially the velocity in the LVB layer. The propagation of explosive sound in the Yellow Sea with a strong thermocline and a top LVB layer exhibits many prominent characteristics: modal dispersion (the ground wave, water wave, Airy phase), two groups of water waves at high frequencies, and the siphon effect which causes abnormally large sound transmission loss at selected frequencies, etc. These observations are used to precisely measure the critical frequency, the Airy frequency, Airy wave velocity, 1st mode group velocity, and to derive the velocities in the LVB layer and in the basement. Using inverted seafloor parameters, the source level-normalized transmission loss and the first mode decay rate in ranges up to 27.66 km, the sound attenuations in the LVB are derived for a frequency range of 13-5000 Hz.

Association of Age with Dual-Task Objective Cognitive Indicators and Gait Parameters in Older Adults.

Background: Early recognition of dementia like Alzheimer's disease is crucial for disease diagnosis and treatment, and existing objective tools for early screening of cognitive impairment are limited. Objective: To investigate age-related behavioral indicators of dual-task cognitive performance and gait parameters and to explore potential objective markers of early cognitive decline. Methods: The community-based cognitive screening data was analyzed. Hierarchical cluster analysis and Pearson correlation analysis were performed on the 9-item subjective cognitive decline (SCD-9) scores, walking-cognitive dual-task performance, walking speed, and gait parameters of 152 participants. The significant differences of indicators that may related to cognitive decline were statistically analyzed across six age groups. A mathematical model with age as the independent variable and motor cognition composite score as the dependent variable was established to observe the trend of motor cognition dual-task performance with age. Results: Strong correlation was found between motor cognitive scores and SCD and age. Gait parameters like the mean value of ankle angle, the left-right difference rate of ankle angle and knee angle and the coefficient of variation of gait cycle showed an excellent correlation with age. Motor cognition scores showed a decreasing trend with age. The slope of motor cognition scores with age after 50 years (k = -1.06) was six times higher than that before 50 years (k = -0.18). Conclusions: Cognitive performance and gait parameters in the walking-cognitive dual-task state are promising objective markers that could characterize age-related cognitive decline.

Bioinformatics characteristics and expression analysis of IL-8 and IL-10 in largemouth bass (Micropterus salmoides) upon Nocardia seriolae infection.

IL-8 and IL-10 are crucial inflammatory cytokines that participate in defending host cells against infections. To demonstrate the function of the two interleukin genes in largemouth bass (Micropterus salmoides), we initially cloned and identified the cDNA sequences of il-8 and il-10 in largemouth bass, referred to as Msil-8 and Msil-10, respectively. The open reading frame (ORF) of Msil-8 was 324 bp in length, encoding 107 amino acids, while the ORF of Msil-10 consisted of 726 bp and encoded 241 amino acids. Furthermore, the functional domains of the SCY domain in MsIL-8 and the IL-10 family signature motif in MsIL-10 were highly conserved across vertebrates. Additionally, both MsIL-8 and MsIL-10 showed close relationships with M. dolomieu. Constitutive expression of Msil-8 and Msil-10 was observed in various tissues, with the highest level found in the head kidney. Subsequently, largemouth bass were infected with Nocardia seriolae via intraperitoneal injection to gain a further understanding of the function of these two genes. Bacterial loads were initially detected in the foregut, followed by the midgut, hindgut, and liver. The mRNA expression of Msil-8 was significantly down-regulated after infection, especially at 2 days post-infection (DPI), with a similar expression to Msil-10. In contrast, the expression of Msil-8 and Msil-10 was significantly upregulated in the foregut at 14 DPI. Taken together, these results reveal that the function of IL-8 and IL-10 was likely hindered by N. seriolae, which promoted bacterial proliferation and intercellular diffusion.

Selenium deficiency-induced high concentration of reactive oxygen species restricts hypertrophic growth of skeletal muscle in juvenile zebrafish by suppressing TORC1-mediated protein synthesis.

Se deficiency causes impaired growth of fish skeletal muscle due to the retarded hypertrophy of muscle fibres. However, the inner mechanisms remain unclear. According to our previous researches, we infer this phenomenon is associated with Se deficiency-induced high concentration of reactive oxygen species (ROS), which could suppress the target of rapamycin complex 1 (TORC1) pathway-mediated protein synthesis by inhibiting protein kinase B (Akt), an upstream protein of TORC1. To test this hypothesis, juvenile zebrafish (45 d post-fertilisation) were fed a basal Se-adequate diet or a basal Se-deficient diet or them supplemented with an antioxidant (DL-α-tocopherol acetate, designed as VE) or a TOR activator (MHY1485) for 30 d. Zebrafish fed Se-deficient diets exhibited a clear Se-deficient status in skeletal muscle, which was not influenced by dietary VE and MHY1485. Se deficiency significantly elevated ROS concentrations, inhibited Akt activity and TORC1 pathway, suppressed protein synthesis in skeletal muscle, and impaired hypertrophy of skeletal muscle fibres. However, these negative effects of Se deficiency were partly (except that on ROS concentration) alleviated by dietary MHY1485 and completely alleviated by dietary VE. These data strongly support our speculation that Se deficiency-induced high concentration of ROS exerts a clear inhibiting effect on TORC1 pathway-mediated protein synthesis by regulating Akt activity, thereby restricting the hypertrophy of skeletal muscle fibres in fish. Our findings provide a mechanistic explanation for Se deficiency-caused retardation of fish skeletal muscle growth, contributing to a better understanding of the nutritional necessity and regulatory mechanisms of Se in fish muscle physiology.

Development of a novel prognostic assessment model for hepatitis B virus-related acute-on-chronic liver failure based on reexamination results.

Acute-on-chronic liver failure (ACLF) is a common clinical emergency and critical illness with rapid progression and poor prognosis. This study aims to establish a more efficient system for the prognostic assessment of hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF), which will provide a guiding scheme for subsequent treatment and improve the survival rate of patients. Data on 623 patients with HBV-ACLF were recorded. Univariate and multivariate analyses were performed to determine the discriminative abilities of the novel prognostic assessment model in predicting 90-day mortality. The area under the receiver operating characteristic curve was used to evaluate the accuracy of the models. Patients were divided into high- and low-scoring groups based on the best critical values, and survival rates were analyzed using Kaplan-Meier survival analysis and compared by applying log-rank tests. The area under the curve of the new scoring system established using the results of the first reexamination, the results of the first examination, the mean daily change in these results (MDCR) and the results of other first examinations were 0.911 (95% confidence interval [CI]: 0.889, 0.933), 0.893 (95% CI: 0.868, 0.917), and 0.895 (95% CI: 0.871, 0.919), respectively. The final prognostic scoring system established using the results of the first reexamination was chosen as a novel prognostic assessment model, and patients with lower scores (first reexamination results [FRER] score ≤ 3.65) had longer survival times (P < .001). The prognostic scoring system established using the FRER combined with other examination results can better assess the prognosis of HBV-ACLF at 90 days.

Long Non-Coding RNA TUG1 Attenuates Insulin Resistance in Mice with Gestational Diabetes Mellitus via Regulation of the MicroRNA-328-3p/SREBP-2/ERK Axis.

BACKGROUND: Long non-coding RNAs (lncRNAs) have been illustrated to contribute to the development of gestational diabetes mellitus (GDM). In the present study, we aimed to elucidate how lncRNA taurine upregulated gene 1 (TUG1) influences insulin resistance (IR) in a high-fat diet (HFD)-induced mouse model of GDM. METHODS: We initially developed a mouse model of HFD-induced GDM, from which islet tissues were collected for RNA and protein extraction. Interactions among lncRNA TUG1/microRNA (miR)-328-3p/sterol regulatory element binding protein 2 (SREBP-2) were assessed by dual-luciferase reporter assay. Fasting blood glucose (FBG), fasting insulin (FINS), homeostasis model assessment of insulin resistance (HOMA-IR), HOMA pancreatic ß-cell function (HOMA-ß), insulin sensitivity index for oral glucose tolerance tests (ISOGTT) and insulinogenic index (IGI) levels in mouse serum were measured through conducting gain- and loss-of-function experiments. RESULTS: Abundant expression of miR-328 and deficient expression of lncRNA TUG1 and SREBP-2 were characterized in the islet tissues of mice with HFD-induced GDM. LncRNA TUG1 competitively bound to miR-328-3p, which specifically targeted SREBP-2. Either depletion of miR-328-3p or restoration of lncRNA TUG1 and SREBP-2 reduced the FBG, FINS, HOMA-ß, and HOMA-IR levels while increasing ISOGTT and IGI levels, promoting the expression of the extracellular signal-regulated kinase (ERK) signaling pathway-related genes, and inhibiting apoptosis of islet cells in GDM mice. Upregulation miR-328-3p reversed the alleviative effects of SREBP-2 and lncRNA TUG1 on IR. CONCLUSION: Our study provides evidence that the lncRNA TUG1 may prevent IR following GDM through competitively binding to miR-328-3p and promoting the SREBP-2-mediated ERK signaling pathway inactivation.

A combined survey and exposure study reveals the distribution characteristic of chromium in fish head.

In this study, the content of chromium (Cr) in three main edible tissues (dorsal muscle, ventral muscle, and head) of 14 different fish species was determined. As expected, Cr level in fish head is generally higher than that in fish muscle. To elucidate the deposition of Cr in the fish head, bighead carp (Hypophthalmichthys nobilis) was chosen as the model fish and a 14-day-exposure experiment of 1 mg/L Cr was subsequently conducted. The fish head was divided into 7 parts, and the results showed that, in different parts of the head, Cr was significantly accumulated in the brain, the muscle after gills, and the muscle of others, and the bone after the fish was exposed to 1-mg/L Cr for 14 days. Additionally, the health risk assessment showed that there was no potential non-carcinogenic risk of consuming the dorsal muscle, the ventral muscle, and the head of the 14 fish species to children, teenagers, and adults as the THQ values were less than 1. However, there was potential carcinogenic risk of consuming the fish head for adults in the 14 fish species. It is worth noting that, in the exposure experiment, the consuming of the lips and the bone of fish head also posed potential carcinogenic risk to adults while there was no potential risk of consuming the total fish head. Overall, compared to the fish muscle, the fish head usually had a high accumulation of Cr, and the Cr was mainly deposited in the position of the bone, which may pose potential carcinogenic risk to adults. Thus, the potential health risk of consuming the fish head is mainly associated with the content of the bone in the head, and, in the health risk assessment, the influence of the bone in the head should be considered, which may overstate the risks as fish head bone is usually not to be eaten.

Environmentally relevant concentrations of selenite trigger reproductive toxicity by affecting oocyte development and promoting larval apoptosis.

As a trace element, selenium (Se) has been widely added to food to maintain the physiological homeostasis of the organism. The adverse effects of Se on the reproduction of zebrafish have been investigated, however, the effects of Se on the maturation and apoptosis of zebrafish oocytes remain unclear. In this study, zebrafish embryos (2 h post fertilization, hpf) were exposed to 0, 12.5, 25, 50, and 100 µg Se/L for 120 days. The results demonstrated that exposure to selenite decreased the gonad-somatic index (GSI) and cumulative production of eggs, inhibited oocyte maturation (OM), and increased oocyte apoptosis in females. Exposure to selenite decreased the contents of sex hormones (E2) in the serum and increased the levels of reactive oxygen species (ROS) and cyclic adenosine monophosphate (cAMP) in the ovary. Furthermore, exposure to selenite downregulated the transcription level of genes on the HPG axis, decreased the phosphorylation level of CyclinB and the protein content of cAMP-dependent protein kinase (Pka), and upregulated the expression of genes (eif2s1a and chop) and proteins (Grp78, Chop) related to endoplasmic reticulum stress (ERS) and apoptosis. Moreover, maternal exposure to selenite resulted in the apoptosis of offspring and upregulated the content of ROS and the transcription level of genes related to ERS and apoptosis.

Hepatic transcriptome analysis reveals the metabolic strategies of largemouth bass (Micropterus salmoides) under different dissolved oxygen condition.

Dissolved oxygen (DO) affects aquatic animals at a fundamental level so that the differences in its metabolic strategies under prolonged hypoxic conditions need an urgent exploration. In this experiment, largemouth bass (Micropterus salmoides) were chronically exposed (6 weeks) to severe hypoxia (S-HYP, DO: 2.0 ± 0.4 mg/L) and mild hypoxia (M-HYP, DO: 5.1 ± 0.4 mg/L). Compared to the control group (CON, DO:8.4 ± 0.4 mg/L), 1196 and 232 differentially expressed genes (DEGs) were obtained in S-HYP and M-HPY groups via transcriptome analysis, respectively. In S-HYP, lipolysis was promoted while anabolism was blocked. Meanwhile, significantly less fat droplet area was observed in the liver histology of S-HYP. Additionally, the cell cycle also responded to hypoxia, being blocked in the G1 phase with the suspension of DNA replication process. In M-HYP, the processing of protein in the endoplasmic reticulum and the synthesis of various aminoacyl t-RNA were inhibited, and a novel balance of the urea cycle might be established in the biosynthesis of arginine. The key DEGs involved in the above metabolic pathways, such as atgl, cpt1, arg1, etc., were validated by Q-PCR yielding results consistent with transcriptome data. This study indicates that the largemouth bass is prone to increase the proportion of lipid as an energy supply to adapt to the reprogramming of energy metabolism, while reducing the rate of cell proliferation to adapt to chronic severe hypoxia. This is also an undescribed observation in fish liver metabolism that largemouth bass may transform the synthesis and processing strategies of protein when exposed to chronic mild hypoxia.

Molecular characterization and expression analysis of selenoprotein W gene in rainbow trout (Oncorhynchus mykiss) with dietary selenium levels.

Selenium (Se) plays an essential role in the growth of fish and performs its physiological functions mainly through incorporation into selenoproteins. Our previous studies suggested that the selenoprotein W gene (selenow) is sensitive to changes in dietary Se in rainbow trout. However, the molecular characterization and tissue expression pattern of selenow are still unknown. Here, we revealed the molecular characterization, the tissue expression pattern of rainbow trout selenow and analyzed its response to dietary Se. The open reading frame (ORF) of the selenow gene was composed of 393 base pairs (bp) and encodes a 130-amino-acid protein. The 3' untranslated region (UTR) was 372 bp with a selenocysteine insertion sequence (SECIS) element. Remarkably, the rainbow trout selenow gene sequence was longer than those reported for mammals and most other fish. A ß1-α1-ß2-ß3-ß4-α2 pattern made up the secondary structure of SELENOW. Furthermore, multiple sequence alignment revealed that rainbow trout SELENOW showed a high level of identity with SELENOW from Salmo salar. In addition, the selenow gene was ubiquitously distributed in 13 tissues with various abundances and was predominantly expressed in muscle and brain. Interestingly, dietary Se significantly increased selenow mRNA expression in muscle. Our results highlight the vital role of selenow in rainbow trout muscle response to dietary Se levels and provide a theoretical basis for studies of selenow.

Characterization of Warmed-Over Flavor Compounds in Surimi Gel Made from Silver Carp (Hypophthalmichthys molitrix) by Gas Chromatography-Ion Mobility Spectrometry, Aroma Extract Dilution Analysis, Aroma Recombination, and Omission Studies.

The warmed-over flavor (WOF) in surimi gels was characterized by gas chromatography-ion mobility spectrometry, aroma extract dilution analysis, aroma recombination, and omission studies. Surimi gels with different WOF levels were prepared by different gelling temperatures, and surimi gels heated at 90, 100, and 121 °C were considered as the samples with light, strong, and medium WOF, respectively. Based on the quantification and odor activity values, 14 aldehydes, 2 ketones, 3 alcohols, 2 benzene-containing compounds, 2 N-containing compounds, 3 S-containing compounds, 3 lactones, undecanoic acid, and 4-methylphenol were recombined to build a spiked model for surimi gels with the strongest WOF, which showed the highest similarity with the original sample. Finally, a triangle test involving omission of the aroma compounds from the spiked model proved that the WOF in surimi gels was attributed to (E,E)-2,4-decadienal, heptanal, octanal, nonanal, decanal, (E)-2-nonenal, (E)-2-octenal, (E)-2-decenal, (E,E)-2,4-heptadienal, 2,3-pentanedione, 2,6-dimethylpyrazine, 2-propylpyridine, benzothiazole, 2-methoxybenzenethiol, and 2-furfurylthiol.

Parental exposure to waterborne selenite induces transgenerational development toxicity in zebrafish offspring.

Excessive selenium (Se), especially selenite form exerts great toxicity to fish. Most studies have attached considerable attention to the adverse effects of Se on parental fish. However, the transgenerational toxicity of Se on fish has been rarely reported. In the present study, zebrafish embryos were exposed to environmentally relevant concentrations of Na2SeO3 (0, 12.5, 25, 50, and 100 µg/L) for 120 days. And the exposed zebrafish (F0) were allowed to spawn with normal zebrafish after sexual maturity. Subsequently, the offspring (F1) were cultured in clean water for 5 days. In the F0 generation, exposure to 100 µg/L Na2SeO3 significantly increased the Se content in the tissues (liver, brain and gonad) and decreased the body length and weight. After parental exposure to 100 µg/L Na2SeO3, the increased mortality, elevated malformation rate and reduced body length were measured in F1 zebrafish. The Se content was only significantly increased in F1 larvae derived from exposed females in the 100 µg/L exposure group. The contents of thyroid hormones (THs), growth hormone (GH) and insulin-like growth factor (IGF) significantly decreased in F0 and F1 zebrafish. The transcriptional levels of genes along the hypothalamic-pituitary-thyroid (HPT) axis and growth hormone/insulin-like growth factor (GH/IGF) axis were detected to further explore the possible mechanisms of Se-induced thyroid and growth hormone disruption. The results suggest that the toxicity of Se in zebrafish can be markedly transmitted to offspring. And the transgenerational development toxicity might be different due to the differences in gender of exposed parents.

Insight into the evolution of aroma compounds during thermal processing of surimi gel from silver carp (Hypophthalmichthys molitrix).

This study aimed to investigate the formation of odor properties in surimi products by exploring changes in aroma compounds and their precursors at setting (40 °C) and gelling (90 °C) stages during surimi gel formation by solvent-assisted flavor evaporation, gas chromatography-mass spectrometry, and ultra performance liquid chromatography. Results revealed a gradual increase in the contents of most aldehydes, alcohols, and phenolics during surimi gel formation, while a decrease in the contents of (E)-2-pentenal, (E)-2-hexnenal, (Z)-4-heptenal, (E)-2-heptenal, and most ketones at gelling stage. During thermal process, 50 % decrease was observed in the contents of some unsaturated fatty acids (palmitoleic acid, oleic acid, etc.), and the contents of tyrosine, phenylalanine, methionine, isoleucine, and leucine decreased significantly (P < 0.05) at gelling stage. Moreover, lipoxygenase activity reached 4.19-4.81 U/min·g at setting stage. Overall, amino acid degradation and lipid auto-oxidation mainly occurred at gelling stage to promote the formation of related compounds.

Effect of an Established Nutritional Level of Selenium on Energy Metabolism and Gene Expression in the Liver of Rainbow Trout.

The nutritional selenium (Se) has been demonstrated to have health-boosting effects on fish. However, its effect on fish energy metabolism remains unclear. This study explores the effect and underlying mechanism of the action of nutritional Se on energy metabolism in fish. Rainbow trout (Oncorhynchus mykiss) were fed a basal diet (0 mg Se/kg diet) and a diet containing an already established nutritional Se level (2 mg Se/kg diet, based on Se-yeast) for 30 days. After the feeding experiment, the plasma and liver biochemical profiles and liver transcriptome were analyzed. The results showed that the present nutritional level of Se significantly increased liver triglyceride, total cholesterol, and plasma total cholesterol contents (P < 0.05) compared with the control. Transcriptome analysis showed that 336 and 219 genes were significantly upregulated and downregulated, respectively. Gene enrichment analysis showed that many differentially expressed genes (DEGs) were associated with lipid metabolism pathways (fatty acid biosynthesis, fatty acid elongation, and unsaturated fatty acid biosynthesis), carbohydrate metabolism pathways (glycolysis, the pentose phosphate pathway, and the citrate cycle), and the oxidative phosphorylation pathway. Real-time quantitative PCR (Q-PCR) validation results showed that the expression profiles of 15 genes exhibited similar trends both in RNA sequencing (RNA-seq) and Q-PCR analysis. These results reveal that optimum dietary Se activates glucose catabolic processes, fatty acid biosynthetic processes, and energy production and hence produces higher liver lipid content. This study concludes that the previously established level of nutritional Se (Se-yeast) (2 mg/kg diet, fed basis) for rainbow trout promotes energy storage in the liver, which may benefit fish growth to some extent.

Effects of polystyrene microplastics on copper toxicity to the protozoan Euglena gracilis: emphasis on different evaluation methods, photosynthesis, and metal accumulation.

Microplastics (MPs) released into aquatic environment interact with other pollutants that already exist in water, potentially altering their toxicity, which poses a new problem for aquatic ecosystems. In the present study, we first evaluated the effects of polystyrene MPs (mPS) on copper (Cu) toxicity to the protozoan Euglena gracilis using three methods based on 96-h acute toxicity, orthogonal test and 12-d sub-acute toxicity data. Thereafter, the 12-d sub-acute exposure was employed to investigate protozoan growth, photosynthetic parameters and pigments, soluble protein, total antioxidant capacity and trace metal accumulation in E. gracilis after exposure to either 1.5 mg/L of Cu, 75-nm mPS (1 and 5 mg/L) or a combination therein, with the objective to understand the underlined mechanisms. The results show that the concentration and exposure time are key factors influencing the effects of the mPS on Cu toxicity. A mPS concentration of 5 mg/L caused significantly more dissipation energy, which is used for photosynthesis and thus decreased photosynthetic efficiency, but this effect weakened after 12 d of exposure. Exposure to Cu alone resulted in significantly high Cu accumulation in the cells and inhibited uptake of manganese and zinc. The presence of mPS did not influence the effects of Cu on trace metal accumulation. Our result suggests that application of multiple methods and indices could provide more information for a comprehensive understanding of the effects of mPS on toxicity of other pollutants. In addition, long-term exposure seems necessary for evaluating mPS toxicity.

Dietary Selenium Deficiency and Excess Accelerate Ubiquitin-Mediated Protein Degradation in the Muscle of Rainbow Trout (Oncorhynchus mykiss) via Akt/FoxO3a and NF-κB Signaling Pathways.

Selenium (Se) deficiency and excess can lead to protein degradation in fish. However, the underlying mechanisms remain unclear. Ubiquitin proteasome system (UPS) is the main pathway of muscle proteolysis. This study aimed to investigate the effect and molecular mechanism of dietary Se on ubiquitin-mediated muscle protein degradation in rainbow trout (Oncorhynchus mykiss). The fish were fed with the Se-deficient diet (0 mg/kg, DSe), Se-adequate diet (4 mg/kg, ASe), and Se-excessive diet (16 mg/kg, ESe), respectively. After a 10-week feeding trial, the growth performance, body composition, antioxidant enzyme activities, and UPS-related gene and protein expressions were detected. Results indicated that DSe and ESe diets significantly decreased the weight gain rate, specific growth rate, feed efficiency, and muscle crude protein content compared with ASe diet. The histological analysis showed that the mean diameter of muscle fibers was significantly decreased in DSe and ESe groups. And DSe and ESe diets significantly increased the contents of malondialdehyde and nitric oxide, but reduced the glutathione peroxidase activity. Additionally, the abundance of muscle ubiquitinated proteins and the expression levels of MuRF1 and Atrogin-1 were significantly increased in DSe and ESe groups. Compared to ASe diet, DSe and ESe diets significantly decreased the phosphorylation level of Akt Ser473 and the ratio of p-FoxO3a/FoxO3a, but significantly increased the phosphorylation level of IκBα and upregulated the expressions of TNF-α, IL-8, and NF-κB. Overall, this study indicated that dietary Se deficiency and excess accelerated the ubiquitin-mediated muscle protein degradation through regulating Akt/FoxO3a and NF-κB signaling pathways in rainbow trout.

Selenium Status Affects Hypertrophic Growth of Skeletal Muscle in Growing Zebrafish by Mediating Protein Turnover.

BACKGROUND: Selenium (Se) status is closely related to skeletal muscle physiological status. However, its influence on skeletal muscle growth has not been well studied. OBJECTIVES: This study aimed to analyze the impacts of overall Se status (deficient, adequate, and high) on skeletal muscle growth using a growing zebrafish model. METHODS: Zebrafish (1.5-mo-old) were fed graded levels of Se (deficient: 0.10 mg Se/kg; marginally deficient: 0.22 mg Se/kg; adequate: 0.34 mg Se/kg; high: 0.44, 0.57, and 0.69 mg Se/kg) as Se-enriched yeast for 30 d. Zebrafish growth, and Se accumulation, selenoenzyme activity, selenotranscriptome profiles, and oxidative status in the whole body, and selenotranscriptome profiles, histological characteristics, biochemicals, and gene and protein expression profiles related to muscle growth in the skeletal muscle were analyzed by model fitting and/or 1-factor ANOVA. RESULTS: Se status biomarkers within the whole body and skeletal muscle indicated that 0.34 mg Se/kg was adequate for growing zebrafish. For biomarkers related to skeletal muscle growth, compared with 0.34 mg Se/kg, 0.10 mg Se/kg decreased the white muscle cross-sectional area (WMCSA) and the mean diameter of white muscle fibers (MDWMF) by 14.4%-15.1%, inhibited protein kinase B-target of rapamycin complex 1 signaling by 63.7%-68.5%, and stimulated the autophagy-lysosome pathway by 1.07 times and the ubiquitin-proteasome pathway (UPP) by 96.0% (P < 0.05), whereas 0.22 mg Se/kg only decreased the WMCSA by 7.8% (P < 0.05); furthermore, 0.44 mg Se/kg had no clear effects on skeletal muscle biomarkers, whereas 0.57-0.69 mg Se/kg decreased the WMCSA and MDWMF by 6.3%-25.9% and 5.1%-21.3%, respectively, and stimulated the UPP by 2.23 times (P < 0.05). CONCLUSIONS: A level of 0.34 mg Se/kg is adequate for the growth of zebrafish skeletal muscle, whereas ≤0.10 and ≥0.57 mg Se/kg are too low or too high, respectively, for maintaining efficient protein accretion and normal hypertrophic growth.