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The present study aimed to compare the nutritional effects of cholesterol, bile acids, and combination of cholesterol with bile acids in plant-based diets on juvenile genetically improved farmed tilapia (GIFT; Oreochromis niloticus). The isonitrogenous (321 g/kg crude protein) and isolipidic (76 g/kg crude fat) diets (Con diet) were based on plant protein sources, which included corn gluten meal, soybean meal, cottonseed meal and rapeseed meal. The Con diet was supplemented with 12 g/kg cholesterol (CHO diet), 0.2 g/kg bile acids (BAs diet), a combination of 12 g/kg cholesterol and 0.2 g/kg bile acids (CHO–BAs diet), respectively. Each diet was fed to three tanks in an indoor recirculating aquaculture system for 9 weeks. Results showed that compared to the Con group, fish had a higher weight gain rate, hepatosomatic index, and a lower feed conversion ratio in the CHO–BAs group. The highest levels of whole-fish fat and ash were found in the Con group. Serum parameters, including activities of alanine aminotransferase (ALT) and aspartate transaminase (AST), along with levels of glucose (GLU) and triglyceride (TG) except for total cholesterol (TCHO), were lower in the CHO, BAs, and CHO–BAs groups than those in the Con group (P < 0.001). Histological examination revealed that fish in the Con group exhibited severe hepatocyte vacuolization and diminished hepatocyte proliferation. Gene expression analysis indicated that the transcriptional levels of bile acid metabolism-related genes (including fxr, fgf19, bsep) were up-regulated in the CHO–BAs group (P < 0.05), whereas cholesterol metabolism-related genes (acly and hmgcr) were down-regulated in both CHO and CHO–BAs groups (P < 0.001). Moreover, UPLC-MS/MS analysis revealed that the higher taurine-conjugated bile acids (T-BAs), followed by free bile acids (Free-BAs) and glycine (G-BAs) were determined in tilapia bile. Among these, taurochenodeoxycholic bile acid was the predominant bile acid. Dietary bile acids supplementation also increased the proportion of T-BAs (tauro β-muricholic acid and taurodehydrocholic acid) while decreasing Free-BAs in the fish bile. In conclusion, the incorporation of cholesterol with bile acids into plant-based diets can effectively reduce cholesterol uptake, suppress bile acids synthesis, enhance bile acids efflux, and promote hepatocyte proliferation, which is helpful for maintaining the normal liver morphology in tilapia, and thus improving its growth performance.

Semi-volatile organic compounds (SVOCs) are modern chemical substances that are present in large quantities in indoor environments. Understanding the emission of SVOCs from building materials is essential to identify the main sources of indoor SVOCs and to improve indoor air quality. In this study, a reference method employing custom-designed microchambers (630 mL) was optimized by improving the structure of the gas path and adding polytetrafluoroethylene inner coating to the chamber. After optimization, the recoveries of the microchamber method were significantly improved (75.4–96.7%), and the background in the microchamber was greatly reduced (SERa) of total SVOCs emitted from architectural coatings and PVC floorings were in the range of 4.09–1309 μg/m2/h) (median: 10.3 μg/m2/h) and 0.508–345 μg/m2/h (median: 11.9 μg/m2/h), respectively. Propanoic acid had the highest SERa (3143 μg/m2/h) in architectural coatings, while methylbenzene (345 μg/m2/h), 2-methylnaphthalene (65.2 μg/m2/h), and naphthalene (60.3 μg/m2/h) were main SVOCs emitted from PVC floorings. Meanwhile, the average second-stage (adsorbed phase) emission mass of the total SVOCs accounts for 66.3% and 47.3% in architectural coatings and PVC floorings, respectively, suggesting that the SVOCs emitted from building materials have a strong tendency to be absorbed on the surface of the room, e.g., the interior wall, the desk or even the skin.

Nile tilapia (Oreochromis niloticus) is a worldwide farmed fish and has been widely used for the study on comparative immunology in teleosts. It is well known that cadmium (Cd) can cause a variety of adverse effects in fish. However, data on the effects of Cd in fish liver and the defensive mechanisms of these effects using transcriptome approach are relatively scarce to date. In this study, by using an RNA sequencing approach, the gene expression profiling was performed in livers of tilapia exposed to 0 (control), 50, 100, and 200 μg/L of Cd for 2 months. The results showed that exposure to 50 μg/L Cd altered the expressions of 911 genes, while exposure to 100 and 200 μg/L Cd resulted in 4318 and 3737 differentially expressed genes compared to the control. Weighted correlation network analysis (WGCNA) and gene ontology (GO) analysis identified a 14-gene network linked to the immune system development. Further, in a fuzzy analysis, the GO term immune system development was enriched in cluster 3, and gene expression decreased with increasing Cd levels in a concentration-dependent manner. The qPCR and RNA-seq results identified 4 genes, i.e., dnmt3bb.1, sf3b1, SMARCAL1, and zap70, as convenient potential biological indicators for detecting waterborne Cd. The present results help systematically understand the effects of Cd on the hepatic transcriptome in tilapia.

The objective of this study was to examine the effects of varying levels of dietary chitosan supplementation on mitigating cadmium stress and its influence on growth performance, serum biochemical indices, antioxidant capacity, immune response, inflammatory response, and the expression of related genes in juvenile Genetically Improved Farmed Tilapia (GIFT, Oreochromis niloticus). Five groups of juvenile tilapias (initial body weight 21.21 ± 0.24 g) were fed five diets with different levels (0%, 0.5%, 1.0%, 1.5%, and 2.0%) of chitosan supplementation for 60 days under cadmium stress (0.2 mg/L Cd2+). The findings indicated that, compared with the 0% chitosan group, dietary chitosan could significantly increase (p < 0.05) the final weight (Wf), weight gain rate (WGR), specific growth rate (SGR), daily growth index (DGI), and condition factor (CF), while the feed conversion ratio (FCR) expressed the opposite trend in juvenile GIFT. Dietary chitosan could significantly increase (p < 0.05) the activities (contents) of cholinesterase (CHE), albumin (ALB), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), acid phosphatase (ACP), and lysozyme (LZM), while glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT), and complement 3 (C3) in the serum of juvenile GIFT expressed the opposite trend. Dietary chitosan could significantly increase (p < 0.05) the activities of superoxide dismutase (SOD) and catalase (CAT) and significantly decrease (p < 0.05) the activities (contents) of glutathione S-transferase (GST), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) in the serum of juvenile GIFT. Dietary chitosan could significantly increase (p < 0.05) the activities (contents) of CAT, GST, GSH-Px, and total antioxidant capacity (T-AOC) and significantly decrease (p < 0.05) the contents of MDA in the liver of juvenile GIFT. Dietary chitosan could significantly increase (p < 0.05) the activities (contents) of SOD, GSH-Px, T-AOC, Na+-K+-ATPase, and Ca2+-ATPase and significantly decrease (p < 0.05) the activities (contents) of CAT, GST, and MDA in the gills of juvenile GIFT. Dietary chitosan could significantly up-regulate (p < 0.05) the gene expression of cat, sod, gst, and gsh-px in the liver of juvenile GIFT. Dietary chitosan could significantly up-regulate (p < 0.05) the gene expression of interferon-γ (inf-γ) in the gills and spleen and significantly down-regulate (p < 0.05) the gene expression of inf-γ in the liver and head kidney of juvenile GIFT. Dietary chitosan could significantly down-regulate (p < 0.05) the gene expression of interleukin-6 (il-6), il-8, and tumor necrosis factor-α (tnf-α) in the liver, gills, head kidney, and spleen of juvenile GIFT. Dietary chitosan could significantly up-regulate (p < 0.05) the gene expression of il-10 in the liver, gills, head kidney, and spleen of juvenile GIFT. Dietary chitosan could significantly up-regulate (p < 0.05) the gene expression of transforming growth factor-β (tgf-β) in the liver and significantly down-regulate (p < 0.05) the gene expression of tgf-β in the head kidney and spleen of juvenile GIFT. In conclusion, dietary chitosan could mitigate the impact of cadmium stress on growth performance, serum biochemical indices, antioxidant capacity, immune response, inflammatory response, and related gene expression in juvenile GIFT. According to the analysis of second-order polynomial regression, it was found that the optimal dietary chitosan levels in juvenile GIFT was approximately 1.42% to 1.45%, based on its impact on Wf, WGR, SGR, and DGI.

The escalating problem of copper (Cu) and cadmium (Cd) pollution in aquatic environments poses a significant threat to the ovarian tissue and reproductive capacity of fish, hindering the development of the aquaculture industry. However, the combined effects of Cu and Cd on fish gonadal development remain unclear. In this study, the fish species Nile tilapia was stressed with rearing water containing 300 μg/L Cu2+ and 100 μg/L Cd2+ for 30 days, followed by an intraperitoneal injection of luteinizing hormone-releasing hormone (LHRH-α) and human chorionic gonadotropin (HCG) at various concentrations. We investigated the ovarian transcriptome profiles before and after injection. Prior to injection, combined treatment with Cu and Cd resulted in reproductive dysfunction and metal ion imbalance in tilapia. Transcriptomic profiling revealed differential gene annotation concentrated in the MAPK signaling pathway and regulation of GTPase activity. Post-injection, all concentrations of LHRH-α and HCG groups showed an upregulated gonadosomatic index (G.S.I) and higher levels of vitellogenin (VTG), gonadotropin-releasing hormone (GnRH), gonadotropin (GTH), and estrogen (E2) in serum compared to the negative control group. Transcriptomic analysis revealed alterations in various ovarian signaling pathways, preliminarily revealing the in vivo molecular mechanisms and differences in LHRH-α and HCG. The findings from this study could help us better understand how to counteract the effects of combined Cu and Cd exposure on tilapia ovarian development, which has significant implications for the Nile tilapia aquaculture industry.

Coating products are widely used for the interior decoration of residential property. However, there is growing concern regarding their odor emissions and their impact on indoor air quality (IAQ). Most manufacturers and government agencies set odor intensity limits to control the odor of coating products, including their raw materials. However, it is difficult to determine product performance by means of their odor intensity index. Although evaluating odor intensity requires odor assessors to distinguish between different intensity levels, low consensus and reproducibility represent challenges that are difficult to avoid. As the odor concentration index only requires odor assessors to ascertain whether the odor is felt or not, the reproducibility of the evaluation results is relatively better. Moreover, suitable methodologies for determining odor concentrations in volatile coating product emissions have rarely been reported. Therefore, establishing an evaluation method for odor concentration of coating products and exploring its key influencing factors should bridge this gap. We examined the influence of the airbag material on the recovery rate of typical volatile organic compounds (VOCs) using direct injection by GC-MS and established that their adsorption effects were in the order: PET > PVF > PTFE. We then explored the influences of the sample curing and odor emission times on odor concentration. The solvent-based and water-based coatings reached equilibrium after 8 h and 16 h curing, respectively, and after 8 h and 12 h odor emission, respectively. The odor concentrations of real coating samples were measured and compared against their odor intensities. The odor concentration method more accurately and reliably discriminated coating products than the odor intensity approach. Thus, to assist manufacturers in improving coating formulations to reduce the odor impact of coating products, we used headspace gas chromatography to determine the odor substances in water- and solvent-based coatings and analyzed the odor contribution of various volatile compounds using the odor activity value (OAV) method. Butyl acetate, ethylbenzene, and 1-methoxy-2-propyl acetate were the key odorants in solvent-based coatings while 1-butanol, ethylbenzene, and butyl acetate were the key odorants in water-based coatings.

Circular RNA (circRNA) is an endogenous biomolecule in eukaryotes. It has tissue- and cell-specific expression patterns and can act as a microRNA sponge or competitive endogenous RNA. Although circRNA has been found in several species in recent years, the expression profiles in fish gonad are still not fully understood. We detected the expression of circRNA in the ovary, testis, and sex-changed gonad of tilapia by high-throughput deep sequencing, and circRNA-specific computing tools. A total of 20,607 circRNAs were obtained, of which 141 were differentially expressed in the testis and ovary. Among these circRNAs, 135 circRNAs were upregulated and 6 circRNAs were downregulated in female fish. In addition, GO annotation and KEGG pathway analysis of the host genes of circRNAs indicated that these host genes were mainly involved in adherens junction, androgen production, and reproductive development, such as ZP3, PLC, delta 4a, ARHGEF10, and HSD17b3. It is worth noting that we found that circRNAs in tilapia gonads have abundant miRNA-binding sites. Among them, 935 circRNAs have a regulatory effect on miR-212, 856 circRNAs have a regulatory effect on miR-200b-3p, and 529 circRNAs have a regulatory effect on miR-200b-5p. Thus, our findings provide a new evidence for circRNA–miRNA networks in the gonads in tilapia.

(1) Background: Singapore grouper iridovirus (SGIV) can cause extensive fish deaths. Therefore, developing treatments to combat virulent SGIV is of great economic importance to address this challenge to the grouper aquaculture industry. Green tea is an important medicinal and edible plant throughout the world. In this study, we evaluated the use of green tea components against SGIV infection. (2) Methods: The safe working concentrations of green tea components were identified by cell viability detection and light microscopy. Additionally, the antiviral activity of each green tea component against SGIV infection was determined with light microscopy, an aptamer (Q5c)-based fluorescent molecular probe, and reverse transcription quantitative PCR. (3) Results: The safe working concentrations of green tea components were green tea aqueous extract (GTAE) ≤ 100 μg/mL, green tea polyphenols (TP) ≤ 10 μg/mL, epigallocatechin-3-gallate (EGCG) ≤ 12 μg/mL, (-)-epigallocatechin (EGC) ≤ 10 μg/mL, (-)-epicatechin gallate (EGC) ≤ 5 μg/mL, and (-)-epicatechin (EC) ≤ 50 μg/mL. The relative antiviral activities of the green tea components determined in terms of MCP gene expression were TP > EGCG > GTAE > ECG > EGC > EC, with inhibition rates of 99.34%, 98.31%, 98.23%, 88.62%, 73.80%, and 44.31%, respectively. The antiviral effect of aptamer-Q5c was consistent with the results of qPCR. Also, TP had an excellent antiviral effect in vitro, wherein the mortality of fish in only the SGIV-injection group and TP + SGIV-injection group were 100% and 11.67%, respectively. (4) Conclusions: In conclusion, our results suggest that green tea components have effective antiviral properties against SGIV and may be candidate agents for the effective treatment and control of SGIV infections in grouper aquaculture.

Singapore grouper iridovirus (SGIV) causes high economic losses in mariculture. Effective drugs for managing SGIV infection are urgently required. Medicinal plant resources are rich in China. Medicinal plants have a long history and significant curative effects in the treatment of many diseases. Reverse-transcription quantitative real-time PCR is the most commonly used method for detecting virus infection and assessing antiviral efficacy with high accuracy. However, their applications are limited due to high reagent costs and complex time-consuming operations. Aptamers have been applied in some biosensors to achieve the accurate detection of pathogens or diseases through signal amplification. This study aimed to establish an aptamer-based high-throughput screening (AHTS) model for the efficient selection and evaluation of medicinal plants components against SGIV infection. Q2-AHTS is an expeditious, rapid method for selecting medicinal plant drugs against SGIV, which was characterized as being dram, high-speed, sensitive, and accurate. AHTS strategy reduced work intensity and experimental costs and shortened the whole screening cycle for effective ingredients. AHTS should be suitable for the rapid selection of effective components against other viruses, thus further promoting the development of high-throughput screening technology.

Estradiol is a steroid hormone that regulates multiple physiological processes in teleosts. The present study aimed to investigate the role of 17β-estradiol (E2) in lipid metabolism in the liver of Nile tilapia. Waterborne exposures were performed using different concentrations of E2 (0 ng/L, 10 ng/L, 25 ng/L and 50 ng/L) and its receptor inhibitor ICI 182,780 (ICI) (1 μM/L). Subsequently, the survival rate and hepatosomatic index (HSI) of tilapia were measured and no significant changes could be found following E2 exposure. Gene expression of VLDL assembly, lipoprotein lipase and lipoprotein receptor, fatty acid uptake and triacylglycerol metabolism were detected by qPCR. E2 exposure up-regulated the expression of lipid metabolism-related genes MTP, LPL, CD36 and DGAT2. ICI exposure inhibited the level of LDLR in the liver of tilapia. This showed that E2 stimulated the MTP expression and promoted VLDL synthesis. In addition, E2 waterborne exposure induced secretion of LDLR and LPL and promoted fatty acid production. Moreover, E2 up-regulated the expression of CD36 to accelerate the transport of fatty acids. Overall, our study provides new information for evaluating Environmental estrogens (EEs) effects on farming fishes and endocrinological regulation on lipid metabolism in fish.

Parachromis managuensis is a native cichlid fish from Central America that has been recently introduced to Southern China. The present study aimed to identify the adaptive evolution of P. managuensis using transcriptome data and provided genetic information regarding this novel fish in China. We obtained the transcriptome sequences from a mixed cDNA library of P. managuensis. A total of 19,419,739 raw reads were obtained from the cDNA library. The de novo assembly generated a total of 102,977 unigenes. The genomic data of Atlantic cod (Gadus morhua) and Nile tilapia (Oreochromis niloticus) were used to identify orthologs by phylogenetic analysis. Based on the phylogeny, we detected 105 positively selected genes in P. managuensis from 6197 orthologous unigenes. The GO annotation revealed that the T-box protein 20 (TBX20) in the category ‘Immune system process’ was positively selected and four positively selected genes were found in the ‘Immune system’ pathway by KEGG analysis. Among them, the genes encoding for phosphoinositide 3-kinase adapter protein 1, ras-related protein Rap-1b, complement factor I and probable ATP-dependent RNA helicase DHX58 were associated with immune adaptation. These findings can provide additional information regarding the natural selection of P. managuensis and can be used as a representative example for future comparative transcriptome and immunological studies.

This study investigated the molecular mechanisms involved in ovarian transcriptomic responses in Nile tilapia under different photoperiod regimes. Histological analysis indicated that ovarian development was significantly affected by photoperiod. The photoperiods tested were as follows: LD (12 h light:12 h dark), LL (24 h light:0 h dark), and DD (0 h light:24 h dark). The longer photoperiod (LL) was shown to induce ovary development earlier than LD and DD. Next, ovary transcriptome levels were sequenced and analyzed. These data indicated that 988, 992, and 1,036 differentially expressed genes (DEGs) were detected by comparing LD–LL, LD–DD, and LL–DD. A number of genes that may be involved in photoperiod-specific regulation of ovarian development were observed. These findings may be useful for investigating the molecular mechanisms underlying light-induced ovarian development in Nile tilapia.

Hypoxia represents a major physiological challenge for prawns and is a problem in aquaculture. Therefore, an understanding of the metabolic response mechanism of economically important prawn species to hypoxia and re-oxygenation is essential. However, little is known about the intrinsic mechanisms by which the oriental river prawn Macrobrachium nipponense copes with hypoxia at the metabolic level. In this study, we conducted gas chromatography-mass spectrometry-based metabolomics studies and assays of energy metabolism-related parameters to investigate the metabolic mechanisms in the hepatopancreas of M. nipponense in response to 2.0 O2/L hypoxia for 6 and 24 h, and reoxygenation for 6 h following hypoxia for 24 h. Prawns under hypoxic stress displayed higher glycolysis-related enzyme activities and lower mRNA expression levels of aerobic respiratory enzymes than those in the normoxic control group, and those parameters returned to control levels in the reoxygenated group. Our results showed that hypoxia induced significant metabolomic alterations in the prawn hepatopancreas within 24 h. The main metabolic alterations were depletion of amino acids and 2-hydroxybutanoic acid and accumulation of lactate. Further, the findings indicated that hypoxia disturbed energy metabolism and induced antioxidant defense regulation in prawns. Surprisingly, recovery from hypoxia (i.e., reoxygenation) significantly affected 25 metabolites. Some amino acids (valine, leucine, isoleucine, lysine, glutamate, and methionine) were markedly decreased compared to the control group, suggesting that increased degradation of amino acids occurred to provide energy in prawns at reoxygenation conditions. This study describes the acute metabolomic alterations that occur in prawns in response to hypoxia and demonstrates the potential of the altered metabolites as biomarkers of hypoxia.

MicroRNAs (miRNAs) are endogenous non-coding small RNAs which play important roles in the regulation of gene expression by cleaving or inhibiting the translation of target gene transcripts. Thereinto, some specific miRNAs show regulatory activities in gonad development via translational control. In order to further understand the role of miRNA-mediated posttranscriptional regulation in Nile tilapia (Oreochromis niloticus) ovary and testis, two small RNA libraries of Nile tilapia were sequenced by Solexa small RNA deep sequencing methods. A total of 9,731,431 and 8,880,497 raw reads, representing 5,407,800 and 4,396,281 unique sequences were obtained from the sexually mature ovaries and testes, respectively. After comparing the small RNA sequences with the Rfam database, 1,432,210 reads in ovaries and 984,146 reads in testes were matched to the genome sequence of Nile tilapia. Bioinformatic analysis identified 764 mature miRNA, 209 miRNA-5p and 202 miRNA-3p were found in the two libraries, of which 525 known miRNAs are both expressed in the ovary and testis of Nile tilapia. Comparison of expression profiles of the testis, miR-727, miR-129 and miR-29 families were highly expressed in tilapia ovary. Additionally, miR-132, miR-212, miR-33a and miR-135b families, showed significant higher expression in testis compared with that in ovary. Furthermore, the expression patterns of the miRNAs were analyzed in different developmental stages of gonad. The result showed different expression patterns were observed during development of testis and ovary. In addition, the identification and characterization of differentially expressed miRNAs in the ovaries and testis of Nile tilapia provides important information on the role of miRNA in the regulation of the ovarian and testicular development and function. This data will be helpful to facilitate studies on the regulation of miRNAs during teleosts reproduction.