Mandarin Fish Research Articles

The protective effect of specific yolk antibody against Nervous necrosis virus infection in Mandarin fish(Siniperca chuatsi)

The protective effect of specific yolk antibody against Nervous necrosis virus infection in Mandarin fish(Siniperca chuatsi)

Transcriptome analysis reveals the importance of phototransduction during the first-feeding in mandarin fish (Siniperca chuatsi).

The mandarin fish (Siniperca chuatsi), as a typical freshwater carnivorous fish, has high economic value. Mandarin fish have a peculiar feeding habit of feeding on other live fry during the first-feeding period, while rejecting zooplankton or particulate feed, which may be attributed to the low expression of zooplankton-associated gene sws1 in mandarin fish. The domesticated strain of mandarin fish could feed on Artemia at 3 days post hatching (dph). However, the mechanism of mandarin fish larvae recognize and forage Artemia as food is still unclear. In this study, we employed transcriptional analysis to identify the representative differential pathways between mandarin fish larvae unfed and fed with Artemia at 3 dph. The comparative transcriptome analysis has unveiled a tapestry of genetic expression, highlighting 403 genes that have been up-regulated and 259 that have been down-regulated, all of which constitute the differentially expressed genes (DEGs). KEGG pathway analysis revealed that the number of differentially expressed genes in the photoconductive signaling pathway was the largest. Next, the Vorinostat (suberoylanilide hydroxamic acid, SAHA) was used to assess whether sws1 induced ingestion of Artemia in mandarin fish larvae. We discovered that SAHA-treated larvae had more food intake of Artemia and up-regulated the transcription level of npy, which might have been associated with the up-regulated of sws1 opsin. Additionally, exposure to 0.5 µM SAHA increased the expression of genes involved in phototransduction pathway. These findings would provide insights on the molecular processes involved in mandarin fish larvae feeding on Artemia at the first-feeding stage.

Mandarin Fish Ranavirus (MRV) Infection Induced Inflammation and Histologic Lesions in the Gut of Mandarin Fish.

Mandarin fish ranavirus (MRV) is widely spread in China and causes huge economic losses to the mandarin fish (Siniperca chuatsi) aquaculture. However, the pathogenesis of MRV is still unclear. In the present study, mandarin fish were artificially infected with MRV, and then different gut compartments from diseased fish were subjected to histologic analysis by H&E staining, quantification of proinflammatory genes and MRV copies by qPCR. MRV-MCP protein expression was assessed using indirect fluorescence assay (IFA) and immunohistochemistry. Proliferation of IgM+ B cells was evaluated by indirect fluorescence assay (IFA). Then, we found that MRV infection caused serious histologic lesions along with inflammatory cell infiltration, especially in the foregut. A significant accumulation of IgM+ B cells was detected in the foregut (~6.5-fold) and hindgut (~3.3-fold), respectively. The expression of inflammation-related genes such as IL-1β, IL-6, IL-8,TNF-α, CSF1r and NCF1 was significantly upregulated in the foregut, varying from ~2.8-fold to ~11.9-fold. In addition, MRV exhibited foregut tropism, according to the investigation of viral loads and MCP protein expression. Overall, our findings indicated that MRV-induced hyperinflammation in the gut eventually led to enteritis. This study provided new insights into uncovering the pathogenesis of MRV infection.

Evaluation of a Low-Temperature Immersion Immunization Strategy for the Infectious Spleen and Kidney Necrosis Virus orf037l Gene-Deleted Attenuated Vaccine

Background: Infectious spleen and kidney necrosis virus (ISKNV) poses a significant threat to aquaculture sustainability, particularly affecting mandarin fish (Siniperca chuatsi) and causing significant economic losses. Methods: To address this challenge, this study developed an ISKNV Δorf037l vaccine strain, where the orf037l gene was knocked out. Infection assays conducted at 28 °C showed that the knocking out the orf037l gene decreased the virulence of ISKNV and reduced lethality against mandarin fish by 26.7% compared to wild-type ISKNV. To further diminish residual virulence, the effect of low-temperature (22 °C) immersion immunization was evaluated. Results: The results indicate that low temperature significantly diminished the virulence of the Δorf037l vaccine strain, elevating the survival rate of mandarin fish to 90%. Furthermore, the vaccine strain effectively triggered the expression of crucial immune-related genes, such as IFN-h, IL-1, IκB, Mx, TNF-α, and Viperin, while inducing the production of specific neutralizing antibodies. Low-temperature immersion with Δorf037l achieved a high relative percentage of survival of 92.6% (n = 30) in mandarin fish, suggesting the potential of Δorf037l as a promising immersion vaccine candidate. Conclusions: These findings contribute to advancing fish immersion vaccine development and demonstrate the importance and broad applicability of temperature optimization strategies in vaccine development. Our work carries profound implications for both the theoretical understanding and practical application in aquaculture disease control.

Effects of artificial diets on lipid and glucose metabolism, antioxidative capacity, and inflammation in the liver of mandarin fish (Siniperca chuatsi)

The mandarin fish (Siniperca chuatsi) is a typical carnivorous fish, which has been able to consume artificial diets after domestication in recent years. However, the potential health consequences of artificial diets in mandarin fish remain unclear. This study aimed to elucidate the molecular mechanisms underlying these concerns. Fish (initial weight: 25.1 ± 0.1 g) were fed with natural (CON group) or artificial diets (AF group) for 8 weeks. Each diet was randomly distributed to sextuplicate circular tanks (300 L) with 40 fish in each tank. The transcriptome analysis revealed significant changes in metabolism-related pathways, particularly those involved in lipid and carbohydrate metabolism. Further investigation confirmed that the artificial diets significantly increased hepatic triglyceride content and fatty acid synthase activity. The artificial diets also significantly increased hepatic glycogen and glucose-6-phosphatase activity. Furthermore, the artificial diets significantly increased hepatic malondialdehyde levels, indicating increased oxidative stress. Antioxidant defense enzyme activities and the expression of antioxidant stress-related genes were significantly decreased. Additionally, the artificial diets significantly increased the expression of proinflammatory genes, including interleukin 1 beta and interferon-gamma. These findings collectively demonstrated that the artificial diets disrupted hepatic lipid and glucose metabolism, leading to oxidative stress and inflammation, thus affecting the health status of mandarin fish.

Bacterial diseases in Siniperca chuatsi: status and therapeutic strategies.

Mandarin fish (Siniperca chuatsi) is a prominent freshwater species with significant economic value in China, while disease poses a major hindrance to the advancement of mandarin fish aquaculture. To date, the understanding of the prevention and management of bacterial disease in mandarin fish remains incomplete. Therefore, there is a need for more comprehensive insights into the preventive and curative strategies to address these bacterial infections. In this review, we summarize the information pertaining to the predominant bacterial pathogens such as Aeromonas spp., Flavobacterium columnare, Edwardsiella tarda, Streptococcus uberis and Vibrio cholerae in the mandarin fish aquaculture, and point out the current strategies for diagnosis and combating these bacterial pathogens, as well as deliberate on the prospective alternative treatments such as vaccines, herbal remedies, and phage therapy for the prevention and control of these bacterial diseases. Furthermore, we also highlights the importance to implement an integrated bacterial disease management (IBDM) approach for the prevention and control of these pathogenic bacteria in aquaculture.

Whole-genome resequencing reveals genetic diversity and selection signatures in five populations of Mandarin Fish (Siniperca chuatsi)

Mandarin fish is an important freshwater economic fish in China, and the genome of mandarin fish population may have specific selection signatures after long-term selection, and studying these selection signatures is one of the important strategies for screening functional genes. In this study, the whole genome was resequenced from five mandarin fish populations (HLJ, HN, AH, FJ, and BJ), and a total of high-quality SNPs with 1659,318 single nucleotide polymorphisms were obtained, and the genetic differentiation index and nucleotide polymorphism ratio between populations were used to detect the selected genomic regions. The results showed that all individuals were divided into two branches, with the HLJ population forming an independent cluster, and the HN, AH, FJ, and BJ populations clustering together. Selection signal analysis on the HLJ mandarin fish population and other mandarin fish populations using the FST and π HLJ/other methods. Finally, we identified 26 important candidate genes based on the enrichment pathways related to fat traits such as Glycerolipid metabolism, acyl-CoA oxidase activity, Wnt signaling pathway, and Notch signaling pathway, including notch3, pla2g12a and acox1. This study explores the genetic diversity and genetic structure of mandarin fish from a whole-genome perspective, identifies candidate genes related to fat traits, and provides references for the protection and utilization of mandarin fish genetic resources.

Refrigerated Storage-Induced Quality Deterioration of Mandarin Fish (Siniperca chuatsi): Analyzing the Role of Endogenous Enzymes through TMT-Based Quantitative Proteomics

Tandem Mass Tag (TMT)-based proteomics was employed to elucidate the pivotal role of endogenous enzymes in the quality deterioration of Mandarin fish (Siniperca chuatsi) during refrigerated storage. Proclean 300 was used to inhibit the growth of psychrophilic microorganisms, emphasizing the contribution of endogenous enzymes. Quality characteristics, including pH, water-holding capacity, color, texture, and myofibrillar fragmentation index (MFI), were compared between the Proclean 300-treated group (P-group) and the control group (C-group). Correlation analysis underscored the collaborative role of calpain and cathepsin B in postmortem degradation. Pearson correlation analysis showed that texture characteristics were significantly negatively correlated with MFI and significantly positively correlated with whiteness and L* in the P-group. Differentially expressed proteins (DEPs) analysis identified 66 DEPs, with 40 exhibiting low abundance, including cytoskeleton proteins and hemoglobin subunits, and 26 showing high abundance, primarily metabolic enzymes. Bioinformatics analysis revealed significant enrichment of DEPs within the glycolysis/gluconeogenesis pathway. Furthermore, protein-protein interaction analysis highlighted key proteins linked to the quality deterioration of Mandarin fish, including beta-enolase, phosphoglycerate kinase 1, and triosephosphate isomerase B. These findings offer valuable insights into the mechanisms behind the quality deterioration of refrigerated Mandarin fish and the intricate relationship with endogenous enzymes.

Recognition of MCF-7 breast cancer cells using native collagen probes: Collagen source effect

Developing superior cancer cell recognition probes is crucial for the development of tumor therapy and cancer early screening materials. In this study, we first achieved effective recognition of MCF-7 breast cancer cells using natural collagen probes. Through cell adhesion, cancer cell selective capture, and flow cytometry techniques, the binding efficiency of mammalian-derived collagens (bovine Achilles tendon collagen, porcine skin collagen) and fish-derived collagens (turbot skin collagen, grass carp skin collagen, mandarin fish skin collagen) to cancer cells (MCF-7 breast cancer cells) and normal cells (human umbilical vein endothelial cells, HUVECs) was analyzed and compared. The feasibility of different source collagens as probes for recognition of MCF-7 cells was explored in vitro. The results indicated that mammalian-derived collagens had a superior advantage over fish-derived collagens in recognizing MCF-7 cells, with bovine Achilles tendon collagen achieving a capture rate of up to 64.7 % in a multicellular co-culture system. Furthermore, in vivo imaging of BALB/c tumor-bearing mice confirmed the high-efficiency targeted recognition performance of the bovine Achilles tendon collagen probe for MCF-7 cells.

Isolation, Identification and Genomic Analysis of Orange-Spotted Grouper Iridovirus Hainan Strain in China.

The orange-spotted grouper (Epinephelus coioides) is an important mariculture fish in China. However, in recent years, with the rapid development of aquaculture activities, outbreaks of viral diseases have affected the grouper aquaculture industry, causing severe economic losses. In the present study, we isolated and identified a virus from diseased, orange-spotted groupers from an aquaculture farm in Hainan Province, China. The isolated virus was identified as orange-spotted grouper iridovirus, hence named the orange-spotted grouper iridovirus Hainan strain (OSGIV-HN-2018-001). OSGIV-HN-2018-001 induces a cytopathic effect after the infection of mandarin fish (Siniperca chuatsi) brain clonal passage (SBC) cells. In addition, the cytoplasm of the OSGIV-HN-2018-001-infected SBC cells was found to contain a large number of hexagonal virus particles with a diameter of approximately 134 nm. Using the Illumina NovaSeq system, we assembled the sequence data and annotated the complete genome of OSGIV-HN-2018-001 (GenBank accession number: PP974677), which consisted of 110,699 bp and contained 122 open reading frames (ORFs). Phylogenetic tree analysis showed that OSGIV-HN-2018-001 was most closely related to ISKNV-ASB-23. The cumulative mortality rate of groupers infected with OSGIV-HN-2018-001 reached 100% on day 8. The spleens were enlarged and blackened after the dissection of the dying groupers. These results contribute to the understanding of the molecular regulatory mechanism of the iridovirus infection and provide a basis for iridovirus prevention.

L-Glutamate Regulates Npy via the mGluR4-Ca2+-ERK1/2 Signaling Pathway in Mandarin Fish (Siniperca chuatsi).

Metabotropic glutamate receptor 4 (mGluR4) is widely regarded as an umami receptor activated by L-glutamate to exert essential functions. Numerous studies have shown that umami receptors participate in food intake regulation. However, little is known about mGluR4's role in mediating food ingestion and its possible molecular mechanism. Mandarin fish, a typical carnivorous fish, is sensitive to umami substances and is a promising vertebrate model organism for studying the umami receptor. In this study, we identified the mGluR4 gene and conducted evolutionary analyses from diverse fish species with different feeding habits. mGluR4 of mandarin fish was cloned and functionally expressed to investigate the effects of L-glutamate on mGluR4. We further explored whether the signal pathway mGluR4-Ca2+-ERK1/2 participates in the process in mandarin fish brain cells. The results suggest that L-glutamate could regulate Neuropeptide Y (Npy) via the mGluR4-Ca2+-ERK1/2 signaling pathway in mandarin fish. Our findings unveil the role of mGluR4 in feeding decisions and its possible molecular mechanisms in carnivorous fishes.

Molecular Cloning of the scd1 Gene and Its Expression in Response to Feeding Artificial Diets to Mandarin Fish (Siniperca chuatsi).

Background/Objectives: Stearoyl-coenzyme A desaturase 1 (SCD1) plays a crucial role in fatty acid metabolism. However, its roles in the feeding habit transformation of mandarin fish (Siniperca chuatsi) remain largely unknown. Methods: Juvenile mandarin fish (10.37 ± 0.54)g were trained to feed on an artificial diet and then divided into artificial diet feeders and nonfeeders according to their feed preference. Afterwards, the scd1 gene of mandarin fish (Sc-scd1) was identified and characterized, and its transcription difference was determined between S. chuatsi fed live artificial diets and those fed prey fish. Results: Our results show that Sc-scd1 coding sequence is 1002 bp long, encoding 333 amino acids. The assumed Sc-SCD1 protein lacks a signal peptide, and it contains 1 N-linked glycosylation site, 24 phosphorylation sites, 4 transmembrane structures, and 3 conserved histidine elements. We found that Sc-SCD1 exhibits a high similarity with its counterparts in other fish by multiple alignments and phylogenetic analysis. The expression level of Sc-scd1 was detected with different expression levels in all tested tissues between male and female individuals fed either live prey fish or artificial diets. Conclusions: In particular, the Sc-scd1 expression level was the highest in the liver of both male and female mandarin fish fed artificial diets, indicating that scd1 genes may be associated with feed adaption of mandarin fish. Taken together, our findings offer novel perspectives on the potential roles of scd1 in specific domestication, and they provide valuable genetic information on feeding habits for the domestication of mandarin fish.

Genome-wide identification, characterization, and expression analysis of the transient receptor potential gene family in mandarin fish Siniperca chuatsi

BackgroundTemperature is a crucial environmental determinant for the vitality and development of teleost fish, yet the underlying mechanisms by which they sense temperature fluctuations remain largely unexplored. Transient receptor potential (TRP) proteins, renowned for their involvement in temperature sensing, have not been characterized in teleost fish, especially regarding their temperature-sensing capabilities.ResultsIn this study, a genome-wide analysis was conducted, identifying a total of 28 TRP genes in the mandarin fish Siniperca chuatsi. These genes were categorized into the families of TRPA, TRPC, TRPP, TRPM, TRPML, and TRPV. Despite notable variations in conserved motifs across different subfamilies, TRP family members shared common structural features, including ankyrin repeats and the TRP domain. Tissue expression analysis showed that each of these TRP genes exhibited a unique expression pattern. Furthermore, examination of the tissue expression patterns of ten selected TRP genes following exposure to both high and low temperature stress indicated the expression of TRP genes were responsive to temperatures changes. Moreover, the expression profiles of TRP genes in response to mandarin fish virus infections showed significant upregulation for most genes after Siniperca chuatsi rhabdovirus, mandarin fish iridovirus and infectious spleen and kidney necrosis virus infection.ConclusionsThis study characterized the TRP family genes in mandarin fish genome-wide, and explored their expression patterns in response to temperature stress and virus infections. Our work will enhance the overall understanding of fish TRP channels and their possible functions.

Formation and characterization of artificial gynogenetic northern snakehead (Channa argus) induced by inactivated sperm of mandarin fish (Siniperca chuatsi)

Artificial gynogenesis is a pivotal technique in the realm of aquaculture breeding. Northern snakehead (Channa argus) is confronting a critical issue of germplasm degradation. To solve this problem, we produced viable northern snakehead offspring via gynogenesis using UV-irradiated sperm from mandarin fish (Siniperca chuatsi). As expected, all gynogenetic northern snakeheads were female, as verified by sex-specific markers. To investigate the characterization of the gynogenetic northern snakehead, including whether the mandarin fish DNA fragments integrate into gynogenetic northern snakehead, we compared their morphological features, growth characteristics, DNA contents, chromosomal numbers, karyotypes, mitochondrial DNA sequences, and microsatellite DNA sequences. The gynogenetic northern snakehead exhibited dominant maternal patterns regarding morphological features, DNA contents, chromosomal numbers, karyotypes, and mitochondrial DNA traits. However, microsatellite assessments confirmed the successful integration of mandarin fish DNA fragments into the gynogenetic northern snakehead genome. Notably, the gynogenetic northern snakehead displayed superior growth compared to the maternal. We induced spawning in the 12-month-old gynogenetic northern snakehead and successfully obtained offspring. This study holds significant commercial potential for northern snakeheads and offers valuable insights for breeding.

Effect of different feeding regimens on physiological indicators, intestinal transcriptome, and bacterial flora of mandarin fish (Siniperca chuatsi)

Mandarin fish (Siniperca chuatsi) represents a typical carnivorous freshwater economic fish in China. Recently, the study of their feeding behavior to acclimate formulated diets has become a research focus. This study evaluated the effects of various diets on the body composition, nutritional content, digestive enzyme activity, gene expression, and gut microbiota of mandarin fish. Firstly, no significant differences were found in the muscle's basic nutritional components (moisture, crude protein, crude fat, and crude ash), as well as in the fatty acid and amino acid content, between the live feed group (LFSC) and the compound feed group (CFSC). However, mandarin fish in the LFSC group exhibited significantly higher lipase activity in the liver and intestine compared to the CFSC group, while amylase activity in the intestine showed an opposite pattern. Additionally, intestinal transcriptome analysis revealed 6238 differentially expressed genes and identified several differentially expressed clock genes associated with diet type. Furthermore, gut microbiota analysis indicated that different feeding regimens influenced microbial composition, revealing correlations between bacterial genera and intestinal gene expression levels. These findings provided novel insights into the gut microbiota and transcriptomic responses of mandarin fish to different dietary types.

Both rapid hyperplasia and hypertrophy promoted skeletal muscle growth in mandarin fish Siniperca chuatsi, compared to big-eye mandarin fish Siniperca kneri

As important cultured fishes in China, mandarin fish, Siniperca chuatsi and big-eye mandarin fish, Siniperca kneri share similar external morphology and genomes, but have significant differences in growth rates. In this study, we used 6 mph (month post hatching) mandarin fish and big-eye mandarin fish to compare differences in skeletal muscle growth over a one-month period, and use transcriptomes to explore the reasons for the growth differences. The results showed that the different value in number of muscle fibers (2.72 times), density (2.56 times), area (1.95 times) and diameter (2.73 times) of mandarin fish are significantly higher than that of big-eye mandarin fish (P<0.05). Hypertrophy (Contribution rate: 97.9%) is the dominant factor in big-eye mandarin fish, and both hypertrophy and hyperplasia (Contribution rate: 2.1%) were significantly different from mandarin fish (P<0.05). Transcriptome results showed that differential genes were enriched in proliferation of satellite cells, protein synthesis and degradation. Further analysis of the transcriptome results showed that the number of Pax7-positive cells per unit area of mandarin fish was 2.3 fold higher that of big-eye mandarin fish (P<0.05). Myod, pax3, pax7, and myf5 mRNA expression of mandarin fish were significantly higher than those of big-eye mandarin fish(P<0.05). In muscle fiber fusion, mef2, myog, and myomaker mRNA expression of mandarin fish were significantly higher than that of big-eye mandarin fish (P < 0.05). In protein deposits, the results showed that the muscle fiber area of mandarin fish was 2.85 times larger than that of big-eye mandarin fish by comparing the muscle fiber area with the same number of nuclei. Polr2a, mtorc1, 4e-bp1, s6, e1, murf, foxo3, atg5, beclin, and atg14 mRNA expression of mandarin fish were significantly higher than that of big-eye mandarin fish (P < 0.05), while eef2, eif2α, gcn2, eif2b, capn and cast of mandarin fish was significantly lower than that of big-eye mandarin fish (P < 0.05). This work verified that the skeletal muscle growth rate of mandarin fish is faster than that of big-eye mandarin fish. The greater number and higher activity of satellite cells of mandarin fish increased hyperplasia efficiency, and the faster fusion rate and protein precipitation rate increased hypertrophy efficiency. Both hyperplasia and hypertrophy contribute to faster skeletal muscle growth of mandarin fish than that of big-eye mandarin fish.

Characterization of sexual size dimorphism in mandarin fish and association with igfbp-5a/b regulation.

Mandarin fish (Siniperca chuatsi) is an important cultured fish in East Asia that shows sexual size dimorphism (SSD), with females growing faster than males when reaching marketable size. However, the regulatory mechanism of SSD is not clear. To characterize SSD of mandarin fish and its association with gh/igf1/igfbp-5 expression, gonadal developmental atlas of the females and the males were described, and growth parameters and serum levels of E2 and T, as well as the relative expression levels of gh, igf1, and igfbp-5a/b mRNAs, were determined. The results showed that the logistic growth equation of body mass and total length of female and male were W(♀) = 667.57/(1 + e^(4.19 - 1.24*t)), W(♂) = 582.71/(1 + e^(4.07 - 1.27*t)), L(♀) = 31.47/(1 + e^1.95 - 1.08*t)), L(♂) = 26.20/(1 + e^(2.56 - 1.5*t)). The month of inflection points for body mass for females and males were 3.37 mph and 3.20 mph, respectively, when the body mass were 333.79g and 291.36g. The month of inflection points for total length growth were 1.80 mph and 1.70 mph, respectively, when the total length were 18.52cm and 16.28cm. At 1.5-2.0 mph, SSD was not clearly demonstrated. At 3.0 mph, the body mass of the females was significantly higher than that of the males (P < 0.05), Serum E2, brain gh, and liver igf1 expression of the females was significantly higher than that of the males (P < 0.05); T content of the males was significantly higher than that of the females (P < 0.05). At 4.0months of age, the body mass of the females was highly significantly higher than that of the males (P < 0.01), Serum E2, brain gh, and liver igf1 expression of the females was highly significantly higher than that of the males (P < 0.05); T content of the males was significantly higher than that of the females (P < 0.05). With the continuous development of gonads, muscle and liver igfbp-5a and -5b expression generally tend to increase in females and males, while igfbp-5a showed a gradual increasing trend, and igfbp-5b expression showed a trend of decreasing and then increasing. Male igfbp-5a/b expression was significantly higher than female at the age of 3.0-4.0months (P < 0.05). This work verified that the females had faster growth rate since 3.0 mph compared to the males, which may be related to higher E2 levels in females leading to higher igf1 level, through inhibition of igfbp-5a/b expression.

Short time-series expression transcriptome data reveal the gene expression patterns and potential biomarkers of blood infection with LPS and poly (I:C) in Mandarin fish (Siniperca chuatsi)

Blood transcriptomics has emerged as a vital tool for tracking the immune system and supporting disease diagnosis, prognosis, treatment, and research. The present study was conducted to analyze the gene expression profile and potential biomarker candidates using the whole blood of mandarin fish (Siniperca chuatsi) infected with LPS or poly (I:C) at 0 h, 3 h, 6 h, and 12 h. Our data suggest that 310 shared differentially expressed genes (DEGs) were identified among each comparison group after LPS infection, and 137 shared DEGs were identified after poly (I:C) infection. A total of 62 shared DEGs were differentially expressed in all compared groups after LPS or poly (I:C) infection. Pathways analysis for DEGs in all different compared groups showed that cytokine-cytokine receptor interaction was the most enrichment pathway. The expression levels of genes C-X-C chemokine receptor type 2-like (cxcr2), chemokine (C-C motif) receptor 9a (ccr9a), chemokine (C-C motif) receptor 9b (ccr9b), chemokine (C-X-C motif) receptor 4b (cxcr4b), and interleukin 10 receptor alpha (il10ra) were significantly different in all compared groups and most enriched in cytokine-cytokine receptor interaction pathway. The protein-protein interactions analysis among all shared DEGs showed that cxcr4 was the hub gene with the highest degree. The biomarker candidates discovered in this study may, following validation, prove effective as diagnostic tools in monitoring mandarin fish diseases.

Cu(OH)2 nanowire arrays@Cu Foam for high–sensitivity nonenzymatical electroanalysis of histamine: Exploration of electron transfer kinetics and determination of histamine levels in Lactobacillus sakei subsp. sakei–inoculated fermented mandarin fish

Presently, Cu(OH)2 nanowire arrays@Cu Foam (Cu(OH)2–NWA@Cu Foam) nanostructure has been confirmed to possess an excellent capacity of nonenzymatical electroanalysis of histamine (His). Based on Cu(OH)2–NWA@Cu Foam electrode, electrochemical investigations elucidated electron transfer kinetics principles of electrooxidation of His. Substantially, it was realized that a four–electron–transferring dehydrogenation was involved in diffusion–controlled electrooxidation of His, contributing tremendously to establishing as–proposed mechanization of His electrooxidation. At optimal conditions, Cu(OH)2–NWA@Cu Foam electrode reflected excellent electrochemical performance such as sensitivity of 3.089 mA mM–1 cm–2, limit of determination of 94 nM, respond time of 1.6 s and linear respond rang of 0.5–1250 μM. The outperformed electroanalytical performance can be physically explicated by the dedications from larger exposed surface area, bigger interface–hydrophilicity–deduced His diffusion coefficient and less charge transfer resistance. Moreover, the outstanding selectivity, stability and reproducibility of Cu(OH)2–NWA@Cu Foam electrode ensured its practical effectiveness in regulating real His levels in fermented mandarin fish. Compared with control group, the mandarin fish by inoculating Lactobacillus sakei subsp. sakei delivered less His contents, deducing that inoculation of Lactobacillus sakei subsp. sakei can effectively depress His generation during fermentation process. Eventually, the one–step as–established Cu(OH)2–NWA@Cu Foam nanostructure positioned itself as an upcoming possibility to pursue commercialized utilization.

Effect of Pond-Based Rice Floating Bed on the Microbial Community Structure and Quality of Water in Pond of Mandarin Fish Fed Using Artificial Diet.

The culture of mandarin fish using artificial feed has been gaining increasing attention in China. Ensuring good water quality in the ponds is crucial for successful aquaculture. Recently, the trial of pond-based rice floating beds (PRFBs) in aquaculture ponds has shown promising results. This research assessed the impact of PRFBs on the microbial community structure and overall quality of the aquaculture pond, thereby enhancing our understanding of its functions. The results revealed that the PRFB group exhibited lower levels of NH4+-N, NO2--N, NO3--N, TN, TP, and Alk in pond water compared to the control group. The microbial diversity indices in the PRFB group showed a declining trend, while these indices were increasing in the control group. At the phylum level, there was a considerable increase in Proteobacteria abundance in the PRFB group throughout the culture period, suggesting that PRFBs may promote the proliferation of Proteobacteria. In the PRFB group, there was a remarkable decrease in bacterial populations related to carbon, nitrogen, and phosphorus metabolism, including genera Rhodobacter, Rhizorhapis, Dinghuibacter, Candidatus Aquiluna, and Chryseomicrobium as well as the CL500_29_marine_group. Overall, the research findings will provide a basis for the application of aquaculture of mandarin fish fed an artificial diet and rice floating beds.