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Crucian carp (Carassius auratus) is widely distributed in the world and has become an economically freshwater fish. The population in Lake Dali Nur can tolerate the extreme alkaline environment with alkalinity over 50 mmol/L (pH 9.6), thus providing a special model for exploring alkali-tolerant molecular markers in an extremely alkaline environment. In this study, we constructed a high-density and high-resolution linkage map with 16,224 SNP markers based on genotyping-by-sequencing (GBS) consisting of 152 progenies and conducted QTL studies for alkali-tolerant traits. The total length of the linkage map was 3918.893 cM, with an average distance of 0.241 cM. Two QTLs for the ammonia-N-tolerant trait were detected on LG27 and LG45. A QTL for the urea-N-tolerant trait was detected on LG27. Interestingly, mapping the two QTLs on LG27 revealed that the mapped genes were both located in the intron of CDC42. GO functional annotation and KEGG enrichment analysis results indicated that the biological functions might be involved in the cell cycle, cellular senescence, MAPK, and Ras signaling pathways. These findings suggest that CDC42 may play an important role in the process of dealing with extremely alkaline environments. [ABSTRACT FROM AUTHOR]

Phenotypic differences between diploid parents and their allotriploid offspring are common in aquaculture breeding. Some allotriploid populations exhibit rapid growth rates and increased body weight, which are significant for supporting fisheries development. Understanding the genetic mechanisms underlying these traits is crucial for implementing diverse breeding strategies to achieve high production in fish farming. Here, we collected the following fish species for our study: red crucian carp (Carassius auratus red var., 2nRR), common carp (Cyprinus carpio L., 2nCC), and two allotriploids (3nR2C and 3 nRC2). These allotriploids were obtained through backcrossing an allotetraploid of C. auratus red var. x C. carpio L. (4nR2C2, ♂) with C. auratus red var. and C. carpio L. (♀), respectively. These allotriploids demonstrated faster growth rates compared to their diploid inbred parents, contributing to the Chinese fisheries industry for several decades. We conducted a systematic comparison of mitochondrial DNA (mtDNA) copy numbers in the liver and muscle tissues of 2nRR, 2nCC, 3nR2C, and 3 nRC2 under different seasons. When entering winter (low water temperature: 13 °C), the triploid fish (3nR2C and 3 nRC2) exhibited lower mtDNA copy numbers in the muscle, indicating a reduction in individual activity and energy expenditure to facilitate weight maintenance when food availability is limited. Furthermore, we analysed the expression levels of three nuclear-regulated mitochondrial genes (tfam, tfb1m, and tfb2m) and observed an imbalance of allelic expression in tfam and tfb1m in the two triploid fish. These findings enhance our understanding of the molecular regulatory mechanisms underlying growth trait differences among fish with different ploidy levels. [ABSTRACT FROM AUTHOR]

Microbial infection can pose a great threat to health of farmed fish. This study aimed to investigate the probiotic characteristics of Bacillus cereus strain fkW8-1-2 isolated from intestine of WCC and its anti-biofilm activity against pathogenic bacteria. The strain fkW8-1-2 showed a high resistance to low pH, bile salt and lysozyme during long-term incubation. The strain fkW8-1-2 displayed a gradual increase of cell surface hydrophobicity with various forms of hydrocarbons. The strain fkW8-1-2 showed the remarkable autoaggregation and coaggregation activity with A. hydrophila L3-3 and E. tarda 1l-4. The culture medium (CM) and cell-free supernatants (CFS) of strain fkW8-1-2 at 48 h cultivation could attenuate biofilm formation of A. hydrophila and E. tarda with the maximum inhibition rates. In addition, the intact cells of strain fkW8-1-2 exhibited the strong antioxidant activity for DPPH removal and superoxide anion clearance. These results indicated that strain fkW8-1-2 possessing probiotic characteristics can pose a protective role in health of farmed fish. [ABSTRACT FROM AUTHOR]

High diversity and differential evolution profiles have been observed for DD34E/ Tc1 transposons; several families originating from these groups, such as DD34E/ ZB , DD34E/ SB , DD35E/ TR , DD36E/ IC, and DD38E/ IT , have been well defined. Even though Frisky , Tiang , Tsessebe, and Topi transposons have been identified in Anopheles gambiae , their taxonomic distribution and phylogenetic relationship in nature remain largely unknown. The evolutionary profiles of Frisky , Tiang , Tsessebe , and Topi homology transposons were investigated in the current study. In total, 254 homology transposons of Frisky , Tiang , Hob , Tsessebe, and Topi were obtained in 200 species by data mining. The phylogenetic tree revealed that these transposons were classified into five main clades (Frisky , Tiang , Hob , Tsessebe , and Topi) forming a monophyletic clade with 98% bootstrap support, belonging to the DD34E/ Tc1 group, and named as Skipper (SK). SK transposons show a wide distribution in animals; however, differential taxonomic distribution patterns were observed for the subfamilies of Frisky , Tiang , Hob , Tsessebe, and Topi ; extensive invasion of Frisky in animals was found, whereas Tiang , Hob , Tsessebe, and Topi were mainly detected in Diptera. SK elements share a similar structural organization and display high sequence identities across subfamilies. Evolutionary dynamics and structural analysis revealed that SK s in some species, such as Bombyx mori , Lordiphosa magnipectinata , Carassius gibelio , Triplophysa dalaica , and Silurus glanis , have recently evolved and present as intact copies, indicating that SK s in these genomes may be active. Together, these observations improve our understanding of the diversity of DD34E/ Tc1 transposons and their impacts on genome evolution in animals. [ABSTRACT FROM AUTHOR]

Due to high-density farming methods and poor farming environments, freshwater fish often have poor muscle texture and a fishy odor before marketing, which impacts consumer acceptance. Short-term low-salinity seawater treatment of freshwater fish before marketing has been found to improve the quality of the fish, but the mechanisms underlying this phenomenon have not yet been revealed. In this study, metabolomics technique was used based on gas chromatography-mass spectrometry (GC–MS) and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) to screen different metabolites and predict potential metabolic pathways after treatment with low-salinity seawater. The results showed that 3838 metabolites were presented in all of the carp samples, while 62 and 64 differential metabolites were found in the comparative groups (FW, SW, and CK represented freshwater, seawater and non-transient group, respectively). Additionally, 25 and 26 metabolic pathways were enriched from these groups. Glutaric acid, PC, and creatinine might be potential biomarkers. Seawater aquaculture significantly altered the lipid metabolism, nucleotide metabolism, and amino acid metabolism of carp, enhancing its freshness and having a significant impact on its quality. This study provided insights into the metabolic changes in carp under different rearing conditions and also served as a theoretical basis for salinity treatment before freshwater fish are brought to the market. [ABSTRACT FROM AUTHOR]

This experiment was conducted to study the effects of Astragalus polysaccharide (APS) on intestinal antioxidant capacity, immunity, structural integrity, and permeability of hybrid crucian carp (control group, Astragalus polysaccharide stress group (APs), and salt and alkali stress group (SAs)) under saline-alkali environment. The results showed that the CAT activity, MDA activity, and total antioxidant capacity in the APs group was significantly higher than that in the control group (P < 0.05). At 6 h, the activity of intestinal GPX in the SAs group was significantly higher than that in the control group and APs group (P < 0.05). At 48h, the activity of C3 in the APs group was significantly higher than that in the control group (P < 0.05). At 24 h, the content of C4 in the APs group was significantly higher than that in the control group (P < 0.05). At 72 h, the ACP and the AKP activity in the APs group and the SAs group was significantly higher than that in the control group (P < 0.05). Inflammatory cells infiltrated the folds in both the APs and SAs groups. At 72 h, the gene expression levels of claudin 7, claudin 12, claudin c, and ZO-1 in the APs group and SAs group were significantly higher than those in the control group (P < 0.05). At 72 h, the expression of inflammation-related genes in the APs group and SAs group was significantly higher than that in the control group (P < 0.05). In conclusion, APS, as an additive, can alleviate the damage of intestinal physical barrier and immune barrier caused by salt-alkali stress to hybrid crucian carp, including up-regulation of genes for inhibiting inflammation and tight junction and alleviating oxidative stress, thus maintaining the integrity of intestinal structure. [ABSTRACT FROM AUTHOR]

Tumor necrosis factor α1 (TNFα) is a pleiotropic cytokine involved in immune regulation and cellular homeostasis, but the crucial role of TNFα in fish gut remained unclear. The current study aimed to evaluate the immunoregulatory function of TNFα1 on gut barrier in a novel hybrid fish (WR), which was produced by crossing white crucian carp (Carassius cuvieri, ♀) with red crucian carp (Carassius auratus red var, ♂). In this study, WR‐tnfα1 sequence was identified, and a high‐level expression was detected in the intestine. Elevated levels of WR‐tnfα1 expressions were detected in immune‐related tissues and cultured fish cells on stimulation. The appearance of vacuolization and submucosal rupture was observed in TNFα1‐treated midgut of WR, along with elevated levels of goblet cell atrophy, whereas no significant changes were detected in most expressions of tight‐junction genes and mucin genes. In contrast, WR receiving gut perfusion with WR‐TNFα1 showed a remarkable decrease in antioxidant status in midgut, whereas the expression levels of apoptotic genes and redox responsive genes increased sharply. These results suggested that TNFα1 could exhibit a detrimental effect on antioxidant defense and immune regulation in the midgut of WR. [ABSTRACT FROM AUTHOR]

Nonylphenol (NP) is a known endocrine-disrupting chemical (EDC) that has been shown to affect bone development in mammals. However, the detrimental impacts of NP on the skeletal growth and development of aquatic species, especially bony fish, remain poorly understood. Bone morphogenic proteins (BMPs), essential for bone formation and osteoblast differentiation, act through the BMP-Smad signaling pathway. In this study, two BMP genes, BMP2 and BMP4, were cloned and characterized in the red crucian carp (Carassius auratus red var.). The full-length cDNAs of BMP2 and BMP4 were 2029 bp and 2095 bp, respectively, encoding polypeptides of 411 and 433 amino acids, and share a typical TGF-β domain with other BMPs. The tissue expression patterns of both genes were identified, showing ubiquitous expression across all studied tissues. Additionally, the exposure of embryos or adult fish to NP stress resulted in a downregulation of BMP2, BMP4, and other genes associated with the BMP-Smad signaling pathway. Moreover, the combined treatment of adult fish with NP and the specific BMP receptor inhibitor significantly reduced these genes' expression. These findings elucidate the mechanism of NP stress on BMP2 and BMP4, suggesting a role for the BMP-Smad signaling pathway in the response to endocrine-disrupting chemicals in fish. [ABSTRACT FROM AUTHOR]

The coexistence of sexual and asexual lineages is rarely documented in vertebrates. Various ecological and evolutionary mechanisms have been proposed to explain their stable coexistence. Gibel carp (Carassius gibelio), a highly invasive freshwater fish in Europe, is one such example of a sexual and asexual vertebrate, combining gynogenesis (sperm-dependent parthenogenesis) and sexual reproduction. In this study, we focused on vigour-related traits in gynogenetic and sexual forms of gibel carp coexisting in the same habitat, to reveal whether there is a link between parasite load and vigour-related traits reflecting the potential advantage of one reproductive form over another, which may eventually facilitate the obligatory coexistence of sperm-dependent gynogenetic females with sexual males. Using physiological parameters (indexes of somatic condition, energetic condition, and reproductive performance; glucose levels; and erythrocytes-related variables), diploid sexual males, diploid sexual females, and triploid gynogenetic females were found to be differentiated from one another. However, based on immune variables representing innate immunity, specific immunity, and index of immunocompetence, mostly sexual males were found to be weakly differentiated from both groups of females. We revealed different patterns of interactions between parasite abundance and immune variables between sexual and gynogenetic forms. Using parasite assemblage composition, different relationships between parasite assemblage and immunity or physiology in sexual males and sexual females were evidenced, potentially related to male reproduction biology. In contrast, gynogenetic females exhibited the advantage that parasite assemblage composition did not affect their immunity or physiology. Our study suggests that reproduction mode-associated costs of physiology and immunity may facilitate the coexistence of the asexual-sexual complex. We highlight that multiple ecological processes and evolutionary mechanisms contribute to the coexistence of asexual and sexual gibel carp. [ABSTRACT FROM AUTHOR]

The swim bladder in some teleost fish functions to transfer the sound energy of acoustic stimuli to the inner ears. This study uses the auditory evoked potential tests, micro-computed tomography scanning, reconstruction, and numerical modeling to assess the contribution of the swim bladder to hearing in crucian carp (Carassius carassius). The auditory evoked potential results show that, at the tested frequency range, the audiogram of fish with an intact swim bladder linearly increases, ranging from 100 to 600 Hz. Over this frequency, the sound pressure thresholds have a local lowest value at 800 Hz. The mean auditory threshold of fish with an intact swim bladder is lower than that of fish with a deflated swim bladder by 0.8–20.7 dB. Furthermore, numerical simulations show that the received pressure of the intact swim bladders occurs at a mean peak frequency of 826 ± 13.6 Hz, and no peak response is found in the deflated swim bladders. The increased sensitivity of reception in sound pressure and acceleration are 34.4 dB re 1 μPa and 40.3 dB re 1 m·s−2 at the natural frequency of swim bladder, respectively. Both electrophysiological measurement and numerical simulation results show that the swim bladder can potentially extend hearing bandwidth and further enhance auditory sensitivity in C. carassius. [ABSTRACT FROM AUTHOR]

Carassius auratus gibelio, commonly known as crucian carp, is the main species of freshwater aquaculture in China. Due to high-density aquaculture and environmental pollution, various diseases continue to emerge, especially the diseases caused by pathogenic bacteria have seriously restricted the development of freshwater aquaculture. Among these, Aeromonas hydrophila (AH) is the one of the most serious fish disease causing economic losses among fish farmers. An in-depth understanding of the crucian carp's immune system and its genes involved in the response to bacterial infection is necessary for disease control. In this study, the breeding period was divided into the control group (C group) and the Bacillus licheniformis (B. licheniformis) group (BL group). After 4 weeks of culture, the crucian carp was infected with AH and divided into the control group (Cg group) and the B. licheniformis group (BLg group). After the 72-h challenge, the Illumina-based paired-end sequencing approach to analyze the transcriptome profile of the crucian carp gut following AH infection. A total of 472.05 million valid reads were found from the four intestinal samples and 403.18 million reads were mapped successfully, of which 243.34 million were unique. About GO enrichment analysis, significant differentially expressed genes (DEGs) were more in biological process (406 DEGs), regulation of transcription, DNA-templated (345 DEGs), and signal transduction (304 DEGs). In the cell components, membrane (1913 DEGs) and integral component of membrane (1789 DEGs) had a higher number of significantly different genes. In the molecular function, metal ion binding (780 DEGs), ATP binding (535 DEGs), transferase activity (491 DEGs), and nucleotide binding (482 DEGs) have a large number of significantly different genes. Regarding the KEGG enrich analysis section, this study is arranged in ascending P-value order, andthe most significant signaling paths are lysosome, glucose metabolism, cycline cycline receiver interaction, and phagosome. Among them, the cycline cycline receiver interaction has the highest difference in significant genes. In addition, 5 immune-related genes were selected for real-time fluorescence quantitative PCR analysis to verify the RNA-seq data, and the results showed that the expression of all 5 genes was upregulated, which was consistent with the results of our RNA-seq analysis. After analysis, it was found that B. licheniformis can alleviate the inflammatory response and protect the fish body. Our results provide a reference for further analysis of the antagonism and mitigation mechanism of B. licheniformis against AH. [ABSTRACT FROM AUTHOR]

Nod-like receptor pyrin domain-containing protein 3 (NLRP3) is a crucial member of NLRs family, which plays an important role in host defense. However, knowledge about inflammation response of NLRP3 in fish was scarce. Herein, a novel NLRP3 homologue (designated as CaNLRP3-like) was identified in Qihe crucian carp Carassius auratus. Full-length cDNA of CaNLRP3-like was composed of 3898 bp, which contained a 3093-bp open reading frame encoding. Structural analysis revealed that CaNLRP3-like lacked the PYD domain at N-terminus. Multiple sequence alignment and phylogenetic analysis revealed that CaNLRP3-like showed the high identity with the fishes in Cyprinidae, distinct from the branch formed by the mammals. Spatial expression analysis revealed that CaNLRP3-like was expressed in all examined tissues, with the highest expression levels in gill. Immune challenge experiments revealed that the expression of CaNLRP3-like was significantly up-regulated in six tissues in cases of challenge with Aeromonas hydrophila, LPS, and polyI:C. The recombined protein of CaNLRP3-like with 3Flag-tag was observed obviously in the cytoplasm. Furthermore, knockdown of CaNLRP3-like reduced the mRNA level of IL-1β, and increased the bacterial loading in liver, spleen, and head kidney. Vice versa, overexpression of CaNLRP3-like increased the mRNA expression of IL-1β, and decreased the bacterial loading in three detected tissues. Taken together, CaNLRP3-like gene, as a NLRP3 homologue, was identified and characterized in C. auratus, and these results revealed its role in regulating IL-1β expression and restricting bacterial infection in vivo, which shed light on the potential of CaNLRP3-like as a therapeutic target upon bacterial infection in teleost fish. [ABSTRACT FROM AUTHOR]

Carassius auratus herpesvirus (CaHV) is a pathogen isolated from crucian carp (Carassius auratus) associated with high mortality. A diagnosis method that can detect the virus at an early stage, specifically and accurately, is an urgent requirement for the prevention of CaHV transmission. In the present study, a droplet digital PCR (ddPCR) method based on the tumor necrosis factor receptor (TNFR) gene was established to detect and quantify CaHV DNA with high specificity and no cross-reactions with other aquatic viruses. Skin mucus samples were collected from infected crucian carp from Day 1-8 after infection, and positive amplification was detected on the first day by ddPCR (0.54 copies/μL), whereas the presence of CaHV was not detected by routine PCR until Day 6. Tissue DNA was then collected from the head kidney of 20 fishes which were injected with CaHV and died during the experiment. The five negative samples checked by routine PCR were detected by ddPCR and real-time PCR (qPCR), respectively. The results showed that the positive detection rate of ddPCR (100%) was higher than that of qPCR (40%). The detection limit of the ddPCR was found to be 0.52 copies/μL, which was much lower than the 50.12 copies/μL determined by qPCR. Overall, ddPCR offers a highly promising diagnosis method for the absolute quantification of CaHV in carrier fish and samples from the skin mucus and head kidney with low viral concentrations. [ABSTRACT FROM AUTHOR]

Frequent outbreaks of emerging infectious diseases in fish, such as Carassius auratus herpesvirus (CaHV) infection has caused great economic losses in China. However, the lack of a sensitive cell culture system has limited studies of CaHV. In the present study, a new cell line (gibel carp skin cell, GiCS) derived from gibel carp (Carassius gibelio) skin tissue was established to create a valuable tool for research of the virus. The GiCS cells consisted mainly of epithelial-like cells, which grew well at 25 °C in L-15 medium supplemented with 10-20% fetal bovine serum. Chromosomal analysis revealed that the skin cell line remained amphitriploid, with most chromosome counts being 156 (54%). The GiCS cells can be efficiently transfected and expressed exogenous genes. In particular, the GiCS cells showed high susceptibility to CaHV infection, which was confirmed by virus infection tests, detection of viral gene expression, and ultrastructural observation. To our knowledge, it is the first cell line that is highly permissive to CaHV infection. In addition, the cells also showed susceptibility to several aquatic animal viruses from different families including Iridoviridae, Rhabdoviridae, and Reoviridae. In conclusion, these results indicated that the establishment of the GiCS cell line is a significant advance that will be beneficial to future studies of CaHV and other aquatic animal viruses. [ABSTRACT FROM AUTHOR]

An 8-week feeding experiment aimed to investigate the effects of fermented soybean residue in diets on the growth performance, serum antioxidant parameters, intestinal digestive capacity, and microbial composition of the hindgut of Furong crucian carp. The feeds were formulated to contain 0%, 6%, 12%, 18%, and 24% fermented soybean residue (CON, FSR6, FSR12, FSR18, and FSR24, respectively), respectively, to form five diets (crude protein: 33%; crude lipid: 5%). The results showed that incorporating 6% fermented soybean residue into the diet significantly increased the weight gain rate (WGR) and specific growth rate (SGR) and decreased the feed coefficient rate (p < 0.05). Through regression analysis of WGR and SGR, the optimal levels of the dietary fermented soybean residue of Furong crucian carp were determined to be 6.78% and 7.06%. Incorporating fermented soybean residue into the diet decreased the lipid content of the whole body and the levels of glucose, total cholesterol, and triglyceride in the serum of Furong crucian carp. The inclusion of 6% and 12% fermented soybean residue in the diet markedly increased the antioxidant capacity, intestinal amylase activity, and intestinal villous height of Furong crucian carp (p < 0.05). At the 6% level, fermented soybean residue significantly increased the abundance of Romboutsia and Clostridium_sensu_stricto_1 while significantly decreasing the abundance of Vibrio (p < 0.05), indicating that a 6% level of fermented soybean residue was beneficial for intestinal health. In conclusion, incorporating 6–7% fermented soybean residue into the diet of Furong crucian carp was recommended. [ABSTRACT FROM AUTHOR]

The trial was conducted to investigate the effects of the replacement of dietary fishmeal (FM) by the blend of Tenebrio molitor meal (TMM), Chlorella meal (CM), Clostridium autoethanogenum protein (CAP), cottonseed protein concentrate (CPC) on growth, protein utilization and intestinal health of gibel carp (Carassius gibelio, CAS Ⅴ). The FM-based diet was used as the control, and the blended proteins (TMM: CM: CAP: CPC) at ratios of 1 : 1:8 : 2 (BLEND A), 1 : 1:6 : 4 (BLEND B), and 1 : 1:4 : 6 (BLEND C) were used to replace FM at three levels (33%, 67%, 100%), respectively. The results showed that, compared to the control group, growth performance increased significantly when dietary FM was fully replaced by BLEND B (P < 0.05), while decreased by BLEND A (P < 0.05). The complete substitution of FM with BLEND B significantly upregulated the mRNA expression of intestinal proinflammatory cytokines, anti-inflammatory cytokines, and tight junction-related genes (P < 0.05), improving intestinal tissue morphology and health. And it also significantly increased intestinal trypsin activity (P < 0.05), upregulated the mRNA expression of amino acid sensory receptor-related and amino acid or peptide transport-related genes (P < 0.05), increased protein apparent digestibility coefficient (P < 0.05). The 100% substitution of FM with BLEND A significantly upregulated the mRNA expression of intestinal proinflammatory cytokines and downregulated the mRNA expression of anti-inflammatory cytokine il-10 (P < 0.05), reduced intestinal villus height (P < 0.05), and decreased protein apparent digestibility coefficient (P < 0.05). In conclusion, BLEND B could completely substitute dietary FM and was beneficial to the growth and health of gibel carp. Dietary digestible essential amino acids index (DEEAI) was found as an important indicator and should be higher than 79.5% to meet the maximum growth of fish. [ABSTRACT FROM AUTHOR]

Mesoporous Fe3O4-loaded silver nanocomposites (Fe3O4@Ag) were simply fabricated as bi-functional nanozymes for the catalysis-based detection and removal of Hg2+ ions. It was found that the as-prepared magnetic Fe3O4@Ag could display peroxidase-like catalysis activity that could be rationally enhanced in the presence of Hg2+ ions. To our surprise, the shell of the Ag element may decrease the catalysis of the Fe3O4 to some degree. However, the Ag particles could serve as the probes for specifically recognizing Hg2+ ions and trigger increased catalysis through the formation of Ag–Hg alloys, with a decreased signal background. A high-throughput colorimetric analytical method was thereby developed based on the Fe3O4@Ag catalysis for probing Hg2+ ions in the muscles of fish by using 96-well plates, at linear Hg2+ concentrations ranging from 0.010 to 2.5 mg kg−1. Moreover, the developed colorimetric analytical method was applied to evaluate Hg2+ levels in muscle samples of different kinds of fish. Unexpectedly, an obvious difference of Hg2+ levels in muscles of four kinds of fish was discovered, with the order of snakehead (Ophicephalus argus) > largemouth bass (Micropterus salmoides) > crucian carp (Carassius auratus) > silver carp (Hypophthalmichthys molitrix), where the carnivorous fish showed higher Hg2+ levels than the omnivorous or plant-based ones. Moreover, the as-fabricated Fe3O4@Ag adsorbents with their large specific surface area and high environmental robustness could exhibit efficient Hg2+ adsorption with capacities of up to 397.60 mg g−1. A removal efficiency of 99.40% can also be expected for Hg2+ ions from wastewater, with the magnet-aided recycling of Fe3O4@Ag adsorbents. Such an Fe3O4@Ag-based colorimetric analysis and removal strategy for Hg2+ ions should find wide applications in the fields of aquatic food safety, environmental monitoring, and clinical diagnostics of Hg-poisoning diseases. [ABSTRACT FROM AUTHOR]

Successful invasive non-native fish species can cause enormous damage to native biodiversity. In mainland Europe, the introduction of the gibel carp (Carassius gibelio) has led to a decline in populations of the formerly widespread native crucian carp (C. carassius). Both invasive and native species develop two phenotypes, namely stunted and deep-bodied, which depend on the intensity of competition and predation in the water body. The deep-bodied phenotype is associated with a more diverse fish community composition, can attain large sizes and is very attractive to recreational anglers. This study analysed trends in the record sizes of native crucian carp and invasive gibel carp (individuals close to the maximum attainable size of the species) reported by recreational anglers over the last 50 years in Czechia, recording the invasion of gibel carp from its beginnings to the fully established population phase. The study provides circumstantial evidence that gibel carp is behind transition from the relative abundance of large crucian carp to near extirpation, while large gibel carp have taken over the reports of record catches in the genus Carassius. This indicates that the crucian carp, which is currently classified as critically endangered in the Red List of Czechia, has very limited possibilities to realise its deep-bodied phenotype. It also shows the potential of using data from recreational anglers for mapping invasion processes and as a source of relatively localised information on endangered species. [ABSTRACT FROM AUTHOR]

Fishes of the genus Carassius are useful experimental vertebrate models for the study of evolutionary biology and cytogenetics. Carassius demonstrates diverse biological characteristics, such as variation in ploidy levels and chromosome numbers, and presence of microchromosomes. Those Carassius polyploids with ≥ 150 chromosomes have microchromosomes, but the origin of microchromosomes, especially in European populations, is unknown. We used cytogenetics to study evolution of tandem repeats (U1 and U2 small nuclear DNAs and H3 histone) and microchromosomes in Carassius from the Czech Republic. We tested the hypotheses whether the number of tandem repeats was affected by polyploidization or divergence between species and what mechanism drives evolution of microchromosomes. Tandem repeats were found in tetraploid and hexaploid Carassius gibelio , and tetraploid Carassius auratus and Carassius carassius in conserved numbers, with the exception of U1 small nuclear DNA in C. auratus. This conservation indicates reduction and/or loss in the number of copies per locus in hexaploids and may have occurred by divergence rather than polyploidization. To study the evolution of microchromosomes, we used the whole microchromosome painting probe from hexaploid C. gibelio and hybridized it to tetraploid and hexaploid C. gibelio , and tetraploid C. auratus and C. carassius. Our results revealed variation in the number of microchromosomes in hexaploids and indicated that the evolution of the Carassius karyotype is governed by macrochromosome fissions followed by segmental duplication in pericentromeric areas. These are potential mechanisms responsible for the presence of microchromosomes in Carassius hexaploids. Differential efficacy of one or both of these mechanisms in different tetraploids could ensure variability in chromosome number in polyploids in general. [ABSTRACT FROM AUTHOR]

In previous studies, an allodiploid lineage (WR-F1-F5) was established by the distant hybridization of white crucian carp (Carassius cuvieri, WCC, ♀) and red crucian carp (Carassius auratus red var., RCC, ♂), an allodiploid fish (WR-II) was produced by WR-F1 (♀) x WCC (♂). In this study, the nutrients in the muscle and ovary of WR-II and its parents (WCC, RCC, and WR) were investigated, including protein, fat, amino acid, docosahexaenoic acid (DHA), moisture, and ash. The results showed that the protein content of WR-II in muscle and ovary (17.90 % and 25.60 % respectively) was higher than that of WR, and was significantly higher than that of WCC and RCC (p < 0.05). The fat content of WR-II in muscle and ovary (4.30 % and 5.31 % respectively) was higher than that of WR and was significantly higher than that of WCC and RCC (p < 0.05), and the muscle and ovary of WR-II showed rich DHA content (0.32 % and 0.54 % respectively) than that of WCC and RCC (p < 0.05). Fifteen amino acids were detected in WR-II and its parents, the total amino acid (TAA) content of WR-II in muscle and ovary (15.49 % and 18.43 % respectively) was significantly higher than that of WCC (p < 0.05), the delicious amino acid (DAA) content of WR-II in muscle and ovary (6.56 % and 8.29 % respectively) was different degrees higher than that of WCC, RCC, and WR. The moisture and carbohydrates of WR-II in muscle and ovary were lower than those in WCC and RCC. Furthermore, protein, fat, TAA, and DAA content in the ovary were significantly higher than those in muscle (p < 0.05), showing tissue differences in all detected fish. This study indicated that WR-II had the characteristics of high protein, high fat, high DHA, high TAA, high DAA, low moisture, and low carbohydrates, which provided theoretical support for its application. [ABSTRACT FROM AUTHOR]

Crucian carp (Carassius auratus gibelio), an extensively cultivated freshwater fish, was one of the model species for the study of fish immunology. Polyclonal antibodies were advantageous molecular tools for studying teleost immune system. Specifically, polyclonal antibodies reacting with immunoglobulins (Ig) were used successfully in studies of the teleost fishes. In the present study, we produced polyclonal antibody against CH2 domains of crucian carp IgM, and measured the in vivo dynamics of IgM mRNA caused by CyHV-2 infection. The recombinant protein IgM with relative molecular weight about 53 KD was correctly expressed in prokaryotic cells. The specificity of the polyclonal antibody was evaluated by Western blotting and results revealed that the antibody not only specifically recognized crucian carp serum but also cross-reacted with grass carp serum. Quantitative RT-PCR analysis demonstrated the expression of IgM mRNA changed significantly after CyHV-2 infection. The expression of IgM in the kidney increased and reached a maximum at 6 h post-infection (hpi), while dropped to a low level at 5 days post-infection (dpi). In conclusion, the expression of IgM was significantly upregulated in the kidney of crucian carp infected with CyHV-2, indicating that IgM played a potential role in systemic immunity against viral infection. Polyclonal antibody against crucian carp IgM had certain clinical relevance, which might provide insight into the early stage of virus infection and prevention of the disease. [ABSTRACT FROM AUTHOR]

Aquatic products are good sources of essential nutrients, but the presence of pyrethroids (PYRs) as contaminants may pose risks to consumer health as the intricate matrices of PYRs usually obstruct chemical hazard detection. In this study, a gas chromatographic method was established and validated for simultaneously detecting residues of seven PYRs (cyhalothrin, permethrin, cyfluthrin, cypermethrin, tau-fluvalinate, fenvalerate, deltamethrin) in aquatic products. The aim of this method was to assess better the potential risks of pesticide residues in aquatic products. The PYRs in aquatic products were extracted with acetonitrile, purified with n-hexane saturated with acetonitrile, and cleaned up on a Cleanert® Alumina N column. Statistical analysis and orthogonal array experimental design were used to optimize the key parameters. To validate the proposed method, commonly consumed aquatic products (such as carp, crucian carp, whiteleg shrimp, river crab, sea cucumber, and scallop) were obtained from local supermarkets in Shanghai. Satisfied linearity of the calibration curves was achieved in a matrix-matched standard solution, with a correlation coefficient (R2) larger than 0.995. The average recoveries at five fortification levels varied from 77.0% to 117.2%, with relative standard deviations (RSDs) below 11.1%. Concerning electron capture detection, the limits of detection (LOD) and limits of quantification (LOQ) were 2.0–5.0 µg/kg and 5.0–10.0 µg/kg, respectively. These results demonstrate the high stability and sensitivity of this method for simultaneously detecting PYRs in aquatic products, having great practicability and which can be popularized easily. [ABSTRACT FROM AUTHOR]

The present work is the first comprehensive study of fungus‐like stramenopilous organisms (Oomycota) diversity in Lithuanian fish farms aimed at proper identification of saprolegniasis pathogens, which is important for water quality control, monitoring infection levels and choosing more effective treatments for this disease in aquaculture. Pathogenic to fish, Saprolegnia and other potentially pathogenic water moulds were isolated from adult fish, their eggs, fry and from water samples. All detected isolates were examined morphologically and confirmed by sequence‐based molecular methods. A total of eight species belonging to the genera Saprolegnia, Achlya, Newbya and Pythium were identified. Four species (S. parasitica, S. ferax, S. australis and S. diclina) were found to be the main causative agents of saprolegniasis in Lithuania. S. parasitica and S. ferax dominated both in hatcheries and open fishponds, accounting for 66.2% of all isolates. S. parasitica was isolated from all farmed salmonid fish species as well as from the skin of Cyprinus carpio, Carassius carassius and Perca fluviatilis. S. australis was isolated from water and once from the skin of Oncorhynchus mykiss, and S. diclina was detected only once on the skin of Salmo salar fish. In addition, Achlya ambisexualis, Saprolegnia anisospora and Newbia oligocantha isolated during this study are noted as a possible source of saprolegniasis. The results of this study are relevant for assessing the risk of potential outbreaks of saprolegniasis or other saprolegnia‐like infection in Lithuanian freshwater aquaculture. [ABSTRACT FROM AUTHOR]

Aeromonas is the main pathogen causing bacterial diseases in fish. The disadvantages of chemical drugs to control fish diseases have been highlighted, and it is urgent to find an eco-friendly control method. In this study, an actinomycete strain with antibacterial activity against fish pathogenic bacteria was screened from soil samples. Combined with morphological characteristics, physiological and biochemical characteristics, and gyrB gene and whole genome comparison analysis, it was identified as a new strain of Streptomyces enissocaesilis, named Streptomyces enissocaesilis L-82. The strain has broad-spectrum antibacterial activity against fish pathogens. A substance with a mass-to-charge ratio of 227.20 [M + H] + was isolated and purified by high-performance liquid chromatography and mass spectrometry. It was presumed to be a derivative of 5-dimethylallylindole-3-acetonitrile. The strain is safe and non-toxic to crucian carp, and can stably colonize crucian carp and inhibit the proliferation of A. hydrophila. After feeding the feed containing 1 × 108 CFU/mL strain concentration, the weight growth rate and specific growth rate of crucian carp increased, the activity of ACP and SOD in serum increased, and the survival rate of crucian carp increased after challenge. Genome-wide analysis showed that the strain had strong ability to metabolize and tolerate extreme environments. And has a strong potential for disease resistance. Therefore, the strain is expected to be developed as a feed additive for fish farming. Key points: • The new Streptomyces enissocaesilis L-82 has a broad spectrum and stable antibacterial activity and meets the safety standards of feed additives. • Strain L-82 can colonize crucian carp, improve the growth, antioxidant, and immune performance of the host, and improve the survival rate after being infected with A. hydrophila. • Genome-wide analysis suggests that the strain has great disease resistance potential and is expected to be developed as a feed additive for fish culture. [ABSTRACT FROM AUTHOR]

The survival of farmed fish can be threatened by incidence of Aeromonas hydrophila infection. In addition, gut infection may promote dysbiosis of gut flora and dysregulate immune response in gut-liver axis in teleost fish. The current study aimed to evaluate the pathogenesis of A. hydrophila on gut barrier breach and synchronized immune response in gut-liver axis of RCCs. RCCs were subjected to continuous anal-intubation with A. hydrophila. Midgut sections were stained with periodic acid-Schiff (PAS) and immune-related gene expressions and biochemical indices in gut-liver axis were investigated. The severe midgut injury was detected in RCC anal-intubated with A. hydrophila, along with atrophy of the midgut villi, and the expression levels of tight junction (TJ) genes were consistently lower than those of the control (P < 0.05). Moreover, RCC receiving anal intubation with A. hydrophila showed the upregulation of pathological indices and immure genes in the midgut and liver. These findings demonstrated that gut infection with A. hydrophila can significantly disrupt epithelial permeability to exacerbate gut barrier breach and increase bacterial burdens in tissues as well as dysregulate immune response in gut-liver axis of RCC. [ABSTRACT FROM AUTHOR]

The experiment aimed to investigate the effects of microbial preparations on the growth and intestinal microbiota of crucian carp. Three hundred evenly sized crucian carp were randomly divided into five groups, with three replicates in each group, and 20 fish in each replicate. The group A was fed a feed containing mixed lactic acid bacteria preparations, the group B was fed a feed containing mixed Clostridium butyricum preparations, the group C was fed a feed containing a mixture of lactic acid bacteria and Clostridium butyricum preparations, the group D was fed a feed containing a mixture of lactic acid bacteria, Clostridium butyricum preparations, and 3 mg/g nano-selenium. The control group (CK group) was fed a basic feed. The experimental period lasted for 28 days. The results showed that the weight gain rate of crucian carp in the group A, group B, and group D was higher than that in the CK group ( P<0.05). The condition factor and feed coefficient of crucian carp in the group A were higher than those in the CK group ( P<0.05). The hepatopancreas SOD activity of crucian carp in the group D was higher than that in the CK group ( P<0.05), and the hepatopancreas LZM activity in the group B was higher than that in the CK group ( P<0.05). The abundance of Fusobacteria in the intestines of crucian carp in the group A significantly increased, while the abundance of Bacteroidetes in the intestines of crucian carp in the group B significantly increased. The study indicates that adding lactic acid bacteria, Clostridium butyricum, and nano-selenium to the feed can promote the growth of crucian carp, alter the community structure of the intestinal microbiota, and inhibit harmful bacteria in the intestines. [ABSTRACT FROM AUTHOR]

The hypoxia-inducible factor (HIF) is considered key in the transcriptional response to low oxygen. Yet, the role of HIF in the absence of oxygen (anoxia) and in preparation for reoxygenation remains unclear. Recent studies suggest that mounting a HIF response may be counterproductive for anoxia survival. We here studied one of the champions of anoxia survival, the crucian carp (Carassius carassius), and hypothesized that expression of prolyl hydroxylase domains (PHDs; the upstream regulators of HIF) are upregulated to circumvent an energy-costly activation of HIF in anoxia and to prepare for reoxygenation. We measured whole brain mRNA and protein levels of the three isoforms PHD1, PHD2, and PHD3, coded for by multiple paralogs of the genes egln2, egln1, and egln3, using quantitative PCR and Western blotting in the brain of crucian carps exposed to 5 days normoxia or anoxia, and 5 days anoxia followed by 3 or 24 h of reoxygenation. The mRNA levels of most egln paralogs were increased in anoxia and upon reoxygenation, with egln3 showing the largest increase in mRNA level (up to 17-fold) and highest relative mRNA abundance (up to 75% of expressed egln). The protein level of all PHDs was maintained in anoxia and increased upon reoxygenation. We then explored PHD distribution in different brain regions and found PHD immunoreactivity to be associated with axonal branches and showing region-specific changes during anoxia-reoxygenation. Our results support an overall upregulation of egln under prolonged anoxia and PHDs upon reoxygenation in crucian carp, likely aimed at suppressing HIF responses, although regional differences are apparent in such a complex organ as the brain. [ABSTRACT FROM AUTHOR]

Aeromonas is the main pathogen causing bacterial diseases in fish. The disadvantages of chemical drugs to control fish diseases have been highlighted, and it is urgent to find an eco-friendly control method. In this study, an actinomycete strain with antibacterial activity against fish pathogenic bacteria was screened from soil samples. Combined with morphological characteristics, physiological and biochemical characteristics, and gyrB gene and whole genome comparison analysis, it was identified as a new strain of Streptomyces enissocaesilis, named Streptomyces enissocaesilis L-82. The strain has broad-spectrum antibacterial activity against fish pathogens. A substance with a mass-to-charge ratio of 227.20 [M + H] + was isolated and purified by high-performance liquid chromatography and mass spectrometry. It was presumed to be a derivative of 5-dimethylallylindole-3-acetonitrile. The strain is safe and non-toxic to crucian carp, and can stably colonize crucian carp and inhibit the proliferation of A. hydrophila. After feeding the feed containing 1 × 108 CFU/mL strain concentration, the weight growth rate and specific growth rate of crucian carp increased, the activity of ACP and SOD in serum increased, and the survival rate of crucian carp increased after challenge. Genome-wide analysis showed that the strain had strong ability to metabolize and tolerate extreme environments. And has a strong potential for disease resistance. Therefore, the strain is expected to be developed as a feed additive for fish farming. Key points: • The new Streptomyces enissocaesilis L-82 has a broad spectrum and stable antibacterial activity and meets the safety standards of feed additives. • Strain L-82 can colonize crucian carp, improve the growth, antioxidant, and immune performance of the host, and improve the survival rate after being infected with A. hydrophila. • Genome-wide analysis suggests that the strain has great disease resistance potential and is expected to be developed as a feed additive for fish culture. [ABSTRACT FROM AUTHOR]

A 56-day feeding trial was conducted to evaluate the effect of different dietary protein sources on the growth performance, muscle flavor substances, and quality structure of Triploid Crucian Carp. Three isonitrogenous (32.00%), isolipidic (8.00%), and isoenergetic (18.00 MJ kg−1) practical diets were formulated. These diets consisted of fishmeal as the animal-derived protein source (AP), a combination of soybean meal and rapeseed meal as the plant-derived protein source (PP), and a mixture of fishmeal, soybean meal, and rapeseed meal as the mixed protein source (MP). Each diet was randomly assigned to triplicate tanks of fish and each tank was stocked with 25 fish (11.5 ± 0.4 g). The fish were fed until apparent satiation twice a day. The results showed a significant enhancement in the growth performance of Triploid Crucian Carp in the AP group compared with both the MP and PP groups (p < 0.05). Dietary plant derived protein can remarkably reduce the crude lipid content and increase the moisture content of the whole body and the dorsal muscle (p < 0.05). The antioxidant ability of fish in the PP group and MP group was better than that in the AP group (p < 0.05). Regarding free amino acids composition of muscle, the contents of glycine, methionine, and lysine were significantly enhanced in the AP group, while the histidine content was significantly increased in the PP group (p < 0.05). In terms of texture, dietary plant protein significantly improved the muscular hardness, gumminess, and chewiness. The activities of intestinal trypsin and alkaline phosphatase (ALP) of fish in the PP group were significantly higher than that in the AP group (p < 0.05). The expression levels of hepatopancreas TOR and IGF1 genes in the PP group were significantly higher than that in the MP group (p < 0.05). The present results indicate dietary fishmeal significantly improved the growth performance and muscular flavor glycine content, while dietary plant-based protein increased crude protein content, antioxidant ability, and muscular texture performance of Triploid Crucian Carp. [ABSTRACT FROM AUTHOR]

In 2011 and 2015, four mass mortalities of Prussian carp (Carassius gibelio) were observed in a recreational freshwater lake and open freshwater in the western part of the Netherlands. Cyprinid herpesvirus 2 (CyHV‐2) infection was suspected in these cases, based on presumptive gross diagnosis. To elucidate the cause of the mass mortalities diagnostic PCR assays were performed for CyHV‐2, based on the helicase gene. Furthermore, the viral isolates were genotyped by sequencing the enlarged marker A and marker B sequences. Diagnostic PCR revealed that three of four samples were positive for CyHV‐2, indicating these three mass mortalities were associated with CyHV‐2 infection. The marker A sequence from one of the isolates found in this study was identical to those from different locations such as Asia and Middle East, suggesting a link among the isolates. This is the first detailed report on mass mortalities of Prussian carp associated with CyHV‐2 infection in natural aquatic environments in the Netherlands. Since 2015, additionally, in total three CyHV‐2 associated outbreaks of Dutch Prussian carp were seen in 2016 and 2020. These outbreaks in Prussian carp from lakes and open water suggest that the virus has been spreading in natural freshwaters in the Netherlands. [ABSTRACT FROM AUTHOR]

Abstract—Opisthorchiasis in Novosibirsk and Novosibirsk oblast is registered annually. Significant differences in the indices of epidemic process in Novosibirsk were noted as compared with those in the Russian Federation, where the maximal and minimal long-term average incidence rates are 6–10 times lower than in Novosibirsk. In the structure of opisthorchiasis incidence in Novosibirsk oblast, the urban population accounts for more than 75% of cases. The incidence rate of individuals with opisthorchiasis in different districts of the city varies from 85.0 per 100 000 population to 170.3 in 2005–2015; there has been an increase in the growth rate of incidence in most administrative districts and in the city in general. The level of infection of domestic carnivores with opisthorchids is 15%. Cats are infected more frequently than dogs (18.1 and 10.7%, respectively). In two districts of the city (Kirovskii and Sovetskii), the level of infection of domestic carnivores and the incidence rates of individuals significantly exceed those in other districts. Three opisthorchid species were identified in six fish species from the family Cyprinidae (Leuciscus idus, L. leuciscus, Rutilus rutilus, Abramis brama, Leucaspius delineatus, and Carassius carassius) caught in urban and suburban reservoirs: Opisthorchis felineus (Rivolta, 1884), Metorchis bilis (Braun, 1890), and M. xanthosomus (Creplin, 1846). The first two species have an epidemic significance; the latter, epizootic. The total extensiveness of infestation of commercial size ides by opisthorchid larvae in the Ob River was 71.8%; out of them, O. felineus metacercariae accounted for 69.1%. There was a general level of infection in small aboriginal fish in small rivers: Nizhnyaya El'tsovka 45.8%, Inya 55.3%, and Tula 22.2%. Thus, favorable environmental conditions were developed in Novosibirsk for the transformation of a natural focus of opisthorchiasis into an anthropogenic one. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effects of vitamin E addition to the water column on immune response, antioxidant capacity, and liver tissue structure of crucian carp (Carassius auratus) under acute cold stress. Crucian carp was placed in the aqueous solution of control group (E1), negative control group (E2), and 100 mg/L vitamin E (E3) and cooled from 20 to 5°C by cold acclimation intelligent cooling device. Samples were taken at three temperature points of 20, 10, and 5°C, respectively, and the samples were detected and analyzed. The results showed that the content of each index increased under acute cold stress. The contents of white blood cell, red blood cell, hemoglobin, platelet, lysozyme, and glutathione peroxidase in E3 treatment group were significantly lower than those in E1 and E2 treatment groups (P < 0.05). The contents of cholinesterase, alkaline phosphatase, acid phosphatase, hydrogen peroxide, superoxide anion, superoxide dismutase, peroxidase, and malondialdehyde in E3 treatment group were significantly lower than those in E1 and E2 treatment groups (P < 0.01). Under acute cold stress, the liver tissue structure of crucian carp also changed, such as hepatocyte vacuolization, and the damage degree of E3 treatment group was lower than that of E1 and E2 treatment groups. In summary, the addition of vitamin E in water to treat crucian carp can reduce the harm caused by acute cold stress to its body and provide a theoretical reference for the application of vitamin E in water to alleviate fish stress. [ABSTRACT FROM AUTHOR]

Background: Amphora coffeaeformis, a unicellular diatom, can significantly accumulate lipids under nitrogen (N) limitation. However, the molecular mechanism underlying lipid accumulation in A. coffeaeformis remains unknown and its application development is lagging. Results: This work analyzed the lipid composition of A. coffeaeformis under N deprivation and investigated its mechanism underlying lipid accumulation using RNA-seq. The results showed that the total lipid content of A. coffeaeformis increased from 28.22 to 44.05% after 5 days of N deprivation, while the neutral lipid triacylglycerol (TAG) content increased from 10.41 to 25.21%. The transcriptional profile showed that N deprivation induced wide-ranging reprogramming of regulation and that most physiological activities were repressed, while the upregulation of glycerol-3-phosphate acyltransferase directly determined TAG accumulation. Moreover, we explored the effect of A. coffeaeformis as a food additive on the lipid composition of crucian carp. The results showed that the contents of unsaturated fatty acids in the meat of fish supplemented with A. coffeaeformis were significantly increased, indicating its potential application in animal nutrition for improving meat quality indicators. Conclusion: The findings shed light on the molecular mechanisms of neutral lipid accumulation and revealed the key genes involved in lipid metabolism in A. coffeaeformis. Moreover, we also confirmed that A. coffeaeformis can be used as feed additive for improving the lipid composition of crucian carp meat, which provided evidence for the biotechnology application of this high-oil microalgae. [ABSTRACT FROM AUTHOR]

TNFα belongs to superfamily of tumor necrosis factor that can exert the pleiotropic effort in a large quantity of biological processes, including immune homeostasis, intracellular modulation and etiopathogenesis, but its regulatory role in mucosal immune regulation of fish is unclear. Currently, this study aimed to evaluate the immunoregulatory function of TNFα1 on gut barrier in teleost fish. In this study, TNFα1 sequences were identified from red crucian carp (RCC, Carassius auratus red var). The high-level expression of RCC-TNFα1 mRNA was detected in gill among all the isolated samples. Then, RCC-TNFα1 expression increased dramatically in immunerelated tissues after A. hydrophila infection and in cultured fish cells after lipopolysaccharide (LPS) treatment. RCC-TNFα1 fusion protein was generated and purified in vitro. RCC receiving RCC-TNFα1 perfusion showed an increased levels of villi fusion and edema in injured midgut with the fuzzy appearance. In addition, The mRNA expressions of tight junction (TJ) genes, mucin genes and redox sensitive genes decreased sharply in TNFα1-treated midgut in comparison with those of the control (P < 0.05), whereas the expression levels of apoptotic genes involved in caspase signals and unfolded protein response (UPR) attained the dramatic increase. These results demonstrated that RCC-TNFα1 stimulation could impair midgut structural integrity and immune function by induction of antioxidant collapse and apoptotic activation. [ABSTRACT FROM AUTHOR]

This research aims to identify the hub genes associated with the senescence of triploid caudal fin cells. Transcriptomic data are obtained from the high and low generation (P6, P60) of triploid crucian carp caudal fin cells by high-throughput sequencing technology. Initially, all differential genes between the high and low generations are screened, yielding 4140 significantly upregulated genes and 3724 significantly downregulated genes. Subsequently, an aging gene set containing 950 genes is downloaded from the CellAge database to extract the differentially expressed genes associated with caudal fin cell aging, totaling 29 genes. GO and KEGG enrichment analyses are performed on these 29 aging differential genes. The GO analysis shows enrichment mainly in cellular processes related to aging, such as regulation of cell division, chromatin organization, cell cycle regulation. KEGG analysis reveals that the 29 aging-related genes are primarily involved in cell cycle and cellular senescence pathways. A PPI network of aging-related genes is constructed using the STRING database and Cytoscape software. Top-ranked genes were identified by using Degree, MCC, MNC, and Closeness algorithms in the Cytohubba plugin in Cytoscape, resulting in hub genes EZH2, JUN, MYD88, RBL2, BMP4, CCND1, NFKB2, MMP9. Lastly, qRT-PCR validation of these eight hub genes further confirmed the involvement of four genes: EZH2, RBL2, BMP4, and CCND1. The hub gene screened in this study may become a potential biomarker of fish caudal fin cell senescence, which provides a valuable experimental basis for the senescence of fish caudal fin cells, especially the senescence of caudal fin cells in polyploid fish, and the reproduction and breeding improvement of polyploid fish. It also provides meaningful data for elucidating the molecular mechanism of polyploid formation in animals, as well as the formation of aging and tumour in human beings. [ABSTRACT FROM AUTHOR]

In the scope of this study, fish fauna of Küçük Menderes River and its tributaries, updated with the comparison of the recent ichthyofaunal studies, as well as the length-weight relations (LWR) and condition factors (CF) were estimated for 7 freshwater fish species belonging to six families from the river basin: endemic Oxynoemacheilus eliasi, Cobitis fahireae; invasive, Carassius gibelio, Atherina boyeri, transloce Perca fluviatilis and the native Squalius fellowesii, Cyprinus carpio. The fish samples were collected with various fishnets and DC electro-fishing devices from six stations in 2018 and 2019. The LWR of the fishes was studied based on 379 specimens. The estimated values of parameter b ranged from 2.884 (A. boyeri) to 3.176 (C. fahireae). The coefficient of determination (R2) was changed between 0.792 to 0.980 for all sampling localities. In the study, Fulton's condition factor ranged between 0.391 (S. fellowesii) to 3.080 (S. fellowesii); the relative condition factor ranged between 0.346 (O. eliasi) to 2.746 (S. fellowesii), respectively. This research is anticipated to contribute valuable insights for the conservation of the species, while also furnishing essential data to inform future fisheries management studies in the region. [ABSTRACT FROM AUTHOR]

Research on the ichthyoparasitic fauna of fish from the Cyprinidae family, taken from the ten dam lakes in the lower sector of Jiu, lakes that are part of the “Preajba-Făcăi Lacustrine Complex” site, revealed the following aspects: 9 species of parasites were identified: 2 cilophores (Chilodonella cyprini, Ichthyophthirius multifiliis), 1 oomycete Saprolegnia sp., 1 monogenous Dactylogyrus sp., 1 myxosporidia Myxobolus sp., 1 acanthocephalus Pomphorhynchus laevis, 2 crustaceans (Lernaea cyprinacea, Argulus foliaceus) and 1 annelid Piscicola geometra, in five of the seven host species studied. (6) species of parasites have been identified in crucian carp (Saprolegnia sp., Ichthyophthirius multifiliis, Myxobolus sp., Dactylogyrus sp., Lernaea cyprinacea, Piscicola geometra), in carp (5) (Chilodonella cyprini, Dactylogyrus sp., Pomphorhynchus laevis, Lernaea cyprinacea, Argulus foliaceus), bream (1) (Saprolegnia parasitica), bream (1) (Myxobolus sp.) and spotted murgoi (1) (Saprolegnia parasitica), followed by slugs and tomatoes in which no parasites were identified. Of the 9 species of parasites identified, 7 species are ectoparasitic. Clinical signs of ectoparasitosis have been identified in both ichthyophthyrosis of the crucian carp where hypoxia reactions and the presence of white punctate colonies have been found, as well as in the case of saprolegniosis due to the appearance of fine wool hyphae and scoliosis, argulosis and piscicolosis highlighted in crucian carp and carp by haemorrhagic wounds and obvious ulcerations but also by the presence of parasites. [ABSTRACT FROM AUTHOR]

Predation is a major evolutionary force determining life‐history traits in prey by direct and indirect mechanisms. This study focuses on life‐history trait variation in crucian carp (Carassius carassius), a species well known for developing a deep body as an inducible morphological defence against predation risk. Here, the authors tested variation in growth and reproductive traits in 15 crucian carp populations in lakes along a predation risk gradient represented by increasingly efficient predator communities. Lakes were located in south‐eastern Norway and were sampled in summer 2018 and 2019. The authors expected crucian carp to attain higher growth rate, larger size, and later age at maturity with increasing predation risk. In the absence of predators, they expected high adult mortality, early maturity and increased reproductive effort caused by strong intraspecific competition. They found that the life‐history traits of crucian carp were clearly related to the presence of piscivores: with increasing predation risk, fish grew in body length and depth and attained larger asymptotic length and size at maturity. This growth was evident at young age, especially in productive lakes with pike, and it suggests that fish quickly outgrew the predation window by reaching a size refuge. Contrary to the authors' predictions, populations had similar age at maturity. High‐predation lakes also presented low density of crucian carp. This suggests that fish from predator lakes may experience high levels of resource availability due to reduced intraspecific competition. Predation regulated life‐history traits in crucian carp populations, where larger size, higher longevity and size at maturity were observed in lakes with large gaped predators. [ABSTRACT FROM AUTHOR]

Biological materials have properties like great strength and flexibility that are not present in synthetic materials. Using the ribs of crucian carp as a reference, we investigated the mechanisms behind the high mechanical properties of this rib bone, and found highly oriented layers of calcium phosphate (CaP) and collagen fibers. To fabricate a fish-rib-bone-mimicking membrane with similar structure and mechanical properties, this study involves (1) the rapid synthesis of plate-like CaP crystals, (2) the layering of CaP–gelatin hydrogels by gradual drying, and (3) controlling the shape of composite membranes using porous gypsum molds. Finally, as a result of optimizing the compositional ratio of CaP filler and gelatin hydrogel, a CaP filler content of 40% provided the optimal mechanical properties of toughness and stiffness similar to fish bone. Due to the rigidity, flexibility, and ease of shape control of the composite membrane materials, this membrane could be applied as a guided bone regeneration (GBR) membrane. [ABSTRACT FROM AUTHOR]

The object of research is the technology of fish products for HELTHY-CAFE with regulated histamine content for the development of health food diets for the population. One of the most problematic places in the technology of food products from raw materials of aquatic origin is microbiological spoilage and, as a result, the formation and accumulation of HisA, which in a certain amount causes a toxic effect. In the course of the study, the methods of isomolar series, sensory analysis, and the study of quality indicators were used. The methodology chosen in the work allows to determine the optimal ratio of hydrocolloids in the system for maximum complexation with histamine in the technology of fish culinary products in gelatin fillings with a harmonious sensory profile and adjustable histamine content. The obtained results of the conducted research allow to state that the proposed method of determining the optimal ratio of sodium alginate and low-esterified pectin substances contributes to the development of a gelatinous filling for fish culinary products in order to ensure the harmonious flavor of ready-made fish dishes and contributes to the expansion of the range of fish products for HELTHY-CAFE with functional and preventive properties. This is due to the fact that taking into account the modern trends in nutrition regarding the safety, functionality, palatability, and attractiveness of fish food products made it possible, based on the method of isomolar series and sensory analysis, to scientifically substantiate the optimal ratio of plant biopolymers, to form requirements for the texture of gelatin filling in fish technology culinary products. On the basis of previous experimental studies, it was shown that the accumulation of histamine occurs more actively in sea fish, which made it possible to substantiate the choice of raw materials for the production of fish culinary products. Taking into account the main global trends in the development of aquaculture, it is proposed to use crucian carp as a raw material, as the main object of aquaculture in Ukraine. The low activity of the peptide hydrolase complex of the muscle tissue of the carp, compared to sea fish, contributes to the formation of a harmonious aromatic profile of fish culinary products, which corresponds to consumer expectations, and the use of natural hydrocolloids of vegetable origin to form a gelatinous structure provides functional properties to the food product and allows controlling the histamine content. [ABSTRACT FROM AUTHOR]

Efficient detection and degradation of fungicides are greatly concerned with aquatic food safety. Herein, a multifunction CoFe2O4/MoS2@Au (ACMS) composite was synthesized for crystal violet (CV) and malachite green (MG) photocatalytic degradation and SERS determination. As the construction of the Z-scheme heterostructure of ACMS, which enhanced the light absorption capability and the separation efficiency of photoexcited carrier significantly, ACMS possessed an excellent photocatalytic performance with a degradation rate of 94.76% for CV under simulated solar light irradiation. Furthermore, the multifunction ACMS exhibited superior SERS capability with a detection limit (LOD) of 4.309 × 10−2 μg L−1 for MG residues in water. And the ACMS substrates could be utilized to determine the MG residues in crucian carp extract, resulting in a recovery rate of 96.00~116.00%. In addition, such multifunction heterojunctions were performed for in situ monitoring of the photodegradation process. This research opened up a novel perspective on the applications of heterojunction-based multifunction materials for food safety control. [ABSTRACT FROM AUTHOR]

In order to study the effect of adding Bacillus licheniformis to the diet on the liver and intestinal tissue structure, antioxidant capacity and immune function of crucian carp, a total of 360 healthy crucian carp selected for the experiment, which were divided into blank control group (CK group), Bacillus licheniformis test group (DY group), Aeromonas hydrophila attack group (CKG group) and Bacillus licheniformis treatment group (DYG group), CK group and CKG group were fed with basic diet, the DY and DYG groups added Bacillus licheniformis to the basic feed. Each group had three replicates, each with 30 crucian carp. After the 6-week feeding test, the CKG group and DYG group crucian carp were challenged by intraperitoneal injection of Aeromonas hydrophila to determine the cumulative death rate within 14 days. The results showed as follows: compared with CK group, DY group significantly increased the activity of acid phosphatase (ACP) and the contents of complement 3 (C3), complement 4 (C4) and immunoglobulin M (IgM) in serum of carp (P<0.05) and the activity of alkaline phosphatase (AKP) had an increasing trend but not significant. DY group significantly increased the activities of superoxide dismutase (SOD) and catalase (CAT) in serum and decreased the content of malondialdehyde (MDA) (P<0.05), after challenge, DYG group significantly inhibited oxidative damage and improved immune ability. Compared with the CK group, the length, width and muscular thickness of intestinal villus in DY group were significantly increased(P<0.05). After challenge, intestinal damage occurred in CKG group, intestinal villi were broken, intestinal epithelial cells were arranged disordered, striatum was arranged irregularly, and intestinal epithelial cells were vacuolated. Compared with CKG group, DYG group had less damage, striatum and epithelial cells were arranged neatly, and cell boundaries were obvious. The histological results of liver showed that there was no significant difference between the CK group and DY group. After the challenge, the liver nuclei were displaced and disordered, hepatocytes were damaged, nucleolysis occurred, vacuolation occurred, and hepatic sinus congestion occurred. Compared with CKG group, the liver cells in DYG group were better, the damage was reduced, the arrangement was gradually clear, and the vacuolation was relieved. The cumulative mortality of crucian carp in DYG group was significantly lower than CKG group(P<0.05). The addition of Bacillus licheniformis to the diet can not only effectively improve the antioxidant capacity of crucian carp serum, improve its immune function, but also increase the intestinal villus height and muscle layer thickness of crucian carp, and improve the damage of liver tissue structure. [ABSTRACT FROM AUTHOR]

The aim of the experiment was to study the amount of oil-producing Rhodotorula strain PR61 as fish feed additive and the effect of wall breaking treatment on feeding effect. A total of 375 red crucian carp seedlings with an average body weight of 4~5 g were randomly divided into five groups with three replicates per group and 25 fish per replicate. Fish in blank control group were fed with 100% basic feed, fish in positive control group were fed with 100% basic feed + 0.25% betaine hydrochloride, fish in T1 group were fed with 99.5% basic feed + 0.5% unbroken red yeast, fish in T2 group were fed with 99.5% basic feed + 0.5% broken red yeast, and fish in T3 group were fed with 99% basic feed + 1.0% broken red yeast. The experiment lasted for 28 d. The results showed that the PR61 strain was rich in nutrition, with protein content up to 45.2%, oil content up to 38.93%, the PR61 strain also contained carotenoid, aspartate, serine and totally 17 kinds of amino acids, and the total amino acid was 44.32%. The survival rate of red crucian carp in T2 group and T3 group was 100%, which was significantly higher than that of blank control group and positive control group (P<0.05). The body weight growth rate of red crucian carp in T3 group was significantly higher than that in other groups (P<0.05), the body length growth rate was significantly higher than that in blank control, positive control group and T1 group (P<0.05), and the feed coefficient was significantly lower than that in other groups (P<0.05). The a* value and L* value of the back skin of red crucian carp in T3 group were significantly higher than those in other experimental groups (P<0.05). The activity of SOD and GSH-Px in serum of red crucian carp in T2 group and T3 group were significantly higher than those in other groups (P<0.05), and the content of MDA was significantly lower than that in other groups (P<0.05). The CAT activity of red crucian carp in T3 group was significantly higher than that in blank control, positive control group and T1 group (P<0.05). The study indicates that adding PR61 in feed can significantly improve the survival rate, weight growth rate and antioxidant enzyme activity of fish fry, decrease the feed coefficient. The growth index of the fish fry reaches the best level and the color of fish body is more vivid when the supplemental amount of red yeast is 1.0%. [ABSTRACT FROM AUTHOR]

Gut microbiome plays an important role in host's development and reproduction. Lotus-fish co-culture (LFC) is a popular integrated agriculture-aquaculture farming system in China. However, there is still a relative dearth of information on how changes of aquaculture modes will affect the fish gut microbiome. In the present study, metagenomic sequencing was used to compare gut bacteria of the hybrid fish Hefang crucian carp (Carassius cuuieri ♀ × C. auratus var. red ♂) cultured in LFC and intensive pond culture (IPC) systems. The results indicated that aquaculture modes exerted great influences on the fish gut bacterial community. A significantly higher gut bacterial diversity was found in LFC than that in IPC (P < 0.05). The relative abundances of Actinobacteria and Chloroflexi were apparently higher in LFC than those in IPC, whereas Planctomycetota, Firmicutes, and Verrucomicrobia showed opposite patterns. Besides, gut bacterial metabolic potentials involved in energy metabolism, carbohydrate metabolism, amino acid metabolism, environmental information processing, and cellular processes were significantly increased in LFC compared to those in IPC. On the contrary, the bacterial functional potentials related to nucleotide metabolism, DNA mismatch repair, as well as homologous recombination were significantly stimulated in the IPC system. Source-tracking analysis suggested that fish gut bacterial community in IPC was originated mainly from water sources, whereas the gut bacterial community in LFC was originated from more unknown sources and soil sources. Our results provided new insight into the influence of aquaculture modes on the microbial community diversity and functionality in aquatic animals and highlighted the importance of environment microbiome in reshaping the gut microbes. [ABSTRACT FROM AUTHOR]

A 60-day feeding trial was conducted to investigate the influence of glutathione (GSH) on growth performance, lipid metabolism and muscle quality of hybrid crucian carp (initial body weight: 15.03 ± 0.11 g) fed a high-fat diet (HFD). Five experimental diets were prepared in this study: the control diet (6.17% fat), HFD (12.37% fat), and HFD with 200 mg/kg, 400 mg/kg and 600 mg/kg GSH supplementation, respectively. The results indicated that feeding HFD to hybrid crucian carp remarkably reduced weight gain rate (WGR), specific growth rate (SGR), total antioxidant capacity (T-AOC) and total superoxide dismutase (T-SOD) activities of serum and liver, glutathione peroxidase (GSH-Px) and glutathione reductase (GR) activities of liver, but significantly increased malondialdehyde (MDA) content of liver compared to the control group. After adding 200-600 mg/kg GSH to HFD, the WGR, SGR, as well as serum and liver T-AOC activity of hybrid crucian carp increased significantly. Moreover, the supplementation of 400 mg/kg GSH significantly increased the activities of T-SOD, catalase (CAT) of serum and liver, as well as the GSH-Px, glutathione-S-transferase (GST) and GR of liver, but decreased MDA content of serum and liver compared to the HFD. The HFD significantly increased muscle crude lipid, polyunsaturated fatty acids (PUFA) contents and fiber diameter, but decreased chewiness, gumminess, hardness and fiber density compared to the control group. The addition of 400-600 mg/kg GSH significantly increased muscle chewiness, gumminess, hardness, and decreased muscle fiber diameter of HFD-fed hybrid crucian carp. Meanwhile, the addition of 200-600 mg/kg GSH significantly reduced the mono-unsaturated fatty acids (MUFA) content and increased the PUFA content of muscle compared to the HFD. The HFD significantly up-regulated the expression of lipid synthesis genes (dgat2 and srebp1) and down-regulated the expression of lipolysis genes (lpl, hsl and acox1) of liver compared to the control group. The addition of 400-600 mg/kg GSH significantly decreased the expression of lipid synthesis genes (dgat2 and srebp1) and increased the expression of lipolysis genes (hsl, lpl, acox1 and ppara) of HFD-fed hybrid crucian carp. This study demonstrated that GSH effectively ameliorated the decline of growth performance and muscle quality of hybrid crucian carp caused by HFD, and reduced the risk of liver lipid deposition of hybrid crucian carp by regulating the expression of genes related to liver lipid metabolism. [ABSTRACT FROM AUTHOR]

MnSOD is a ubiquitous metalloenzyme that constitutes the first line of antioxidant defense against oxidative stress. In this study, full length sequence of MnSOD was identified from hybrid crucian carp (WR, Carassius cuvieri ♀ × Carassius auratus red var ♂). Tissue-specific analysis revealed that the highest expression of WR-MnSOD was detected in kidney. Aeromonas hydrophila challenge could dramatically enhance WR-MnSOD mRNA expression in tissues. In vivo administration of purified WR-MnSOD peptide could maintain gut mucosal barrier function, rescue redox balance as well as decrease apoptotic cell death in midgut upon bacterial infection, suggesting that WR-MnSOD is playing a crucial role in gut mucosal barrier function and could be used as feed additive to improve gut immunity in fish. [ABSTRACT FROM AUTHOR]

Heavy metal toxicity is a significant threat to human health and the environment. Contamination of the food chain with heavy metals in water sources may impact the health of consumers adversely. This study aimed to determine the concentrations of Pb, Cd, Cr, Cu, and Zn in the invasive fish species Carassius gibelio inhabiting two important lakes in Türkiye: Lake Beyşehir and Lake Eğirdir, from the Lake District Region and assess any health risks posed by the consumption of these species. For this purpose, C. gibelio species were obtained from two lakes in dry and rainy seasons and heavy metal concentrations were determined via ICP-OES analyses. The Cd concentrations in the muscle samples obtained from both lakes were below the analysis limits. The mean heavy metal concentrations (mg/kg) in the Beyşehir and Eğirdir lake samples were found as Pb: 0.32, Cr: 0.09, Cu: 0.52, and Zn: 6.88 and Pb: 0.88, Cr: 0.08, Cu: 0.46, and Zn: 12.6, respectively. The average heavy metal concentrations in the muscle tissues were below the national/international legislation limits, and the estimated daily intake (EDI), target hazard quotients (THQs), total THQs (TTHQs), and carcinogenic rates (CRs) did not exceed these limits. The results suggested that the consumption of these invasive fish species from these two lakes might not pose any potential health risk for consumers. Transference values (TF) for the digestive tract were also calculated, and biomagnification was determined for Pb, Cd, and Cr. Risk assessment studies are very important in terms of evaluating the effects of fish consumption on human health via applying different indices. This is the first study in which heavy metal concentrations were determined simultaneously in Lake Beyşehir and Lake Eğirdir, and the public health risk of consuming their invasive fish species was estimated. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effects of adding Brevibacillus laterosporus (B. laterosporus) PBC01 to aquarium water on water quality, including Aeromonas spp. counts, growth performance, digestive enzyme activities, and antioxidant activity of the crucian carp Carassius auratus. One hundred and twenty healthy crucian carp (13.56 ± 0.2 g) were reared for 56 days in four different treatments with three replications, as the control group (clean water) and three test groups with PBC01 at levels 5 × 103 CFU/ml, 5 × 104 CFU/ml, and 5 × 105 CFU/ml added to the rearing water. As a result, B. laterosporus in rearing water can lower the concentrations of nitrogen and the number of Aeromonas spp. to varying degrees. As the B. laterosporus concentration increased, the effect became more significant. Crucian carp reared in water supplemented with B. laterosporus showed marked growth performance in comparison with the control group. In addition, rearing water supplemented with B. laterosporus improved antioxidant status in the serum and liver of crucian carp, and increased the intestinal digestive enzyme activity. In conclusion, certain amounts of B. laterosporus PBC01 used as a probiotic supplement in the aquarium water can promote crucian carp growth and improve the health status of these fish. [ABSTRACT FROM AUTHOR]

Aeromonas hydrophila can pose a great threat to the survival of farmed fish. In current study, we investigated the pathological characteristics and immune response in gut–liver axis of white crucian carp (WCC) upon gut infection. WCC anally intubated with A. hydrophila exerted a tissue deformation in damaged midgut with elevated levels of goblet cells along with a significant decrease in tight junction proteins and villi length‐to‐width ratios. In addition, immune‐related gene expressions and antioxidant properties increased dramatically in gut–liver axis of WCC following gut infection with A. hydrophila. These results highlighted the immune modulation and redox alteration in gut–liver axis of WCC in response to gut infection. [ABSTRACT FROM AUTHOR]

The levels of heavy metals and possible health risks in water and crucian carp (Carassius auratus gibelio) were assessed from two coal mining subsidence pools and a reference pool in the Huaibei coal mining region. The concentrations of Cd, Cr, Cu, Mn, Ni, and Pb in subsidence pools were the highest, 8.71, 110.06, 13.85, 48.36, 22.19, and 38.76 ug L-1, respectively. Compared with water quality standards, some metals in subsidence pools were higher than the standard limits. Correlation analysis indicated that all metals were related to coal mining activities except for Mn. The average concentrations of metals in crucian carp from the study area followed the order: Mn>Ni>Cu>Cr>Pb>Cd. Heavy metals in fish showed the order of viscera>gill>muscle (except for Cu in crucian carp in the reference pool). The levels of Cd and Pb in the muscle of crucian carp in subsidence pools exceeded the standard limits. The mean bioaccumulation factor of the metals showed that Cu, Mn, and Ni in the water could accumulate in the fish. The target hazard quotient results indicated that consumption of crucian carp from subsidence pools by children and adults may result in significant non-carcinogenic health risks. These results showed that water pollution due to coal mining activities may lead to fish contamination and ultimately endanger human health. [ABSTRACT FROM AUTHOR]