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In order to comprehensively characterize the nutrient composition of Cyprinus carpio, Hypoph⁃ thalmichthys molitrix, Carassius auratus and Aristichthys nobilis in Yuqiao reservoir, the muscle of the four species was analyzed and evaluated in terms of moisture, ash, crude fat, crude protein, mineral ele‐ ment content, amino acid and fatty acid composition. The results showed that Hypophthalmichthys moli⁃ trix had the highest content of crude protein (16.13%), while Carassius auratus had the lowest content (15.00%). Aristichthys nobilis had the highest content of crude fat (3.10%), while Carassius auratus had the lowest content (0.70%). The four species were rich in mineral elements, including K, Na, Ca, Mg, P, Fe, Zn, and Se, which all were high-potassium and low-sodium dietary sources. There were more than 37.54% essential amino acids in the muscle of these four species. The ratio of Umami amino acids in to‐ tal amino acids ranged from 40.51% to 41.04%, with the maximal glutamic acid in the muscles of four species. There were 11, 10, 16 and 15 kinds of fatty acids in Cyprinus carpio, Hypophthalmichthys moli⁃ trix, Carassius auratus and Aristichthys nobilis respectively. There has low difference between the relative contents of saturated fatty acid, monounsaturated fatty acid, and polyunsaturated fatty acids in the four species. Also, these species have high protein content, including 16 kinds of amino acids, min‐ eral elements and fatty acids, with high nutritional value and edible flavor. [ABSTRACT FROM AUTHOR]

The experiment aimed to comprehensively understand the nutritional characteristics of fish in the ponds of the Dahuangpu Wetland buffer zone. The conventional nutritional components, mineral content, as well as the amino acid and fatty acid composition in the muscles of the Hypophthalmichthys molitrix, Aristichthys nobilis, and Plagiognathops microlepis from the ponds in the Dahuangpu Wetland buffer zone were analyzed. The results showed that the muscle protein content of Hypophthalmichthys molitrix, Aristichthys nobilis, and Plagiognathops microlepis were 15.00%, 15.60%, and 13.80%, respectively, with crude fat content at 0.60%, 0.50%, and 1.10%. They were rich in macro elements such as potassium, sodium, calcium, magnesium, and phosphorus required by the human body, as well as trace elements like iron, zinc, and selenium. All three species had 16 kinds of amino acids detected in their muscles, with high glutamic acid content. The essential amino acids accounted for 38.69%, 38.76%, and 39.98% of the total amino acids, with essential amino acid indices of 101.90, 83.88, and 87.18 respectively. Hypophthalmichthys molitrix, Aristichthys nobilis, and Plagiognathops microlepis muscles were found to contain 10, 10, and 14 kinds of fatty acids respectively, with the order of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids from high to low being Plagiognathops microlepis, Hypophthalmichthys molitrix, and Aristichthys nobilis. The study indicates that Hypophthalmichthys molitrix, Aristichthys nobilis, and Plagiognathops microlepis from the Dahuangpu buffer zone ponds are good sources of protein with a reasonable composition of amino acids, rich in minerals and beneficial fatty acids, and have high nutritional value and edibility. [ABSTRACT FROM AUTHOR]

Daphnia can avoid predation by sensing fish kairomones and producing inducible defenses by altering the phenotype. In this study, the results showed that the morphological and life‐history strategies of two Daphnia species (Daphnia pulex and Daphnia sinensis) exposed to Aristichthys nobilis kairomones. In the presence of fish kairomones, the two Daphnia species exhibited significantly smaller body length at maturity, smaller body length of offspring at the 10th instar, and longer relative tail spine of offspring. Nevertheless, other morphological and life‐history traits of the two Daphnia species differed. D. pulex showed a significantly longer relative tail spine length and earlier age at maturity after exposure to fish kairomones. The total offspring number of D. sinensis exposed to fish kairomones was significantly higher than that of the control group, whereas that of D. pulex was significantly lower. These results suggest that the two Daphnia species have different inducible defense strategies (e.g., morphological and life‐history traits) during prolonged exposure to A. nobilis kairomones, and their offspring also develop morphological defenses to avoid predation. It will provide reference for further exploring the adaptive evolution of Daphnia morphology and life‐history traits in the presence of planktivorous fish. [ABSTRACT FROM AUTHOR]

In order to explore the differences of biochemical and physical properties of Aristichthys nobilis muscle in different operation and management modes and different reservoirs, the biochemical characteristics such as fat, protein, amino acid, fatty acid and physical properties such as texture of two-year-old bighead carp muscle in Qingcaosha Reservoir, Chenhang Reservoir and Jinze Reservoir were analyzed by conventional biochemical analysis and histological characteristics analysis. The results showed that the crude protein content of bighead carp muscle was between 18. 11% and 19. 38%, and the crude ash content was between 1. 27% and 1. 34%, without significant difference among the three reservoirs. The pH value （6. 45%） and moisture content （80. 69%） of bighead carp muscle in Qingcaosha Reservoir were significantly higher than those in Chenhang Reservoir （6. 27%, 78. 43%） and Jinze Reservoir （6. 24%, 79. 28%）. The crude fat content of bighead carp in Jinze Reservoir （1. 31%） was significantly higher than that in Qingcaosha Reservoir （0. 93%） and Chenhang Reservoir （0. 91%）. There were 17 kinds of amino acids and fatty acids detected in the muscle of bighead carp in the three reservoirs. The contents of total SFA （14. 15%） and MUFA （40. 87%） in the muscle of bighead carp in Jinze Reservoir were significantly higher than those in Qingcaosha Reservoir （12. 93%, 30. 29%） and Chenhang Reservoir （11. 18%, 29. 64%）. The contents of total PUFA in Qingcaosha Reservoir（56. 79%） and Chenhang Reservoir （59. 24%） were significantly higher than those in Jinze Reservoir （44. 88%）. The texture indexes such as hardness, elasticity and cohesiveness were significantly different, except for adhesion. The number and length of muscle cells of bighead carp in Jinze Reservoir were significantly lower than those in Qingcaosha Reservoir and Chenhang Reservoir. The results showed that different reservoir environments had no significant difference in crude protein and crude ash content of bighead carp muscle, but had significant difference in fat content and histological characteristics of muscle fiber. The muscle of bighead carp in the three reservoirs was a high-quality protein source, and the nutritional value of bighead carp muscle in Chenhang Reservoir was higher. [ABSTRACT FROM AUTHOR]

Abstract Daphnia can avoid predation by sensing fish kairomones and producing inducible defenses by altering the phenotype. In this study, the results showed that the morphological and life‐history strategies of two Daphnia species (Daphnia pulex and Daphnia sinensis) exposed to Aristichthys nobilis kairomones. In the presence of fish kairomones, the two Daphnia species exhibited significantly smaller body length at maturity, smaller body length of offspring at the 10th instar, and longer relative tail spine of offspring. Nevertheless, other morphological and life‐history traits of the two Daphnia species differed. D. pulex showed a significantly longer relative tail spine length and earlier age at maturity after exposure to fish kairomones. The total offspring number of D. sinensis exposed to fish kairomones was significantly higher than that of the control group, whereas that of D. pulex was significantly lower. These results suggest that the two Daphnia species have different inducible defense strategies (e.g., morphological and life‐history traits) during prolonged exposure to A. nobilis kairomones, and their offspring also develop morphological defenses to avoid predation. It will provide reference for further exploring the adaptive evolution of Daphnia morphology and life‐history traits in the presence of planktivorous fish.

In this study, the bighead carp (Aristichthys nobilis) was the object of research to compare and analyze the contents of conventional nutrients, amino acids, fatty acids, inosinic acid, and earthy-smelling compounds (geosmin and 2-methylisoborneol) in muscles of its dorsal, belly, tail, opercula, eye socket, and mandible in order to evaluate their quality. The findings could inform recommendations for the consumption and processing of different muscle parts of the bighead carp. The results showed that the water content in the abdominal muscle was significantly lower than that in other parts, and the crude fat content was significantly higher than that in other parts (p < 0.05, the same below). Seventeen kinds of amino acids were detected in the muscles of the six parts of the fish, and the dorsal muscles had the highest umami amino acids, essential amino acids and total amino acids, which were 6.45 g/100 g, 6.82 g/100 g and 17.26 g/100 g, respectively. The total amount of essential amino acids in the muscle was higher than that in the FAO/WHO standard model. According to the AAS standard, the first limiting amino acid in the muscle of the six parts was valine (Val). There were 26 kinds of fatty acids in the abdomen, under the gill cover and in the eye socket muscles, and the content of polyunsaturated fatty acids in the mandibular muscles was the highest (45.41%). The content of inosine in the dorsal muscle was significantly higher than that in other parts. Geosmin was the main substance in the muscle. There was no correlation between the distribution of earthy-smelling compounds and fat content, but the content of earthy-smelling compounds in the muscle of the belly and eye socket was the highest. Therefore, the muscle quality of different parts of the bighead carp has its own characteristics, and targeted development and utilization can make more efficient use of bighead carp resources. [ABSTRACT FROM AUTHOR]

Polyculture is an effective way to achieve efficient utilization of nutrient resources in high-density intensive aquaculture systems. In order to study the optimal culture mode of Oreochromis niloticu, Aristichthys nobilis, and Cherax quadricarinatus, the budget of nitrogen and phosphorus in various polyculture systems (CH, CHC1, CHC2, CHC3) was studied with land-based enclosures. The results showed that all the three polyculture systems had higher total yields of cultured animals than the control group (two polyculture systems) (p < 0.05). The co-cultured organisms absorbed artificial feed or organic matter (such as plankton and sediment) from the polyculture system to different degrees. Feed was the main input of nitrogen (98.22–98.33%) and phosphorus (99.43–99.56%) in all systems. Considering the N and P outputs, 46.64–64.58% and 81.60–84.79%, respectively, accumulated in the sediment, and 34.43–52.55% and 14.89–17.30% of the N and P outputs, respectively, were harvested by aquaculture organisms. The pollution production coefficients of TN and TP in the O. niloticus polyculture ponds were 5.35–6.26 g/m2 and 1.17–1.61 g/m2, respectively. The TN production coefficients of O. niloticus and the ternary polyculture groups (CHC1, CHC2, and CHC3) were lower than that of the control group (CH). The TP production coefficients showed the opposite pattern. The N and P utilization efficiencies in the group with the optimal ratio of O. niloticus, A. nobilis, and C. quadricarinatus (4, 0.15, and 3 ind/m2, respectively) were 2.56–12.82% and 6.62–11.03% higher, respectively, compared with those of the other groups. The N utilization efficiency was effectively improved in this group with the optimum stocking density for the polyculture systems, resulting in improved ecological efficiency and economic benefits. [ABSTRACT FROM AUTHOR]

In this study, the bighead carp (Aristichthys nobilis) was the object of research to compare and analyze the contents of conventional nutrients, amino acids, fatty acids, inosinic acid, and earthy-smelling compounds (geosmin and 2-methylisoborneol) in muscles of its dorsal, belly, tail, opercula, eye socket, and mandible in order to evaluate their quality. The findings could inform recommendations for the consumption and processing of different muscle parts of the bighead carp. The results showed that the water content in the abdominal muscle was significantly lower than that in other parts, and the crude fat content was significantly higher than that in other parts (p < 0.05, the same below). Seventeen kinds of amino acids were detected in the muscles of the six parts of the fish, and the dorsal muscles had the highest umami amino acids, essential amino acids and total amino acids, which were 6.45 g/100 g, 6.82 g/100 g and 17.26 g/100 g, respectively. The total amount of essential amino acids in the muscle was higher than that in the FAO/WHO standard model. According to the AAS standard, the first limiting amino acid in the muscle of the six parts was valine (Val). There were 26 kinds of fatty acids in the abdomen, under the gill cover and in the eye socket muscles, and the content of polyunsaturated fatty acids in the mandibular muscles was the highest (45.41%). The content of inosine in the dorsal muscle was significantly higher than that in other parts. Geosmin was the main substance in the muscle. There was no correlation between the distribution of earthy-smelling compounds and fat content, but the content of earthy-smelling compounds in the muscle of the belly and eye socket was the highest. Therefore, the muscle quality of different parts of the bighead carp has its own characteristics, and targeted development and utilization can make more efficient use of bighead carp resources.

The paper performs a comparative analysis of some biometric (total length, standard length, head length and caudal footstalks length) in two cultured cyprinids species grown in a controlled system, namely: Aristichthys nobilis (bighead carp) and Hypophthalmichthys molitrix (silver carp), of various ages (starting with the first up to the fourth growth summer). The results obtained evidenced that, along the four growing stages, the representatives of Hypophthalmichthys molitrix show slightly higher values than those of Aristichthys genus for the total and standard bodily length, while for the head length the situation is reversed.

Polyculture is an effective way to achieve efficient utilization of nutrient resources in high-density intensive aquaculture systems. In order to study the optimal culture mode of Oreochromis niloticu, Aristichthys nobilis, and Cherax quadricarinatus, the budget of nitrogen and phosphorus in various polyculture systems (CH, CHC1, CHC2, CHC3) was studied with land-based enclosures. The results showed that all the three polyculture systems had higher total yields of cultured animals than the control group (two polyculture systems) (p < 0.05). The co-cultured organisms absorbed artificial feed or organic matter (such as plankton and sediment) from the polyculture system to different degrees. Feed was the main input of nitrogen (98.22–98.33%) and phosphorus (99.43–99.56%) in all systems. Considering the N and P outputs, 46.64–64.58% and 81.60–84.79%, respectively, accumulated in the sediment, and 34.43–52.55% and 14.89–17.30% of the N and P outputs, respectively, were harvested by aquaculture organisms. The pollution production coefficients of TN and TP in the O. niloticus polyculture ponds were 5.35–6.26 g/m2 and 1.17–1.61 g/m2, respectively. The TN production coefficients of O. niloticus and the ternary polyculture groups (CHC1, CHC2, and CHC3) were lower than that of the control group (CH). The TP production coefficients showed the opposite pattern. The N and P utilization efficiencies in the group with the optimal ratio of O. niloticus, A. nobilis, and C. quadricarinatus (4, 0.15, and 3 ind/m2, respectively) were 2.56–12.82% and 6.62–11.03% higher, respectively, compared with those of the other groups. The N utilization efficiency was effectively improved in this group with the optimum stocking density for the polyculture systems, resulting in improved ecological efficiency and economic benefits.

• PS-NPs and MC-LR coexposure induced congenital immune deficiency of bighead carp. • The coexposure increased susceptibility of bighead carp to acquired diseases. • The metabolic and biosynthetic processes of pigments were impaired by MC-LR exposure. • Exposure to NPs alone impaired C5 branched diacid metabolism. Nanoplastics (NPs) and microcystin-LR (MC-LR) are two common and harmful pollutants in water environments, especially at aquafarm where are full of plastic products and algae. It is of great significance to study the toxic effects and mechanisms of the NPs and/or MC-LR on fish at the early stage. In this study, the embryo and larvae of a filtering-feeding fish, Aristichthys nobilis , were used as the research objects. The results showed that the survival and hatching rates of the embryo were not significantly affected by the environmental concentration exposure of these two pollutants. Scanning electron microscopy (SEM) observation displayed that NPs adhered to the surface of the embryo membrane. Transcriptomic and bioinformatic analyses revealed that the NPs exposure activated neuromuscular junction development and skeletal muscle fiber in larvae, and affected C5-Branched dibasic acid metabolism. The metabolic and biosynthetic processes of zeaxanthin, xanthophyll, tetraterpenoid, and carotenoid were suppressed after the MC-LR exposure, which was harmful to the retinol metabolism of fish. Excessive production of superoxide dismutase (SOD) was detected under the MC-LR exposure. The MC-LR and NPs coexposure triggered primary immunodeficiency and adaptive immune response, leading to the possibility of reduced fitness of A.nobilis during the development. Collectively, our results indicate that environmental concentration NPs and MC-LR coexposure could cause toxic damage and enhance sick risk in A.nobilis , providing new insights into the risk of NPs and MC-LR on filtering-feeding fish. [ABSTRACT FROM AUTHOR]

【Objective】Understand the current state of plankton resources in the Juyan lake as well as the water nutritional status and the productivity of Hypophthalmichthys molitrix and Aristichthys nobilis.【Methods】The plankton resources in Juyan lake were investigated from November 2020 to September 2021 following the Technical Specification for Freshwater Plankton Investigation (SC/T 9402—2010). The productivity of Hypophthalmichthys molitrix and Aristichthys nobilis in Juyan lake was evaluated based on the plankton biomass.【Results】In the Juyan lake, there are 63 phytoplankton species belonging to six phyla. The majority are 29 species of Bacillariophyta, 21 species of Chlorophyta and 6 species of Cyanophyta. The average density is 163 900 ind/L, and the average biomass is 0.52 mg/L. The community structure is dominated by 16 major species, including Symedra sp., Navicula sp., and Ankistrodesmus falcatus. There are 22 zooplankton species, including 16 Rotifera species and 6 Cladocera species, with an average density of 87.30 ind/L, and average biomass of 0.61 mg/L. The community structure is dominated by 17 prominent species, including Brachionus sp., Asplanchna sp. and Cyclops strennus. The yield of Hypophthalmichthys molitrix and Aristichthys nobilis is estimated to be 33.04-38.12 t based on the plankton biomass in the lake.【Conclusion】 According to the biomass of plankton in Juyan lake, it was oligotrophic. However, the plankton population pattern revealed that Juyan lake was eutrophic. The predicted productivity of Hypophthalmichthys molitrix and Aristichthys nobilis in Juyan lake is substantially higher than the actual quantity, indicating that the plankton in the Juyan lake is underutilized and has significant potential. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) is one of the highest volume chemicals produced in the world and is frequently used in dental sealants, water bottles, food, and beverage packaging. Due to persistent applications, BPA has become a potential threat to a variety of organisms including public health. In this study, a total of 80 bighead carps were randomly placed in different four groups (A–D). Fish in groups B, C, and D were exposed to BPA @500, 1000, and 1500 μg/L, respectively for 60 days. Fish in group A served as an untreated control group. The body weight was significantly decreased while the absolute and relative weight of different visceral organs increased significantly (p < 0.05) in fish exposed to higher concentration (1500 μg/L) of BPA. Results on proximate analysis showed significantly lower values of crude proteins, lipids, and moisture contents while increased contents of ash in muscles of treated fish. The erythrocyte counts, hemoglobin concentration, lymphocytes, and monocytes significantly decreased while total leukocyte and neutrophil counts significantly increased in treated fish. Results exhibited that different serum biochemistry parameters like serum albumin and total proteins decreased significantly (p < 0.05) while alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP), urea, creatinine, glucose, cholesterol, and lactate dehydrogenase (LDH) increased significantly (p < 0.05) in treated fish. Histopathological ailments like pyknosis, degeneration of glomeruli, increased Bowman's space, ceroid formation in kidneys while ceroid formation, hemorrhages, pyknosis, karyorrhexis, karyolysis, nuclear hypertrophy, and eccentric nuclei were observed in the liver of treated fish. Histological observation of different sections of the brain of treated fish exhibited degeneration of neurons in the cerebellum, lipofuscin deposition, microgliosis, necrotic neurons, inflammatory cells, and hemorrhage. Results on light microscopic observation of different sections of the heart of bighead carp revealed necrosis, inflammatory reaction, neutrophilic myocarditis, and hemorrhages. In conclusion, it is suggested that BPA induces adverse effects on physical, blood-biochemical parameters, and histopathological changes in multiple visceral tissues of exposed fish. [ABSTRACT FROM AUTHOR]

HIF-l is the earliest documented and most widely studied hypoxia-inducible factor (HIF) and plays a key role in the cell hypoxia signal transduction pathway. Particularly, the HIF-1α protein is sensitive to oxygen and plays a critical role in hypoxia regulation. This study is the first to report on the molecular cloning and characterization of HIF-1α in bighead carp (Aristichthys nobilis; anHIF-1α). The full-length cDNA of anHIF-1α was 2361 bp, and encodes an estimated 674 amino acids with a predicted molecular mass of 76.10 kDa and a theoretical isoelectric point of 7.72. Moreover, the conserved basic Helix-Loop-Helix domain along with two Per-ARNT-Sim domains (A/B), and C-TAD were identified in this protein. Interestingly, the tertiary structure of the anHIF-1α protein was found to be extremely similar to that of mice. Multiple comparison and phylogenetic tree results demonstrated that anHIF-1α was highly conserved. Under normoxic conditions, anHIF-1α mRNA transcripts could be detected in all tissues examined with the highest expression level in the heart. With gradually decreasing oxygen concentrations, anHIF-1α mRNA level was upregulated significantly in the gill, liver, kidney, spleen, intestine, brain, and muscle tissues (P < 0.05). Similarly, anHIF-1α was expressed in all examined bighead carp tissues, and the results suggested that the upregulation of anHIF-1α at the transcriptional level may be an important stress response adaptation to hypoxia in bighead carp. Finally, based on the tertiary structure comparative analyses between anHIF-1α with mouse HIF-1α, we think the physiological function, and protein structure of HIF-1α could be compared between fish and mammal in the future. [ABSTRACT FROM AUTHOR]

The effect of heating temperature and duration on the texture and protein composition of bighead carp (Aristichthys nobilis) muscle was investigated. Samples were heated at 90°C, 100°C, 110°C, and 120°C for different times. The results showed that cooking loss increased significantly with increasing temperature and heating time, and a fractional conversion model was used to describe the increase. Hardness, chewiness, and gumminess exhibited a similar four-phase change with two peaks at 90°C, 100°C, and 110°C, and the trend was not observed at 120°C. Analysis of sodium dodecyl sulfate polyacrylamide gel electropheresis (SDS-PAGE) revealed that contents of myosin heavy chain decreased entirely to disappear and contents of actin significantly decreased. Increasing the intensity of the heavy molecular weight bands indicated the aggregation of myosin. Content of water-soluble proteins presented an increasing trend, which reflected the protein degradation and the release of low-molecular-weight compounds.

A 60‐day feeding trial was conducted to estimate the effects of dietary iron (Fe) levels on growth, Fe concentration in the liver, spleen, and blood, and transferrin and hepcidin concentrations in the blood of bighead carp (Aristichthys nobilis). The six experimental diets were formulated to contain different Fe levels (0, 43.1, 84.2, 123.3, 162.2 and 203.1 mg/kg of dry diet) using ferrous sulphate (FeSO4) as the source. The weight gain (WG) and the specific growth ratio (SGR) of A. nobilis fed with a dietary Fe level of 123.3 mg/kg were significantly higher than that of the 0 mg/kg Fe group (p <.05). The results indicated that the growth was affected by dietary Fe levels. Regression analysis of WG and SGR at different levels of dietary Fe suggests that the appropriate dietary requirement of Fe for the bighead carp larvae is 120–134.36 mg/kg. The Fe contents in different tissues were as follows: spleen > liver > whole body. When the Fe dietary content increases to 162.2 mg/kg, the blood concentrations of Fe significantly decreased and thereafter increased, hepcidin significantly decreased and thereafter decreased, and transferrin significantly increased and thereafter decreased. The results indicate that the transferrin blood content significantly increased with decreasing hepcidin of up to 264.63 μg/ml content and thereafter decreased. It could be concluded that after transferrin saturation, hepcidin functions to maintain iron balance in the blood of A. nobilis by decreasing transferrin content. [ABSTRACT FROM AUTHOR]

Bighead carps (Aristichthys nobilis) were divided into four groups with different feeding strategies: group A, nature live food only (fertiliser only, 200 g urea + 160 g ethylamine phosphate + 250 g Huangjintai bio-fertiliser); group B, nature live food + 1/2 formulated feed; group C, nature live food + formulated feed; and group D, formulated feed only. The intestinal microbiomes of the different groups were compared through the Illumina MiSeq sequencing of the bacterial 16S rRNA gene. The specific growth rate (SGR), survival and blood biochemical factors of the fish were also investigated. Results showed that feeding treatment influenced the intestinal communities in the fish. In specific, more bacterial phyla dominated in groups A and B (phyla Bacteroidetes, Fusobacteria, Firmicutes and Proteobacteria in group A, phyla Proteobacteria and Fusobacteria in group B) than in groups C and D (phylum Proteobacteria). The diversity was also lower in groups C and D than in groups A and B. Unweighted pair-group method analysis revealed a clear difference in intestinal microbiota among the different feeding treatments. No difference in survival rate was found among the treatment groups, but the SGR was significantly higher (P < 0.01) in groups B, C and D than in group A. Functional analysis showed that the intestinal bacteria correlated with fish glucose metabolism in group A but with lipid metabolic activity in groups B, C and D. In summary, the intestinal microbiomes and their potential functions vary in bighead carp under different feeding treatments. This study provides new insights into the gut microbiomes of filter-feeding and formulated diet-fed fish.

Fish physiology and behavior are affected by exposure to light of varying colors, but little is known about the effects on swimming performance and metabolism. The purpose of this study was to measure the effects of light color on the swimming performance of bighead carp (Aristichthys nobilis), a planktivorous fish species widely used in aquaculture. Stepped velocity testing was conducted in a modified Brett-type swim tunnel respirometer to determine critical swimming speed (Ucrit), oxygen consumption (MO2), and excess post-exercise oxygen consumption (EPOC) for juvenile bighead carp under red, yellow, blue, and green lights at 25 °C. Ucrit was significantly lower for fish swimming under yellow and green lights compared with red and blue light. Cost of transport (COT), a measure of swimming efficiency, also varied with color. The results, obtained under controlled conditions, add to our knowledge on the effects of artificial color light on fish physiology and behavior and inform decisions on the use of artificial color light in aquaculture and fishway design. [ABSTRACT FROM AUTHOR]

Factor-inhibiting HIF-1 (FIH-1) is an asparagine hydroxylase that interacts with hypoxia-inducible factor 1α (HIF-1α) to regulate transcriptional activity of HIF-1. Few studies of fish FIH-1 have been reported to date. In this study, the cDNA of FIH-1 gene was cloned and characterized for bighead carp, Aristichthys nobilis (AnFIH-1). The AnFIH-1 cDNA is 2065 bp in length, encoding a protein of 357 amino acid (aa) residues, which contains a JmjC homology region of the jumonji transcription factors. AnFIH-1 shares high identities with other vertebrate FIH-1 (79.1–96.4%), especially in the JmjC homology region, suggesting its conserved function. During the embryonic stages of A. nobilis, AnFIH-1 had significantly high expression levels in unfertilized egg and blastula. In healthy tissues, its predominant mRNA expression was detected in muscle. The mRNA levels of AnFIH-1 were significantly upregulated in the liver, gill, hypothalamus, and spleen after hypoxic treatment, and then decreased to pretreatment levels after 6-h re-oxygenation. However, in the muscle, continual increasing of mRNA expression was observed after hypoxic shock and re-oxygenation. These results indicate that FIH-1 may play an important role in physiological regulation for adapting to hypoxia stress in A. nobilis. [ABSTRACT FROM AUTHOR]

Abstract Dietary protein plays a major role in determining the rate of fish growth and overall health. Given that the liver is an important organ for metabolism and detoxification, we hypothesized that optimal dietary protein levels may benefit liver function. Herein, we investigated the effects of dietary protein level on serum biochemistry, liver histology and transcriptome profiling of juvenile bighead carp Aristichthys nobilis fed for 8 weeks on a diet supplemented with high protein (HP, 40%), low protein (LP, 24%) or optimal protein (OP, 32%; controls). The results revealed a significant change in liver morphology in LP and HP groups compared with the OP group, coupled with increased serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activity. RNA sequencing (RNA-Seq) analysis of the liver transcriptome yielded 47 million high-quality reads using an Illumina platform, which were de novo assembled into 80,777 unique transcript fragments (unigenes) with an average length of 1021 bp. Subsequent bioinformatics analysis identified 878 and 733 differentially expressed unigenes (DEGs) in liver in response to LP and HP diets, respectively. KEGG enrichment analysis of DEGs identified immune and metabolism-related pathways, including Toll-like receptor signaling, PI3K-Akt signaling, NF-κB signaling, complement and coagulation, peroxisome, nitrogen metabolism, PPAR signaling, and glycolysis and gluconeogenesis pathways. Transcriptome profiling results were validated by quantitative real-time PCR for 16 selected DEGs. The findings expand our understanding of the molecular mechanisms underlying the effects of dietary protein level on liver function in bighead carp. Highlights • The effects of dietary protein level on liver function in bighead carp were explored. • A high protein diet caused hepatic injury, and an optimal protein diet did not. • Many differentially expressed genes were linked to immune responses and metabolism. • KEGG analysis identified inflammatory and Toll-like receptor signaling pathways. [ABSTRACT FROM AUTHOR]

In the present study, we aimed to investigate the effects of the neonicotinoid insecticide thiamethoxam on the hepatic glycogen in bighead carp (Aristichthys nobilis Rich.). Fish were exposed to 6.6 mg/L, 10 mg/L and 20 mg/L of the insecticide under laboratory conditions for 96 hours. The PAS-reaction was applied to liver cryostat sections in order to indicate the amount of glycogen. The results showed that the hepatic glycogen amount increased with increasing the insecticide concentrations. On the other hand, we observed glycogen conglomerates in certain hepatocytes. Hence, our results demonstrated an enhanced process of glyconeogenesis in the fish liver under the influence of thiamethoxam.

Objective Nitrite exposure induces growth inhibition, metabolic disturbance, oxidative stress, organic damage, and infection-mediated mortality of aquatic organism. This study aimed to investigate the mechanism in responses to acute nitrite toxicity in bighead carp ( Aristichthys nobilis , A . nobilis ) by RNA-seq analysis. Methods Bighead carps were exposed to water with high nitrite content (48.63 mg/L) for 72 h, and fish livers and gills were separated for RNA-seq analysis. De novo assembly was performed, and differentially expressed genes (DEGs) between control and nitrite-exposed fishes were identified. Furthermore, enrichment analysis was performed for DEGs to annotate the molecular functions. Results A total of 406,135 transcripts and 352,730 unigenes were tagged after de novo assembly. Accordingly, 4108 and 928 DEGs were respectively identified in gill and liver in responses to nitrite exposure. Most of these DEGs were up-regulated DEGs. Enrichment analysis showed these DEGs were mainly associated with immune responses and nitrogen metabolism. Conclusions We suggested that the nitrite toxicity-induced DEGs were probably related to dysregulation of nitrogen metabolism and immune responses in A . nobilis , particularly in gill. [ABSTRACT FROM AUTHOR]

Nitrite (NO2−) contamination of water can severely impact the health of aquatic life and is a major concern for commercial aquaculture. In order to study the effect of nitrite on Aristichthys nobilis, we investigated the oxygen-carrying capacity, NF-κB/HIF-1α pathway, and the gill tissue structure under nitrite stress. In the current study, bighead carp (initial weight 180.05 ± 0.092 g) were exposed to nitrite (48.634 mg/L) for 96 h and then for 96 h recovery test. After nitrite exposure for 6 h, hypoxia-inducible factor-1α (HIF-1α) and nuclear factor-κB (NF-κB) mRNA expression increased significantly in the gill of bighead carp (P < 0.05). After nitrite exposure for 12 h, hemoglobin (Hb) and methemoglobin reductase (MHBR) content in blood decreased significantly (P < 0.05); TLR4 mRNA expression increased significantly (P < 0.05). After nitrite exposure for 24 h, methemoglobin (MetHb) content increased significantly (P < 0.05). After recovery test, all the indicators except TLR4 mRNA expression level recovered to initial level. In conclusion, nitrite exposure can affect hemoglobin dynamics, as oxidization of nitrite by hemoglobin results in the reduction of Hb to MetHb leading to hypoxia and nitrite exposure can also result into gill tissue damage. In the face of nitrite exposure, NF-κB and HIF-1α mRNA expression level increased immediately to protect the body from oxidative damage and eased hypoxic condition caused by nitrite. It was also observed that nitrite damage is recoverable in Aristichthys nobilis, but it may be need more than 96 h. [ABSTRACT FROM AUTHOR]

Bighead carp (Aristichthys nobilis) is one of the most economically and ecologically important fish species widely stocked in lakes or cultured in ponds throughout China. The natural populations are facing the stringent challenges of germplasm resources reduction because of pollution and culture. Thus, developing sufficient molecular markers for the conservation and molecular-aided selection of bighead carp is urgent. In this study, we used SNaPshot to develop single nucleotide polymorphism (SNP) markers in bighead carp. A total of 38861 putative SNP markers were identified from the RAD sequencing of bighead carp. Among the markers, 28 SNPs were randomly selected and 25 loci exhibited significant polymorphisms in genotyping by SNaPshot. To the best of our knowledge, this is the first report about SNP marker development in bighead carp based on SNaPshot. These SNP markers can provide an effective tool for the resource conservation and genetic improvement of bighead carp. [ABSTRACT FROM AUTHOR]

Nitrite (NO 2 − ) can cause oxidative stress in aquatic animal when it accumulates in the organism, resulting in different toxic effects on fish. In the present study, we investigated the effects of nitrite exposure on the antioxidant enzymes and glutathione system in the liver of Bighead carp ( Aristichthys nobilis ). Fish [Initial average weight: (180.05 ± 0.092) g] were exposed to 48.634 mg/L nitrite for 96 h, and a subsequent 96 h for the recovery test. Fish livers were collected to assay antioxidant enzymes activity, hepatic structure and expression of genes after 0 h, 6 h, 12 h, 24 h, 48 h, 72 h, 96 h of exposure and12 h, 24 h, 48 h, 72 h, 96 h of recovery. The results showed that the activity of glutathione peroxidase (GSH-Px), glutathione S-transferase (GST), and glutathione reductase (GR) increased significantly in the early stages of nitrite exposure. The study also showed that nitrite significantly up-regulated the mRNA levels of glutathione peroxidase ( GSH-Px ), glutathione S-transferase ( GST ), and glutathione reductase ( GR ) after 6, 48, and 72 h of exposure respectively. Nitrite also increased the formation of malondialdehyde (MDA), oxidized glutathione (GSSG), and the activity of catalase (CAT). Nitrite was observed to reduce the activity of superoxide dismutase (SOD) and the level of glutathione (GSH). In the recovery test, GSH and the GSSG recovered but did not return to pre-stress levels. The results suggested that the glutathione system played important roles in nitrite-induced oxidative stress in fish. The bighead carp responds to oxidative stress by enhancing the activity of GSH-Px, GST, GR and up-regulating the expression level of GSH-Px , GST , GR , a whilst simultaneously maintaining the dynamic balance of GSH/GSSG. CAT was also indispensable. They could reduce the degree of lipid peroxidation, and ultimately protect the body from oxidative damage. [ABSTRACT FROM AUTHOR]

The effect of heating temperature and duration on the texture and protein composition of bighead carp (Aristichthys nobilis) muscle was investigated. Samples were heated at 90°C, 100°C, 110°C, and 120°C for different times. The results showed that cooking loss increased significantly with increasing temperature and heating time, and a fractional conversion model was used to describe the increase. Hardness, chewiness, and gumminess exhibited a similar four-phase change with two peaks at 90°C, 100°C, and 110°C, and the trend was not observed at 120°C. Analysis of sodium dodecyl sulfate polyacrylamide gel electropheresis (SDS-PAGE) revealed that contents of myosin heavy chain decreased entirely to disappear and contents of actin significantly decreased. Increasing the intensity of the heavy molecular weight bands indicated the aggregation of myosin. Content of water-soluble proteins presented an increasing trend, which reflected the protein degradation and the release of low-molecular-weight compounds. [ABSTRACT FROM AUTHOR]

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The correlation coefficients between fish size (body weight and total length) and metal contents (Na, K, Ca, Mg, Mn, Fe, Cu, Zn, Cr, Co, Cd and Pb) in whole fish (Aristichthys nobilis) were determined. A total of 71 fish samples were collected from hatcheries and fish reservoirs located in Islamabad and Fatehjung. Highly significant (P

Sublethal adverse effects may result from exposure of aquatic organisms to insecticides at environmentally relevant concentrations. Fingerlings of the common carp (Cyprinus carpio, Linnaeus, 1758), grass carp (Ctenopharyngodon idella, Valenciennes, 1844), and bighead carp (Aristichthys nobilis, Richardson, 1845) were exposed to diafuran, an insecticide widely used during rice cultivation in Southern Brazil. The aim of this study was to verify the relationship between the lethal concentration (LC50) of diafuran and the acetylcholinesterase (AChE) activity in brain and muscle tissues of these species as a possible early biomarker of exposure to this insecticide. LC50 was determined for fish exposed to diafuran concentrations during 96 h (short term): common carp: control, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 mg L-1; grass carp: control, 1.0, 2.0, 3.0 and 3.5 mg L-1 and, bighead carp: control, 0.5, 1.0, 1.5, 2.0, 3.0 and 4.0 mg L-1, as well as the determination of AChE at concentrations near LC50 for these species. LC50 values (nominal concentrations) were 1.81 mg L-1 for the common carp, 2.71 mg L-1 for the grass carp and, 2.37 mg L-1 for the bighead carp. All carps exposed to diafuran were lethargic (lower concentrations) or immobile. Diafuran inhibited the acetylcholinesterase activity in brain (~38%) and muscle (~50%) of all species. Muscle of bighead carp under control treatment showed higher specific AChE activity than brain (14.44 against 5.94 µmol min-1 g protein-1, respectively). Concentrations of diafuran used for rice cropping may affect Cyprinus carpio, Ctenopharyngodon idella and Aristichthys nobilis behaviors and the AChE activities in brain and muscle of these species may be an early biomarker of toxicity of this insecticide.Exposição a inseticidas em concentrações elevadas no ambiente podem ocasionar efeitos adversos subletais em organismos aquáticos. Alevinos de carpa húngara (Cyprinus carpio, Linnaeus, 1758), carpa capim (Ctenopharyngodon idella, Valenciennes, 1844) e carpa cabeça grande (Aristichthys nobilis, Richardson, 1845) foram expostos ao diafuran, um inseticida utilizado na cultura do arroz no sul do Brasil. O objetivo deste estudo foi verificar a relação entre concentração letal mediana (CL50) do diafuran e a atividade da enzima acetilcolinesterase (AChE) em cérebro e músculo dessas espécies, como um possível biomarcador inicial da exposição a este inseticida. A CL50 foi determinada com peixes expostos a concentrações de diafuran em 96 h: carpa húngara: controle; 0,5; 1,0; 1,5; 2,0; 2,5 e 3,0 mg L-1; carpa capim: controle; 1,0; 2,0; 3,0 e 3,5 mg L-1 e carpa cabeça grande: controle; 0,5; 1,0; 1,5; 2,0; 3,0 e 4,0 mg L-1, bem como a determinação da AChE em concentrações próximas da CL50 para essas espécies. Valores de CL50 (concentrações nominais) foram de 1,81 mg L-1 para carpa húngara, 2,71 mg L-1 para carpa capim e 2,37 mg L-1 para carpa cabeça grande. Todas as carpas expostas ao diafuran estavam letárgicas (menores concentrações) ou imóveis. Diafuran inibiu significativamente a atividade da AChE em cérebro (~38 %) e músculo (~50 %) de todas as espécies estudadas. Atividade da AChE em músculo para carpa cabeça grande foi mais alta que cérebro (14,44 contra 5,94 µmol min-1 g proteína-1, respectivamente). Este estudo demonstrou que concentrações de diafuran utilizadas na cultura do arroz podem afetar o comportamento de Cyprinus carpio, Ctenopharyngodon idella e Aristichthys nobilis, e a atividade da acetilcolinesterase cerebral e muscular pode ser um biomarcador inicial de toxicidade deste inseticida.

Biological regulation means to inhibit proliferation of harmful phytoplankton by adjusting the community structure of the lake ecosystem and to rebuild a stable and healthy one using the self-regulating ability of the lake; but its effectiveness is still controversial. Two ways of biological control (i.e., a combination of filter-feeding fishes plus submerged plants and submerged plants alone) were tested in a large-scale in situ enclosure experiment, carried out at Gonghu Bay of Taihu Lake, China. Changes of both phytoplankton flora and water quality under two experimental conditions were dynamically monitored. The results showed that (1) filter-feeding fishes decreased the phytoplankton density and promoted phytoplankton biodiversity, while submerged plants inhibited phytoplankton only in spring and showed no significant effect on phytoplankton biodiversity. (2) Submerged plants improved the water quality, however, filter-feeding fishes had adverse impact on it. Thus, we tentatively concluded that filter-feeding fishes is more effective than submerged plants in regulating phytoplankton flora, while submerged plants play an important role in improving water quality. [ABSTRACT FROM AUTHOR]

In the present study, we aimed to investigate the effects of the neonicotinoid insecticide thiamethoxam on the hepatic glycogen in bighead carp (Aristichthys. nobilis Rich.). Fish were exposed to 6.6 mg/L, 10 mg/L and 20 mg/L of the insecticide under laboratory conditions for 96 hours. The PAS-reaction was applied to liver cryostat sections in order to indicate the amount of glycogen. The results showed that the hepatic glycogen amount increased with increasing the insecticide concentrations. On the other hand, we observed glycogen conglomerates in certain hepatocytes. Hence, our results demonstrated an enhanced process of glyconeogenesis in the fish liver under the influence of thiamethoxam. [ABSTRACT FROM AUTHOR]

Bighead carp ( Aristichthys nobilis) is an important aquaculture fish worldwide. Genetic linkage maps for the species were previously reported, but map resolution remained to be improved. In this study, a second-generation genetic linkage map was constructed for bighead carp through a pseudo-testcross strategy using interspecific hybrids between bighead carp and silver carp. Of the 754 microsatellites genotyped in two interspecific mapping families (with 77 progenies for each family), 659 markers were assigned to 24 linkage groups, which were equal to the chromosome numbers of the haploid genome. The consensus map spanned 1917.3 cM covering 92.8% of the estimated bighead carp genome with an average marker interval of 2.9 cM. The length of linkage groups ranged from 52.2 to 133.5 cM with an average of 79.9 cM. The number of markers per linkage group varied from 11 to 55 with an average of 27.5 per linkage group. Normality tests on interval distances of the map showed a non-normal marker distribution; however, significant correlation was found between the length of linkage group and the number of markers below the 0.01 significance level (two-tailed). The length of the female map was 1.12 times that of the male map, and the average recombination ratio of female to male was 1.10:1. Visual inspection showed that distorted markers gathered in some linkage groups and in certain regions of the male and female maps. This well-defined genetic linkage map will provide a basic framework for further genome mapping of quantitative traits, comparative mapping and marker-assisted breeding in bighead carp. [ABSTRACT FROM AUTHOR]

Effect of cooking temperature (40 - 100°C) on changes in protein composition of big head carp muscle and exudate was investigated. The results showed that the proportion of salt-soluble and water-soluble proteins in cooked muscle decreased with temperature up to 50°C and 60°C, respectively. Alkali-soluble proteins content in muscle increased with increasing temperature in the range of 40 - 98°C, while both non-protein nitrogen (NPN) and alkali-insoluble proteins content showed no significant change. Content of soluble collagen in muscle and collagen in exudates increased with increasing temperature. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns revealed disappearance of most muscle protein bands when the temperature reached 60°C for water-soluble proteins, and 50°C for salt-soluble proteins, but proteins with molecular weight (MW) about 37 kDa was observed when heated to 98°C. Visible β and α band of collagen in exudates were clear. [ABSTRACT FROM AUTHOR]

The motility and fertilizing ability of Aristichthys nobilis spermatozoa were studied. Activation solutions containing cations (Na, K, Ca, and Mg) were used to investigate the effect of ions on motility characteristics of spermatozoa (sperm movement duration and percentage of motile spermatozoa) and fertilizing capacity of sperm (fertilization rate, hatching rate, larvae length during hatching, larvae length during active feeding, and survival rate). The results showed that highest sperm movement duration is in solutions containing 99 mEq/L NaCl and 27 mg/dL KCl, respectively. Our results showed that solutions containing CaCl did not have impact on fertilizing capacity of spermatozoa compared to other ions. Among tested ions, solutions containing NaCl had more influence on fertilizing capacity of spermatozoa than other ions. Understanding the effects of these ions could be useful to the aquaculture industry and subsequently to the improvement of the quality of fish sperm during artificial reproduction. [ABSTRACT FROM AUTHOR]

The correlation coefficients between fish size (body weight and total length) and metal contents (Na, K, Ca, Mg, Mn, Fe, Cu, Zn, Cr, Co, Cd and Pb) in whole fish (Aristichthys nobilis) were determined. A total of 71 fish samples were collected from hatcheries and fish reservoirs located in Islamabad and Fatehjung. Highly significant (P<0.001) relationship between metal concentrations and fish size was found. Most of the metals (Na, K, Ca, Mg, Cu, Zn, Cr, Cd and Pb) showed an isometric increase, while Mn, Fe and Co showed an allometric increase in with increasing body weight. All metals showed isometric increase, while, Na, Mn, Fe, Cu, and Co showed positive allometric growth in relation to total length. The correlation coefficient (r) between different variables and wet body weight, condition factor was found highly significant (P<0.001) in examined fish except for Na, Ca, Cu, Zn, Cd and Pb while for total length the same results found except Ca, Cd, Zn and Pb. Variance inflation factor values of regression coefficients in multiple regression analysis for each variable were lesser than 10. The metal levels of the examined fish were lower than the recommended values in fish and fishery products set by FAO. [ABSTRACT FROM AUTHOR]