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This study identified vitamin B12 compounds in traditional fermented Japanese seafoods, such as heshiko made with a mackerel, kusaya made with a flying fish, Akazukuri-shiokara made with a squid, and funazushi made with a crucian carp, using reversed-phase high-performance liquid chromatography and liquid chromatograph–tandem mass spectrometry. The vitamin B12 content of these fermented seafoods was approximately 4–13 µg/100 g wet weight, indicating that vitamin B12 is the predominant corrinoid in all seafoods tested. However, kusaya contained approximately 8% of inactive cobamides such as 2-methyladenylcobamide and 2-methylmercaptoadenylcobamide. In conclusion, these traditional fermented Japanese seafoods can be a source of vitamin B12. [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]

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]

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]

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]

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 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]

The establishment of introduced fishes can be inhibited by the biotic resistance from species in the receiving environment, including strong consumptive resistance from specific piscivorous fishes. In response to predation pressure, prey fish population responses include predator-induced morphological changes, where an extreme example is seen in the crucian carp Carassius carassius, which forms deep-bodied morphs in predator presence that reduces individual predation risk. As its congener, gibel carp Carassius gibelio is a highly invasive fish across in its non-native range in Eurasia. Here we test whether their introduced populations also respond to the presence of piscivorous fishes by altering their body shape and trophic ecology by testing differences across 16 non-native lentic populations in Turkey that provided groups of piscivorous fish presence versus absence. In piscivore presence, gibel carp had a higher ratio of body length-to-depth than in piscivore absence, but with their body condition factor being higher in absence. Stable isotope mixing models predicted that gibel carp had diets that were more animal based (gastropods and zooplankton) in piscivore absence, but plant based in piscivore presence. Moreover, diet predictions of piscivore diet suggested gibel carp were consistently consumed less than other prey fishes. These results suggest that these alien gibel carp were responding to piscivory as per crucian carp, reducing their predation risk at the individual level by forming deep-bodied morphs. We suggest these morphological responses then decrease the strength of the biotic resistance against their invasion at the population level. [ABSTRACT FROM AUTHOR]

The crucian carp (Carassius carassius) is a cyprinid fish with its natural distribution in Europe and the western part of Asia. Due to its hardiness and unique ability to survive winter anoxia, it has been translocated to small lakes and ponds, and in Northern Europe since medieval times has been used as a food source. Crucian carp was the only fish in the pond that survived anoxia. Small lakes and ponds with winter anoxia result in dense populations of stunted and slender fish. In lakes with other fish species present, the crucians' numbers and densities are low and they grow to large sizes. In the presence of piscivores such as pike, crucians are deep bodied. The presence of pike-eating crucians, or the pike odors, induce a change in the body form of crucians. The change in body form makes it more difficult for pikes to swallow crucians and the handling time increases. Closely related invasive Carassius species have become a serious threat to crucian carp populations in Central-Eastern Europe and South-Eastern England through competition for space and food resources and hybridization. The crucian carp's close relationship to goldfish (Carassius auratus), the most studied species concerning sex pheromones, has made it possible to demonstrate that sex pheromones are also present in a wild Carassius species and in their natural environment. The results indicate that two species use the same sex hormonal pheromone system. The crucian carp has become an important model for laboratory studies of olfaction and taste. [ABSTRACT FROM AUTHOR]

Gin-buna crucian carp Carassius sp. is a widely distributed cyprinid fish inhabiting lakes and rivers throughout Japan. The species is categorized on the Red List of Shiga Prefecture as a "Species of Concern", given a suspected population decline in Lake Biwa; however, its spawning ecology in the lake is yet to be fully elucidated. Therefore, in this study, we examined the spawning and migratory behavior of gin-buna crucian carp at a lakeside biotope connected to the lake via egg survey and acoustic telemetry. DNA analyses of field-collected eggs showed that gin-buna spawned in the biotope during March–April in 2019 and 2020. Three gin-buna captured in the biotope were tagged with acoustic transmitters and released into the lake in October 2019, and one individual returned to the biotope in March 2020. These results suggest that some individuals of gin-buna use the biotope as a spawning ground for multiple years. [ABSTRACT FROM AUTHOR]

Toll-like receptors (TLRs), as the members of pattern-recognition receptors (PRRs), play a crucial role in innate immunity due to its significant function to recognize pathogens and activate downstream elements in signaling pathway. In the present study, the full-length cDNA sequences of TLR1 and TLR2 were cloned in the natural triploid Qihe crucian carp (Carassius auratus). The complete cDNA sequence of TLR1 was 2754 bp which was comprised of 5′ UTR of 60 bp, 3′ UTR of 300 bp, and an open reading frame of 2394 bp encoding 797 amino acids. The full-length cDNA sequence of TLR2 was 2605 bp, containing 5′ UTR of 36 bp, 3′ UTR of 202 bp, and an open reading frame of 2367 bp, encoding 788 amino acids. The mRNA expressions of CaTLR1 and CaTLR2 were detected to be constitutive at various embryonic developmental stages, and it was indicated that the similar expression pattern that mRNA expression levels were high at early development, then went down, and increased at later development stage. With regard to mRNA expression levels of CaTLR1 and CaTLR2 in various tissues of Qihe crucian carp, it showed to be constitutive with being higher in the liver and heart and the lowest in ovary. The mRNA expressions of CaTLR1 and CaTLR2 were profiled by quantitative real-time PCR following intraperitoneal injections of Aeromonas hydrophila and TLR ligands including LPS, PGN, and PolyI:C. Compared with the control, both CaTLR1 and CaTLR2 expressions were upregulated in most tissues of fish after challenges of LPS, PGN, PolyI:C, or A. hydrophila, although expression patterns varied in different tissues (gill, liver, spleen, trunk kidney, and head kidney). Together, these data highlighted the important role of CaTLR1 and CaTLR2 in recognizing LPS, PGN, PolyI:C, and A. hydrophila and in augmenting the innate immune ability against bacterial and viral infections in Qihe crucian carp. [ABSTRACT FROM AUTHOR]

The fish-flower symbiosis model is an eco-friendly sustainable farming technology combining plants, fish and microorganisms in a recirculating aquaculture system. However, there are few studies on the structure and diversity of microbial communities in fish intestines, culture water and plant roots during fish-flower symbiosis. Here, we cultured carp (Cyprinus carpio), crucian carp (Carassius auratus) and grass carp (Ctenopharyngodon idella) with mint (Mentha spicala L.) and extracted total genomic DNA from intestinal microorganisms, culture-water microorganisms and root microorganisms for each fish species for high-throughput sequencing of 16S rRNA genes. Analysis of microbial community structure and diversity revealed changes in abundance of microbial genera in the intestines and culture water of each fish species, including changes in the dominant taxa. Pirellula, Truepera, Aquincola, Cetobacterium and Luteolibacter were widespread in the fish intestine, culture water and mint root system. This study revealed the effects of mint feeding on the structure and diversity of microbial communities of fish, water bodies and the mint root system during fish-flower symbiosis, providing a theoretical reference for the promotion and application of fish-flower (mint) symbiosis technology and healthy fish culture technology. [ABSTRACT FROM AUTHOR]

The detection of emerging contaminants (ECs) and understanding their ecotoxicity has brought new challenges to water pollution control. Triclosan (TCS), as an emerging contaminant, is a commonly used antibacterial agent widely present in the environment. Microdialysis (MD), as a sampling technique, can overcome some of the deficiencies of traditional approaches to sampling, using sources such as blood, urine, tissue, and target organs, in terms of invasiveness, time from collection to analysis, and possible changes during sample preparation. In this study, we coupled MD with analysis using UHPLC-QTOF/MS to identify the endogenous metabolites in the liver as biomarkers of the exposure of living crucian carp to TCS. The identified biomarkers were then quantified using UHPLC-MS/MS to continuously monitor the effect of TCS on endogenous metabolites in the liver of living crucian carp, which contributes to a better understanding of the toxicological effect of TCS. The experimental results demonstrated that TCS exposure interfered with the metabolic pathways of amino acids (l-isoleucine and l-histidine), purines (xanthine and hypoxanthine), and small nerve molecules (acetylcholine and choline). [ABSTRACT FROM AUTHOR]

It is important to segment fish images accurately for realizing automatic and welfare fish farming. In aquaculture, there is a large amount of overlap between fish bodies due to the three-dimensional water space in which they dwell and various swimming gestures. The majority of existing fish image segmentation methods are for non-overlapping fish and aren't applied to actual fish segmentation. To address the above problems, a segmentation method based on point search and pairing for overlapping fish images was proposed, using crucian carp as the research object. The top view images of crucian carp in the fish tank were collected and pre-processed. The overlapping crucian carp target was recognized based on the morphological factors and segmented using the proposed point detection and pairing method, which can automatically determine the number of segmentation lines according to the shape of the overlapping crucian carp. The proposed method outperformed the comparison methods on a real crucian carp image dataset, with a segmentation precision of 98.86%, segmentation recall of 97.52%, mean absolute error of 0.1180, average intersection over union of 0.8311, average precision of 90.63%, and average recall of 91.52%, demonstrating that it does well in segmenting overlapping crucian carp images. The proposed method for overlapping fish image is of great significance for well completing the basic farming operations, promoting the welfare farming of fish, and improving the benefits of aquaculture enterprises. [ABSTRACT FROM AUTHOR]

Cyprinid herpesvirus 2 (CyHV-2) is the etiological agent of herpesviral hematopoietic necrosis disease (HVHND), which causes severe mortality in ornamental goldfish (Carassius auratus), crucian carp (Carassius auratus), and gibel/prussian carp (Carassius gibelio). Quick and hassle-free point-of-care detection of CyHV-2 is vital for the maintenance of ornamental fish health. In this manuscript, we describe the development of a rapid and sensitive RPA (recombinase polymerase amplification) assay, coupled with lateral flow dipsticks (LFD), that can achieve sensitive diagnosis of CyHV-2 in goldfish within 20 min at 36 °C with the satisfactory detection limit of 102 gene copies per reaction. This is the first report wherein major capsid protein (MCP) of CyHV-2 was targeted for RPA-LFD assay development. The assay did not show any cross-reactivity with other viral pathogens like cyprinid herpesvirus 3 (CyHV-3), spring viremia of carp virus (SVCV), infectious spleen and kidney necrosis virus (ISKNV), and viral nervous necrosis virus (VNNV). Furthermore, screening of CyHV-2 infection in CyHV-2-infected goldfish did not yield any false positive/negative results. In short, the RPA-LFD assay developed in this study presents a simple, rapid, and sensitive method for point-of-care diagnosis of CyHV-2, especially under resource-limited conditions. [ABSTRACT FROM AUTHOR]

Aeromonas phage AHP-1 was originally isolated from crucian carp (Carassius carassius) tissue. It was able to infect Aeromonas hydrophila and A. salmonicida. Genome sequence analysis revealed a 218,317-bp-long linear genome with an overall G + C content of 47.9%, 315 open reading frames (ORFs), and 25 tRNA sequences. Its genome was found to contain 67 unique ORFs (21.26%) that did not show any homology to previously characterized proteins. A comparative genome analysis suggested that its closest neighbors are unclassified phages belonging to the genus Tequatrovirus of the subfamily Tevenvirinae. [ABSTRACT FROM AUTHOR]

The genetic backgrounds of crucian carp (Carassius auratus) and goldfish are highly similar, and these fish are often considered a single variety. It is therefore difficult to distinguish crucian carp using traditional genetic and molecular methods. In this study, we developed microsatellite markers for the laboratory red crucian carp (C1HD strain) by analyzing its genome sequence using a Perl script. We investigated the polymorphism of these potential markers in the C1HD strain, two other crucian carp lineages (DLCC strain and red crucian carp-like fish, RCC-L), and two other cyprinid species (Ryukin and koi carp, Cyprinus carpio haematopterus, KOC). Among nine screened loci, two loci (SSR-4, SSR-21) showed specific genotypes to C1HD, SSR-4, and SSR-21 observed in C1HD with 209/238 and 214/238, respectively. Additionally, one locus (SSR-763) presented one private allele in C1HD (389) and other locus (SSR-228) detected with one private allele in C1HD (135). Across the five strains, a total of 42 alleles were identified in the nine microsatellite markers. Nei's unbiased genetic distances revealed a close relationship between the C1HD strain and the red crucian carp-like fish. The laboratory red crucian carp was recovered on an independent branch in the evolutionary tree drawn based on genetic distance. Our microsatellite makers clearly distinguish the laboratory crucian carp for RCC-L, DLCC, and Ryukin lineages. [ABSTRACT FROM AUTHOR]

To study the effect of 3-aminobenzoic acid ethyl ester methanesulfonate (MS-222)–assisted deep dormancy temperature (DDT) cultivation on the meat quality of crucian carp (Carassius auratus), crucian carp was treated with MS-222 and then cultivated at DDT. The research studied the lactic acid content, pH, water retention rate, cooking loss rate, color, texture, nucleotide content, and sensory score of the crucian carp meat and the serum glucose and residual MS-222 contents in the crucian carp bodies. The results indicated that the required concentration of MS-222 for the anesthetization of crucian carp was 40 mg/L. The serum glucose and lactic acid contents and the cooking loss rate of crucian carp meat increased from 0 to 10 days, whereas the pH and water holding capacity of the crucian carp decreased from 0 to 10 days; all indexes of the crucian carp treated with MS-222 were higher than those of the control from 2 to 10 days. The texture profile, color, and nucleotide content of the crucian carp meat decreased from 0 to 10 days; however, the decline rate of the MS-222-treated group was slower than that of the control. The metabolism results indicated that MS-222 was metabolized into 0 mg/g on the 5th day. These results demonstrated that MS-222-assisted DDT cultivation was superior to the control for the cultivation of crucian carp. [ABSTRACT FROM AUTHOR]

Individual variations in metabolic rate, locomotion capacity and hypoxia tolerance and their relationships were investigated in three cyprinid species [crucian carp (Carassius auratus), common carp (Cyprinus carpio) and qingbo (Spinibarbus sinensis), in 60 individuals of each species]. Either the active metabolic rate (AMR) and critical swimming speed (Ucrit) (30 individuals) or critical oxygen tension (Pcrit) and loss of equilibrium (LOE) (30 individuals) were measured in each species after measuring the resting metabolic rate (RMR). Both the AMR and Ucrit were found to be significantly and positively correlated with the RMR in all three cyprinid species, indicating that high-RMR individuals have high aerobic capacity and thus good swimming performance. Pcrit was positively correlated with the RMR in all three species, whereas the LOE was highly positively correlated, weakly positively correlated and not correlated with the RMR in qingbo, common carp and crucian carp, respectively, possibly due to specialized morphological and biochemical adaptations involved in hypoxia tolerance in crucian and common carp. Crucian carp showed relatively poor swimming performance, i.e., a low Ucrit (relatively high variation), strong hypoxia tolerance, and low LOE (relatively low variation); qingbo showed relatively good swimming performance (relatively low variation) and weak hypoxia tolerance (relatively high variation); and common carp showed moderate swimming performance and relatively strong hypoxia tolerance (moderate variation). These interspecific differences may be due to the different lifestyles of these cyprinid fishes based on their associated fast–slow-flow regime and are outcomes of long-term selection. [ABSTRACT FROM AUTHOR]

The aboriginal form of the Prussian carp in lakes and rivers in the south of Western Siberia is currently being replaced by the Amur forms of the same species introduced into the water bodies of the region in the late 1970s. We analyze the genetic diversity of this species in Southern Siberia based on the polymorphism of a D-loop fragment of mitochondrial DNA (460 bp) and reveal the presence of two haplogroups, one of which (B) is extremely rare in South East Asia and is likely an indicator of the autochthonous forms of the Prussian carp, and the other (A) is similar to haplotypes typical of the Far Eastern populations. [ABSTRACT FROM AUTHOR]

The present study aims to explore the effects of oral astaxanthin administration on the growth performance and innate immunity of juvenile crucian carp (Carassius auratus). Juvenile crucian carps with a bodyweight of 40.06 ± 2.17 g were randomly assigned to four groups, i.e., one control group fed with a basic diet and three treatment groups fed with a diet that contains 200, 400 and 800 mg/kg astaxanthin. After 60 days of feeding, the groups fed with astaxanthin-containing diets had improved body weight gain rate; feed conversion ratio; intestinal digestive protease, lipase and amylase levels; serum superoxide dismutase, catalase, acid phosphatase, alkaline phosphatase and lysozyme activities; complement 3 and complement 4 levels; interleukin (IL)-10 and resistance to Aeromonas hydrophilia and reduced serum aspartate aminotransferase and alanine aminotransferase activities and tumour necrosis factor-α, IL-1β and IL-8 levels compared with those of the control group. Based on the efficiency of the oral administration of astaxanthin on the growth performance of juvenile crucian carps, the optimum dose of astaxanthin was 400 mg/kg. Results indicated that astaxanthin may be used as a dietary supplement for the crucian carp. [ABSTRACT FROM AUTHOR]

While the fish gut microbiome composition is important to fish health, studies of the gut microbiome of fish lag behind those of terrestrial vertebrates. Whether the microbial communities in an aquatic habitat affect the gut microbiomes of resident fish is unclear. This study investigates and compares the composition of bacterial communities in the gut of crucian carp and humpback and in the water of their habitat using high-throughput sequencing of two hypervariable regions (V3 and V4) of the 16S rRNA gene. We identified 2058 operational taxonomic units (OTUs) in the humpback, 2551 OTUs in crucian carp, and 1760 OTUs in their habitat water. 218 OTUs were common to all three bacterial communities. Linear discriminant analysis revealed multiple species that differed significantly in abundance between the communities. This study aims to improve our understanding of the influence of the aquatic habitat on fish–microbe relationships. [ABSTRACT FROM AUTHOR]

Tactile reception in cyprinid fish (silver crucian carp Carassius auratus gibelio and common carp Cyprinus carpio) was investigated by noninvasive recording of action potentials from the head skin in response to rhythmic tactile stimulation. Responses shaped as electric potentials following synchronously with changes in the pressure force on the skin were recorded using chloro-silver electrodes. It was shown that fish, like all terrestrial vertebrates, have phasic and tonic tactile receptors. Three main types of tactile responses were distinguished: (1) tonic responses as potential fluctuations repeating the dynamics of the tactile stimulus, (2) phasic responses as on-, off-, and on-off potentials, and (3) slow deflections from the resting potential. Compound responses comprising simultaneously different types of responses were also recorded. The response latency averaging 6.1 ms for tonic and 4.4 ms for phasic responses was clearly independent of the stimulus direction (switch-on, switch-off). The threshold level of tactile sensitivity in the perioral and gular head areas was 0.05–0.2 g/mm2. Tactile receptors on the silver crucian carp and common carp heads exhibited zonal distribution patterns, with sensory areas differing in their tactile sensitivity. Most sensitive areas were on the upper and lower lips, in the perilabial skin and the gular area on the ventral side of the head. Less sensitive areas were situated rostrally and ventrally to the eyeball. The areas situated dorsally and caudally to the eyeball proved to be insensitive to the applied tactile stimulation. In all sensory areas on the fish head, most intense responses were evoked by sliding tactile stimuli. The distribution specificity of tactile sensory areas meets their functional significance for fish feeding behavior. [ABSTRACT FROM AUTHOR]

Contracaecum rudolphii (s. l.) is a complex of sibling species of anisakid nematodes having the fish-eating birds belonging to the Family Phalacrocoracidae as final hosts. The great cormorant Phalacrocorax carbo sinensis is parasitized by C. rudolphii A and C. rudolphii B. Adults and L4 specimens of C. rudolphii (s. l.) (N = 3282) were collected in cormorants from brackish and freshwater ecosystems of Central Italy. Third-stage larvae of Contracaecum (N = 882) were obtained from the fish species Dicentrarchus labrax, Anguilla anguilla, Aphanius fasciatus, Atherina boyeri, Leuciscus cephalus, Barbus barbus, and Carassius carassius captured in the same geographical areas of cormorants' standings. Contracaecum rudolphii A and C. rudolphii B were identified by a multilocus genetic approach: allozymes, sequences analysis of the mtDNA cox2, and ITS region of rDNA gene loci. Differential distribution of the two parasite species was observed in different aquatic environments. Contracaecum rudolphii B outnumbered C. rudolphii A in wintering cormorants from freshwater ecosystems; the opposite trend was found in cormorants from brackish water. Analogously, C. rudolphii A larvae were more prevalent in brackish water fish, while C. rudolphii B larvae were found infecting only freshwater fish. The findings seem to confirm that C. rudolphii A and C. rudolphii B would have a life-cycle adapted to brackish and freshwater environments, respectively. A differential feeding behavior of wintering cormorants, the ecology of the infected fish species, and abiotic factors related to early stages of the parasites are supposed to maintain the distinctiveness of the two parasite species' life cycles in the two different aquatic ecosystems. [ABSTRACT FROM AUTHOR]

In the present study, a Gram-positive bacterium was isolated from the intestine of healthy crucian carp Carassius auratus and named strain R8. It was initially identified as Enterococcus faecium according to its morphological, physiological and biochemical characteristics. Further identification by using 16S rRNA gene sequence analysis confirmed the R8 strain (Genbank accession no. MF928076) as E. faecium. Challenge and hemolysis experiments showed that the E. faecium R8 strain had no toxicity to the crucian carp. Bacteriostatic experiment showed that this isolate obviously inhibited the growth of Aeromonas veronii and Staphylococcus haemolyticus. The proliferation of E. faecium R8 strain occurred after exposure to various growth conditions such as at pH values from 2.0 to 4.0 for 8 h, bile concentrations from 0.2 to 1.2% and high temperature of 80 °C. This bacterial strain grew best under the condition of 37 °C, pH 7.0 and salinity 30 ppt, and its growth curve exhibited four distinct phases. These results showed that the E. faecium R8 strain had potential probiotic characteristics and could be used as a candidate strain for aquatic probiotics. [ABSTRACT FROM AUTHOR]

Fasting influences the overall physiology of fish, and the knowledge how the gut microbiota, growth performances, and immune function in response to intermittent and long-term fasting is still insufficient. Here, we characterized the effects of fasting on the host-gut microbiota in crucian carp, which would enhance our insight into physiological adaptation to fasting. To achieve this, we investigated the gut microbial communities of crucian carp with different fasting stress, and corresponding immune and growth parameters. The gut microbial communities were structured into four clusters according to different fasting stress, namely one control group (feed regularly), two intermittent fasting groups (fasting period and re-feeding period, respectively), and one long-term fasting group. Intermittent fasting significantly improved the activity of superoxide dismutase (SOD) and lysozyme (LZM) (ANOVA, p < 0.05) and significantly increased alpha diversity and ecosystem stability of gut microbiota (ANOVA, p < 0.05). Gut length (GL) and condition factor (CF) showed no significant difference between the control group (CG) and intermittent fasting group under re-feeding period (RIF) (ANOVA, p = 0.11), but relative gut length (RGL) in group RIF was higher than that in the CG (ANOVA, p = 0.00). The bacterial genera Bacteroides, Akkermansia, and Erysipelotrichaceae were enriched in fishes under intermittent fasting. Two Bacteroides OTUs (OTU50 and OTU1292) correlated positively with immune (SOD, complement, and LZM) and growth (GL and RGL) parameters. These results highlight the possible interplay between growth performances, immune function, and gut microbiota in response to fasting. [ABSTRACT FROM AUTHOR]

A nidovirus was isolated from crucian carp (Carassius auratus). The complete genome of the crucian carp nidovirus (CCNV) is 25,971 nt long and has five open reading frames, encoding the polyprotein 1ab (pp1ab), spike glycoprotein (S), membrane protein (M), and nucleocapsid protein (N). CCNV has the highest similarity to Chinook salmon nidovirus (CSNV). However, the CCNV HB93 pp1ab protein sequence has three long fragment deletions compared with the CSNV. Phylogenetic analysis based on the complete genome sequence showed that CCNV HB93 clusters with CSNV, indicating that CCNV represents a second species in the new genus Oncotshavirus within the new family Tobaniviridae in the order Nidovirales. [ABSTRACT FROM AUTHOR]

Fish typically prefer to live in big shoals due to the associated ecological benefits. Shoaling is a behavior that depends on the ability to quantitatively discriminate. The fundamental mechanism involved in quantity discrimination determines whether fish can discriminate a shoal using numerical discrete cues (e.g., number of shoal members), non-numerical continuous traits (e.g., total body surface area) or both; however, the mechanism is currently a controversial topic. In the present study, we used a spontaneous choice experiment to test whether guppy (Poecilia reticulata), zebrafish (Danio rerio), Chinese crucian carp (Carassius auratus) and qingbo (Spinibarbus sinensis) rely on continuous (i.e., body surface area) or discrete (i.e., number of shoal members) information for shoal selection by altering the body surface area (cumulative body surface area ratio of 3:2 or 1:1) between two stimulus shoals with a different number of members (2 individuals vs 3 individuals). All four fish species preferred to shoal with the stimulus shoal with the larger cumulative surface area even if the shoal had fewer members; however, fish showed no shoal preference when the cumulative surface body areas of both stimulus shoals were equal. Furthermore, qingbo did not numerically discriminate between a shoal with 1 individual and a shoal with 3 individuals when the cumulative surface areas of both stimulus shoals were equal; however, qingbo showed a preference for the shoal with the larger cumulative surface area when the two stimulus shoals each had 3 individuals. In conclusion, the present study demonstrated that all four fish species relied only on non-numerical continuous quantity information for shoal selection, at least under a difficult task (i.e., 2 vs 3). [ABSTRACT FROM AUTHOR]

The variation in the body shape of crucian and prussian carps has been studied by methods of geometric morphometrics in sympatric populations from two geographically close lakes in the Southern Urals subjected to different degrees of contamination with anthropogenic radionuclides. Along with particular interspecies features, interpopulation differences have been detected as multidirectional reorganization of cyprinid morphogenesis under different ecological conditions of adjacent lakes. The morphogenetic divergence of crucian carp from adjacent lakes is almost two times smaller than that of the prussian carp coexisting with them. The increased intragroup morphodiversity in prussian carp indicates incomplete adaptation of the fish to anthropogenic radionuclide contamination of the lakes and their high morphogenetic plasticity and high adaptive potential than in crucian carp. [ABSTRACT FROM AUTHOR]

This paper presents data on the polymorphism of inter simple sequence repeats of DNA in the silver crucian carp Carassius auratus gibelio in water bodies in the southern part of Western Siberia. The share of polymorphic ISSR-PCR bands in silver crucian carp populations from different lakes varied from 40 to 70%, and Nei’s gene diversity index varied from 0.16 to 0.25. The genetic diversity indices were lower in the populations that were largely represented by females than in bisexual ones. The highest levels of genetic polymorphism were revealed in populations with diploid-triploid complexes. The gene diversity index of the silver crucian carp population is positively correlated with the reservoir size (r = 0.90, p = 0.015; Rs = 0.74, p = 0.036). [ABSTRACT FROM AUTHOR]

Fish gut microbiota play important roles in fish immunity, nutrition, and the adaptation to environmental changes. To date, few studies have focused on the interactions among environmental factors, fish diseases, and gut microbiota compositions. We compared the gut bacterial communities of healthy crucian carps ( Carassius auratus) with those of individuals affected by 'red-operculum' disease and corresponding water and sediment microbiota in four fish farm ponds. Distinct gut bacterial communities were observed in healthy and diseased fish. The bacterial communities of diseased fish were less diverse and stable than those of healthy individuals. The differences in bacterial community compositions between diseased and healthy fish were explained by the changes in the relative abundances of some specific bacterial OTUs, which belonged to the genera such as Vibrio, Aeromonas, and Shewanella, and they were prevalent in diseased fish, but rare or even absent in environmental samples. Water temperature and ammonia concentration were the two most important environmental factors that impacted gut microbiota in diseased fish. These results highlighted the surge of some potential pathogens as bacterial signatures that were associated with 'red-operculum' disease in crucian carps. [ABSTRACT FROM AUTHOR]

Approximately three dozen Myxobolus spp. (Myxozoa: Myxosporea: Bivalvulida) have been described to parasitize the gills of carp of the genera Cyprinus and Carassius. Hitherto, these fish were often introduced to temperate waters worldwide as food and ornamental fish from Asia, their place of origin. The present study examined the myxosporean infection of seven common carp ( Cyprinus carpio) and seven Japanese silver crucian carp ( Carassius langsdorfii) collected from the Fushinogawa River around the university in Yamaguchi City, Japan, during the period April 2015 to October 2016. In total, four Myxobolus spp. were detected in the gill lamellae of Cy. carpio and Ca. langsdorfii, i.e., two species in each species of fish. The four species were characterized morphologically and genetically based on the 18S ribosomal RNA gene (rDNA). A new species, Myxobolus tanakai n. sp., from four individuals of Cy. carpio had an elongated pyriform spore (15.4-18.6 μm by 6.3-8.4 μm), resembling the spore shape of Myxobolus koi from Cy. carpio or Carassius auratus in Japan, China, and the USA, but bigger than it (13.2-15.6 μm by 6.6-7.8 μm). The new species formed a clade with M. koi but was distinct from any of the isolates of this species (nucleotide identities less than 98.6%). The second new species, Myxobolus paratoyamai n. sp., from a single Cy. carpio with its one prominent and one rudimentary polar capsule closely resembled the spore morphology of Myxobolus toyamai from Cy. carpio or Carassius gibelio in Japan, China, and the USA. However, the isolate formed a clade with Myxobolus longisporus from Cy. rubrofuscus in China rather than with M. toyamai isolates (nucleotide identities less than 97.9% with known species). Another new species, Myxobolus ginbuna n. sp., from two individuals of Ca. langsdorfii had similar-shaped spores to Myxobolus wulii, but the dimensions were smaller (11.7-13.9 μm by 8.5-9.8 μm vs. 17.6-18.5 μm by 8.9-10.0 μm). This new species formed a clade with M. wulii but was distinct from any of the M. wulii isolates from Ca. gibelio in China (nucleotide identities less than 99.1%). An additional species, Myxobolus pyramidis, from six individuals of Ca. langsdorfii was morphologically and genetically similar to the previous record from Ca. gibelio in China (99.6% nucleotide identity of the 18S rDNA). Two of these six individuals were mix-infected with M. ginbuna n. sp. This is a new host and geographical distribution record for M. pyramidis. [ABSTRACT FROM AUTHOR]

Enclosure experiment was carried out to evaluate the effects of dietary phosphorus levels on water quality, phosphorus budget, and plankton composition in intensive culture of crucian carp ( Carassius auratus). Monocalcium phosphate was used to formulate extruded feed containing total phosphorus of 8.7 (D1), 11.4 (D2), 13.5 (D3), and 18.4 (D4) g kg. Twelve polyethylene enclosures (each 4 × 4 × 1.5 m depth) were assigned to four groups with each one stocked with 120 juveniles (44.08 ± 1.36 g). Fish was fed twice daily at a rate of 3% body weight in the experiment. After 70 days of feeding, growth and survive rate of crucian carp were not affected by diet of different P level. It was found that physiochemical factors in all the enclosures did not show obvious threat on fish. Diets of different P level did not affect dissolved oxygen (DO), secchi depth (SD), total ammonium nitrogen (TAN), and total nitrogen (TN) concentration in enclosures. However, increased diet P level seemed to increase averaged pH, soluble reactive phosphorus (SRP), and total phosphorus (TP) concentration and decrease nitrite concentration and TN/TP. During later period of experiment, treatments with high diet P level (D3 and D4 treatments) had very high cyanobacterial biomass dominated by Microcystis spp., while phytoplankton in D1 and D2 treatments was mainly composed of edible algae. Composition and density of zooplankton in different treatments varied in similar pattern. Peak density of cladocerans (mainly Moina spp.) seemed to be related to diet P level. The present study indicated that changing P level in diets might bring complicated changes to the intensive crucian carp culture ecosystem. [ABSTRACT FROM AUTHOR]

Crucian carp Carassius auratus herpesvirus (CaHV) was isolated from diseased crucian carp with acute gill hemorrhages and high mortality. The CaHV genome was sequenced and analyzed. The data showed that it consists of 275,348 bp and contains 150 predicted ORFs. The architecture of the CaHV genome differs from those of four cyprinid herpesviruses (CyHV1, CyHV2, SY-C1, CyHV3), with insertions, deletions and the absence of a terminal direct repeat. Phylogenetic analysis of the DNA polymerase sequences of 17 strains of Herpesvirales members, and the concatenated 12 core ORFs from 10 strains of alloherpesviruses showed that CaHV clustered together with members of the genus Cyprinivirus, family Alloherpesviridae. [ABSTRACT FROM AUTHOR]

Mobilization of glycogen stores was examined in the anoxic crucian carp ( Carassius carassius Linnaeus). Winter-acclimatized fish were exposed to anoxia for 1, 3, or 6 weeks at 2 °C, and changes in the size of glycogen deposits were followed. After 1 week of anoxia, a major part of the glycogen stores was mobilized in liver (79.5 %) and heart (75.6 %), and large decreases occurred in gill (46.7 %) and muscle (45.1 %). Brain was an exception in that its glycogen content remained unchanged. The amount of glycogen degraded during the first anoxic week was sufficient for the anaerobic ethanol production for more than 6 weeks of anoxia. After 3 and 6 weeks of anoxia, there was little further degradation of glycogen in other tissues except the brain where the stores were reduced by 30.1 and 49.9 % after 3 and 6 weeks of anoxia, respectively. One week of normoxic recovery following the 6-week anoxia was associated with a complete replenishment of the brain glycogen and partial recovery of liver, heart, and gill glycogen stores. Notably, the resynthesis of glycogen occurred at the expense of the existing energy reserves of the body in fasting fish. These findings indicate that in crucian carp, glycogen stores are quickly mobilized after the onset of anoxia, with the exception of the brain whose glycogen stores may be saved for putative emergency situations. [ABSTRACT FROM AUTHOR]

Body colour and pattern are the important characteristics for ornamental fish. Owing to the complexity of colour heredity in fish, this study attempts to reveal the rule of red and black body colour formation in crucian carp, carp and their hybrids by observation and statistical analysis. It is found that melanocytes occur during the stage of embryo or larva in the skin of red crucian carp, and then, the body colour changes from dark grey to red-orange after about 3 months old. For Kohaku and Yamabaki ogon, which are two kinds of koi carp without melanocyte in the body colour of the adults, no melanocyte is observed in skin during the stage of embryo or larva. However, for the hybrids originating from red crucian carp and Kohaku or from red crucian carp and Yamabaki ogon, the body colours are dark grey. By statistical methods, regression models are constructed to describe the inheritance rule on the red and black body colours in fish. In virtue of the models, some interesting properties in inheritance are revealed for crucian carp and carp: (1) the percentage of the black colour in parents generates negative cross-correlation with the red colour of offspring for both of crucian carp and carp. (2) The negative effect on the percentage of the red colour in offspring by the black colour in parents is stronger for carp than that for crucian carp. [ABSTRACT FROM AUTHOR]

Although once popular prior to the last century, the aquaculture of crucian carp Carassius carassius (L. 1758) in Sweden gradually fell from favour. This is the first genetic comparison of crucian carp from historic man-made ponds in the Scandinavian Peninsula. The aim was to identify old populations without admixture and to compare the relationship of pond populations from different provinces in Sweden. In total, nine microsatellite loci from 234 individuals from 20 locations in varied parts of Sweden were analysed. The genetic distances of crucian carp populations indicated that the populations in the southernmost province of Sweden, Scania, shared a common history. A pond population in the province Småland also showed a common inheritance with this group. In the province Uppland, further north in Sweden, the population genetic distances suggested a much more complex history of crucian carp distributions in the ponds. The data showed that there are some ponds with potentially old populations without admixture, but also that several ponds might have been stocked with fish from many sources. [ABSTRACT FROM AUTHOR]

Electrical stimulation of certain part of the neural tissue could evoke specific functional response. The interface plays an important role in stimulation process. Tungsten wire electrodes have long been used as an ideal interface for neural signal recording and stimulation. In this work, an electrode array with good electrochemical property and biocompatibility was successfully fabricated in a novel and convenient way. A PDMS electrode holder was made to fix the electrodes with certain distance. To achieve a better stimulation effect, a platinum black coating was electroplated, and the electrochemical properties of the electrode were tested. Tests results of the impedance and charge injection capacity showed great improvement in electrochemical property. To test the durability of the platinum black coating, the electrode was dealt with ultrasound vibration for 10 min and then re-tested for charge storage capacity lost. The array was then implanted into the midbrain of crucian carp by a surgical procedure. A stimulation pulse was applied in order to elicit a change in locomotion. By stimulating the midbrain part of the fish brain, both side turning movements were observed. Also, this work provides the fundamental experiment for the development of bio-robotic fish. [ABSTRACT FROM AUTHOR]

Tumor necrosis factor (TNF[31]) is a potent inflammatory cytokine produced during inflammation. In this study, two crucian carp TNF-α genes, TNFα-1 and TNFα-2, were cloned and sequenced. The TNFα-1 is 720 bp long and consists of a 699 bp opening reading frame (ORF) encoding 232 amino acids and TNFα-2 is 793 bp long and contains an ORF of 687 bp, which encodes 228 amino acids. The genomic structure of both genes consists of 4 exons and 3 introns similar to the other known TNF-α genes. The amino acid sequences of the crucian carp TNFα-1 and TNFα-2 share the highest identity with common carp, goldfish and the lowest with flounder and humans. The phylogenetic analysis grouped crucian carp TNFα-1 and TNFα-2 with other cypriniformes, which are more closely related to goldfish and common carp TNFα-1 and TNFα-2. Real time PCR analysis showed a constitutive expression of crucian carp TNFα-1 and TNFα-2 in all seven tissues examined. The TNFα-1 mRNA was expressed significantly higher in the liver and kidney than those of TNFα-2, while TNFα-2 in turn was expressed significantly higher in the muscle. The Aeromonas hydrophila BSK-10 strain upregulated the expression level of both TNFα-1 and TNFα-2 in all of the tested tissues. At 6 h, the expression levels of TNFα-1 were increased significantly higher in the muscles, skin, and liver, while the expression levels of TNFα-2 were increased significantly higher in the muscles and gills. TNFα-1 was expressed much stronger than TNFα-2. At 12 h the expression levels started to decline and were even lower at 24 h. These results imply that both TNFα-1 and TNFα-2 mRNA are distributed differently in tissues and are implicated in the immune response to bacterial infection. [ABSTRACT FROM AUTHOR]

It has been demonstrated by the example of the crucian carp ( Carassius carassius) that a 1-hour stay of fish in a combined magnetic field with resonance parameters for calcium ions decreases the proteolytic and amylolytic activities of their intestinal enzymes. It has been found that a 1-hour exposure to a combined magnetic field with resonance parameters for potassium ions has almost no effect on the activity of proteinases, but it decreases the amylolytic activity. It has been noted that the activity of proteases and glycosidases is lower under hypomagnetic conditions. Upon the inversion of the vertical component of the geomagnetic field, the proteolytic activity of the intestinal mucosa in C. carassius decreases, while the amylolytic activity becomes higher compared to the control. Possible effects of magnetic fields on the activity of digestive hydrolases in fish are discussed. [ABSTRACT FROM AUTHOR]

In our previous study, transcriptomes of crucian carp were sequenced using 454 Sequencing, which generated many expressed sequence tag (EST) sequences that are useful to develop gene-based markers. In this study, from these ESTs, 5505 simple sequence repeats (SSRs) were identified, among which dinucleotide repeats (43.6 %) and AC/GT motifs (39.6 %) were the most frequent, followed by AAT/ATT (15.5 %). We designed 3932 primers with sufficient amplified flanking sequences. To verify the identified EST-SSRs, 500 primers were randomly selected for polymerase chain reaction (PCR), of which 408 (81.6 %) were successfully amplified, among which 151 (30.2 %) were polymorphic. These polymorphic markers were further surveyed among an F population. The results showed that 148 loci were informative in both parents, with segregation ratios of 1:1:1:1 (23, 15.5 %), 1:1 (59, 39.9 %), and 1:2:1 (66, 44.6 %). In addition, the general linear model (GLM) procedure in the SPSS software package was used to analyze the correlations between these 148 loci and two growth traits. Twelve loci were discovered to be significantly ( P < 0.05 or P < 0.01) associated with body weight (BW), and 13 loci were significantly ( P < 0.05 or P < 0.01) correlated with standard length (SL). Meanwhile, genotypes that favorably affect BW and SL traits were determined. Therefore, the EST-SSRs developed in this work may be useful in linkage map studies and for marker-assisted selection (MAS) in breeding programs of this species. [ABSTRACT FROM AUTHOR]

This study investigated the plasma biochemical profiles and gene expression levels of crucian carp Carassius carassius subjected to anesthetization with low-voltage constant direct current (DC) and tricaine methanesulfonate (MS222). Fish in the MS222 treatments and the DC treatments were exposed to either two concentrations of MS222 (100 and 200 mg/l) or constant DC with a voltage of 26 V, at a voltage gradient of 0.68 V/cm, respectively. The results showed that low-voltage constant DC immobilized fish more quickly, resulting in significant elevations of plasma cortisol levels compared to exposure of high or low doses of MS222. Electronarcosis led to an increased expression of heat shock proteins 70 ( HSP70) as well as HSP90 compared to the treatment group with MS222. Also, electronarcosis enhanced mitochondrial respiratory chain gene ( atp6, cox1 and nd5) and antioxidant enzyme gene ( CAT, SOD and GSH- px1) expression levels. In conclusion, low-voltage constant DC can disturb fish plasma biochemical profiles and gene expression levels. [ABSTRACT FROM AUTHOR]

Cell membranes play a key role in cellular activities. Fish erythrocytes, prototype of the nucleated erythrocytes of lower vertebrates, are predominantly oval, biconvex discs with elliptical nucleus and much larger in size than human erythrocytes. In attempts to disclose the correlation of membrane structure between fish and human erythrocytes, we used in situ atomic force microscope (AFM) combined with single-molecule force spectroscopy to study the membrane structure of Crucian carp erythrocytes under quasi-native conditions. Our results revealed the asymmetric distribution of proteins in Crucian carp erythrocyte membrane: the outer leaflet of membrane is rather smooth without any proteins, whereas the inner leaflet of membrane is very rough with dense proteins. The asymmetry of fish erythrocyte membrane structure fits well with the semi-mosaic model of human erythrocyte membrane structure. This similarity of membrane structure between human and fish erythrocytes extends the semi-mosaic model of erythrocytes membrane structure to a wider range of species. [ABSTRACT FROM AUTHOR]

Significant differences in pH dependence of proteolytic and amylolytic enzyme activities in the gut microbiota between crucian carps from different habitats (the Dniester River and Kuchurgan Reservoir) have been revealed for the first time. The proteolytic activity in fish from these water bodies reaches a peak at pH values varying from 7 to 10, while the peak of amylolytic activity is consistently observed at pH 7.0. Both proteolytic and amylolytic activities are higher in fish from the Kuchurgan Reservoir (characterized by increased trophicity and high abundance of bacterioplankton) than in fish from the Dniester. For comparison, the effect of pH on proteinase and glycosidase activities in the gut mucosa and chyme of the same fish has been studied. [ABSTRACT FROM AUTHOR]

Within the study, the in vitro fertilization (ivF) in crucian carp, Carassius carassius (L.), with the use of three activating solutions (AS) [reverse osmosis water (RO), Woynarovich (WS) and Billard (BS) solutions] as well as the period of the capacity of eggs to be fertilized (up to 180 s post-egg-activation) in those solutions. Moreover, CASA analysis of sperm motility was conducted with each AS. In control groups (0 s), the highest ( P < 0.05) fertilization rate (93.2 %) was observed with WS. The application of RO and BS affected lower ( P < 0.05) embryo survival (63.5 and <5 %, respectively). High fertilization rate (over 90 %) was recorded up to 30 (RO) and 90 s (WS) post-egg-activation. Progressive sperm motility (pMOT) was high (over 48 %) in all treatment groups up to 30 s. In RO and WS groups, pMOT significantly decreased ( P < 0.05) after 45 s post activation. BS affected pMOT over 10 % up to the 165 s. No differences ( P > 0.05) between the groups were found considering the curvilinear velocity (VCL) 15 s post-sperm-activation. Between 30 and 135 s, the lowest ( P < 0.05) VCL after application of RO was noted. The highest VCL ( P < 0.05) up to 135 s was noted after application of BS and WS. All AS activated crucian carp sperm. The lowest fertilization rate was noted when BS was used, despite the high pMOT and VCL. It suggest that the AS which activates the sperm properly may not activate the eggs probably due to high osmolality of BS (262 mOsm kg). Because eggs retained the longest period of activity in WS, this AS is suggested for ivF in crucian carp. [ABSTRACT FROM AUTHOR]

Silver crucian carp Carassius auratus langsdorfii comprises a diploid-polyploid complex in wild Japanese populations. Bisexually reproducing diploids are sympatrically distributed with gynogenetically developing triploids and tetraploids. Triploid and tetraploid males are very rare among Japanese silver crucian carp due to their gynogenetic reproduction. We examined the genetic characteristics of progeny that arose in a tank by natural spawning of a tetraploid silver crucian carp pair. The ploidy status of 120 samples randomly collected from these progeny was determined to be tetraploid by DNA content flow cytometry. DNA fingerprints from a random amplified polymorphic DNA assay indicated that almost all the progeny examined had genotypes identical to the maternal tetraploid female with no paternally derived fragments. Selected specimens’ cytogenetic analyses revealed that the progeny examined had tetraploid chromosome numbers, categorized into 40 metacentric, 80 submetacentric, and 80 subtelocentric or telocentric chromosomes, which were arranged into quartets and six supernumerary microchromosomes. Fluorescence in situ hybridization signals were detected in four homologous chromosomes in all analyzed metaphases prepared from diploid goldfish specimens. Contrary, tetraploid silver crucian carp gave eight rDNA signals. These results suggest that gynogenetic development in eggs spawned by tetraploid females should be triggered by tetraploid males’ homospecific sperm. [ABSTRACT FROM AUTHOR]

Cardiac function in fish acclimates to long-term temperature shifts by generating compensatory changes in structure and function of sarcoplasmic reticulum (SR) including the sarco(endo)plasmic reticulum Ca-ATPase (SERCA2). The current study compares temperature responses of the cardiac SERCA in two fish species, burbot ( Lota lota) and crucian carp ( Carassius carassius), which differ in regard to thermal tolerance and activity pattern. Burbot are cold stenothermal and cold-active, while crucian carp are eurythermal and cold-dormant. The fish were acclimated at 4 °C (cold-acclimation, CA) or 18 °C (warm-acclimation, WA) and expression of SERCA proteins and transcript was measured from atrium and ventricle. Burbot heart expresses one major isoform of SERCA (110 kDa), while crucian carp heart expresses two isoforms (110 and 93 kDa). Expression of SERCA proteins was about four times higher ( P < 0.05) in the heart of CA burbot than WA burbot, in both cardiac chambers. In the heart of crucian carp, thermal acclimation did not affect SERCA proteins, in either chamber ( P > 0.05). The expression of SERCA transcripts did not follow the expression pattern of SERCA protein in either species, suggesting that SERCA expression is mainly regulated posttranscriptionally. These findings show that the stenothermal and cold-active burbot compensates for the decrease in ambient temperature by increasing the expression of SERCA. In the eurythermal and cold-dormant crucian carp SERCA expression is independent of temperature, while the presence of two SERCA isoforms may provide some thermal independence in SR Ca pumping. [ABSTRACT FROM AUTHOR]