Bighead Carp Research Articles

Proteomic evidence of protein degradation and oxidation in brined bighead carp fillets during long-term frozen storage

Protein degradation and oxidation are two major alterations during the storage of processed bighead carp fillets. This study conducted a comparative analysis of degraded and oxidized products as well as oxidation sites in fresh, frozen and brined frozen bighead carp fillets. Frozen storage played a dominant role in protein degradation and oxidation, and brining promoted these changes. In brined frozen samples, the decreased SDS-PAGE band intensities for tropomyosin, troponin, and myosin light chain were mainly due to their degradation. Myosin heavy chain fast skeletal muscle was the most oxidized and degraded protein during storage, with modifications such as monooxidation, protein-lipid peroxidation adducts, and α-aminoadipic semialdehydes formation. Amino acids in the tail portion of myosin were prone to oxidation than the head portions. Our results provided comprehensive insights into protein degradation and oxidation in bighead carp during storage, helping to assess the specific fate of oxidative products in future dietary investigations.

Non-linear effects on the population performance of Bighead Carp under different maturation schedules

Bighead Carp currently threatens to invade the Laurentian Great Lakes from the Mississippi River, but the novel climatic conditions it will encounter by expanding northwards could affect its population performance. Bighead Carp in colder climates exhibits slower growth and matures later, with later maturation typically leading to larger adult size and increased fecundity and survival. Accordingly, the life-history strategies of Bighead Carp at its northern range limits could differ from those observed in its current invaded range. To explore how population performance could differ across changing environmental conditions, we used a stage- and age-based matrix population model parameterized with values reported for Bighead Carp populations around the world. The model was used to evaluate how different ages of maturity and their resulting impacts to body size, survival, and fecundity could impact rates of population growth and establishment. Age of maturity had a non-linear effect on population growth, with maturation at intermediate ages (4–6 years) resulting in better performance. However, performance differed less between maturation ages when fecundity was allowed to increase disproportionately with body size. Greater population growth at younger ages of maturity suggest that invasion at lower latitudes could enable establishment in fewer years due to faster rates of development in warmer temperatures. Across all maturation schedules, population growth was most sensitive to the recruitment of age-1 individuals and least sensitive to adult survival, and vital rates overall varied more in their contribution to population growth at younger ages of maturity. Thus, understanding the factors that control age-1 recruitment would inform projections of population performance for Bighead Carp in the Laurentian Great Lakes.

Preparation of polysaccharide-based nanoparticles by chitosan and flaxseed gum polyelectrolyte complexation as carriers for bighead carp (Aristichthys nobilis) peptide delivery

Polysaccharide-based nanoparticles formed by the polyelectrolyte complexation between chitosan (CS) and flaxseed gum (FG) was developed in this work, and it was further used as a carrier for bighead carp peptide (BCP) delivery. The CS molecular weight (MW) of 50 kDa and CS/FG mass ratio of 1:2 at pH 3.5 were optimal conditions for the NP preparation, with the minimum particle size (∼155.1 nm) and the maximum BCP encapsulation efficiency (60.3 %). The BCP-loaded CS/FG NPs exhibited the smallest particle size (175.8 nm). Both CS/FG NPs and CS/FG-BCP NPs exhibited roughly uniform spherical shape. FT-IR spectra confirmed the existence of hydrogen bonds and electrostatic interactions in the nanoparticles. The BCP-loaded NPs displayed a higher thermal stability than BCP. Moreover, the release of BCP was controllable and dose-dependent, following a first-order kinetics model. These findings suggested that our CS/FG NPs are a promising carrier for bioactive peptide delivery.

Incorporating metapopulation dynamics to inform invasive species management: Evaluating bighead and silver carp control strategies in the Illinois River

Abstract Invasive species management can benefit from predictive models that incorporate spatially explicit demographics and dispersal to guide resource allocation decisions. We used invasive bigheaded carps (Hypophthalmichthys spp.) in the Illinois River, USA as a case study to create a spatially explicit model to evaluate the allocation of future management efforts. Specifically, we compared additional harvest (e.g. near the invasion front vs. source populations) and enhanced movement deterrents to meet the management goal of reducing abundance at the invasion front. We found additional harvest in lower river pools (i.e. targeting source populations) more effectively limited population sizes upriver at the invasion front compared to allocating the same harvest levels near the invasion front. Likewise, decreasing passage (i.e. lock and dam structures) at the farthest, feasible downriver location limited invasion front population size more than placing movement deterrents farther upriver. Synthesis and applications. Our work highlights the benefits of adopting a multipronged approach for invasive species management, combining suppression of source populations with disrupting movement between source and sink populations thereby producing compounding benefits for control. Our results also demonstrate the importance of considering metapopulation dynamics for invasive species control programs when achieving long‐term management goals.

A Study on Nitrogen and Phosphorus Budgets in a Polyculture System of Oreochromis niloticus, Aristichthys nobilis, and Cherax quadricarinatus

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.

Amino Acid Variation at the Mitochondrial Binding Site of Antimycin A is Proposed to Reflect Sensitivity and Toxicity Differences among Fish Species

To better understand differential sensitivities among fish species to the piscicidal compound Antimycin-A (ANT-A), we hypothesized that variations in amino acids at the ANT-A binding site may reflect toxicity differences. Protein sequences for six motifs comprising the ANT-A binding site were obtained and compared for invasive carp species (N = 515) and seven non-target species (N = 277); a consensus was delineated from each species. The carp species, Common Carp (Cyprinus carpio), Silver Carp (Hypophthalmichthys molitrix), Bighead Carp (Hypophthalmichthys nobilis), Grass Carp (Ctenopharyngodon idella), and Black Carp (Mylopharyngodon piceus), showed the same amino acids at the site; thus, it was termed the carp consensus motif sequence (CCM). Channel Catfish (Ictalurus punctatus) showed the most amino acid polymorphisms, with three motifs 96–100% different from CCM. Within a species, Bluegill (Lepomis macrochirus) and Fathead Minnow (Pimephales promelas) variation per motif was most dissimilar (46.7% and 21.6%, respectively). Organismal mortality data from the literature indicated Yellow Perch (Perca flavescens), Walleye (Sander vitreus), and American Gizzard Shad (Dorosoma cepedianum) to be most sensitive to the piscicide, Catfish least sensitive, and all others intermediate. The protein sequence variations of the binding site appeared to be in accord with organismal sensitivity categories when they differed from the CCM; the motifs in Gizzard Shad and Walleye were the same as in CCM. The physical/chemical nature of ANT-A is important to consider in organismal response comparisons. This cellular approach of studying ANT-A binding at its target enzyme is a non-destructive way to predict piscicidal efficacy of ANT-A against fishes of interest, informs management decisions in control efforts for invasives, and can be used to forecast effects on sympatric species.

Coupled multimedia fate and bioaccumulation models for predicting fate of florfenicol and fluoroquinolones in water and fish organs in the seasonal ice-sealed reservoir

Ice formation in reservoirs could promote the accumulation of antibiotics in fish, potentially leading to elevated concentrations in fish muscles, kidneys, and livers. However, for the seasonal ice-sealed reservoirs, antibiotic sampling and detecting conditions in water and fish are normally limited by the ice cover. Additionally, previous studies on the prediction of antibiotics accumulated in seasonal ice-sealed reservoir fish are scarce. This study presents a coupled model incorporating a multimedia fate model and a bioaccumulation model to predict antibiotic fate in water and the muscles, kidneys, and livers of fish in seasonal ice-sealed reservoirs. Prediction concentrations of florfenicol were higher than those of ofloxacin and norfloxacin in both water and fish from the seasonal ice-sealed reservoir. Log bioaccumulation factors of antibiotics in Cyprinus carpio and Hypophthalmichthys nobilis in January 2021 were higher than those in October 2020 by 21.5% and 12.6%, respectively. Antibiotics mean transfer fluxes from water to fish muscles, kidneys, and livers increased owing to the reservoir ice-cover formation date advancing by 13.0%, 77.1%, and 61.0%, respectively. This work provides a modeling tool for investigating the fate and mass transfer flux of antibiotics in biological and environmental phases in seasonal ice-sealed reservoirs.

Bioaccumulation and Health Risk Assessment of Heavy Metals in Some Fish Species Available in Local Fish Markets of Kathmandu, Nepal

In this study, concentrations of Cd, Cr, Mn, Pb, and Zn were determined by flame atomic absorption spectrophotometer (FAAS) in edible muscle tissues of a total of 25 fish samples belonging to five fish species viz., Hypophthalmichthys nobilis (Bighead), Wallago attu (Buhari), Catla catla (Catla), Clarias batrachus (Mugree), and Labeo rohita (Rohu) marketed in Kathmandu, Nepal and evaluated potential health risks for adults using USEPA deterministic approaches. The average metal accumulation in all fish species followed the order of Zn (27.89) > Mn (5.36) > Pb (2.37) > Cr (1.12) > Cd (0.44) mg/kg, exceeding the FAO/WHO guidelines except for Zn. Likewise, the sum of average metal concentrations (∑5HM) followed the descending order of C. catla (49.61) > C. batrachus (44.49) > W. attu (34.51)> H. nobilis (32.10) > L. rohita (25.18) mg/kg. The correlation matrix showed significant correlations among some HMs indicating their common sources of origin in the examined fish species. The estimated daily intakes (EDIs) of HMs were lower than the maximum tolerable daily intake (MTDI). The target hazard quotients (THQs) of a single element in all fish species were less than 1.0 while the total target hazard quotients (TTHQs) in C. batrachus, C. catla, and H. nobilis exceeded the safe limit of 1.0 suggesting a potential non-carcinogenic risk. Moreover, the target cancer risks (TRs) of Cd and Cr were higher than the acceptable risk limit (10−4) in all fish species suggesting that their consumption might pose a lifetime cancer risk for adults. Therefore, the study recommends regular monitoring of HMs in commercial fish to ensure the safety of consumer health. Int. J. Appl. Sci. Biotechnol. Vol 11(2): 85-98.

Genetic structure of the herds of two bighead carp species in «Аgrofirm Кolos» PLC

The allelic and genotypic composition of herds of silver carp and bighead carp of Agrofirma Kolos PLC (Kyiv region) was studied. The method of electrophoresis in a polyacrylamide gel with histochemical staining and subsequent genotyping of samples according to the three most variable blood proteins: transferrin, albumin, and esterase is used to detect molecular genetic markers. The number of three-year-old fish that were used to take blood samples for genetic research was 20 specimens for each species of fishes. The frequency of alleles and genotypes, actual and expected heterozygosity, and fixation indices were calculated. According to the results of the study, the predominance of heterozygous genotypes over homozygous genotypes at all three studied loci was found in the herds of both types of fish. The highest level of heterozygosity was established at the transferrin locus (98% in silver carp and 66.2% in bighead carp), the lowest was at the albumin locus (65% in silver carp and 50.8% in bighead carp). A slight excess of heterozygous individuals was found for transferrin and esterase loci in the herd of silver carp. For the bighead carp, this was found only in the transferrin locus. The influence of inbreeding on the formation of the genetic structure of herds of both species of fishes was revealed. To prevent the negative impact of inbreeding, it is recommended to use the high genetic variability of herds for the heterogeneous selection of fish for breeding purposes and to carry out cyclic genetic monitoring of the stock.

Herbivorous Grass Carp (Ctenopharyngodon idella) Exhibit Greater Olfactory Response to Amino Acids Than Filter-Feeding Bighead (Hypophthalmichthys nobilis) and Silver Carp (Hypophthalmichthys molitrix)

Due to their invasiveness in North America, grass (Ctenopharyngodon idella), bighead (Hypophthalmichthys nobilis), and silver carp (Hypophthalmichthys molitrix) are management priorities. Comparing electrophysiological responses to olfactory cues, such as amino acids, could help identify stimuli to facilitate management efforts (i.e., repellants or baits). We assessed olfactory response magnitude to individual amino acids between fish species using electro-olfactogram recording techniques (EOG). We measured EOG responses (peak EOG magnitude) of juvenile grass (n = 21), bighead (n = 21), and silver carp (n = 22) to 10−4 molar amino acid solutions containing one of L-alanine, L-arginine, L-aspartic acid, L-asparagine, L-glutamine, or L-glutamic acid. Amino acid EOG responses differed across species; grass carp had the greatest mean EOG response. Statistical analyses showed no inter- or intra-specific differences in EOG response among amino acids. The greater EOG response of grass carp matched their selective grazing habits compared to more passive, generalist-tending, filter-feeding bighead and silver carp. All amino acids elicited significant EOG responses in all species, meaning they are candidates for future behavioral research. Such research could explore the management potential of amino acids, testing if amino acids are attractants or deterrents that could facilitate the removal of these fishes by congregating and/or directing movement.

FIRST RECORD OF A PARASITE, DACTYLOGYRUS CF. SKRJABINI (MONOGENOIDEA: DACTYLOGYRIDAE), INFECTING INVASIVE SILVER CARP, HYPOPHTHALMICHTHYS MOLITRIX (VALENCIENNES, 1844) (CYPRINIFORMES: XENOCYPRIDIDAE) IN NORTH AMERICA.

The parasites infecting invasive carps in North America (all Cypriniformes: Xenocyprididae: grass carp, Ctenopharyngodon idella [Valenciennes, 1844]; silver carp, Hypophthalmichthys molitrix [Valenciennes, 1844]; bighead carp, Hypophthalmichthys nobilis [Richardson, 1845]; and black carp, Mylopharyngodon piceus [Richardson, 1846]) are little studied, and no parasite has been reported from silver carp there. We herein surveyed silver carp from Barkley Reservoir and Cheatham Reservoir (Cumberland River, Tennessee; June and December 2021) and the White River (Arkansas; May 2022) and collected numerous monogenoid specimens infecting the pores on the outer face of the gill raker plate. We heat-killed, formalin-fixed, and routinely stained some specimens for morphology and preserved others in 95% ethanol for DNA extraction and sequencing of the large subunit ribosomal DNA (28S). We identified our specimens as Dactylogyrus cf. skrjabini because they had a dorsal anchor deep root that is much longer than the superficial root, an approximately parallel penis and accessory piece, and a relatively large marginal hook pair V. No type specimen of Dactylogyrus skrjabiniAkhmerov, 1954 (type host and locality is silver carp, Amur River, Russia) is publicly available, but we borrowed several vouchers (NSMT-Pl 6393) that infected the gill rakers of silver carp captured in the Watarase River, Japan. The original description of D. skrjabini was highly stylized and diagrammatical, differing from the specimens we studied from North America and Japan by the dorsal anchor having a superficial root and shaft that comprise a strongly C-shaped hook (the superficial root curves toward the dorsal anchor point) (vs. superficial root straight, at ∼45° angle to deep root and directed away from the dorsal anchor point), a single, much reduced transverse bar that is narrow for its entire breadth (vs. dorsal and ventral transverse bars robust and broad, having an irregular outline), an accessory piece that lacks digitiform projections (vs. accessory piece with 4 digitiform projections), and an accessory piece that lacks a half cardioid-shaped process (vs. accessory piece having a half cardioid-shaped process). Our 28S sequences (generated from 4 specimens of D. cf. skrjabini: 2 from Tennessee [763 base pairs (bp)] and 2 from Arkansas [776 bp]) were identical to 1 ascribed to D. skrjabini from Japan. The present study is the first verifiable and credible report of a parasite from silver carp in North America and the first nucleotide information for a parasite from silver carp in North America.

Species specifics of morphology of the liver of the fishes of the Cyprinidae family

Providing mankind with high-quality products of aquaculture is possible only by introduction of modern industrial technologies to fish farming, growing fish based on modern scientific achievements. Assessment of the ecotoxic situation and identification of impacts of various unfavourable factors of aquatic environment on aquatic organisms should be made through morphological studies of the organs that are first to encounter the impact. The study revealed species specifics of the morphology of the liver of the fishes of the Cyprinidae family – Prussian carp (Carassius gibelio), Eurasian carp (Cyprinus carpio), and bighead carp (Hypophthalmichthys nobilis), which vary by extent of the motor activity in the aquatic environment, nutrition, etc. We determined that during phylogenetic development of fish that grow in the aquatic environment, there occurs a certain restructuring of the liver: the adaptation to various living conditions were accompanied by changes in a number of parameters of macro- and microscopic architectonics of the liver. Cyprinus carpio and Carassius gibelio (omnivores) have a two-lobe liver, while Hypophthalmichthys nobilis (a herbivore) has a three-lobe liver. For C. carpio and H. nobilis, a characteristic feature of the liver was presence of the hepatopancreatitis (the liver and the pancreas, associated into a single organ), and in C. gibelio, they are differentiated into individual organs. A peculiarity of the microscopic structure of the liver of the Cyprinidae family is poorly developed interlobular connective tissue, and parenchyma of the liver lobule has a tubular structure as polyhedral, curved thick-walled tubules, the walls of which are hepatocytes. The greatest amounts of cytoplasm and karyoplasms were seen in C. gibelio, equaling respectively 12.98 ± 1.42 and 0.40 ± 0.02 µm³. The lowest volume of the indicated parameters was in C. carpio, particularly 2.97 ± 0.22 and 0.21 ± 0.01 µm³, respectively. The lowest nuclear-cytoplasmic ratio was observed in hepatocytes of C. gibelio (0.0316 ± 0.0024). The conducted morphological studies at the levels of organs, tissues and cells can reveal how the fishes’ bodies adapt to particular living conditions and impacts of environmental factors.

The dynamic changes of microbial diversity and biogenic amines in different parts of bighead carp (Aristichthys nobilis) head during storage at −2 ℃

Microorganisms are important factors in fish spoilage, causing the degradation of amino acids to form undesired biogenic amines (BAs). Thus, the composition of BAs and microorganisms in the four parts of bighead carp head and the surface mucus were evaluated in this work during storage at −2 ℃. Seven BAs were measured in fish head samples, including tryptamine (TRY), phenethylamine (PHE), putrescine (PUT), cadaverine (CAD), tyramine (TYR), spermidine (SPD), and spermine (SPM). PHE, TYR and PUT were the predominant ones, whose contents in different parts of fish heads generally ascended during the storage. These samples contained microbiota comprising 202 species and a total of 41 phyla and 391 genera. As the storage proceeded, the bacterial diversity of all samples decreased significantly. Additionally, the main phyla of Proteobacteria, Bacteroidetes, and Firmicutes were identified, and the major genera were Shewanella, Flavobacterium, and Lactococcus. In-depth correlation analysis also found that the abundances of Streptococcus, Proteocatella and Lactococcus were positively related to the accumulation of PUT, PHE and TYR, indicating the key roles of these bacteria in the formation of BAs. These findings in the present work would provide a guideline for future investigations on the preservation and processing of fish.

Effects of protein and lipid oxidation on the water holding capacity of different parts of bighead carp: Eye, dorsal, belly and tail muscles

The quality of fish can change due to differences in the lipid and protein oxidation rates in different muscles. This study examined vacuum-packed eye muscle (EM), dorsal muscle (DM), belly muscle (BM), and tail muscle (TM) of bighead carp frozen for 180 days. The results reveal that EM had the highest lipid content and the lowest protein content, while DM had the lowest lipid content and the highest protein content. EM also showed the highest values of centrifugal loss and cooking loss, and the correlation analysis showed that these losses were positively correlated with dityrosine content and negatively correlated with conjugated triene content. The content of carbonyl, disulfide bond, and surface hydrophobicity of myofibrillar protein (MP) also increased with time, with DM having the highest values. The microstructure of EM was looser than other muscles. Therefore, DM had the fastest oxidation rate and EM had the lowest water holding capacity.

Limnotrachelobdella hypophthalmichthysa n. sp. (Hirudinida: Piscicolidae) on Gills of Bighead Carp Hypophthalmichthys nobilis in China.

We describe the characterization of a novel fish leech species found on the gills of bighead carp (Hypophthalmichthys nobilis) from lakes and reservoirs in China. This leech is morphologically similar to Limnotrachelobdella sinensis recorded on goldfish and common carp. However, there are 0-2 pairs of symmetrical or asymmetrical eyes and 10 pairs of pulsatile vesicles in the newly discovered leech, in remarkable contrast to L. sinensis. Except for bighead carp, where it demonstrated a higher than 90% prevalence, and silver carp (H. molitrix), where there was low infection, this leech was not detected on any other fish from the Qiandao reservoir in China that were examined during this investigation. Molecular analyses indicated 87.8% ITS sequence identity with L. sinensis and 85.0 and 86.1% COX1 sequence identity with L. sinensis and L. okae, respectively. The uncorrected p-distance based on the COX1 sequence was found to be 15.1 and 14.0% for L. sinensis and L. okae, respectively, suggesting interspecific variation. Phylogenetic analyses based on the combination of 18S and COX1 sequences showed that the newly discovered leech groups with Limnotrachelobdella species. Histopathological observation indicated that attachment of the leech on the gill rakers and gill arches causes a loss of connective tissue, hemorrhage, and ulceration. Based on the morphology, molecular analyses, and host specificity, we conclude that this leech is a new species of Limnotrachelobdella and named it Limnotrachelobdella hypophthalmichthysa n. sp.

The impact of culture systems on the gut microbiota and gut metabolome of bighead carp (Hypophthalmichthys nobilis)

BackgroundThe gut microbiota of fish confers various effects on the host, including health, nutrition, metabolism, feeding behaviour, and immune response. Environment significantly impacts the community structure of fish gut microbiota. However, there is a lack of comprehensive research on the gut microbiota of bighead carp in culture systems. To demonstrate the impact of culture systems on the gut microbiome and metabolome in bighead carp and investigate a potential relationship between fish muscle quality and gut microbiota, we conducted a study using 16S ribosomal ribonucleic acid sequencing, gas chromatography-mass spectrometry, and liquid chromatography-mass spectrometry techniques on bighead carp in three culture systems.ResultsOur study revealed significant differences in gut microbial communities and metabolic profiles among the three culture systems. We also observed conspicuous changes in muscle structure. The reservoir had higher gut microbiota diversity indices than the pond and lake. We detected significant differences in phyla and genera, such as Fusobacteria, Firmicutes, and Cyanobacteria at the phylum level, Clostridium sensu stricto 1, Macellibacteroides, Blvii28 wastewater sludge group at the genus level. Multivariate statistical models, including principal component analysis and orthogonal projections to latent structures-discriminant analysis, indicated significant differences in the metabolic profiles. Key metabolites were significantly enriched in metabolic pathways involved in "arginine biosynthesis" and "glycine, serine, and threonine metabolism". Variation partitioning analysis revealed that environmental factors, such as pH, ammonium nitrogen, and dissolved oxygen, were the primary drivers of differences in microbial communities.ConclusionsOur findings demonstrate that the culture system significantly impacted the gut microbiota of bighead carp, resulting in differences in community structure, abundance, and potential metabolic functions, and altered the host's gut metabolism, especially in pathways related to amino acid metabolism. These differences were influenced substantially by environmental factors. Based on our study, we discussed the potential mechanisms by which gut microbes affect muscle quality. Overall, our study contributes to our understanding of the gut microbiota of bighead carp under different culture systems.

Changes of Fatty Acid Compositions, Volatile Compounds, and Microbial Flora of Bighead Carp (Aristichthys nobilis) Heads during the Simulated Fresh Logistics Transportation

The changes of fatty acid compositions, volatile components, and microbial flora of bighead carp heads during fresh transportation were investigated. The brain, eye muscle, muscle near the incision (on the abdomen 5 cm away from the gills), and jaw muscle of bighead carp heads at ambient temperature (25°C) for 6 h and simulated fresh transportation (underwent ice storage and vibration) for 36 h and 72 h were evaluated. The content of monounsaturated fatty acids (38.98%) in four parts of bighead carp heads was the highest followed with saturated fatty acids (30.92%) band polyunsaturated fatty acids (24.50%), and their contents as well as the sensory quality were decreased significantly with the prolongation of fresh transportation time. There were significant differences in the composition and contents of volatile flavor compounds in the bighead carp heads during fresh transportation, including alcohols, aldehydes, esters, aromatic compounds, hydrocarbons, and other compounds, especially ketones and amines. In addition, the species richness of bighead carp heads decreased gradually with the extension of transportation time. The flora was mainly composed of Firmicutes and Proteus at the phylum level and Streptococcus and Lactococcus at the genus level. Conclusively, ketone and amine compounds in volatile substances as well as the dominant spoilage bacteria (Streptococcus) in the flora could be used as spoilage markers during the fresh transportation of bighead carp heads. Practical Application. Bighead carp head has gradually become a hot online product in China due to its rich nutrition and delicious taste. Fresh transportation is one of the most common methods for preserving fish to improve its nutrition, flavor, and taste. This paper is aimed at investigating the changes in quality, fatty acid content, volatile compounds, and microbial flora of bighead carp heads during fresh transportation. The results of this study provide a better understanding of the spoilage volatiles and bacteria for bighead carp heads during fresh transportation. It could provide a guiding and theoretical basis for the routine fresh-keeping transportation of bighead carp heads and offer a security assessment for their nutritional value.

Transcriptome analyses reveal differentially expressed genes associated with development of the palatal organ in bighead carp (Hypophthalmichthys nobilis)

The palatal organ is a filter-feeding related organ and occupies a considerable proportion of the head of bighead carp (Hypophthalmichthys nobilis), a large cyprinid fish intensive aquaculture in Asia. In this study, we performed RNA-seq of the palatal organ during growth periods of two (M2), six (M6) and 15 (M15) months of age after hatching. The numbers of differentially expressed genes (DEGs) were 1384, 481 and 1837 for M2 VS M6, M6 VS M15 and M2 VS M15 respectively. The following signaling pathways of energy metabolism and cytoskeleton function were enriched, including ECM-receptor interaction, Cardiac muscle contraction, Steroid biosynthesis and PPAR signaling pathway. Several members of collagen family (col1a1, col2a1, col6a2, col6a3, col9a2), Laminin gamma 1 (lamc1), integrin alpha 1 (itga1), Fatty acid binding protein 2 (fads2) and lipoprotein lipase (lpl), and Protein tyrosine kinase 7 (Ptk7) are candidate genes for growth and development of basic tissues of the palatal organ. Furthermore, taste-related genes such as fgfrl1, fgf8a, fsta and notch1a were also identified, which may be involved in the development of taste buds of the palatal organ. The transcriptome data obtained in this study provide insights into the understanding functions and development mechanisms of palatal organ, and potential candidate genes that may be related to the genetic modulation of head size of bighead carp.

Impact of Enzymatic Hydrolysis Using Two Proteases on Functional, Structural, and Antioxidant Properties of Protein Hydrolysates Derived from Fresh and Microwave-dried Substrates of Bighead Carp (Hypophthalmichthys Nobilis)

Impact of Enzymatic Hydrolysis Using Two Proteases on Functional, Structural, and Antioxidant Properties of Protein Hydrolysates Derived from Fresh and Microwave-dried Substrates of Bighead Carp (Hypophthalmichthys Nobilis)

Species-specific bioaccumulation and risk prioritization of psychoactive substances in cultured fish

Psychoactive substances are becoming new concern in environmental research with their increasing applications and the potential threats to fishery production as these substances could alter the behavior of fish and consequently affect the yield and quality of cultured fish. In this study, the accumulation and risk of twenty psychoactive substances were investigated in five species of cultured fish in Eastern China. The results showed that the total concentrations of these twenty psychoactive substances ranged from 0.15 to 0.92 ng mL−1 in the plasma among the five species of cultured fish with an order of perch > crucian carp > bighead carp > grass carp > silver carp. Diazepam (DIAZ) and methamphetamine (MAMP) were identified as the most frequently detected compounds, which were found in 100% and 93% of the samples with a median concentration of 0.15 and 0.12 ng mL−1 in the plasma, respectively. Although all of the psychoactive substances posed low or negligible risk, species-specific analysis of risk prioritization revealed that alprazolam, MAMP, temazepam and DIAZ exhibited the greatest potentials of hazard to all species of the cultured fish but with a species-dependent variation. These findings suggest that the adverse effects of psychoactive substances on fishery production, especially on different species, should be considered.