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Aeromonas salmonicida is one of the most prevalent pathogens that causes huge economic losses to aquaculture. Effective vaccination is the first choice for preventing infection. Bacterial ghost (BG), an empty bacterial shell devoid of cytoplasm, is a promising vaccine antigen with distinct advantages. Herein, we established strategies for producing a substantial yield of A. salmonicida ghost (ASG) and investigated the immune-protective properties of it. As a result, 2.84 mg/ml NaOH was discovered to be capable of inducing considerable amounts of ASG. Furthermore, the ASG vaccine elicited adaptive immunity in turbots after rapid activation of innate immunity. Even though formalin-killed cells (FKC) produced a few more antibodies than ASG, ASG ultimately provided a much stronger immune protection effect because it strengthened cellular immunity, with a relative percentage survival (RPS) of 50.1 % compared to FKC. These findings demonstrated that ASG effectively activated cell-mediated immunity, which helped get rid of microorganisms inside cells. Therefore, this study presented novel perspectives for future research on furunculosis vaccine products based on ASG as an antigen. • Aeromonas salmonicida ghost (ASG) is a superior immunogen for inactivated vaccines. • The relative percentage survival of immunized turbot was up to 50.1 %. • ASG has the ability to induce a stronger cellular immune response. [ABSTRACT FROM AUTHOR]

Fish physiological health is often negatively impacted by high-temperature environments and there are few studies on how dietary lipids affect fish growth and physiology when exposed to heat stress. The main objective of this research was to examine the impact of dietary lipid levels on growth and physiological status of juvenile turbot (Scophthalmus maximus L.) and determine if dietary lipid concentration could alleviate the possible adverse effects of heat stress. Five diets containing 6.81%, 9.35%, 12.03%, 14.74%, and 17.08% lipid, respectively, were formulated and fed to turbot (initial weight 5.13 ± 0.02 g) under high-temperature conditions (24.0–25.0 °C). Meanwhile, the diet with 12.03% lipid (considered by prior work to be an optimal dietary lipid level) was fed to turbot of the same size at normal temperature. Results suggested that, among the different dietary lipid levels under high-temperature conditions, fish fed the optimal lipid (12.03%) exhibited better growth compared to non-optimal lipid groups, as evidenced by higher weight gain and specific growth rate. Simultaneously, the optimal lipid diet may better maintain lipid homeostasis, as attested by lower liver and serum lipid, along with higher liver mRNA levels of lipolysis-related genes (pgc1α , lipin1 , pparα , lpl and hl) and lower levels of synthesis-related genes (lxr , fas , scd1 , pparγ , dgat1 and dgat2). Also, the optimal lipid diet might mitigate oxidative damage by improving antioxidant enzyme activity, decreasing malondialdehyde levels, and up-regulating oxidation-related genes (sod1 , sod2 , cat , gpx and ho-1). Furthermore, the optimal lipid may enhance fish immunity, as suggested by the decrease in serum glutamic-oxalacetic/pyruvic transaminase activities, down-regulation of pro-inflammatory genes and up-regulation of anti-inflammation genes. Correspondingly, the optimal lipid level suppressed MAPK signaling pathway via decreased phosphorylation levels of p38, JNK and ERK proteins in liver. In summary, the optimal dietary lipid level facilitated better growth and physiological status in turbot under thermal stress. [Display omitted] • Optimal lipids improved growth and health of turbot at high temperature. • Optimal lipids at high temperature reduced growth compared to ambient temperature. • Based on SGR, optimal dietary lipid at high temperature was 12.05%. [ABSTRACT FROM AUTHOR]

The Pleuronectiformes order, which includes several commercially-important species, has undergone extensive chromosome evolution. One of these species is Solea senegalensis, a flatfish with 2n = 42 chromosomes. In this study, a cytogenomics approach and integration with previous maps was applied to characterize the karyotype of the species. Synteny analysis of S. senegalensis was carried out using two flatfish as a reference: Cynoglossus semilaevis and Scophthalmus maximus. Most S. senegalensis chromosomes (or chromosome arms for metacentrics and submetacentrics) showed a one-to-one macrosyntenic pattern with the other two species. In addition, we studied how repetitive sequences could have played a role in the evolution of S. senegalensis bi-armed (3, and 5–9) and acrocentric (11, 12 and 16) chromosomes, which showed the highest rearrangements compared with the reference species. A higher abundance of TEs (Transposable Elements) and other repeated elements was observed adjacent to telomeric regions on chromosomes 3, 7, 9 and 16. However, on chromosome 11, a greater abundance of DNA transposons was detected in interstitial BACs. This chromosome is syntenic with several chromosomes of the other two flatfish species, suggesting rearrangements during its evolution. A similar situation was also found on chromosome 16 (for microsatellites and low complexity sequences), but not for TEs (retroelements and DNA transposons). These differences in the distribution and abundance of repetitive elements in chromosomes that have undergone remodeling processes during the course of evolution also suggest a possible role for simple repeat sequences in rearranged regions. [ABSTRACT FROM AUTHOR]

Propolis is non-hazardous resinous substance mixture containing bioactive ingredients such as polyphenols, flavonoids and organic acid. It has been widely used as food supplement and immune adjuvant due to its benefits in anti-microbial and immunomodulation. Edwardsiella piscicida is a kind of threatening pathogen which could cause high mortality in turbot. However, whether propolis could enhance the innate immune response against E. piscicida infection in turbot remains unknown. In this study, we found dietary propolis addition could improve the expression of anti-oxidative stress related enzymes, e.g., SOD, CAT and GPT, and relieved the histopathological changes of juvenile turbot after E. piscicida infection. Moreover, propolis addition increased the expression of cytokines such as il-1β , il-6 and tnf-α in different organs of juvenile turbot. Importantly, rescued survival and decreased bacterial loads were observed in propolis feeding group. Taken together, these findings suggest that the important roles of propolis in protecting juvenile turbot from E. piscicida infection, indicating propolis might be applied as a promising immunopotentiator candidate in aquaculture. • Dietary propolis addition could enhance anti-oxidant stress activity of turbot. • Dietary propolis addition improved immune defense against E. piscicida infection of turbot. • The protection period could last at least 3 weeks after 4-week propolis feeding trail. [ABSTRACT FROM AUTHOR]

Peroxisome proliferator‐activated receptor alpha (PPARα), as a transcription factor, plays an important role in the regulation of lipid metabolism. To better understand the regulatory role of PPARα in lipid metabolism in turbot, we analyzed the sequence structure of PPARα and its stress response to a high temperature. We also investigated the regulation of genes related to lipid metabolism after the knockdown of PPARα. The CDS of PPARα was 1410 bp, encoding 469 amino acids. The relative molecular weight of the protein was 52.64 kDa, and the predicted pI was 5.63. The architecture of the PPARα gene exhibited a ZnF‐C4 domain and a HOLI domain. Phylogenetic analysis indicated that PPARα has been highly conserved during evolution. The qPCR results showed that the mRNA level of PPARα was significantly increased, and the expression of the lipid synthesis genes FASN and SCD was significantly downregulated under high‐temperature stress. PPARα interference and inhibition results showed that the expression levels of FASN and SCD were significantly increased. Our results suggest that high temperatures activate PPARα and inhibit lipid synthesis by downregulating the expression of FASN and SCD in order to reduce lipid deposition and maintain lipid metabolism disorder caused by high‐temperature stress. This is the first report of PPARα in turbot. It will help for studying the evolution of PPARα and provide a reliable reference for studying the regulation mechanism of lipid metabolism in fish under stress. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the organismal responses of farmed and wild-caught turbot, Scophthalmus maximus, based on analyses of biochemical plasma parameters, leukocyte profile, and histological tissue profile of gills, kidney, liver, intestine, and spleen, as well as gene expression of stress proteins in kidney and liver tissue. The results revealed significant differences in plasma triglycerides (TRIG), total protein (TP), albumin (ALB), globulin (GLOB), bilirubin (TBIL), creatinine (CRE) levels, creatine kinase (CK), and superoxide dismutase (SOD) activities that were higher, and A/G ratio, calcium (Ca) and phosphorus (P) concentrations, alkaline phosphatase (ALP), and glutathione peroxidase (GPx) activity, which were lower in farmed population. The neutrophil-leukocyte (N:L) ratio and gene expression of HSP70, HSP90, and WAP65-2 were increased in the wild-caught turbot. The wild-caught turbot were infested with the gill digenean parasite Dactylogyrus sp. and tapeworm Bothriocephalus scorpii. The obtained results provide valuable data for the assessment of the physiological responses of turbot for future comparative studies of the effects of various endogenous and exogenous factors on homeostasis of this species. [ABSTRACT FROM AUTHOR]

Other genes identified in PF08 included some general stress response-related genes, including the antioxidant protein-coding gene I ahpC i , glutathione peroxidase-coding gene I bsaA i , starvation stringent protein-coding genes I sspA i and I sspB i , and heavy metal detoxification-related genes I cusS i and I merR i . Effects of Quorum Sensing System on the Transcription of Spoilage-Related Genes in PF08 An overnight culture of I P. fluorescens i PF08 (OD SB 595 sb = 1) was diluted 1:100 in fresh LB broth (pH 7.0 ± 0.2). Moreover, the QS system in PF08 was inhibited or activated by cinnamaldehyde or C SB 4 sb -HSL in this study and the regulatory effect of the QS system on spoilage-related genes in PF08 was evaluated by analyzing the changes of transcription level of these key genes. Keywords: Pseudomonas fluorescens PF08; complete genome; spoilage ability; quorum sensing; specific spoilage organism EN Pseudomonas fluorescens PF08 complete genome spoilage ability quorum sensing specific spoilage organism 1 13 13 04/21/22 20220418 NES 220418 Introduction Food spoilage is a complex process that is caused mainly by the metabolic activities of specific spoilage organisms (SSOs). [Extracted from the article]

(i) the signalling pathway of fish-specific TLRs remain unclear; (ii) the ligand of some fish TLRs remains unclear; (iii) the expressions of fish TLRs are species-specific and tissue-specific, indicating that the function of the same TLR might vary in different fish species (Roach et al., 2005). Keywords: gene expression; innate immune; Micropterus salmoides; toll-like receptors EN gene expression innate immune Micropterus salmoides toll-like receptors 2562 2566 5 03/21/22 20220415 NES 220415 INTRODUCTION Toll-like receptors (TLRs) are important patterns recognition receptors (PRRs) of host which mainly involve in recognizing pathogens (Moresco et al., 2011). Only 13 TLRs were identified in mammals (10 TLRs in human: TLR1-TLR10; and 12 TLRs in mouse: TLR1-TLR9, TLR11-TLR13; Vidya et al., 2018). [Extracted from the article]

Fatty acid-binding proteins (fabps) play important roles in lipid homeostasis. In the present study, 7 fabp isoforms, namely, fabp1, fabp2, fabp3, fabp4, fabp6, fabp7, and fabp10, in two marine teleosts, were characterized. In general, turbot and tiger puffer fabp genes showed high identity to their orthologs in other fish species and mammals, but tiger puffer Fabp6 shared the lowest identity to its known orthologs in zebrafish and human. The tissue distribution patterns of fabps were generally in accordance with their function features. However, tiger puffer fabps, in particular Fabp1, Fabp2, Fabp6 and Fabp7, may have functions distinct from other teleosts, as indicated by the phylogenetic tree and tissue distribution patterns. In both species, high dietary lipid levels downregulated the expression of fabp2, fabp3, fabp6, and fabp7a but tended to upregulate the fabp1 expression. Starvation downregulated the expression of most fabps in both fish species, but the downregulation of fabp expression in turbot was much more drastic and earlier compared to tiger puffer. Long-term (30-day) starvation increased the fabp7 expression in tiger puffer and tended to increase the fabp6 expression in turbot. Results of this study contribute to fish fabp physiology and its nutritional regulation. [ABSTRACT FROM AUTHOR]

Successful viral infection and multiplication chiefly rely on virus subversion mechanisms against host anti-viral immune responses. In this study, in order to reveal the anti-viral immune-related pathways suppressed by megalocytivirus infection, transcriptome analysis was performed on the head-kidney of turbot (Scophthalmus maximus) infected with lethal dose of RBIV-C1 at 3, 6 and 9 days post challenge (dpc). The results showed that, compared to unchallenged groups, 190, 1220, and 3963 DEGs were detected in RBIV-C1 infected groups at 3, 6 and 9 dpc, respectively, of which, DEGs of complement components and pattern recognition proteins were up-regulated at 3 dpc and down-regulated at 6 and 9 dpc, DEGs of cytokines were up-regulated at 6 dpc and down-regulated at 9 dpc. Expression trend analysis revealed that DEGs of profiles 9 and 13 featured decreased expression patterns and were significantly enriched into 10 immune-related pathways, i.e., complement and coagulation cascades, cytokine-cytokine receptor interaction, chemokine signaling pathway, B/T cell receptor signaling pathway, antigen processing and presentation, and so on. Further co-expression network analysis (WGCNA) revealed positive correlated innate immune related pathways at 3 and 6 dpc, and negative correlated innate and adaptive immune related pathways at 9 dpc. This study revealed a set of anti-viral immune genes/pathways that would also be potential targets subverted by RBIV-C1 for immune evasion, which can serve as a valuable resource for future studies on the molecular mechanisms of anti-viral immune defense of turbot and immune escape of megalocytivirus. • Transcriptome analysis was performed on the head-kidney of turbot infected with RBIV-C1. • Innate immune related DEGs exhibited an earlier increasing and later decreasing expression trend. • Adaptive immune related DEGs exhibited a trend toward down-regulation. • Down-regulated immune pathways would be potential targets suppressed by virus for immune evasion. [ABSTRACT FROM AUTHOR]

The aim of the experiment was to study effect of complex probiotics on the growth performance, immune level and intestinal health of Scophthalmus maximus. A total of 180 juvenile Scophthalmus maximus weight (7.36±0.04) g were randomly divided into three groups, with three replicates in each treatment and 20 fish in each replicate. Fish in control group were fed with basal diet without addition, fish in 0.4% probiotics group were fed with basal diet + 4 g/kg of probiotics, and fish in 0.8% probiotics group were fed with basal diet + 8 g/kg of probiotics. The results showed that compared with the control group, the feed coefficient of the treatment group with complex probiotics in the feed was significantly lower compared with the control group (P<0.05), and the feed coefficient of 0.4% probiotics group was lower than that of 0.8% probiotics group. The muscle and fish crude protein content in 0.4% probiotics group and 0.8% probiotics group were significantly increased compared with control group (P<0.05). Superoxide dismutase, total antioxidant capacity and lysozyme were significantly higher in 0.4% probiotics group and 0.8% probiotics group than in control group (P<0.05). The villus height was significantly higher and the crypt depth was significantly lower in the treatment group with the addition of complex probiotics in the feed (P<0.05), and the ratio of villus height to crypt depth in control group was significantly lower than that in treatment group with the addition of complex probiotics (P<0.05). The experiment indicates that the addition of complex probiotics to Scophthalmus maximus diets can improve feed conversion efficiency by enhancing antioxidant and non-specific immune functions and improving intestinal health, thereby reducing breeding costs. [ABSTRACT FROM AUTHOR]

The bycatch in fishing gears is a significant threat to cetaceans. However, there is almost no information on the impact of bycatch in the Black Sea shore of Bulgaria. Our study aimed to identify and estimate the bycatch of the three endemic species of cetaceans occurring in the Black Sea by turbot fisheries. Between 2014 and 2018, data on bycatch from 1337 km turbot gillnets were collected. A total of 413 cetaceans were recorded as bycatch. The results suggest that bycatch is likely to have significant demographic effects on populations of the Black Sea cetaceans. The most bycaught cetacean is the harbour porpoise representing 82.8 % of the total bycatch. However, more data and long-term monitoring are needed to understand better the impact of interactions between cetaceans and fisheries. [ABSTRACT FROM AUTHOR]

Presence of PBDEs tested in 127 liver samples from Atlantic Cod (Gadus morhua) and Turbot (Scophthalmus Maximus) and 80 adult participants from two rural Newfoundland communities. Seafood consumption was measured through a validated seafood consumption questionnaire. PBDEs (-28, -47, -99, -156, and -209) were found in all fish liver samples, and PBB-153 and PBDEs-28, -47, -99, -100, -153 were identified as the most prominent congeners from the participants' serum samples. Cod was the most frequently consumed species in the seafood consumption survey. PBB-153 was higher amongst older (> 50 years age) participants (p < 0.0001), however, no PBDE congeners were significantly different by age. PBB-153 (p = 0.001), PBDE-153 (p = 0.006), and 5PBDE (p = 0.008) levels were significantly higher in males. The study shows that the marine ecosystem around Newfoundland has been contaminated by PBDEs, and that rural coastal residents are potentially exposed to these contaminants through local seafood consumption. [ABSTRACT FROM AUTHOR]

This study was performed to investigate the fermentation efficiency of Lactobacillus acidophilus and compare the effects of dietary soybean meal (SM) or L. acidophilus-fermented SM (LASM) on turbot. Two hundred and seventy juvenile turbots (13.50 ± 0.13 g) were randomly divided into three treatments fed with a fishmeal-based diet (CNT) and two experimental diets with 45% fishmeal protein replaced by SM or LASM for 8 weeks. The results showed that fermentation significantly improved the essential amino acid profile, increased the lactic acid content, and reduced the antinutritional factor level in SM. Inferior growth of fish was observed in the SM group after the feeding trial, while the LASM group exhibited comparable performance to the CNT group. Activities of intestinal digestive enzymes (trypsin and diastase) and immune-related enzymes (alkaline phosphatase, acid phosphatase, and lysozyme) decreased significantly in the SM group, while no significant reduction was found in the LASM group compared to the CNT group. Dietary LASM alleviated SM-induced intestinal pathological disruption with higher villus and normal lamina propria width. Dietary LASM positively regulated the intestinal microbiota, making the overall profile more coherent with that in the CNT group. Spearman's correlation analysis revealed that the altered intestinal microbiota was closely linked to the digestive enzyme activities. Collectively, this study indicated that L. acidophilus fermentation significantly improved the nutritional quality of SM and relieved SM-induced adverse effects on turbot, in terms of growth, intestinal digestive and immune-related enzyme activities, morphology, and microbiota. [ABSTRACT FROM AUTHOR]

Various kinds of fermented soybean meal are now commercially available, whereas the quality of these products is uneven due to different processing technologies, fermentation strains, and raw soybean meal, which would lead to different effects on bioavailability of nutrients in aquaculture feeds. Thus, a 10-week feeding trial was conducted to evaluate the effects of six different commercially available fermented soybean meal (FSBM) on growth performance of juvenile turbot (Scophthalmus maximus L.) and to analyze the correlation between growth parameters and FSBM components. Seven isonitrogenous and isolipidic diets were formulated: fish-meal-based diet (the control group, FM) and FM with 450 g/kg of fish meal substituted by six commercially available FSBM (the replacement groups, FSBM1, FSBM2, FSBM3, FSBM4, FSBM5, and FSBM6). Results showed that specific growth rate (SGR) and weight gain rate (WGR) were significantly higher in groups FMSB3 and FMSB4 than in other replacement groups, but significantly lower in the control group. Besides, no significant differences were observed in feed efficiency ratio (FER) and protein efficiency ratio (PER) among groups FSBM3, FSBM4, and FM. Correlation analysis revealed that SGR, PER, and protein retention (PR) of turbot were all positively correlated with the water-soluble protein and trichloroacetic acid- (TCA-) soluble protein content of FSBM, but negatively correlated with the content of trypsin inhibitor. In summary, the commercial FSBM3 and FSBM4 could yield higher growth performance of juvenile turbot than the rest selected FSBM when replacing 450 g/kg of fish meal in diets, and the content of water-soluble protein, TCA-soluble protein, and trypsin inhibitor could serve as relatively accurate indicators in the quality evaluation of FSBM. [ABSTRACT FROM AUTHOR]

Infectious pancreatic necrosis (IPN) is a highly contagious disease of young salmonid fish and is one of the most severe economic diseases in aquaculture. In Turkey, an increase in infectious pancreatic necrosis virus (IPNV) outbreaks in freshwater rainbow trout have been reported in recent years. This study aimed to analyze the VP2 gene from recent IPNV isolates from Turkey to determine whether there are epidemiological links between IPNV isolates from rainbow trout (Oncorhynchus mykiss; 62) and sea bass (Dicentrarchus labrax; 1), wild turbot (Scophthalmus maximus; 1) and the environment in order to investigate potential wild and farmed fish interactions. In this study, 62 Turkish IPNV isolates collected over 10 years (2005–2014) from rainbow trout, sea bass and turbot were genotypically characterized. The phylogenetic analysis indicated that Turkish IPNV isolates are closely related to strains from Denmark, Iran and Spain and that all Turkish IPNV isolates belong to genogroup V, serotype A2 (Sp strain). Furthermore, low genetic diversity was found among the Turkish isolates (identity, 95.5%–100% nucleotides and 97.8%–100% amino acids). The result of the analysis of the amino acid residues found at positions 217, 221 and 247 (proline, threonine and alanine, respectively) could be associated with virulence. [ABSTRACT FROM AUTHOR]

Identification of Vibrio harveyi, Vibrio ichthyoenteri, and Photobacterium damselae isolated from olive flounder Paralichthys olivaceus in Korea by multiplex PCR developed using the rpoB gene. Keywords: bacterial fish pathogen; conventional PCR; quantitative PCR; recA gene; Vibrio scophthalmi EN bacterial fish pathogen conventional PCR quantitative PCR recA gene Vibrio scophthalmi 373 378 6 01/17/22 20220201 NES 220201 Since it was first isolated from the intestine of the turbot (Cerdà-Cuéllar et al., 1997), I Vibrio scophthalmi i has been considered an opportunistic pathogen in several fish species (Gauger et al., 2006; Valdenegro-Vega et al. 2013). Bacterial fish pathogen, quantitative PCR, conventional PCR, recA gene, Vibrio scophthalmi. [Extracted from the article]

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A 56-day feeding trial was conducted in a flow-through seawater system to investigate the effects of lysophosphatidylcholine (LPC) on growth performance and lipid metabolism of turbot. Four experimental diets were prepared, differing only in the LPC supplementation, namely, 0 (LPC-0, control), 0.1 (LPC-0.1), 0.25 (LPC-0.25), and 0.5% (LPC-0.5) of dry matter. Each diet was randomly fed to triplicate tanks. LPC-0.1 and LPC-0.25 led to significantly higher weight gain than the control diet, and the highest weight gain was observed in LPC-0.1. Compared to the control group, the LPC-supplemented groups had higher survival and lower hepatosomatic index and viscerosomatic index. LPC-0.25 led to significantly lower contents of crude lipid and ash in whole fish. Dietary LPC supplementation led to a basic decrease in the lipid metabolism-related biochemical parameters in serum but had only very minor influence on the fatty acid composition in the liver and subcutaneous tissue around the fin (STF). High LPC levels upregulated the mRNA expression of BSAL and ApoEα in both the liver and STF. In conclusion, dietary LPC supplementation (0.1-0.25%) enhanced the growth, lowered the lipid accumulation in juvenile turbot, and significantly regulated the lipid metabolism. However, it seldom influenced the fatty acid composition. [ABSTRACT FROM AUTHOR]

The class A scavenger receptors play important roles in innate immunity and are distributed on plasma membrane of macrophages and other cell types. Notably, the class A scavenger receptor 4 (SCARA4) contains a typical C-type (calcium-dependent) lectin domain, which belongs to the collectin family of pattern recognition receptors and is involved in the immune response against infection. Here, one turbot SCARA4 gene was identified with a 2,292 bp open reading frame (ORF) encoding 763 amino acid residues. Multiple sequence analysis and phylogenetic analysis confirmed that Sm SCARA4 gene was more close to that of P. olivaceus. Gene structure and syntenic analysis showed conserved exon/intron organization pattern and syntenic pattern across selected vertebrate species. Tissue distribution analysis showed Sm SCARA4 was expressed in all the tested healthy tissues with the relative high expression levels in skin, gill and spleen. Following both E. tarda and V. anguillarum challenge in vivo , Sm SCARA4 was significantly repressed in gill and intestine. Remarkably, Sm SCARA4 showed the strongest binding ability to LPS and strongest upregulation in turbot head kidney macrophages in response to LPS. Knockdown and overexpression of Sm SCARA4 revealed its interactions with the two pro-inflammatory cytokines, TNF-α and IL-1β. Finally, repression of Sm SCARA4 via combined treatment of LPS and overexpression of Sm SCARA4 construct in turbot head kidney macrophages further indicated an inhibitory role of Sm SCARA4 in LPS-stimulated inflammation. Taken together, turbot Sm SCARA4 plays an important role in turbot immunity, especially in the mucosa-related systems; Sm SCARA4 possesses strong binding specificity to LPS, and exerts protective roles in response to LPS infection by reducing the release of pro-inflammatory cytokines. The mechanisms of inhibitory role of Sm SCARA4 in LPS-elicited inflammation await further investigation. • Gene structure and syntenic analysis of SCARA4 showed conserved patterns across selected vertebrate species. • Sm SCARA4 was expressed in all the tested healthy tissues with the relative high expression levels in skin, gill and spleen. • Following both E. tarda and V. anguillarum challenge, Sm SCARA4 was significantly repressed in gill and intestine. • Sm SCARA4 showed the strongest binding ability to LPS and strongest upregulation in turbot head kidney macrophages in response to LPS. • Knockdown and overexpression of Sm SCARA4 revealed its interactions with TNF-α and IL-1β. [ABSTRACT FROM AUTHOR]

A specimen of a sixgill bluntnose shark, Hexanchus griseus (Bonnaterre, 1788), was caught 1.5 NM north of Cape Ronek (Izola, Slovenia) in a fishing net for large-sized flatfish (such as turbot) on 28 January 2018. Three other older cases of catch of sixgill bluntnose sharks were recorded in Slovenia and the Gulf of Trieste. Among these, the finding of the specimen in the Lagoon of Marano and Grado is unusual although there are reported cases of sixgill bluntnose sharks in rivers. An analysis of the available data on the bluntnose sixgill shark in the Adriatic Sea, obtained from different published papers, social media and other sources, was done to understand whether the occurrence of H. griseus in the northern Adriatic differs from other parts. A generalised linear model (GLM) approach revealed that larger specimens are more frequently sighted across the Adriatic Sea, while in the Northern Adriatic part, significantly smaller specimens (juveniles) were recorded in comparison to the Central and Southern parts. It seems that the bluntnose sixgill shark is not in conjunction with a common large shark decreasing trend across the whole Mediterranean Sea. [ABSTRACT FROM AUTHOR]

A common problem that arises from the use of plant ingredients is the presence of mycotoxins. The plant meals with more potential to be used in turbot diets have a natural tendency to be contaminated by fumonisins (FUM). Psetta maxima fed: FUM 1.0, FUM 2.0 and FUM 5.0 mg kg−1 diets showed a significantly lower final mean body weight, specific growth rate and protein efficiency ratio, and a concomitantly higher feed conversion ratio, than those fed the Control or FUM 0.5 diet. At dietary concentrations of 1 to 5 mg kg−1, FUMs caused a reduction of the brush border villi length in the distal intestine and a reduction of hepatic lipid inclusion. In conclusion, dietary FUM contamination over the course of 63 days, lead to significant damaging effects on the overall growth performance, nutrient retention, organ morphology and immune status of turbot. [ABSTRACT FROM AUTHOR]

Metalloproteases represent a class of extracellular proteases found in Vibrio anguillarum that can generate toxic and pathogenic effects in turbot (Scophthalmus maximus). The toxicological effect partly results from oxidative damage due to the production of excessive reactive oxygen species (ROS). Catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) are major antioxidant enzymes induced by various oxidative stresses and can scavenge peroxides generated in cells. To evaluate the effects of metalloprotease-induced ROS on the antioxidation defense mechanism of S. maximus head kidney cells, the cDNA of CAT gene (designated as SmCAT) was cloned and characterized. SmCAT comprises a 1 584-bp coding sequence that encodes a protein containing 527 amino acids with a poly(A) tail. Bioinformatics analysis revealed an active site signature sequence, a heme-ligand signature sequence, and three catalytic amino acid residues. The deduced SmCAT amino acid sequence shares a sequence similarity of 66.1%–92.4% with those of other species. Phylogenetic analysis revealed that SmCAT is classified with CAT of other fishes. Quantitative real-time PCR analysis showed that SmCAT was extensively expressed in all tested tissues, especially in blood. The expression of SmCAT, SmMnSOD, and SmGPx were inhibited significantly in head kidney cells treated with metalloprotease from 12 to 24 h. In 6 to 24 h metalloprotease-treated groups compared to that of the untreated group, it was found that the production of ROS was markedly increased, and the mitochondrial membrane potential was decreased considerably. Hoechst 33342 staining revealed the presence of apoptotic bodies when the cells were incubated with 8.0 or 40.0 μg/mL metalloprotease for 12 and 24 h. Hence, the toxic effects of metalloprotease are associated with the down-regulation of antioxidant enzyme expression and increased ROS levels, which trigger the activation of apoptosis in the head kidney cells of turbot. Our findings provide a better understanding on the mechanism of metalloprotease-induced apoptosis in fish. [ABSTRACT FROM AUTHOR]

In this study sperm characteristics (sperm volume, sperm volume per kg fish, spermatocrit, sperm concentration, pH, and sperm motility) of wild‐caught and hatchery‐reared turbot (Scophthalmus maximus), originated from the Black Sea population, were assessed. In this regard, two different trials were conducted. On the Trial‐I, sperm characteristics of wild‐caught and hatchery‐reared turbot (4‐, 7‐, and 10‐year‐old) were comparatively investigated during the spawning season (May), on the Trial‐II, monthly variations of sperm characteristics of hatchery‐reared turbot (4‐year‐old) were investigated. On the Trial‐I, a positive correlation between body weight and sperm volume was recorded. Significant differences were noted in sperm volume, and sperm concentration, however, there was no significant difference between the groups in terms of sperm volume per kg of body weight, spermatocrit, and pH. The sperm motility showed a significant decrease after the 15 minutes post‐activation in all the specimens. The active spermatozoa rate of the wild‐caught turbot was 44% at 15 minutes post‐activation, whereas it was 16%, 13%, and 64% for 4‐, 7‐, and 10‐year‐old turbot, respectively. The average motility duration of the wild‐caught turbot spermatozoa was significantly longer compared to hatchery‐reared turbot despite having a comparatively lower initial motility rate than hatchery‐reared turbot. On Trial‐II spermiation duration of hatchery reared Black Sea turbot was determined as 6 months, starting from February until the end of July. The highest and the lowest sperm volume, and sperm volume per kg were recorded in June and July, respectively. Significant differences were determined between the months in terms of sperm volume per kg, sperm volume, spermatocrit, and sperm concentration, however, the pH was similar. These results demonstrate the sperm characteristics of wild‐caught and hatchery‐reared Black Sea turbot were different in the spawning season (May) and the potential spermiation season was between February and July. [ABSTRACT FROM AUTHOR]

Turbot (Scophthalmus maximus, Linnaeus 1758) is a marine bottom fish and is considered to be one of the most commercialy valuable species in Black Sea. The aim of this survey was to determine the heavy metal concentrations in turbot tissue from the Bulgarian part of the sea. Samples were collected during the fishing season between June and September in 2020 from Varna and Burgas regions. Metals were determined using ICP-MS (Inductively Coupled Plasma - Mass Spectrometry). The order of the levels of the heavy metals in the fish samples was Zn > Al > Mn > As > Hg > Pb = Cd from Varna and Zn > Al > As >Mn > Hg > Pb = Cd from Burgas. The current data demonstrated higher concentrations of Mn and Zn from Varna. According to the obtained results Pb, Cd, Hg levels in the tested turbot samples were within the limits set by the EC regulations. [ABSTRACT FROM AUTHOR]

Oral vaccination is the most convenient method for disease protection in aquaculture due to possibility of adding vaccines as part of fish diet. However, low protective efficiency is the major problem of oral vaccination owing to some reasons, especially for antigens degradation. In this study, we developed an oral inactivated vaccine based on a chitosan/aluminum adjuvant system, and investigated immune response induced by the vaccine. As a result, Th1 and Th2 cells mediated immune responses were observed after the vaccination according to the upregulation of IL-6, IL-12, IFNγ and IgM genes expression that were deemed as the driver cytokines for triggering the responses. Moreover, ratio of IgT+/IgM+ B cells was elevated in intestine after vaccination, while IgM antibodies were also observed in the sera of vaccinated fish, suggested that both local and systemic immune responses were induced by the inactivated vaccine. Totally, this oral vaccine can be used for V. anguillarum protection and this chitosan/aluminum system is an efficient candidate adjuvant for developing more vaccines in the future. [ABSTRACT FROM AUTHOR]

A 12‐week feeding trial was conducted to investigate the effects of dietary Lactobacillus casei, stachyose, or combined (synbiotic) on immunity and intestinal health of turbot (Scophthalmus maximus. L). Four isonitrogenous and isolipidic diets were formulated: Control diet, Control diet with 1.0×108 CFU/g L. casei (LC), 25.0 g kg‐1 stachyose (ST) or 1.0 × 108 CFU/g L. casei + 25.0 g kg‐1 stachyose (SL) supplementation separately. The results showed that fish‐fed diets ST and SL had a significant higher activity of lysozyme and concentration of complement 3 and 4, and IgM in serum, while the higher activity of ACP was observed in LC and SL group. The highest viable counts of L. casei in mucosa and content of DI were observed in SL group. Diet SL significantly increased the PR of DI, expression of tight junction proteins, pcna and the bcl‐2/bax, while decreased the expression of caspase‐3 and caspase‐9. Moreover, diets LC, ST and SL remarkably decreased the abundance of Mycoplasma but increased the abundance of Lactobacillus and Bacteroides, α‐diversity, and altered the bacterial communities in DI. Therefore, both stachyose and L. casei could enhance the immunity and intestinal health of turbot, while the synbiotic was superior to individual administration of stachyose or L. casei. [ABSTRACT FROM AUTHOR]

Tetraploid fish are the key source of diploid gametes in polyploid breeding, and they can be induced by disrupting the first mitotic cell cleavage. In this study, the induction protocol of tetraploid by hydrostatic pressure shock and the viability of the tetraploid progenies were investigated in turbot, Scophthalmus maximus. Under water temperature of 14.5 ± 0.5 °C, fertilized diploid zygotes were treated by different combination of timing (65–90 min after fertilization, maf), pressure intensity (60–85 MPa), and duration (2–10 min), respectively. Ploidy level was determined by silver staining of NOR regions, karyotype analysis, and flow cytometry. The optimal protocol for the pressure shock induction was determined to be the combination of timing of 80 maf, 75 MPa of hydrostatic pressure, and 6 min of duration time. Two batches of tetraploid-induced progenies with a total of more than 73,000 morphologically normal larvae were produced. The hatching rates and tetraploidy rates of the two induction groups were 8.97% and 4.09% and 53.33% and 46.67% at 1 day after hatching (dah), respectively. At 150 dah, 1 out of 20 juveniles was identified as tetraploid by karyotype analysis. However, none of tetraploid juveniles was detected by the flow cytometry analysis among the 446 juveniles survived at 365 dah. This preliminary study provides the evidence supporting the large-scale production of tetraploid turbot progenies, thus encouraging further research on the subject. [ABSTRACT FROM AUTHOR]

Soya-saponins represent key anti-nutritional factors that contribute to soybean meal-induced enteritis, and glutamine is an effective fish intestine protectant that combats the negative effects of soya-saponins. Nuclear transcription factor-kappa B (NF-кB) systems are involved in the interactions between soya-saponins and glutamine, and the goal of the present work was to clarify the related molecular mechanisms used by the NF-кB kinase (IKK)/inhibitor of NF-κB (IκB)/NF-кB system. Primary cultured turbot (Scophthalmus maximus L.) intestinal epithelial cells were concurrently administrated with 1 mg/mL of soya-saponins and several levels of glutamine (0, 0.5, 1.0 and 2.0 mM) for 12 h and then subjected to real-time PCR and Western blot assays. Compared with cells treated with soya-saponins alone, glutamine significantly decreased the expression of interleukin-1 beta, interleukin 8 and tumor necrosis factor α genes, significantly reduced nuclear and cytosolic NF-κB p65 abundance levels in a dose-dependent manner, increased the IκBα protein level but decreased its phosphorylation, and down-regulated the IKKα/β and phosphorylated IKKα/β levels. In conclusion, this in vitro work confirmed that glutamine attenuated soya-saponin-induced inflammatory responses in turbot intestines. Moreover, it identified molecular pathways in which glutamine first decreased the p65 level and then prevented its nuclear translocation. In addition, glutamine reduced IκBα phosphorylation and maintained its level. Finally, glutamine decreased IKK expression and phosphorylation. ● Glutamine significantly decreased the expression of NF-кB target genes ● Glutamine significantly reduced nuclear and cytosolic NF-κB p65 abundance ● Glutamine increased the IκBα protein level but decreased its phosphorylation ● Glutamine down-regulated the IKKα/β and phosphorylated IKKα/β levels [ABSTRACT FROM AUTHOR]

Seven immune factors, lysozyme, hepcidin, heat-shock protein (HSP) 70, HSP90, immunoglobulin M, C-type lectin, and Lily-type lectin, were measured by PCR in the livers, spleens, and head kidneys of turbot infected with Vibrio anguillarum. Additive main effects and multiplicative interaction (AMMI) and genotype main effects and genotype × environment interaction (GGE) biplot analysis were used to analyze genotype × tissue interactions for immunological factors. The AMMI analysis revealed that immune factor expression was significantly affected by genotype, tissue, and genotype × tissue interactions. Genotype (65.85%) was the major contributor to the total variation in immune factor expression in comparison to tissue effects (7.54%) and genotype × tissue interactions (12.52%). GGE biplot analysis revealed differences in the ranking of the seven immune factors in the three tissues; head kidney possessed the strongest ability to distinguish the seven immune factors. The test tissue locations were divided into liver-spleen and head kidneys regions; HSP70 was expressed the highest in the liver-spleen regions, and lysozyme had the highest expression in the head kidney region. Overall, HSP70 and HSP90 had the best expression and stability in the three tissues. • Genotype was the major contributor to the total variation in immune factor expression. • HSP70 and lysozyme had the highest expression in the liver-spleen region and the head kidney region, respectively. • HSP70 and HSP90 would be the preferred breeding index. [ABSTRACT FROM AUTHOR]

Non-coding RNAs are a class of RNAs, including circRNA and miRNA, that cannot be translated into proteins, but play an important role in the regulation of the expression of protein-coding genes. More and more evidences showed that circRNA can regulate the expression of miRNA target genes by adsorbing miRNA and form the circRNA-miRNA-mRNA regulatory network. The inactivated Aeromonas salmonicida vaccine is a commercial vaccine for many teleost. Understanding the role of circRNA and miRNA in the early stage of vaccine injection will provide a new insight for the study of the early immune response process in teleost. In this study, the expression profiles of circRNA, miRNA and mRNA were analyzed by high-throughput sequencing at 6 h, 12 h, 24 h and 96 h after injection of inactivated Aeromonas salmonicida vaccine and normal turbot spleen. Compared with the control group, 111, 141 and 453 differentially expressed circRNAs, miRNAs and mRNAs were identified in the four vaccination groups, respectively. The targeting relationships of differentially expressed miRNA to circRNA and mRNA were predicted by using miRanda software, and the results showed that a variety of differentially expressed immune-related genes were targeted. A total of 53 differentially expressed circRNA-miRNA-mRNA regulatory networks were constructed according to circRNA-miRNA pairs and miRNA-mRNA pairs. Among them, cell adhesion molecule 3 and immunoglobulin superfamily member 21 were regulated by the same miRNA (novel_880) and circRNA (novel_circ_0000311/novel_circ_0005326). These suggest that these circRNA-miRNA-mRNA regulatory networks may be a multi-molecule regulatory network, and its regulatory mechanism needs to be further studied. • High quality circRNA, miRNA and mRNA high-throughput sequencing data were obtained. • 111, 141 and 453 DE-circRNAs, miRNAs and mRNAs were identified respectively. • Immune-related genes were included in circRNA/miRNA/mRNA pairs or triplets. • Multiple molecules were involved in regulation and form a larger regulatory network. [ABSTRACT FROM AUTHOR]

Alike other flat fish, marine turbot has the particularity that changes from larvae with bilateral symmetry to adult with asymmetry, in terms of the position of the eyes. As expected, the skin configuration of this species is also affected by the development and transformation suffered by fish during metamorphosis. In this context, changes in the epidermis of marine turbot were studied using conventional staining and histochemical techniques using six lectins (UEA‐I, PNA, RCA‐I, WGA, Con A and SBA). During development from larvae to juvenile (3–300 days post‐hatching), the epidermis increased in both thickness and the number of cell layers. In fact, the simple cuboidal epithelium observed in larvae at day 3 already became stratified at days 10–12, which sequentially increase in thickness with fish development. Turbot epidermis is composed basically of four cell types: epithelial and mucous or secretory cells that are present through the development, and pigmented cells and a type that the authors described as club‐like cells that appear during and post‐metamorphosis. The Alcian blue‐periodic acid Schiff (AB‐PAS) histochemical method revealed the presence of neutral glycoconjugates in mucous and club‐like cells at post‐metamorphic stages of fish. Accordingly, lectin analysis showed mucous cells containing glycoproteins rich in fucose (UEA‐I labelling) and glycoconjugates rich in the sequence galactose‐N‐acetyl galactosamine (PNA and RCA‐I labelling) when this cell type appears. Interestingly, melanophores were observed in the dorsal epidermis of post‐metamorphic juveniles. This type of cell contains a black‐to‐brown pigment that provides the skin the typical colour of this fish species. Changes in mucous coat composition were observed during fish development, which was attributed to different roles of the glycoconjugates. [ABSTRACT FROM AUTHOR]

The genetic parameters and activity of five immune factors, including lysozyme (LZ), acid phosphatase (ACP), nitric oxide synthase (NOS), superoxide dismutase (SOD), together with the concentration of total protein (PC), were evaluated in the serum of turbot infected with Vibrio anguillarum. A total of 900 turbot individuals from 30 full-sib families were subjected to experimental infection with V. anguillarum. The genetic parameters of the above-mentioned traits were determined and subsequently analysed: the heritability values of PC, LZ, ACP, NOS and SOD were 0.27, 0.21, 0.27, 0.29 and 0.20 respectively. The ranges of phenotypic, genetic and environmental correlations within each of the five immune factors were -0.252-0.711, -0.223-0.685 and -0.268-0.730 respectively. Considering that the heritabilities of LZ, ACP, NOS and SOD were moderate and that the genetic correlations between LZ, ACP, NOS and SOD were highly positive, it is inferred that the whole immunocompetence of turbot against V. anguillarum can be optimized through genetic improvement of these four immune traits using multi-trait integrated breeding technology or indirect selection. [ABSTRACT FROM AUTHOR]

The composition of mineral in fermented soybean meal (FSBM) was far from that of fish meal (FM). The lack of minerals might be one of the factors restricting the replacement of FM by FSBM. Thus, a 10‐week feeding experiment was conducted to evaluate the effects of mixed inorganic salts (IS) supplementation in FSBM‐based diets on growth, bone mineral deposition, intestinal morphology and immune response of turbot juveniles (Scophthalmus maximus L.). The whole FM diet was used as the FM group. Three isonitrogenous (544 g/kg crude protein) and isolipidic (108 g/kg crude lipid) diets were formulated. Three graded levels of IS were supplemented in FSBM‐based diet (the control group) at 0, 1 fold and 2 folds according to the difference in composition of minerals from major ingredients. To be more specific: FM (0), FSBM (0), FSBM/IS‐1 (Ca(H2PO4)2: 13.10 g/kg, CaCl2: 11.00 g/kg, NaCl: 9.55 g/kg, FeSO4·7H2O: 0.92 g/kg, Na2SeO3: 0.56 mg/Kg, ZnSO4·H2O: 5.60 mg/Kg); FSBM/IS‐2 (Ca(H2PO4)2: 26.58 g/kg, CaCl2: 21.87 g/kg, NaCl: 19.11 g/kg, FeSO4·7H2O: 1.84 g/kg, Na2SeO3: 1.12 mg/Kg, ZnSO4·H2O: 13.66 mg/Kg). Each diet was randomly allocated to quadruplicate groups of 30 turbot juveniles. Results showed that no significant difference in survival rate was observed among dietary treatments (p >.05). Fish fed the diet with 2 folds IS had significantly higher specific growth rate than the control group and 1 fold IS (p <.05). Feed efficiency of fish fed the diet with 2 folds IS was significantly enhanced compared with the control group and 1 fold IS (p <.05). Bone deposition of calcium, phosphorus, zinc, iron and selenium was significantly increased with increasing dietary IS while sodium was significantly decreased (p <.05). The activities in intestinal trypsin, amylase and lipase significantly increased with increasing dietary IS (p <.05). Besides, the activities of hepatic total antioxidant, total superoxide dismutase and catalase were significantly increased with increasing dietary IS (p <.05). The activities in plasma lysozyme, glutamic pyruvic transaminase, glutamic oxalacetic transaminase and γ‐glutamyl transferase were significantly decreased with increasing dietary IS (p <.05). Results of the present study indicated that 2 folds IS could partially relieve the growth retardation caused by high proportion of dietary FSBM, improve bone mineralization and enhance immune responses. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Length-weight relationships (LWR) were described for fourteen demersal and pelagic fish species; whiting (Merlangius merlangus), red mullet (Mullus barbatus), picarel (Spicara maena), scorpion fish (Scorpaena porcus), anchovy (Engraulis encrasicolus), sprat (Sprattus sprattus), horse mackerel (Trachurus mediterraneus), bluefish (Pomatomus saltatrix), turbot (Scophthalmus maximus), thornback ray (Raja clavata), shore rockling (Gaidropsarus mediterraneus) round goby (Neogobius melanostomus), black goby (Gobius niger) and stargazer (Uranoscopus scaber) caught with bottom trawl (12 mm mesh size) from the Eastern Black Sea. Samples were caught in depths from 10 m up to 60 m between April 2017 and March 2018 at monthly intervals. The minimum and maximum lengths and weights, length-weight relationships, parameters of a and b, ± 95% CI of b, r², growth type (isometric or allometric) of samples, and statistical analyses of the relationship were determined. Estimates for parameter b of the length-weight relationship ranged between 2.44 and 3.54. [ABSTRACT FROM AUTHOR]

The killer whale (Orcinus orca) behavior termed "depredation" is a major issue negatively affecting fisheries worldwide. Information on killer whale depredation in the northwestern Pacific Ocean is limited. The goal of this work was to assess the extent of killer whale depredation on the groundfish fisheries in the western Bering Sea and the Sea of Okhotsk. Observations of killer whale depredation were conducted on 8 of the 42 (19%) longline fishing vessels between October 2018 and September 2019. Killer whales depredated during 2.0% of vessel days in the western Bering Sea and 18.6% of vessel days in the Sea of Okhotsk, taking exclusively Greenland turbot (Reinhardtius hippoglossoides). Seventy-one killer whales were identified depredating on longlines in the Sea of Okhotsk, with the best estimation for the total number of killer whales depredating about 139 individuals. Results suggest that killer whale depredation is an issue for Greenland turbot longline fisheries in the northwestern Pacific. There is a strong need for mitigation measures, as this has an economic impact on the fisheries and also affects the killer whale population and associated ecosystems. [ABSTRACT FROM AUTHOR]

Temperature tolerance is an important trait from both an economic and evolutionary perspective in fish. Because of difficulties with measurements, genome-wide selection using quantitative trait loci (QTLs) affecting Upper temperature tolerance may be an alternative for genetic improvement. Turbot Scophthalmus maximus (L.) is a cold-water marine fish with high economic value in Europe and Asia. The genetic bases of upper temperature tolerance (UTTs) traits have been rarely studied. In this study, we constructed a genetic linkage map of turbot using simple sequence repeats (SSRs) and single nucleotide polymorphism (SNP) markers. A total of 190 SSR and 8,123 SNP were assigned to 22 linkage groups (LGs) of a consensus map, which spanned 3,648.29 cM of the turbot genome, with an average interval of 0.44 cM. Moreover, we re-anchored genome sequences, allowing 93.8% physical sequences to be clustered into 22 turbot pseudo-chromosomes. A high synteny was observed between two assemblies from the literature. QTL mapping and validation analysis identified thirteen QLTs which are major effect QTLs, of these, 206 linked SNP loci, and two linked SSR loci were considered to have significant QTL effects. Association analysis for UTTs with 129 QTL markers was performed for different families, results showed that eight SNP loci were significantly correlated with UTT, which markers could be helpful in selecting thermal tolerant breeds of turbot. 1,363 gene sequences were genomically annotated, and 26 QTL markers were annotated. We believe these genes could be valuable candidates affecting high temperatures, providing valuable genomic resources for the study of genetic mechanisms regulating thermal stress. Similarly, they may be used in marker-assisted selection (MAS) programs to improve turbot performance. [ABSTRACT FROM AUTHOR]

Background: The high fecundity of fish species allows intense selection to be practised and therefore leads to fast genetic gains. Based on this, numerous selective breeding programmes have been started in Europe in the last decades, but in general, little is known about how the base populations of breeders have been built. Such knowledge is important because base populations can be created from very few individuals, which can lead to small effective population sizes and associated reductions in genetic variability. In this study, we used genomic information that was recently made available for turbot (Scophthalmus maximus), gilthead seabream (Sparus aurata), European seabass (Dicentrarchus labrax) and common carp (Cyprinus carpio) to obtain accurate estimates of the effective size for commercial populations. Methods: Restriction-site associated DNA sequencing data were used to estimate current and historical effective population sizes. We used a novel method that considers the linkage disequilibrium spectrum for the whole range of genetic distances between all pairs of single nucleotide polymorphisms (SNPs), and thus accounts for potential fluctuations in population size over time. Results: Our results show that the current effective population size for these populations is small (equal to or less than 50 fish), potentially putting the sustainability of the breeding programmes at risk. We have also detected important drops in effective population size about five to nine generations ago, most likely as a result of domestication and the start of selective breeding programmes for these species in Europe. Conclusions: Our findings highlight the need to broaden the genetic composition of the base populations from which selection programmes start, and suggest that measures designed to increase effective population size within all farmed populations analysed here should be implemented in order to manage genetic variability and ensure the sustainability of the breeding programmes. [ABSTRACT FROM AUTHOR]

Tongue sole tissue factor pathway inhibitor 2 (TFPI-2) C-terminus derived peptide, TC38, has previously been shown to kill Vibrio vulnificus cells without lysing the cell membrane; thus, the remaining bacterial shell has potential application as an inactivated vaccine. Therefore, this study aimed to evaluate the immune response induced by the novel V. vulnificus vaccine. The protective potential of TC38-killed V. vulnificus cells (TKC) was examined in a turbot model. Fish were intramuscularly vaccinated with TKC or FKC (formalin-killed V. vulnificus cells) and challenged with a lethal-dose of V. vulnificus. The results showed that compared with FKC, TKC was effective in protecting fish against V. vulnificus infection, with relative percent of survival (RPS) rates of 53.29% and 63.64%, respectively. The immunological analysis revealed that compared with the FKC and control groups, the TKC group exhibited: 1) significantly higher respiratory burst ability and bactericidal activity of macrophages at 7 d post-vaccination; 2) increased alkaline phosphatase, acid phosphatase, lysozyme, and total superoxide dismutase levels post-vaccination; 3) higher serum agglutinating antibody titer with corresponding higher serum bactericidal ability, and a more potent serum agglutination effect, as well as an increased IgM expression level; 4) higher expression of immune relevant genes, which were involved in both innate and adaptive immunity. Taken together, this is the first study to develop a novel V. vulnificus inactivated vaccine based on AMP inactivation, and TKC is an effective vaccine against V. vulnificus infection for aquaculture. • TKC was generated by using TC38, a tongue sole TFPI-2 C-terminus derived peptide. • Fish vaccinated with TKC exhibited greater protection than that of FKC. • TKC stimulated higher innate and adaptive immune response in turbot than FKC. [ABSTRACT FROM AUTHOR]

Accumulating evidence supports that vitamin D 3 (VD 3) possesses immunomodulatory properties besides its classical actions in calcium and bone homeostasis. In this study, juvenile turbots were fed with the diets containing 0 IU/kg VD 3 or the optimum dose of 400 IU/kg VD 3 for 8 weeks. To investigate the effects of VD 3 on anti-infectious immunity in fish, 107 CFU Edwardsiella tarda was injected intraperitoneally to each juvenile turbot after the feeding trial. Our results showed that the mortality of infected turbots with dietary VD 3 was much lower than that in VD 3 deficient group, and the supplementation of dietary VD 3 significantly reduced the bacterial load in the spleen of infected turbots. Further analysis demonstrated that the production of reactive oxygen species (ROS) in haemocytes and lysozyme activity in serum was elevated, and the responses of T cells and B cells were modulated in VD 3 -supplemented turbots. Moreover, the inflammation was significantly exacerbated in the infected turbots fed with 0 IU/kg VD 3 compared to the fish fed with 400 IU/kg VD 3. In addition, the head kidney macrophages (HKMs) in turbots were isolated and incubated with VD 3 in vitro , the results showed that VD 3 significantly promoted the bactericidal activity in HKMs. In conclusion, our study has shown clear evidence that VD 3 positively regulates the innate and adaptive immunity in fish, which is beneficial to the defense in fish against pathogen infection. • VD 3 reduces the mortality and bacterial load in E. tarda -infected turbot. • VD 3 enhances the expression of antibacterial components in turbot. • VD 3 regulates the activity of T and B lymphocytes in infected turbot. • VD 3 alleviates the inflammation induced by bacterial infection in turbot. [ABSTRACT FROM AUTHOR]

In this study, we cloned and identified melanoma differentiation‐associated antigen 5 (MDA5), mitochondrial antiviral signalling protein (MAVS), TNF receptor‐associated factor (TRAF3), TRAF family member‐associated NF‐kappa‐B activator (TANK) and TANK‐binding kinase 1 (TBK1) from turbot (Scophthalmus maximus). The smMAD5 encodes 996 amino acids containing two CARD domains at N‐terminus, a DExD/H domain, a HELICc domain and a regulatory domain (RD) at the C‐terminus. The smMAVS encodes 563 amino acids containing one CARD domain at N‐terminus and one PVDQT motif, lacking proline‐rich region in the middle and transmembrane domain (TM) at C‐terminal. The smTRAF3 encodes 984 amino acids containing a ring finger domain and two zinc finger domains 1 and 2 and a MATH‐TRAF3 domain. The smTANK encodes 341 amino acids containing a TBD superfamily domain. The smTBK1 encodes 721 amino acids containing a protein kinase domain, a ubiquitin‐like domain (ULD) and a coiled–coil region. Immune responsive expression analysis showed that the five genes were all rapidly and significantly upregulated in vivo after poly (I:C) (LMW and HMW) and TRBIV challenge in spleen, gills, head kidney and muscle tissues. Our results indicate that the smMDA5, smMAVS, smTRAF3, smTANK and smTBK1 molecules play crucial role in antiviral immune response. [ABSTRACT FROM AUTHOR]

Aeromonas salmonicida is an aquatic pathogen that can infect a variety of fish. Phage therapy has been applied to treat bacterial infections. In this study, we obtained three A. salmonicida subsp. masoucida phage isolates from sewage, and one phage (vB_AsM_ZHF) exhibited the best antibacterial effect, based on in vitro kinetics experiments. Sequencing indicated that the vB_AsM_ZHF genome is 161,887 bp (41.24% C+G content) with 237 predicted open reading frames. No antibiotic resistance or virulence genes were detected in the complete genome, which is a requirement for phage therapy safety. Intraperitoneal injection of phage vB_AsM_ZHF into turbot at 8 x 104 PFU/fish rescued turbot from A. salmonicida subsp. masoucida injection and reduced the bacterial burden by 1 order of magnitude. Injection of vB_AsM_ZHF also decreased levels of inflammatory cell infiltration in muscle tissue, cytokines interleukin-1 β (IL-1 β), tumor necrosis factor alpha (TNF-α), and gamma interferon (IFN-γ) in serum and the expression of the inflammatory factors IL-1 β, IL-6, IFN-γ, transforming growth factor β, TNF-α, and hepcidin in the liver, spleen, and head kidney of turbot. Phage vB_AsM_ZHF demonstrated antibacterial ability in vitro and in vivo and significantly reduced mortality in turbot challenged by A. salmonicida subsp. masoucida. This study revealed that phage vB_AsM_ZHF can effectively treat the infection caused by A. salmonicida subsp. masoucida in turbot. IMPORTANCE A. salmonicida is an aquatic pathogen that can infect different fish and causes economic loss to the global aquaculture industry. Clinical strains of A. salmonicida have developed multidrug resistance, and phage therapy is being evaluated for controlling bacterial infections. Phages are biological antibacterial agents and have the potential to be therapeutic agents against multidrug-resistant bacteria. In this study, three A. salmonicida subsp. masoucida phages were isolated from sewage, and their biological behaviors were characterized. The newly isolated phage vB_AsM_ZHF could inhibit A. salmonicida subsp. masoucida infection in vitro and in vivo, suggesting that it may be an alternative strategy to antibiotics for protecting fish against multidrug-resistant A. salmonicida subsp. masoucida in the aquaculture industry. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pathogenic bacteria of Scophthalmus maximus enteritis were isolated from and identified in an aquaculture farm in Changli County, Hebei Province, China. The feasibility of rapid selection of prevention and treatment drugs via PCR technology was investigated through drug resistance phenotype analysis and drug resistance gene detection. A dominant bacterial strain was isolated from S. maximus and designated HC-1. Morphological observations, culture property investigations, and physiological-biochemical experiments were conducted, which showed that the strain was consistent with the phenotypic characteristics of Vibrio. Based on 16S rRNA sequence determination and homology analysis, HC-1 was determined to be 99.65% similar to Vibrio harveyi NR 043165.1. Therefore, the bacterium was identified as V. harveyi. The sensitivity of the V. harveyi isolate to 41 antibiotics was determined by the Kirby-Bauer method. The results showed that HC-1 was resistant to 8 agents, namely, penicillin, oxacillin, amoxicillin, ampicillin, spectinomycin, azithromycin, florfenicol, and carbenicillin. The antimicrobial resistance gene analysis results showed that tem, ant(3˝)-I and tetA are carried by the chromosome of the strain and the plasmid, while sul1 is carried by the chromosome of the strain but not the plasmid. In contrast, floR is carried only by the plasmid but not by the chromosome. vanA, qnrA, and mefA are not carried by the plasmid or chromosome of the strain. Although the resistant phenotype of the strains is regulated by resistance genes, the relationship between the phenotype and genotype should be revealed by numerous databases. To accelerate the speed of treatment selection, it is necessary to apply PCR technology to detect resistance genes to replace drug sensitivity testing. These results provide useful information for further understanding the antimicrobial resistance factors and treatment of bacterial disease in S. maximus. [ABSTRACT FROM AUTHOR]

A 60‐day feeding trial was conducted to investigate the effect of enzymatic hydrolysis chicken by‐product (EHC) supplementation in high plant protein diets on growth performance, digestive capacity, antioxidant capacity and non‐specific immunity of juvenile turbot (Scophthalmus maximus L.). The diet with 620 g/kg fish meal (FM) was used as the positive control group (FM group), while the diet with 372 g/kg FM and 256 g/kg degossypolled cottonseed protein were used as the negative control group (0 g/kg EHC group). Based on the negative control diet, grade levels of EHC (10, 20, 30 and 40 g/kg) were added, respectively. Results showed that fish fed with a high plant protein diet showed significantly lower growth performance, digestive capacity, antioxidant capacity and non‐specific immunity than those of the positive control. The supplementation of 20 g/kg EHC significantly increased growth performance of fish as compared to the negative control. Furthermore, the digestive capacity of turbot fed the diet with 20 g/kg EHC was significantly improved by increasing activities of trypsin, pepsin and lipase and the expression of peptide transporter 1 (pept1). The antioxidant capacity and non‐specific immunity of fish fed the diet with 20, 30 and 40 g/kg EHC were significantly improved by increasing activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), total antioxidant capacity (T‐AOC), lysozyme (LZM) and acid phosphatase (ACP) in serum, decreasing the expression of interleukin‐1β (il‐1β) and tumour necrosis factor‐α (tnf‐α) and increasing the expression of transforming growth factor‐β (tgf‐β). In conclusion, the adverse effect of high plant protein diet on growth performance of turbot could be improved with the supplementation of 20 g/kg EHC, which could be due to the positive effect of EHC on digestive capacity, antioxidant capacity and non‐specific immunity of juvenile turbot. [ABSTRACT FROM AUTHOR]

Turbot is one of the most valuable fish species in the Black Sea commercial fishery. The serious, dramatic depletion of the turbot stock and catches that began in the 1980s was caused by overfishing and poor ecological conditions. The state of the turbot stock began to improve in the northwestern part of the Black Sea in 2016. Landings were at their 30-year maximum in this part of the sea. Catches per unit effort (CPUEs) have been at a stable, high level there for the last few years. Average turbot weight and length have also been increasing. The Stock Synthesis (SS3) framework was used in the stock assessment. According to SS3 analysis, fishing mortality (F) reached the minimum level of 0.29 in 2018. The cumulative SPR (Spawner Potential Rate) index was 0.27, which approximately equaled SPRMSY = 0.25. Thus, currently the turbot stock is mostly moderately exploited at a level close to the management target in the northwestern part of the Black Sea. However, the entire Black Sea population has not fully recovered yet. [ABSTRACT FROM AUTHOR]

C-type lectins (CTLs) are important pathogen pattern recognition receptors that recognize carbohydrate structures. In present study, a C-type lectin domain family 4 member E-like gene from turbot, which tentatively named SmCLEC4E-like (SmCLEC4EL), was identified, and the expressional and functional analyses were performed. In our results, SmCLEC4EL showed conserved synteny with CLEC4E-like genes from several fish species in genome, and possessed a typical type II transmembrane CTL architecture: an N-terminal intracellular region, a transmembrane domain and a C-terminal extracellular region which contained a predicted carbohydrate recognition domain (CRD). In addition, SmCLEC4EL exhibited the highest expression level in spleen in healthy fish, and showed significantly induced expression in mucosal tissues, intestine and skin, under bacteria challenge. Finally, the recombinant SmCLEC4EL protein combined with LPS, PGN, LTA and five different kinds of bacteria in a dose-dependent manner, and agglutinated these bacteria strains in the presence of calcium. These findings collectively demonstrated that SmCLEC4EL, a calcium-dependent CTL, could function as a pattern recognition receptor in pathogen recognition and participate in host anti-bacteria immunity. • SmCLEC4EL showed conserved synteny to its counterparts in other vertebrates. • SmCLEC4EL was ubiquitously expressed in turbot tissues. • SmCLEC4EL showed different expression patterns following different bacterial challenge. • SmCLEC4EL had strong binding ability to LPS, LTA, PGN, and five different kinds of bacteria in a dose-dependent manner. [ABSTRACT FROM AUTHOR]

TLRs are the first and best-characterized pattern recognition receptors conserved across all the species. Different from mammals, the TLRs in teleost fishes are very diversified due to various evolutionary mechanisms. Here, we characterized one TLR1 gene in turbot, with a 2,415 bp open reading frame (ORF), that encoding 804 amino acid residues, and have the highest similarity and identity both to Paralichthys olivaceus with 88.9% and 79.9%. In phylogenetic analysis, it was firstly clustered with P. olivaceus , and then clustered with Takifugu rubripes. TLR1 was widely expressed in all the examined healthy tissues with the highest expression level in spleen, followed by head-kidney. In addition, it was significantly regulated in gill, skin and intestine following Edwardsiella tarda and Vibrio anguillarum challenge with different expression patterns. In in vitro stimulation with pathogen-associated molecular patterns, TLR1 showed significantly strong and elevated responses to LPS, but only responded to LTA and Poly(I:C) at the highest evaluated concentration, while no response was detected using PGN stimulation. Moreover, in subcellular localization analysis, TLR1 was distributed in the cytoplasm, membrane and nucleus. Taken together, TLR1 played vital roles for host immune response to bacterial infection, only with strong binding ability to LPS and involved in the production of inflammatory cytokines. However, the specific ligand for TLR1 and its functional association with other TLRs should be further characterized in fish species. • The TLR1 gene from turbot exhibited highly similarities with that in other teleosts. • Turbot TLR1 was widely expressed in all the examined tissues and significantly regulated in mucosal tissues following different bacteria challenge. • Turbot TLR1 showed much more significantly strong responses to LPS than LTA, poly I:C and PGN stimulation.. • Turbot TLR1 was distributed in the cytoplasm, membrane and nucleus. [ABSTRACT FROM AUTHOR]

Fish parvalbumin is a major allergen known to cause allergy and has been a serious concern of food safety all over the world. Recombinant allergen has been broadly applied in allergy diagnosis and immunotherapy in recent years, but different immune activities of several recombinant allergens compared with their natural forms were found. To further characterize and explain the difference between natural and recombinant allergens, in this study, the difference of structure, Ca2+ binding, IgE/IgG binding activity, degranulation ability and digestion stability between natural and recombinant turbot parvalbumins were compared. Both recombinant and natural parvalbumins bind to specific immunoglobulin E from fish allergic patients and rabbit IgG antibody, whereas recombinant parvalbumin showed lower IgG binding activity in inhibition assays. Moreover, recombinant parvalbumin showed comparable ability with natural parvalbumin in Ku812 cells degranulation assay. Besides, intestinal digestion stability of recombinant parvalbumin was similar with natural form while gastric digestion stability was reduced. In addition, similar secondary structure change as well as different tertiary structure change between recombinant and natural parvalbumins due to heating, Ca2+ depletion and heating after Ca2+ depletion was characterized by spectra analysis. Different Ca2+ binding of two forms of parvalbumins was also found according to their different structural changes after Ca2+ depletion. These results revealed that recombinant turbot parvalbumin preserved fundamental immunological properties of its natural form while improper folding of tertiary led to its different Ca2+ binding, lower IgG binding activity and digestion stability. [ABSTRACT FROM AUTHOR]