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TGF-β1/Smads is a classic signaling pathway, which plays important roles in the development process of organisms. Black porgy Acanthopagrus schlegelii and red porgy Pagrus major are valuable economic fishes, and their hybrid offspring show excellent heterosis traits. Yet the molecular regulation mechanism of the heterosis traits is less clear. Here, we explored the TGF-β1/Smads pathway's molecular genetic information for heterosis in A. schlegelii ♂ × P. major ♀ (AP) and A. schlegelii ♀ × P. major ♂ (PA) in terms of growth and development. The mRNA expression levels of TGF-β1, TβR-I, TβR-II, and Smad2 genes in different developmental stages of A. schlegelii were detected. Furthermore, the expression levels of TGF-β1, TβR-I, TβR-II, and Smad2 genes in different tissues of adult (mRNA level) and larva (mRNA and protein level) of A. schlegelii, P. major, and their hybrids were determined by both real-time quantitative PCR and Western blot techniques. The results indicated the ubiquitous expression of these genes in all developmental stages of A. schlegelii and in all tested tissues of A. schlegelii, P. major, and its hybrids. Among them, the mRNA of TGF-β1, TβR-I, and TβR-II genes is highly expressed in the liver, gill, kidney, and muscle of black porgy, red porgy, and their hybrid offspring. There are significant changes in gene and protein expression levels in hybrid offspring, which indirectly reflect hybrid advantage. In addition, there was no correlation between protein and mRNA expression levels of Smad2 protein. The results provide novel data for the differential expression of growth and development genes between the reciprocal hybridization generation of black porgy and red porgy and its parents, which is conducive to further explaining the molecular regulation mechanism of heterosis in the growth and development of hybrid porgy. [ABSTRACT FROM AUTHOR]

Simple Summary: Fish meal is widely used as a feed ingredient in formulated feeds for marine fish species due to its high nutritional value and palatability. However, the increasing cost and limited availability of fish meal highlight the high need to look for an alternative protein source for fish meal in fish feeds to achieve sustainable aquaculture. Tuna by-product meal, derived from the tuna canning process, shows promise as a viable substitute for fish meal in fish feeds. This study aimed to investigate the effect of replacing fish meal with tuna by-product meal on the growth of red sea bream. The findings of this study suggested that 40% fish meal replacement with tuna by-product meal is viable without compromising growth, feed consumption, and feed utilization, while simultaneously providing the highest economic return for fish farmers. The effect of substituting fish meal (FM) by tuna by-product meal (TBM) on growth and feed availability of red sea bream (Pagrus major) was investigated. Six experimental diets were crested to be isonitrogenous (51.5%) and isolipidic (14.5%). The control (Con) diet contained 55% FM. FM substitution in the Con diet was made in increments of 20 percentage points (20, 40, 60, 80, and 100%), named as the TBM20, TBM40, TBM60, TBM80, and TBM100 diets, respectively. Juvenile red sea bream were stocked into 18, 300 L flow-through tanks (50 fish/tank). Red sea bream were hand-fed with each diet until satiation for 8 weeks. No statistical differences in weight gain, specific growth rate (SGR), and feed consumption were found among red sea bream fed the Con, TBM20, and TBM40 diets. Furthermore, feed utilization of fish fed the TBM20, TBM40, TBM60, and TBM80 diets was comparable to red sea bream fed the Con diet. The biological indices, biochemical composition, and hematological parameters of fish were not statistically altered by dietary FM replacement with TBM. The greatest economic profit index was achieved in the TBM40 diet. In conclusion, the replacement of 40% FM with TBM in red sea bream diet appears to be the most recommendable approach without producing retarded growth and feed availability, but maximizing EPI to farmers. [ABSTRACT FROM AUTHOR]

Red sea bream is a commercially valuable fish that is used as ingredients in the food industry. To prevent a decrease in fishing yield, farmed red sea bream is released. However, this may cause a decrease in the genetic diversity of wild populations, so systematic resource management is required. In this study, 68 single nucleotide polymorphism (SNP) markers were developed using a genotyping-by-sequencing (GBS) analysis. The minor allele frequency (MAF) ranged from 0.1802 to 0.5000, the observed heterozygosity (Ho) ranged from 0.0864 to 0.5000, expected heterozygosity (He) ranged from 0.2955 to 0.5000, and the polymorphism information content (PIC) ranged from 0.2518 to 0.3750. Of these SNPs, 25 loci significantly deviated from the Hardy–Weinberg equilibrium after a Bonferroni correction (p < 0.00074). These SNP markers will be useful for the further genetic analysis of the red sea bream population. [ABSTRACT FROM AUTHOR]

Karenia mikimotoi is a common species of red tide dinoflagellate that causes the mass mortality of marine fauna in coastal waters of Republic of Korea. Despite continuous studies on the ecophysiology and toxicity of K. mikimotoi, the underlying molecular mechanisms remain poorly understood. Red sea bream, Pagrus major, is a high-value aquaculture fish species, and the coastal aquaculture industry of red sea bream has been increasingly affected by red tides. To investigate the potential oxidative effects of K. mikimotoi on P. major and the molecular mechanisms involved, we exposed the fish to varying concentrations of K. mikimotoi and evaluated its toxicity. Our results showed that exposure to K. mikimotoi led to an accumulation of reactive oxygen species (ROS) and oxidative DNA damage in the gill tissue of P. major. Furthermore, we found that K. mikimotoi induced the activation of antioxidant enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase, in the gill tissue of P. major, with a significant increase in activity at concentrations above 5000 cells/mL. However, the activity of glutathione S-transferase did not significantly increase at the equivalent concentration. Our study confirms that oxidative stress and DNA damage is induced by acute exposure to K. mikimotoi, as it produces ROS and hypoxic conditions in P. major. In addition, it was confirmed that gill and blood samples can be used as biomarkers to detect the degree of oxidative stress in fish. These findings have important implications for the aquaculture of red sea bream, particularly in the face of red tide disasters. [ABSTRACT FROM AUTHOR]

ABSTRACT Aquatic animal viruses are considered to be transmitted via environmental water between fish farms. This study aimed to understand the actual transmission risk of red sea bream iridovirus (RSIV) through environmental water among fish farms. An environmental DNA (eDNA) method using iron-based flocculation coupled with large-pore filtration was used to monitor RSIV DNA copies in seawater from fish farms and from an experimental infection model. RSIV dispersion in seawater from a net pen where the disease outbreak occurred was visualized by the inverse distance weighting method using multiple-sampling data sets from a fish farm. The analysis demonstrated that the center of the net pen had a high viral load, and RSIV seemed to be quickly diluted by the tidal current. To evaluate the transmission risk of RSIV in environmental water, the red sea bream Pagrus major (approximately 10 g) was exposed to RSIV-contained seawater (103, 104, 105, 106, and 107 copies/L) for 3 days, which mimicked field exposure. A probit analysis of the challenge test indicated that the inferred infection rates of seawater containing 105.9 copies/L and 103.1 copies/L of RSIV were 50% and 0.0001%, respectively. In the surveillance for 3 years at 10 fixed points (n = 306), there were only seven samples in which the viral load exceeded 104 copies/L in seawater. These results suggest that the transmission of RSIV among fish farms via seawater is highly associated with the distance between the net pens, and the environmental water is not always an infection source for the transmission of RSIV between fish farms. IMPORTANCE Our surveillance of viral loads for red sea bream iridovirus (RSIV) by monitoring environmental DNA in fish farms suggested that the viral loads in the seawater were low, except for the net pens where RSIV outbreaks occurred. Furthermore, our experimental infection model indicated that the infection risk of RSIV-contained seawater with less than 103 copies/L was extremely low. The limited risk of environmental water for transmission of RSIV gives an insight that RSIV could be partly transmitted between fish farms due to the movement of equipment and/or humans from the fish farm where the disease outbreaks. Since our data suggest that seawater can function as a potential wall to reduce the transmission of RSIV, biosecurity management, such as disinfection of equipment associated with fish farms could be effective, even in the semi-open system aquaculture that the environmental water can be freely transferred, to reduce the risk of RSIV outbreaks.

The feeding ecology of red seabream, Pagrus major was studied using 1046 specimens collected by danish seine and bottom trawl from January to December 2018 in the Korea Strait. The size of the individuals ranged from 18.4 to 70.4 cm in fork length. Red seabream was a carnivore that consumed mainly anthozoans, brachyurans, and cephalopods. Its diets included also small quantities of amphipods, anomurans, ophiurids, gastropods, polychaetas, etc. We calculated the trophic level as 3.57 for red seabream. As red seabream grows, the proportion of relatively small prey items such as anomurans and ophiuroids decreases, while that of large prey items such as anthozoans, brachyurans, and cephalopods increases. In the largest size class (≥45 cm FL), cephalopods and pisces are its main prey. Alsoe, the body size of red seabream increased the mean weight of prey per stomach tended to increase significantly (One-way ANOVA: p < 0.05). The diet composition of red seabream showed seasonal changes. The cephalopods were the dominant prey items for all seasons. The weight proportion of brachyurans was higher in summer and autumn, whereas anthozoans feeding rate was the highest in winter. PERMANOVA analysis showed significant variations among size classes and seasons. The feeding intensity by size class and season observed no significant difference (One-way ANOVA: p > 0.05). As a result of the feeding strategy analysis, red seabream was a generalized feeder, with a wide niche width. [ABSTRACT FROM AUTHOR]

CD96 is a membrane-bound receptor discovered in humans in 1992 that is mainly present in natural killer cells and T cells derived from haematopoietic cells and performs immune functions. Based on the sequence of CD96 obtained from red seabream (Pagrus major), phylogenetic analysis with other species, infections of normal fish, Streptococcus iniae and red sea bream iridovirus (RSIV), and expression analysis was conducted using real-time polymerase chain reaction. Phylogenetic analysis showed the highest homology with Sparus aurata, and multiple sequence analysis confirmed the conservation of major domains between different fish species. Normal fish high expression results were confirmed in the head kidney, and spleen, which are the haematopoietic organs of the fish. High expression levels were confirmed in the gills, liver, spleen, and kidney on day three after RSIV infection. After S. iniae infection, high expression was confirmed in the gills and liver on day one, and high expression was confirmed in the spleen from 12 hours. These results show that PmCD96 functions as an immune gene in P. major and is considered a basic research case for CD96 in fish’s hematopoietic organ immune system.

Red sea bream Pagrus major is extremely important in the aquaculture of Japan. The breeding of red sea bream, which has a history of more than half a century, can be divided into three main categories. The first is selective breeding. The Aquaculture Research Institute, Kindai University, began breeding fast-growing red sea breams in the early 1960s through mass selection. I summarized the results of the selection and characteristics of the fish in the 1990s. The second is breeding through chromosome manipulation and sex control. Two types of gynogenetic diploids (G2N) were artificially induced. Although growth and survival of G2N were inferior, the growth of heterozygous clones produced by mating G2N was comparable to normal diploids. The sex differentiation process and the induction condition of all-male groups by 17α-methyltestosterone treatment were clarified, and the percentage of females could be increased to more than 85%. The third is breeding through genetic manipulation. We first developed the microinjection method, and succeeded in increasing the percentage of edible ratio by deleting the function of myostatin gene by genome editing. Combining new technologies, such as genome editing, with the existing breeding methods mentioned above would result in faster and more effective breeding. [ABSTRACT FROM AUTHOR]

The effect of substituting fish meal (FM) by tuna by-product meal (TBM) on growth and feed availability of red sea bream (Pagrus major) was investigated. Six experimental diets were crested to be isonitrogenous (51.5%) and isolipidic (14.5%). The control (Con) diet contained 55% FM. FM substitution in the Con diet was made in increments of 20 percentage points (20, 40, 60, 80, and 100%), named as the TBM20, TBM40, TBM60, TBM80, and TBM100 diets, respectively. Juvenile red sea bream were stocked into 18, 300 L flow-through tanks (50 fish/tank). Red sea bream were hand-fed with each diet until satiation for 8 weeks. No statistical differences in weight gain, specific growth rate (SGR), and feed consumption were found among red sea bream fed the Con, TBM20, and TBM40 diets. Furthermore, feed utilization of fish fed the TBM20, TBM40, TBM60, and TBM80 diets was comparable to red sea bream fed the Con diet. The biological indices, biochemical composition, and hematological parameters of fish were not statistically altered by dietary FM replacement with TBM. The greatest economic profit index was achieved in the TBM40 diet. In conclusion, the replacement of 40% FM with TBM in red sea bream diet appears to be the most recommendable approach without producing retarded growth and feed availability, but maximizing EPI to farmers.

Red sea bream iridovirus (RSIV) poses a significant threat to global aquaculture and wild fish populations, leading to substantial economic and ecological losses. Despite its recognition as a major viral disease, our understanding of the dynamics of RSIV infection and transmission in naturalistic conditions remains limited. Therefore, the present study aimed to investigate the kinetics, shedding, and interspecies transmission of RSIV in red sea bream (Pagrus major) through immersion and cohabitation challenge models. The primary objectives were to (1) elucidate the pathogenicity of RSIV in red sea bream through naturalistic immersion challenges, (2) analyze the viral load and shedding dynamics in RSIV-infected fish, and (3) assess the risk of horizontal transmission to other species. Our results indicated that red sea bream exposed to high doses of RSIV (101–107 RSIV copies/mL) experienced rapid cumulative mortality, particularly at 25 °C. Notably, red sea bream infected by immersion at 25 and 15 °C showed a significant increase in RSIV shedding into seawater when the viral load exceeded approximately 102.48 RSIV copies/mg, highlighting a critical threshold for understanding disease spread in aquaculture settings. Histopathological analysis revealed that the spleen and kidney were primarily affected, with significant lesion scores correlating with viral loads. We observed a strong correlation between viral load and histopathological infection grades, particularly in these primary tissues. Furthermore, cohabitation experiments highlighted the risk of RSIV transmission to other fish species, including rock bream (Oplegnathus fasciatus) and flathead grey mullet (Mugil cephalus), indicating the possibility of horizontal spread in multi-species farming systems. These findings emphasize the importance of continuous surveillance and robust biosecurity measures in aquaculture systems to manage RSIV infection effectively. Overall, this study contributes to understanding RSIV dynamics in red sea bream, offering insights into the impact of this virus in aquaculture environments, particularly concerning viral shedding and transmission. • RSIV infection in red sea bream was studied using immersion, cohabitation models. • The critical threshold of viral shedding into seawater was determined. • Histopathological changes in red sea bream correlated with viral loads. • RSIV-infected red sea bream horizontally transmit RSIV to other fish species. [ABSTRACT FROM AUTHOR]

Prohibitin 1 (PHB1) is ubiquitously expressed in multiple compartments within cells and is involved in the cell cycle, cell signaling, apoptosis, transcriptional regulation, and mitochondrial biogenesis at the cellular level and in the inflammation-associated and immunological functions of B and T lymphocytes. PHB1 is an important protein that performs antioxidant regulation and immune functions inside and outside cells but has not been sufficiently studied in teleost fish. Our study aimed to elucidate the functional properties and gain new insights into the biological processes and immune system of red seabream (Pagrus major), a commercially important fish cultured in South Korea and East Asia. PHB1 mRNA was most abundantly expressed in the head kidney of healthy red seabream, and significant changes in its expression were observed after artificial infection with bacteria and viruses. On analysis, reporter gene was also significantly upregulated by polyinosinic-polycytidylic acid, lipopolysaccharides, and hydrogen peroxide. Consequent to the functional characterization of PHB1 in cells via recombinant protein preparation, the activity of leukocytes was enhanced and the reactive oxygen species-induced stress in red blood cells was reduced. The results reveal the functional characteristics of PHB1 and provide new insights into the biological processes and immune system of P. major, with beneficial implications in the study of stress responses. • We cloned and identified the coding sequence of prohibitin 1 (PHB1) from red sea bream (Pagrus major). • PmPHB1 mRNA was highly expressed in head kidney, spleen and brain from healthy state Pagrus major. • PmPHB1 expression levels were significantly regulated by pathogens and ligands. • The biological function of recombinant PmPHB1 on blood cells was confirmed. [ABSTRACT FROM AUTHOR]

Karenia mikimotoi is a common species of red tide dinoflagellate that causes the mass mortality of marine fauna in coastal waters of Republic of Korea. Despite continuous studies on the ecophysiology and toxicity of K. mikimotoi, the underlying molecular mechanisms remain poorly understood. Red sea bream, Pagrus major, is a high-value aquaculture fish species, and the coastal aquaculture industry of red sea bream has been increasingly affected by red tides. To investigate the potential oxidative effects of K. mikimotoi on P. major and the molecular mechanisms involved, we exposed the fish to varying concentrations of K. mikimotoi and evaluated its toxicity. Our results showed that exposure to K. mikimotoi led to an accumulation of reactive oxygen species (ROS) and oxidative DNA damage in the gill tissue of P. major. Furthermore, we found that K. mikimotoi induced the activation of antioxidant enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase, in the gill tissue of P. major, with a significant increase in activity at concentrations above 5000 cells/mL. However, the activity of glutathione S-transferase did not significantly increase at the equivalent concentration. Our study confirms that oxidative stress and DNA damage is induced by acute exposure to K. mikimotoi, as it produces ROS and hypoxic conditions in P. major. In addition, it was confirmed that gill and blood samples can be used as biomarkers to detect the degree of oxidative stress in fish. These findings have important implications for the aquaculture of red sea bream, particularly in the face of red tide disasters.

A 56-day feeding trial was conducted to determine the effect of dietary supplementation with Bacillus sp. isolated from the intestines of red sea bream on the growth performance, immunity, and gut microbiome composition of red sea bream. Three diets (a control diet and two treatments) were formulated without Bacillus sp. PM8313 or β-glucan (control, CD), 1 × 108 CFU g-1 PM8313 (BSD), and 1 × 108 CFU g-1 PM8313 + 0.1% β-glucan (BGSD). At the end of the experiment, the weight, specific growth rate, feed conversion ratio, and protein efficiency ratio of the fish in the BSD and BGSD diet groups were significantly improved than those of the control group (P < 0.05). Additionally, amylase and trypsin activities were significantly higher (P < 0.05) in both groups compared to the control. Superoxide dismutase and lysozyme activity, which are serum non-specific immune responses, only increased in the BGSD group. The two treatment groups exhibited a marked difference in the intestinal microbiota composition compared to the control group. Furthermore, the treatment groups exhibited an upregulation of IL-6 and NF-κb, coupled with high survival rates when challenged with Edwardsiella tarda. Therefore, dietary supplementation with PM8313 improved the growth performance, digestive enzyme activity, non-specific immunity, and pathogen resistance of red sea bream, in addition to affecting the composition of its intestinal microflora. [ABSTRACT FROM AUTHOR]

The optimum level of fishmeal (FM) protein replacement by bacterial protein meal (BPM) was determined in the diet of juvenile red sea bream, Pagrus major. Six isoproteic and isolipidic diets were formulated to replace 0 (control diet), 190 , 280, 370, 470 and 560 g of the FM protein kg‐1 diet with BPM protein, and referred to as C, BP19, BP28, BP37, BP47 and BP56, respectively. Each diet was fed to triplicate groups of twenty fish (mean weight ~43 g) twice per day to apparent satiation. Fish fed diets C and BP19 did not show significant differences (p >.05) in growth, apparent digestibility or protein and lipid retention efficiency, but the daily feeding rate (DFR) was significantly lower under BP19 than under C. However, almost all growth parameters were significantly reduced when FM protein replacement with BPM was further increased from 280 to 560 g kg‐1 diet (p <.05). The results of polynomial regression analysis (second‐order) revealed significant negative correlations between dietary copper levels and final mean weight (R2 =.913), specific growth rate (R2 =.913) and DFR (R2 =.956). The results indicated that BPM could replace approximately 190 g of FM protein kg‐1 diet in the juvenile red sea bream diet without compromising growth performance or feed efficiency. [ABSTRACT FROM AUTHOR]

Abstract Background Henneguya Thélohan, 1892 (Myxobolidae) is one of the most species-rich genera of myxosporean parasites infecting fish. Although common in nature, there are few reports of these parasites causing important disease in aquaculture. In this paper, we describe a new species of Henneguya infecting Pagrus major (Temminck & Schlegel), a fish host introduced to the Mediterranean Sea from Japan in the late 1980s. Results Large plasmodia of the parasite were found in the bulbus arteriosus and in the ventricle of the infected fish. Spores were found mainly in the kidney and heart and were accompanied by melanized macrophages or vascular intimal proliferation mixed with a mild non-suppurative response, respectively. Comparisons of morphometric data for spore and polar capsule length and width, suggest a unique combination of features in the newly described species. Molecular analysis, based on 18S rDNA sequence of the parasite, followed by phylogenetic analysis, indicated that the parasite described here is a novel species of Henneguya, clustered with the marine congeneric species. Conclusions Henneguya aegea n. sp. infects in aquaculture P. major, a host introduced as eggs to the Mediterranean from Japan. Despite the high host specificity of the myxobolid parasites, H. aegea n. sp. seems to be able to use P. major as a host and propagate successfully, causing morbidity and mortality. This could result in spillback of the new species from high density cultured non-native P. major to native fish hosts.

Red sea bream (Pagrus major) is described as one of the marine fishes with high economic value, which is widely cultivated in East Asia. With large-scale and intensive aquaculture, bacterial diseases outbreak more frequently than before. In order to effectively prevent and control Vibrio anguillarum disease in red sea bream, we systematically analyzed the immune response mechanism of the head kidney and spleen of P. major infected with Vibrio anguillarum by RNAseq technology. In this study, we obtained 225,106,036 clean reads. By using Nr, Nt, Pfam, KOG/COG, Swiss-prot, KEGG, GO databases, we annotated 85,595 genes. In the head kidney and spleen, we obtained 3963 and 4981 DEGs (different expressed genes) respectively. To further study the function of DEGs, we performed GO and KEGG enrichment analysis on them. In pathway enrichment, the pathways which significantly enriched in both head kidney and spleen included Antigen processing and presentation, Phagocytosis and Cell adhesion molecules. In the head kidney, Ubiquitin-mediated proteolysis was specially enriched; while Intestinal immune network for IgM production, Complement and coagulation cascade were specially enriched in the spleen. This study provide effective data support for the comprehensive analysis of mechanism in P. major immune response following V. anguillarum infection, which would lay the foundation for further disease prevention and treatment.

Polymorphisms of growth- and immune-related genes in cultured red sea bream Pagrus major identified by gene-related DNA markers Keywords: domestication; gene-related microsatellite; outlier; Pagrus major; red sea bream EN domestication gene-related microsatellite outlier Pagrus major red sea bream 410 416 7 05/20/21 20210601 NES 210601 INTRODUCTION Red sea bream, I Pagrus major i , is an important farmed marine fish in Japan, cultured for nearly half a century. However, growth is known to be a polygenic trait (Tsai et al., 2015), and other growth-related genes such as the I GH i receptor gene and insulin-like growth factor genes ( I IGF-I i and I -II i ) may have been subject to selection pressure during domestication. All gene-related markers showed lower numbers of alleles in domestic populations (mean 6.7 in growth-related and 7.4 in immune-related genes) compared to wild (mean 15.6 in growth- and 17.5 in immune-related genes). [Extracted from the article]

Red sea bream iridovirus (RSIV) causes substantial economic damage to aquaculture. In the present study, RSIV in wild fish near aquaculture installations was surveyed to evaluate the risk of wild fish being an infection source for RSIV outbreaks in cultured fish. In total, 1102 wild fish, consisting of 44 species, were captured from 2 aquaculture areas in western Japan using fishing, gill nets, and fishing baskets between 2019 and 2022. Eleven fish from 7 species were confirmed to harbor the RSIV genome using a probe-based real-time PCR assay. The mean viral load of the RSIV-positive wild fish was 101.1 ± 0.4 copies mg-1 DNA, which was significantly lower than that of seemingly healthy red sea bream Pagrus major in a net pen during an RSIV outbreak (103.3 ± 1.5 copies mg-1 DNA) that occurred in 2021. Sequencing analysis of a partial region of the major capsid protein gene demonstrated that the RSIV genome detected in the wild fish was identical to that of the diseased fish in a fish farm located in the same area in which the wild fish were captured. Based on the diagnostic records of RSIV in the sampled area, the RSIV-infected wild fish appeared during or after the RSIV outbreak in cultured fish, suggesting that RSIV detected in wild fish was derived from the RSIV outbreak in cultured fish. Therefore, wild fish populations near aquaculture installations may not be a significant risk factor for RSIV outbreaks in cultured fish.

We evaluated the efficacy of mozuku fucoidan supplementation to alternative dietary proteins used in fish meal (FM) replacement to enhance growth, immunity, and stress resistance of Pagrus major. Seven isonitrogenous (45% protein) experimental diets were formulated where diet 1 (D1) was FM-based control diet. Diets 2 to 7 were formulated by replacing 25, 50, and 75% of FM protein with soy protein isolate (SPI) protein, and each replacement level was supplemented without or with fucoidan at 0.4% for diet groups D2 (FM25), D3 (FM25Fu), D4 (FM50), D5 (FM50Fu), D6 (FM75), and D7(FM75Fu), respectively. Each diet was randomly allocated to triplicate groups of fish (4.1 g) for 56 days. Significantly higher weight gain and specific growth rate were observed in fish fed FM50Fu diet group, and it was not differed (P > 0.05) with fish fed FM25Fu diet group. FM-based control diet showed intermediate value, and it was not differed (P > 0.05) with or without fucoidan-supplemented ≤ 50% FM replacement groups and FM75Fu diet group. Significantly lower growth performances were observed in FM75 diet group. At each replacement level, fucoidan-supplemented groups showed nonsignificant improvement of feed utilization performances. Fish fed fucoidan-supplemented diets showed best condition of oxidative and freshwater stress resistance. Lysozyme activity, NBT, and peroxidase activity showed higher (P > 0.05) values in fucoidan-supplemented groups compared with the non-supplemented groups. Catalase activity was significantly lower in FM75Fu diet group. Catalase activity is significantly influenced by the interaction effects of fucoidan and FM replacement level. In conclusion, fucoidan supplementation could increase the efficiency of utilizing SPI (≥ 75%) without any adverse effects on red sea bream performance. [ABSTRACT FROM AUTHOR]

Polymorphisms of the myostatin gene (MSTN) have been studied in vertebrates including several aquaculture species, revealing their role in growth. We attempted to identify polymorphisms in MSTN associated with growth traits of juvenile farmed red sea bream Pagrus major, an important cultured fish species in Japan. Polymorphisms in the coding region of MSTN were screened, and six polymorphisms were found among three exons: a deletion in exon 1, a single nucleotide polymorphism (SNP) in exon 2 and four SNPs in exon 3. The deletion in exon 1 eliminated a codon (glutamine) from the region comprising the polyglutamine structure, but all SNPs were synonymous. We analysed the polymorphisms for association with growth phenotype in large and small P. major specimens obtained from commercial production at 50 days post hatching. Two SNPs located in exon 3 (c.+846T>C and c.+1140T>C) were significantly more frequent in the large group, while no SNPs were significantly associated with the small phenotype. Haplotypes were reconstructed using genotype information of the two phenotype groups, and nine haplotypes (Hap_1 to Hap_9) were successfully reconstructed. Hap_6 and Hap_7 were significantly more often observed in small and large groups respectively. Analysis of diplotypes (haplotype combinations) of individual specimens revealed 19 diplotypes. The Hap_7/Hap_7 diplotype was found in 46.7% of large phenotype specimens, significantly more frequently than in the small group (13.5%). These results will be useful for marker‐assisted selection of red sea bream to improve production with respect to growth. [ABSTRACT FROM AUTHOR]

Calpains (CAPNs) belong to the papain superfamily of cysteine proteases, and they are calcium-dependent cytoplasmic cysteine proteases that regulate a variety of physiological processes. We obtained the sequence of CAPN3 from an NGS-based analysis of Pagrus major (PmCAPN3) and confirmed the conserved molecular biological properties in the predicted amino acid sequence. The amino acid sequence and predicted domains of CAPN3 were found to be highly conserved in all of the examined species, and one catalytic domain and four calcium binding sites were identified. In healthy P. major , the PmCAPN3 mRNA was most abundantly expressed in the muscle and skin, and ubiquitously expressed in the other tissues used in the experiment. After artificial infections with fish pathogens, significant changes in its expression levels were found in immune-related tissues, most of showed upregulation. In particular, the highest level of expression was found in the liver, a tissue associated with protease activity. Taken together, these results suggest a physiological activity for PmCAPN3 in P. major and reveal functional possibilities that have not yet been reported in the immune system. • The calpain 3 (CAPN3) was identified by NGS analysis from red sea bream (Pagrus major). • PmCAPN3 showed high sequence similarity with other species CAPN3. • PmCAPN3 mRNA was most abundantly distributed in the muscle and skin of healthy P. major. • PmCAPN3 mRNA by fish pathogen challenge has showed a significant change in expression level, particularly in the liver. [ABSTRACT FROM AUTHOR]

Background: Henneguya Thélohan, 1892 (Myxobolidae) is one of the most species-rich genera of myxosporean parasites infecting fish. Although common in nature, there are few reports of these parasites causing important disease in aquaculture. In this paper, we describe a new species of Henneguya infecting Pagrus major (Temminck & Schlegel), a fish host introduced to the Mediterranean Sea from Japan in the late 1980s. Results: Large plasmodia of the parasite were found in the bulbus arteriosus and in the ventricle of the infected fish. Spores were found mainly in the kidney and heart and were accompanied by melanized macrophages or vascular intimal proliferation mixed with a mild non-suppurative response, respectively. Comparisons of morphometric data for spore and polar capsule length and width, suggest a unique combination of features in the newly described species. Molecular analysis, based on 18S rDNA sequence of the parasite, followed by phylogenetic analysis, indicated that the parasite described here is a novel species of Henneguya, clustered with the marine congeneric species. Conclusions: Henneguya aegea n. sp. infects in aquaculture P. major, a host introduced as eggs to the Mediterranean from Japan. Despite the high host specificity of the myxobolid parasites, H. aegea n. sp. seems to be able to use P. major as a host and propagate successfully, causing morbidity and mortality. This could result in spillback of the new species from high density cultured non-native P. major to native fish hosts. [ABSTRACT FROM AUTHOR]

Heavy rainfall can reduce salinity and increase turbidity in coastal waters, creating stressful conditions for the organisms found there, especially for the early stages of their ontogeny. The effects of salinity and turbidity on the embryonic stages of red sea bream Pagrus major were examined under controlled laboratory conditions. In the first experiment, eggs of red sea bream were exposed to different salinity stresses [34 (control), 30, 26, 22, 18, 14 psu] for 3 h. In the second experiment, eggs were exposed to higher turbidity levels of 100, 300, 500, and 700 NTU from 0 NTU (control) obtained by dissolving kaolin clay for the same duration as in the first experiment. The results showed that the embryos of red sea bream are tolerant to short-term exposure to low salinity stress. There were no significant differences in the hatching rate, yolk sac consumption of newly hatched larvae, or survival of larvae at 6 days post-hatching. However, the short exposure to turbidity stress reduced the hatching rate, total length, and yolk sac volume of newly hatched larvae, and larval viability of red sea bream. Turbidity had a significant impact on the abnormality rate at hatching, with higher values observed for elevated turbidity. [ABSTRACT FROM AUTHOR]

Red sea bream Pagrus major is a commercially important fish in Japan. In eastern Seto Inland Sea (SIS), the catch has increased from 297 tons in 1972 to 2,039 tons in 2010. We examined the relationship, 1972–2010, between increase in catch and winter temperature, based on the catch in February and March and the lowest water temperature at 10 m depth. In 1972–1986, the lowest water temperatures in the inner SIS areas (Osaka Bay, Harima‐nada, and Bisan‐seto) were <8°C, which is physiologically unfavorable for red sea bream. However, in 1987–2010 temperatures were generally ≥8°C. In the inner areas, the catch during winter had been minimal until the early 1980s, presumably because most red sea breams moved to the Kuroshio‐influenced (warmer) Kii Channel area. However, the winter catch in the inner areas of SIS increased from the late 1980s with warm winters. In addition, the catch between April and June, the spawning season, increased in the inner areas from the 1990s, and the catch rate of the inner areas was more than twice higher in the 2000s than in the 1980s. The results suggest that expansion of the distribution area during winter due to warm winter and increase in egg production in the inner areas greatly contributes to the increasing in catch in the eastern SIS. [ABSTRACT FROM AUTHOR]

Tetraploid fish are important for mass production of triploids in polyploid breeding. In this study, we reported a novel protocol for artificial induction of tetraploidy by a combination of cold shock and hydrostatic pressure administered to gynogenetically developed eggs in Japanese flounder Paralichthys olivaceus. The induction was carried out by activating the eggs with UV-irradiated sperm of red sea bream Pagrus major, administering a cold shock (0°C, 5 to 45 min) 3 min after fertilization to inhibit second polar body exclusion, incubating the eggs for 60 min at 17°C, and treating them with a 650 kg/cm2 hydrostatics pressure shock for 6 min. We named the embryos gyno-tetraploids that developed from eggs after such treatments. The hatching rate of the gyno-tetraploids ranged from 20.99%±3.66% to 36.01%±2.79%, and the tetraploid rate ranged from 80.00% to 100.00%. All-maternal inheritance was verified using 6 high-recombination-rate microsatellite markers. This method successfully induced gyno-tetraploidy. The successful induction of gyno-tetraploidy lays the foundation for triploidization of new varieties with improved economic traits of interest that can benefit commercial culture. [ABSTRACT FROM AUTHOR]

In aquaculture, periodic measurement of fish body size is required to suitably assess growth progress. The aim of this study is to monitor the growth of free-swimming red sea bream, Pagrus major, farmed in net cages using multi-stereo-image measurement to determine the efficacy and potential applications of the method. After estimating appropriate sample sizes based on mean fork length and varying acceptable error ranges, we tracked fish growth using both multi-stereo-image measurement and traditional scoop-net capture methods for 1 year. Measurements were conducted four times every 3 months. In fish with fork length exceeding 40 cm, the appropriate sample sizes with acceptable error ranges of 1%, 2%, 3%, 4%, and 5% were around 100, 26, 12, 7, and 5 individuals, respectively, based on a 95% confidence interval. The fish exhibited most of their growth from June to December, with slower growth from February to June. This study provides evidence that multi-stereo-image measurement is an accurate and useful tool to enhance understanding of growth processes in cultured fish. [ABSTRACT FROM AUTHOR]

Cathepsin Z (CTSZ) is a lysosomal cysteine protease that is known to be involved in the maintenance of homeostasis and the biological mechanisms of immune cells. In this study, we have confirmed the tissue specific expression of the cathepsin Z (PmCTSZ) gene in Pagrus major , and confirmed its biological function after producing recombinant protein using Escherichia coli (E. coli). Multiple sequence alignment analysis revealed that the active site of the cysteine proteases and three N -glycosylation sites of the deduced protein sequence were highly conserved among all of the organisms. Phylogenetic analysis revealed that PmCTSZ was included in the clusters of CTSZ and the cysteine proteases of other bony fish and is most closely related to Japanese flounder CTSZ. PmCTSZ was distributed in all of the tissues from healthy red sea bream that were used in the experiment and was most abundantly found in the spleen and gill. Analysis of mRNA expression after bacterial (Edwardsiella piscicida : E. piscicida and Streptococcus iniae : S. iniae) or viral (red seabream iridovirus: RSIV) challenge showed significant gene expression regulation in immune-related tissues, but they maintained relatively normal levels of expression. We produced recombinant PmCTSZ (rPmCTSZ) using an E. coli expression system and confirmed the biological function of extracellular rPmCTSZ in vitro. We found that bacterial proliferation was significantly inhibited by rPmCTSZ , and the leukocytes of red sea bream also induced apoptosis and viability reduction. • A cathepsin Z (CTSZ) was identified from red sea bream (Pagrus major). • PmCTSZ share high conserved cysteine proteases active site and three N-glycosylation sites with that of other species. • PmCTSZ mRNA was highly expressed in spleen and gill from healthy condition. • RPmCTSZ inhibited bacterial growth and induced leukocyte apoptosis. [ABSTRACT FROM AUTHOR]

Atypical chemokine receptor 4 (ACKR4) is regulated by cytokines, binds chemokines and regulates the chemokine gradient. We verified the cDNA sequence by confirming ACKR4 from red sea bream (PmACKR4) by next generation sequencing (NGS) and analysed the molecular characteristics and gene expression profile. In the analysis using the predicted amino acid sequence of PmACKR4, a highly conserved G protein-coupled receptor 1 region and two cysteine residues were identified and included in the ACKR4 teleost cluster in the phylogenetic analysis. In healthy red sea bream, PmACKR4 mRNA was expressed at the highest levels in head kidney and was upregulated in all immune -related tissues used in the experiment after challenges with Streptococcus iniae (S. iniae) and red sea bream iridovirus (RSIV). These results suggest that ACKR4 is highly conserved in red sea bream and may play an important role in the immune system as previously reported. It is thought that ACKR4 acts as a regulator of immune -related cells via immune reactions after pathogenic infection. • An atypical chemokine receptor 4 (ACKR4) was identified in red sea bream (Pagrus major). • PmACKR4 share high conserved structural characteristics with that of other species. • PmACKR4 mRNA was highly expressed in head kidney and spleen from healthy condition. • PmACKR4 mRNA was significantly up-regulated after challenge with fish pathogens. [ABSTRACT FROM AUTHOR]

We developed a novel strain of red sea bream Pagrus major that showed resistance to red sea bream iridoviral disease (RSIVD) using marker-assisted selection combined with DNA-based family selection and evaluated survival of its G 2 in a farm environment. The G 1 population was derived from a single RSIVD-resistant male (G 0). The G 1 progeny of the resistant male were identified by DNA parentage analysis using microsatellites. Marker-assisted selection using a quantitative trait locus linked to the RSIVD-resistant trait (Pma4_014) was conducted, and individuals inheriting the resistant allele of Pma4_014 (+) were selected. Two G 2 populations were produced in 2016 and 2017, and reared for approximately three months, during the summer, at an aquaculture facility. A normal production cohort was also reared at the same farm in 2016 and survival compared. Survival rates of the G 2 populations produced in 2016 and 2017 were 78.8% and 83.5%, respectively. The survival rate of the 2016 normal production cohort was 63.8%. The segregation pattern of the resistant allele showed 1 (+/+): 2 (+/−): 1 (−/−) in G 2 , and genotype frequency of Pma4_014 was calculated using approximately 200 individuals collected from 2016 and 2017 G 2 populations before and after the field trial. Numbers of each genotype were estimated based on the number of introduced and surviving fish. Individuals with the resistant allele, (+/+) and (+/−), showed over 80% of the estimated survival rates, but individuals without the resistant allele (−/−) showed lower survival (50%) in both years. This result strongly suggests that the resistant allele dominantly affects RSIVD resistance, and the newly developed G 2 population is useful for further propagation of RSIVD-resistant red sea bream fingerlings. • An RSIVD-resistant strain of red sea bream was developed by marker-assisted selection. • Survival rate of F 2 was ~80% in two field trials. • Survival rates of F 2 individuals inheriting the resistant allele were over 80% in both trials. • The RSIVD resistant allele of Pma4_014 was found to be dominant. [ABSTRACT FROM AUTHOR]

Summary: Recrystallisation often occurs in the freeze‐thaw cycles and results in poor food quality. This study was undertaken to analyse the effects of recrystallisation on the changes of protein conformation and moisture migration within red seabream fillets after the freeze‐thaw cycles. The UV second‐derivative spectroscopy, intrinsic fluorescence measurement and Raman spectroscopy were employed to evaluate the protein conformational changes. The Low‐field NMR spectra analysis was used to evaluate moisture migration. The results indicated that the freeze‐thaw cycles altered the secondary and tertiary structure of proteins. It was noticed that interactions between water and protein molecules were decreased gradually and eventually induced the thermal instability of the myosin molecules. The immobilised water content declined and the free water content increased. There were significant destructions in fillet muscle microstructure. These observations unambiguously reflect how the recrystallisations affect the protein conformation and moisture migration patterns of red seabream fillets during freeze‐thaw cycles. [ABSTRACT FROM AUTHOR]

The effect of rapeseed meal (RM) and Aspergillus oryzae fermented rapeseed meal (RM‐Koji) on red sea bream (Pagrus major) was examined. Three groups of fish (initial weight, 4.5 ± 0.02 g) were fed a basal diet (RM0) and two test diets where half of fishmeal was replaced by RM (RM50) and RM‐Koji (FRM50) for 56 days. The obtained results showed that fish fed RM0 and FRM50 exerted significantly higher growth performance, feed utilization and haemoglobin level but lower triglyceride and cholesterol than RM50 group (p < 0.05). Interestingly, except of antiprotease activity, all the immune parameters including lysozyme, respiratory burst (NBT) and bactericidal activities were significantly increased in fish fed RM0 and FRM50 diets compared to RM50 diet (p < 0.05). In addition, malondialdehyde and reactive oxygen metabolites were significantly reduced in RM0 and FRM50 groups over RM50 group (p < 0.05). The present results suggest that fermented RM induced better growth performance and immune responses than feeding red sea bream with non‐fermented RM and both RM and RM‐Koji improved the antioxidative status of fish, making RM‐Koji an interesting candidate as a functional feed for aquatic animals. [ABSTRACT FROM AUTHOR]

We assessed the effects of fishmeal (FM) replacement by soy protein concentrate (SPC) with inosine monophosphate (IMP) supplementation on growth, digestibility, immunity, blood health, and stress resistance of red sea bream, Pagrus major. FM protein of a FM-based control diet (FM100) was replaced with 25 (FM75), 50 (FM50), 75 (FM25), and 100% (FM0) by SPC protein, and each replacement group was supplemented with 0.4% IMP to formulate five experimental diets. Each diet was randomly allocated to triplicate groups of fish (4.8 g) for 56 days. Results demonstrated that fish fed diet groups FM50 and FM75 had significantly the highest final weight, weight gain, specific growth rate, and feed intake. Meanwhile, in comparison to the control, growth performance and feed utilization did not significantly differ with the 75% FM-replaced diet group by SPC with IMP supplementation. Apparent digestibility coefficient of dry matter, protein, and lipid also followed a similar trend. All growth, feed utilization, and digestibility parameters were significantly lower in the FM0 diet group. Triglyceride level was increased (P < 0.05) with the increasing replacement level and it was significantly highest in the FM0 diet group. The fish fed diet groups FM100 and FM50 showed the best condition of oxidative and freshwater stress resistance, respectively. Meanwhile, the groups with up to 75% FM-replaced diet also showed acceptable stress resistance status. Overall, enhanced innate immune responses were observed in the entire FM replaced with IMP-supplemented diet groups in comparison to the control. Considering SGR as a model, the regression analysis determined that 71.7% FM protein could be replaced by SPC protein with IMP supplementation in diets for the growth of red sea bream. [ABSTRACT FROM AUTHOR]

Abstract Moina macrocopa (Straus, 1820), was cultured on different animal manures (i.e. chicken manure, Pig manure and cow manure) and food waste to detect the influence of these food sources on its mass production. Then M. macrocopa was used as feed for the rearing of Pagrus major larvae and its effects on their performance was studied. At first, the experiment was carried out for 21 days to identify the best culture medium for M. macrocopa. Food waste treatment resulted in higher density of M. macrocopa compared to other animal wastes. The percentage of unsaturated fatty acids was also significantly higher in the food waste treatment. Subsequently, we compared the effect of M. macrocopa cultured on food waste, Artemia and artificial diet on rearing the larvae of Pagrus major , red sea bream. The feeding time differed for each treatment, but the feeding number and amount were adjusted for all treatments. Results showed that larvae fed with M. macrocopa showed higher survival rates, growth rates, stress tolerance rate and DHA/EPA ratio than larvae fed with Artemia and artificial diet. The present results revealed that M. macrocopa cultured on food waste has an outstanding food potential and a probable substitute for Artemia. [ABSTRACT FROM AUTHOR]

We determined the supplementation effects of dietary fucoidan on growth, immune responses, blood characteristics, and oxidative stress resistance of juvenile red sea bream. A fishmeal (FM)-based basal diet supplemented with 0% (D1, control), 0.05% (D2), 0.1% (D3), 0.2% (D4), 0.4% (D5), and 0.8% (D6) mozuku fucoidan to formulate six experimental diets. Each diet was randomly allocated to triplicate groups of fish (3.8 g) for 60 days. Results showed that fish-fed diet D5 showed significantly higher (P < 0.05) growth performance compared to the control (D1). Diet groups D2 to D4 also showed intermediate values compared to D1. Feed conversion efficiency and protein efficiency ratio were significantly higher in diet group D5, which was not significantly different with D3. Fucoidan supplementation increased whole-body lipid, which was significantly higher in the D5 group. Condition factor (CF) was significantly higher in fish fed ≥ 0.2% fucoidan-supplemented diet groups. Diet group D5 and D4 showed significantly lower blood urea nitrogen (BUN) and aspartate aminotransferase (AST) level, respectively. Dietary fucoidan reduced the oxidative stress of fish. Among the measured nonspecific immune parameters, only peroxidase activity (PA) and total serum protein (TSP) were significantly influenced by dietary supplementation and it was higher in D4 group. Fucoidan supplementation reduces thiobarbituric acid reactive substance (TBARS) values numerically and it was lowest in fish-fed diet group D5. Under the present experimental condition, finally, we concluded that 0.3-0.4% dietary fucoidan supplementation enhanced the growth and health performance of red sea bream by increasing growth, immune response, blood characteristics, and oxidative stress resistance. [ABSTRACT FROM AUTHOR]

Dietary supplementation of selenium nanoparticles (Se-NPs) at different levels (0, 0.5, 1, and 2 mg kg−1 diet) was evaluated to find out the effects on serum and skin immune responses as well as stress resistance in the red sea bream (Pagrus major). After 45 days of experimental trial, serum and mucosal immune responses were significantly high in fish fed 1 mg Se-NPs kg−1 diet (P < 0.05). In this group, alternative complement pathway, total serum protein, antioxidant activity of catalase enzyme, serum bactericidal activity, serum lysozyme activity, and amounts of skin mucus secretions as well as stress resistance against low salinity stress increased significantly, when compared to fish fed Se-NP-free diet (P < 0.05). Furthermore, fish fed Se-NPs at 2 mg kg−1 diet exhibited higher alternative complement pathway, total serum protein, mucus lysozyme activity, serum and mucus peroxidases, amount of mucus secreted, and tolerance against low salinity stress than the fish fed Se-NP-free diet (P < 0.05). Interestingly, the nitro blue tetrazolium activity in all groups fed with diets supplemented with Se-NPs are significantly higher than Se-NP-free diet (P < 0.05). The present results demonstrate that the dietary supplementation with Se-NPs (mainly from 1 to 2 mg kg−1 level) could be useful for maintaining the overall health status of red sea bream. [ABSTRACT FROM AUTHOR]

A large number of farmed red sea bream (Pagrus major) and their gametes have escaped and dispersed into the wild from net-cage aquaculture since the advent of the technology in the mid-20th century. These escapees have likely been recruited into wild populations, affecting their genetic diversity. In this study, we used assignment methods with microsatellite markers to assess the frequency of escapee farmed red sea bream within the wild populations in a major aquaculture production region (UWJ) and in two regions with relatively lower production (IWG and SIJ) in Ehime Prefecture, Japan. The frequency of escapees in UWJ ranged from 14.1% to 30.2%, as shown by three methods of assignment. Escapees were frequently identified among specimens caught by angling (ranging from 26.7% to 46.7%), suggesting that they stay in the same area even after escape or are less cautious than wild individuals. No escapee was found in IWG and SIJ, areas with less extensive aquaculture. Some wild-caught fish appeared to have hybridized with farmed fish, as indicated by the threshold of membership coefficients obtained by simulation. These results clearly indicate that large numbers of farmed individuals have escaped from UWJ, a major aquaculture area, since the inception of red sea bream farming in Japan. Genetic reshuffle has possibly occurred following hybridization of wild and farmed individuals. [ABSTRACT FROM AUTHOR]

The complete mitochondrial genome of hybrid F2 from Acanthopagrus schlegelii (♀) × Pagrus major (♂) was obtained using high-throughput sequencing technology. The circular genome was 16,648 bp in length, consisting of 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and a control region. Overall, nucleotide composition was A: 28.02%, T: 27.88%, C: 27.93%, G: 16.17%. Nine genes were encoded on the light strand and the remaining 28 genes were encoded on the heavy strand. All protein initiation codons are ATG except for COI that begins with GTG. The phylogenetic analysis suggested that hybrid F2 of A. schlegelii (♀) × P. major (♂) was closest to A. schlegelii. The newly described mitochondrial genome may provide valuable data for the genetic and taxonomic research on artificial hybrid seabream.

Three different highly consumed fish species from Al-Ahsa market, Saudi Arabia namely Spangled emporer (Lethriuns nebulosus), Red striped seabream (Pagrus major) and Black seabream (Spondyliosoma cantharus) were evaluated for their muscle contents of heavy metals (e.g., Cd and Pb) and trace elements (e.g., Cu, Zn, Fe and Mn). The possible risks associated with their human consumption were also studied. A total of 60 fresh fish samples comprising of 20 samples from each above mentioned fish were collected, and were subjected for determination of heavy metal and trace element contents by Atomic Absorption Spectrophotometry after Microwave Wet Digestion. The results showed that, accumulation patterns of the heavy metals and trace elements followed the order: Fe > Zn > Cu > Mn > Pb > Cd. There were variations among metal contents in the muscles of the three fish species; S. cantharus accumulated the highest levels of Cu, Zn and Mn, while the highest level of Fe could be detected in the muscles of P. major. The concentration of Cd and Pb remained comparable in the muscles of all three fish species. The calculated maximum daily intake (MDI) values were found as 0.0003, 0.0009, 0.0035, 0.0001, 0.0000, 0.0000 mg/day/person for Cu, Zn, Fe, Mn, Cd and Pb, respectively. Conclusively, the present study indicated that, fish muscles contain relatively less burden of heavy metals and trace elements, and no health problem can be raised from human consumption of the examined commercial fishes at Al-Ahsa market, Saudi Arabia. [J Adv Vet Anim Res 2015; 2(3.000): 271-278]

Aquatic animal viruses are considered to be transmitted via environmental water between fish farms. This study aimed to understand the actual transmission risk of red sea bream iridovirus (RSIV) through environmental water among fish farms. An environmental DNA (eDNA) method using iron-based flocculation coupled with large-pore filtration was used to monitor RSIV DNA copies in seawater from fish farms and from an experimental infection model. RSIV dispersion in seawater from a net pen where the disease outbreak occurred was visualized by the inverse distance weighting method using multiple-sampling data sets from a fish farm. The analysis demonstrated that the center of the net pen had a high viral load, and RSIV seemed to be quickly diluted by the tidal current. To evaluate the transmission risk of RSIV in environmental water, the red sea bream Pagrus major (approximately 10 g) was exposed to RSIV-contained seawater (10 3 , 10 4 , 10 5 , 10 6 , and 10 7 copies/L) for 3 days, which mimicked field exposure. A probit analysis of the challenge test indicated that the inferred infection rates of seawater containing 10 5.9 copies/L and 10 3.1 copies/L of RSIV were 50% and 0.0001%, respectively. In the surveillance for 3 years at 10 fixed points ( n = 306), there were only seven samples in which the viral load exceeded 10 4 copies/L in seawater. These results suggest that the transmission of RSIV among fish farms via seawater is highly associated with the distance between the net pens, and the environmental water is not always an infection source for the transmission of RSIV between fish farms. IMPORTANCE Our surveillance of viral loads for red sea bream iridovirus (RSIV) by monitoring environmental DNA in fish farms suggested that the viral loads in the seawater were low, except for the net pens where RSIV outbreaks occurred. Furthermore, our experimental infection model indicated that the infection risk of RSIV-contained seawater with less than 10 3 copies/L was extremely low. The limited risk of environmental water for transmission of RSIV gives an insight that RSIV could be partly transmitted between fish farms due to the movement of equipment and/or humans from the fish farm where the disease outbreaks. Since our data suggest that seawater can function as a potential wall to reduce the transmission of RSIV, biosecurity management, such as disinfection of equipment associated with fish farms could be effective, even in the semi-open system aquaculture that the environmental water can be freely transferred, to reduce the risk of RSIV outbreaks.

In order to evaluate the effects of magnetic nanoparticles plus microwave (MNPMT) or far-infrared (MNPFT) thawing on protein conformation changes and moisture migration of red seabream ( Pagrus major ) fillets, cold storage thawing, microwave thawing, MNPMT, far-infrared thawing and MNPFT were subjected to red seabream fillets. DSC and dynamic rheology were conducted to analyze physicochemical changes. Raman spectra before and after isotope H/D exchange, intrinsic fluorescence and UV second derivative spectra were carried out to explore myofibrillar protein structural changes. Low-field NMR was used to test water migration. SEM was performed to observe fiber microstructure. Results indicated that MNPMT and MNPFT both had a desirable thermal stability and gelation property. Besides, both showed stable protein secondary and tertiary structure. Immobilized water in them also had no significant changes compared with fresh sample. This research provided some novel thawing technologies for application in food industry. [ABSTRACT FROM AUTHOR]

Abstract Both inosine (INO) and vitamin C (l -ascorbic acid, AsA) play important roles in growth performance, feed utilization and health status of fish. Therefore, a 56 days feeding trial was conducted to determine the interactive effects of dietary INO and AsA on growth performance, oxidative status, innate and adaptive immune responses of red sea bream. Fish growth performance and fed utilization parameters were significantly affected by dietary INO supplementation but not by AsA. Fish fed diets with INO at 4 g kg−1 diet in combination of high and low levels of AsA (3.1 g kg-1 and 9.3 g kg-1) produced the highest growth and feed utilization performances. In terms of growth and feed utilization performances no significant interaction effects were observed between INO and AsA. Dietary INO significantly influenced hematocrit, glucose and glutamyl oxaloacetic transaminase (GOT) content of red sea bream meanwhile AsA also significantly influenced hematocrit, glucose, total cholesterol, blood urea nitrogen (BUN) and glutamic-pyruvate transaminase (GPT) content of the test fish. No significant interaction effects was also observed between INO and AsA on measured hematological parameters. Reactive oxygen metabolites (d-ROMs) significantly influenced by both INO and AsA. Fish fed diet groups D1, D4 and D6 showed best oxidative stress resistance. Only INO was a significant factor on nitro-blue-tetrazolium activity (NBT) and bactericidal activity (BA). Neither INO nor AsA was a significant factor on serum catalase activity (CAT), total serum protein (TSP), peroxidase activity (PA) and lysozyme activity (LA). No significant interaction effects was observed between INO and AsA on measured innate immune parameters. Agglutination antibody titer was significantly influenced by dietary supplementation, after 15 days of vaccination but not in 21 days. In the day 15th fish and diet group D3 and D5 showed significantly higher values compared to diet groups control and D1. INO was the only significant factor of increasing agglutination antibody titer in 15 t h day. While AsA was not a significant factor on agglutination antibody titer values in day 15 t h, there was an interaction between dietary INO and AsA levels. Finally under the experimental conditions, fish fed high INO and low AsA levels (4 g kg−1 and 0.31 g kg−1 diet, respectively) showed best growth and feed utilization performance. Simultaneously, low level of INO and high level of AsA (2 g kg−1 and 0.93 g kg−1 diet, respectively) improved blood chemistry and immunological parameters. Furthermore, combined use of INO and AsA is possible to improve hemato-immunological responses of red sea bream. Highlights • No previous work has addressed the interactive effects of functional supplements, inosine (INO) and vitamin C (l -ascorbic acid, AsA) for Pagrus major. • INO significantly influenced growth and feed utilization performances but not AsA and no interaction observed between the supplements. • No significant interaction effects were observed between INO and AsA on measured innate immune and oxidative stress parameters. • While INO only significantly influenced agglutination antibody titer as a marker of adaptive immune functions in day 15th after vaccination, there was an interaction between dietary INO and AsA levels. • Combined use of INO and AsA is possible to improve hemato-immunological responses of juvenile red sea bream. [ABSTRACT FROM AUTHOR]

Genome editing is a powerful tool as a new breeding technology including for aquaculture because of the high efficiency of gene targeting without the requirement for exogenous gene integration. CRISPR/Cas9 system, a genome editing tool, has been widely used in various species due to its efficiency and flexibility. We demonstrate the establishment of a new breed of myostatin ( Pm-mstn ) complete knockout red sea bream ( Pagrus major ) using CRISPR/Cas9. This is the first report of the establishment of a new breed in aquaculture marine fish using genome editing. The mutations were formed by deletions in the first exon of the Pm-mstn , which cause disruption of the C-terminal active domain of MSTN. The breed exhibited a 16% increase of skeletal muscle, that is, an increase of edible parts. The breed showed the phenotype of short body length and small centrum, which is not observed in mice and other teleost fish. We established the homozygous gene disrupted breed in 2 years, which is far shorter than the conventional breeding method. Our study indicates that genome editing can accelerate the speed of aquaculture fish breeding. [ABSTRACT FROM AUTHOR]

Ultrasound assisted vacuum thawing (UVT) or microwave vacuum thawing (MVT) with red seabream fillets were compared to fresh, chill storage thawing, vacuum thawing, microwave thawing and ultrasound thawing. The thermal stability and gelation properties were studied with DSC and dynamic rheology, respectively. Raman spectra before and after H/D isotope exchange and intrinsic fluorescence were used to measure protein secondary and tertiary structure. Low-field NMR was done to measure water migration. The two thawing techniques both retained actin thermal stability and generally retained more stable tertiary structures than the other thawing methods. MVT showed a desirable viscoelasticity of muscle proteins and UVT had a relatively stable secondary structure. There were no significant changes in free water. Thus, UVT and MVT could be used to improve the physicochemical properties of proteins during thawing of fillets. [ABSTRACT FROM AUTHOR]

Abstract: The genetic diversity of the growth hormone gene in domesticated red sea bream (pmaGH) was evaluated using a minisatellite DNA marker located in intron 3 (pmaGH22) and nucleotide sequences. The number of alleles of pmaGH22 was largely decreased in domesticated strains of red sea bream, and the possibility of selection pressures was also detected based on the analysis of the Hardy–Weinberg equilibrium in some strains. However, each strain inherited a small number of alleles of pmaGH22, and the entire domesticated population (combining all strains) showed a large number of alleles (n = 17), similar to the allelic richness of the wild population (n = 18.5). Based on nucleotide sequencing analysis, three synonym mutations were found in the coding regions, and also several SNPs and indels were found in the noncoding regions. In addition, four genealogies of growth hormone haplotypes were identified based on principal coordinate analysis, and these genealogies of pmaGH partly reflected allele size ranges of pmaGH22. Several haplotypes shared alleles of pmaGH22, and also fragment size homoplasy in pmaGH22 was suspected. These alleles of pmaGH22 and the haplotypes will be a useful indicator for divergence of pmaGH and for broodstock individual selection with minimum inbreeding effect. [ABSTRACT FROM AUTHOR]

We previously reported a body color deformity in juvenile red sea bream, which shows transparency in the juvenile stage because of delayed chromatophore development compared with normal individuals, and this finding suggested a genetic cause based on parentage assessments. To conduct marker-assisted selection to eliminate broodstock inheriting the causative gene, developing DNA markers associated with the phenotype was needed. We first conducted SNP mining based on AFLP analysis using bulked-DNA from normal and transparent individuals. One SNP was identified from a transparent-specific AFLP fragment, which significantly associated with transparent individuals. Two alleles (A/G) were observed in this locus, and the genotype G/G was dominantly observed in the transparent groups (97.1%) collected from several production lots produced from different broodstock populations. A few normal individuals inherited the G/G genotype (5.0%), but the A/A and A/G genotypes were dominantly observed in the normal groups. The homologs region of the SNP was searched using a medaka genome database, and intron 12 of the Nell2a gene (located on chromosome 6 of the medaka genome) was highly matched. We also mapped the red sea bream Nell2a gene on the previously developed linkage maps, and this gene was mapped on a male linkage group, LG4-M. The newly found SNP was useful in eliminating broodstock possessing the causative gene of the body color transparency observed in juvenile stage of red sea bream. [ABSTRACT FROM AUTHOR]

In finfish aquaculture, fish meal is heated during the manufacturing process, which affects the digestibility and protein absorption by fish. However, manufactured fishmeal that is not heated does not undergo thermal denaturation. Few studies have investigated the effects of non-heated animal protein sources on the growth performance of fish. We investigated the effects of heated and non-heated squid and krill meal as diets for red sea bream. Five test diets were formulated to contain heated squid meal, non-heated squid meal, heated krill meal, non-heated krill meal, and fish meal as a control. Fifty fish (initial mean weight = 3.5 g) were distributed in ten 100-l experimental tanks. Fish were fed one of the five diets 3 times daily until satiation for 5 weeks. Regarding growth performance, fish fed the krill meal diet exhibited better growth than those fed squid meal during the first week of the rearing period. However, the squid meal diet group showed better performance than the krill meal diet group during the third week. Moreover, differences in body weight among treatments were greater during the fifth week. Better weight gain and thermal growth coefficient were recorded in the non-heated diet groups than in the heated diet groups. Higher feed intake was observed in the non-heated diet groups than in the heated diet groups. These results suggest higher performance of non-heated squid and krill meal as the protein source of the red sea bream diet. Further, the suitability of the diet type (e.g., squid and krill) might depend on the feeding period and/or developmental stage of fish. [ABSTRACT FROM AUTHOR]

The red seabream ( Pagrus major ) is an economically important marine fish species that is cultured in Japan. Natural outbreaks of red seabream iridovirus (RSIV) and/or Streptococcus iniae can cause massive mortalities and severe economic losses in red seabream production. No effective single-injection vaccine for protecting red seabream against both diseases has yet become commercially available. Here, we evaluated the efficacy of a bivalent formalin-killed vaccine (PISCIVAC™ Irido Si) against RSIV and S. iniae infections in red seabream. In laboratory trials, intraperitoneally vaccinated fish reared at 25 °C were protected against challenges with RSIV and S. iniae as early as 3 days post vaccination (dpv), with a relative percent survival (RPS) of 69% and 90%, respectively. The protection was also observed in fish reared at 15 °C, with a RPS of 88% and 89% after challenging the fish with RSIV and S. iniae at 10 dpv and 14 dpv, respectively. Furthermore, intramuscular vaccination effectively protected fish against RSIV (RPS of 100% and 65–96% at 10 and 20 dpv, respectively) and S. iniae (RPS of 92–100% at 14 dpv). The vaccine conferred protection against RSIV infection for at least 2 months and against S. iniae infection for at least 6 months in the field trial. These results indicate that PISCIVAC™ Irido Si is effective for protecting red seabream against RSIV and S. iniae infections. [ABSTRACT FROM AUTHOR]