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This study evaluated the effects of Jamun fruit extract (JFE) on the growth, immunity, and health of juvenile Cyprinus carpio (average weight: 9.08±0.47 g). Diets containing five different JFE concentrations, that is, 0 (control), 2 (JFE2), 3 (JFE3), 4 (JFE4), and 5 g Kg−1 (JFE5) were fed to five fish groups (maintained in triplicate) for eight weeks. Growth parameters were examined at 4 and 8 weeks post-feeding; whereas, immune and antioxidant-related parameters were measured at 8 weeks post-feeding. Fish were challenged with Aeromonas hydrophila at the end of the feeding trial and mortalities were recorded over 14 days post-infection. Weight gain rate (%) was significantly higher in JFE3, compared to the control. RBC and WBC counts, hemoglobin, total protein level, albumin, and phagocytic activity were significantly enhanced in JFE3 than in control; whereas, there was no significant effect on hematocrit, and blood glucose level. Skin mucosal lysozyme and peroxidase levels were significantly higher in JFE2 ̶ JFE4 than in the control. Significantly higher mucosal total immunoglobulin, alkaline phosphatase, and protein levels were recorded in JFE3. Serum MDA and AST levels were significantly lower in JFE2 ̶ JFE4 than in the control; however, the MPO level was highest in JFE3. Liver antioxidant enzymatic activities were strongly enhanced in JFE3. Further, JFE supplementation upregulated the expression of antioxidant-related genes in the liver. The mRNA expression of TNF-α and IL-1β was upregulated in the kidney and intestine in JFE3. Kaplan–Meier survival curves revealed that the probability of survival (64.69%) was highest in JFE3. Quadratic regression analysis followed by optimization showed that the optimal dietary JFE level was estimated to be 2.59 ̶ 2.74 g Kg−1 to maximize the growth performance. Therefore, JFE at appropriate doses could improve the growth, immunity, and disease resistance of C. carpio against A. hydrophila.

Yersinia pseudotuberculosis is an important animal pathogen, particularly for birds, rodents, and monkeys, which is also able to infect humans. Indeed, an increasing number of reports have been published on zoo animals that were killed by this species. One option to treat diseased animals is the application of strictly lytic (virulent) phages. However, thus far relatively few phages infecting Y. pseudotuberculosis have been isolated and characterized. To determine the prevalence of Y. pseudotuberculosis phages in zoo animals, fecal samples of birds and some primates, maras, and peccaries kept in the Tierpark Berlin were analyzed. Seventeen out of 74 samples taken in 2013 and 2017 contained virulent phages. The isolated phages were analyzed in detail and could be allocated to three groups. The first group is composed of 10 T4-like phages (PYps2T taxon group: Myoviridae; Tevenvirinae; Tequatrovirus), the second group (PYps23T taxon group: Chaseviridae; Carltongylesvirus; Escherichia virus ST32) consists of five phages encoding a podovirus-like RNA polymerase that is related to an uncommon genus of myoviruses (e.g., Escherichia coli phage phiEcoM-GJ1), while the third group is comprised of two podoviruses (PYps50T taxon group: Autographiviridae; Studiervirinae; Berlinvirus) which are closely related to T7. The host range of the isolated phages differed significantly. Between 5.5 and 86.7% of 128 Y. pseudotuberculosis strains belonging to 20 serotypes were lysed by each phage. All phages were additionally able to lyse Y. enterocolitica B4/O:3 strains, when incubated at 37°C. Some phages also infected Y. pestis strains and even strains belonging to other genera of Enterobacteriaceae. A cocktail containing two of these phages would be able to lyse almost 93% of the tested Y. pseudotuberculosis strains. The study indicates that Y. pseudotuberculosis phages exhibiting a broad-host range can be isolated quite easily from zoo animals, particularly birds.

We report here the complete genome sequence and characterization of Yersinia bacteriophage vB_YenP_ϕ80-18. ϕ80-18 was isolated in 1991 using a Y. enterocolitica serotype O:8 strain 8081 as a host from a sewage sample in Turku, Finland, and based on its morphological and genomic features is classified as a podovirus. The genome is 42 kb in size and has 325 bp direct terminal repeats characteristic for podoviruses. The genome contains 57 predicted genes, all encoded in the forward strand, of which 29 showed no similarity to any known genes. Phage particle proteome analysis identified altogether 24 phage particle-associated proteins (PPAPs) including those identified as structural proteins such as major capsid, scaffolding and tail component proteins. In addition, also the DNA helicase, DNA ligase, DNA polymerase, 5′-exonuclease, and the lytic glycosylase proteins were identified as PPAPs, suggesting that they might be injected together with the phage genome into the host cell to facilitate the take-over of the host metabolism. The phage-encoded RNA-polymerase and DNA-primase were not among the PPAPs. Promoter search predicted the presence of four phage and eleven host RNA polymerase –specific promoters in the genome, suggesting that early transcription of the phage is host RNA-polymerase dependent and that the phage RNA polymerase takes over later. The phage tolerates pH values between 2 and 12, and is stable at 50°C but is inactivated at 60°C. It grows slowly with a 50 min latent period and has apparently a low burst size. Electron microscopy revealed that the phage has a head diameter of about 60 nm, and a short tail of 20 nm. Whole-genome phylogenetic analysis confirmed that ϕ80-18 belongs to the Autographivirinae subfamily of the Podoviridae family, that it is 93.2% identical to Yersinia phage fHe-Yen3-01. Host range analysis showed that ϕ80-18 can infect in addition to Y. enterocolitica serotype O:8 strains also strains of serotypes O:4, O:4,32, O:20 and O:21, the latter ones representing similar to Y. enterocolitica serotype O:8, the American pathogenic biotype 1B strains. In conclusion, the phage ϕ80-18 is a promising candidate for the biocontrol of the American biotype 1B Y. enterocolitica.

Yellow-pigmented, circular bacteria (strain SNU WT7) were isolated from the liver of moribund eastern catfish (Silurus asotus). Our study focused on the taxonomic description of SNU WT7 using phylogenetic, phenotypic, and chemotaxonomic analyses. The 16S rRNA gene sequence of the SNU WT7 strain was highly similar to that of Chryseobacterium haifense H38T (97.29% similarity), followed by Chryseobacterium hominis P2K6T (97.22% similarity), while other species exhibited similarity values of less than 97.0%. The genome of strain SNU WT7 displayed average nucleotide identity and genome-to-genome distance values of 72.35% and 22.0%, respectively, which clearly indicated that the novel species was distant from the other Chryseobacterium species, with its closest relative being C. haifense H38T. Furthermore, the phenotypic characteristics, including acid production from glucose, D-fructose, lactose, and maltose, of strain SNU WT 7 differed from those of C. haifense H38T. The major polar lipid of the strain was phosphatidylethanolamine, and several unidentified aminolipids and lipids were also present. Similar to other Chryseobacterium species, the quinone system was composed mainly of MK-6. The genome of SNU WT7 is 2,690,367 bp with a G + C content of 43.6%. Taken together, our data indicate that the isolate SNU WT7 represents a novel species of the genus Chryseobacterium. Thus, we present the name Chryseobacterium siluri sp. nov. for the novel type strain SNU WT7T (KCTC 72626, JCM 33707).

Edwardsiella species are one of the top causative pathogens of mortality in various fisheries worldwide. Their role in zoonotic infections and increase in antibiotic-resistance has raised concerns and interests in many research fields. Similar to the studies investigating human clinical cases, there has been an increase in research examining the potential pathogenic role of the bacterium in aquaculture. Within the Edwardsiella family, Edwardsiella anguillarum was lastest group to be differentiated from the Edwardsiella tarda group, and many studies focusing on the virulence of this species have since ensued. In Korea, only E. tarda infections have been reported in aquaculture industries, and there have been no reports on economic losses incurred owing to E. anguillarum infection. There has been a recent report investigating the pathogenicity and pathological changes caused by E. anguillarum infection in a tilapia farm located in the Costa Rica. To the best of our knowledge, as ours is the first report of E. anguillarum infection in a Nile tilapia (Oreochromis niloticus) farm located in an Asian country, the pathogenicity of the bacterial strain was histopathologically compared to that of the past studies. As tilapia is one of the most globally consumed fish species, particularly throughout Asia, Europe, and America, an epidemiological study regarding the disease distribution is necessary for the control and prevention of the disease. Here, we report the first mass mortality case caused by E. anguillarum infection in a Nile tilapia farm located in Korea; the bacterial strain responsible was isolated, characterized, and pathologically analyzed.

This study aimed to re-evaluate the pathogenic characteristics of Chryseobacterium balustinum, generally known as a food spoilage bacterium. We observed mass mortality in a rainbow trout farm in Jeonbuk province, Republic of Korea. Fewer studies have reported on rainbow trout mortality or infections in Korea than in other countries; among these, few studies have reported cases of Chryseobacterium infections. Sequencing analysis revealed that this bacterium is closely related (99.24%) to Chryseobacterium balustinum. Bacterial identification assays, including the API test, sequencing, and phylogenetic analysis, found the 24 isolates to be C. balustinum. The strain showed multiple resistance to 18 of 25 antibiotics tested. Primary clinical symptoms of its infection are damage to the fins, necrosis, and cytoplasmic vacuolation in hepatocytes. The pathogenicity of the strain was determined following Koch’s postulates and the challenge test. The present results suggest that C. balustinum WLT can be considered a multidrug-resistant zoonotic pathogen responsible for mortality and economic losses.

Yersinia enterocolitica is a food-borne Gram-negative pathogen responsible for several gastrointestinal disorders. Host-specific lytic bacteriophages have been increasingly used recently as an alternative or complementary treatment to combat bacterial infections, especially when antibiotics fail. Here, we describe the proteogenomic characterization and host receptor identification of the siphovirus vB_YenS_ϕR2-01 (in short, ϕR2-01) that infects strains of several Yersinia enterocolitica serotypes. The ϕR2-01 genome contains 154 predicted genes, 117 of which encode products that are homologous to those of Escherichia bacteriophage T5. The ϕR2-01 and T5 genomes are largely syntenic, with the major differences residing in areas encoding hypothetical ϕR2-01 proteins. Label-free mass-spectrometry-based proteomics confirmed the expression of 90 of the ϕR2-01 genes, with 88 of these being either phage particle structural or phage-particle-associated proteins. In vitro transposon-based host mutagenesis and ϕR2-01 adsorption experiments identified the outer membrane vitamin B12 receptor BtuB as the host receptor. This study provides a proteogenomic characterization of a T5-type bacteriophage and identifies specific Y. enterocolitica strains sensitive to infection with possible future applications of ϕR2-01 as a food biocontrol or phage therapy agent.

Shark meat is consumed as a food source worldwide, especially in Asian countries. However, since sharks are apex predators in the ocean food chain, they are prone to bioaccumulation of heavy metals. More than 100 million sharks are caught annually for human consumption, and the safety of shark meat cannot be overemphasized. Here, we examined heavy metal concentration in the muscle tissue of 6 shark species including 3 migratory species (Carcharhinus brachyurus, Carcharhinus obscurus, and Isurus oxyrinchus) and 3 local species (Triakis scyllium, Mustelus manazo, and Cephaloscyllium umbratile) from fish markets in Jeju Island, Republic of Korea. The concentrations of 11 heavy metals (Cr, Fe, Cu, Zn, As, Se, Cd, Sn, Sb, Pb, and Hg) and MeHg were analyzed. The result showed that the average concentrations of all metals, except for that of As, were below the regulatory maximum limits of many organizations, including the Codex standard. Hg and MeHg were significantly correlated with body length, body weight, and age, and the concentration of Hg was expected to exceed the limit in C. brachyurus with a body length or weight of over 130 cm or 25 kg, respectively. Our results indicate that shark meat can expose consumers to a high level of As and that copper sharks bigger than the predicted size should be avoided for excessive Hg. Considering these findings, a detailed guideline on consumption of meat of different shark species should be suggested based on further investigation.

The Yersinia bacteriophages fPS-2, fPS-65, and fPS-90, isolated from pig stools, have long contractile tails and elongated heads, and they belong to genus Tequatroviruses in the order Caudovirales. The phages exhibited relatively wide host ranges among Yersinia pseudotuberculosis and related species. One-step growth curve experiments revealed that the phages have latent periods of 50–80 min with burst sizes of 44–65 virions per infected cell. The phage genomes consist of circularly permuted dsDNA of 169,060, 167,058, and 167,132 bp in size, respectively, with a G + C content 35.3%. The number of predicted genes range from 267 to 271. The phage genomes are 84–92% identical to each other and ca 85% identical to phage T4. The phage receptors were identified by whole genome sequencing of spontaneous phage-resistant mutants. The phage-resistant strains had mutations in the ompF, galU, hldD, or hldE genes. OmpF is a porin, and the other genes encode lipopolysaccharide (LPS) biosynthetic enzymes. The ompF, galU, and hldE mutants were successfully complemented in trans with respective wild-type genes. The host recognition was assigned to long tail fiber tip protein Gp38, analogous to that of T-even phages such as Salmonella phage S16, specifically to the distal β-helices connecting loops.

This study presents a novel Janthinobacterium strain, SNU WT3, isolated from the kidney of rainbow trout. A phylogenetic study using 16S rRNA sequences indicated that the strain is closely related to Janthinobacterium svalbardensis JA-1T. However, biochemical analysis found differences in D-xylose adonitol, N-acetylglucosamine, arbutin, and cellobiose. As for genome-to-genome distance and average nucleotide identity values calculated between strain SNU WT3 and other related strains such as J. lividum EIF1, J. svalbardensis PAMC 27463, and J. agaricidamnosum BHSEK were all below the cutoff value between species. DNA-DNA hybridization between strain SNU WT3 and other close relatives indicated the results of J. lividum DSM 1522T (47.11%) and J. svalbardensis JA-1T (38.88%) individually. The major fatty acid compositions of strain SNU WT3 were cylco-C17:0 (41.45%), C16:0 (33.86%) and C12:0 (5.87%). The major polar lipids were phosphatidylethanolamine, phosphatidylcholine, phosphatidylglycerol, and diphosphatidylglycerol. The quinone system was composed mainly of ubiquinone Q-8. The genome of strain SNU WT3 consists of 6,314,370 bp with a G + C content of 62.35%. Here, we describe a novel species of the genus Janthinobacterium, and the name Janthinobacterium tructae has been proposed with SNU WT3T (=KCTC 72518 = JCM 33613) as the type strain.

A novel Citrobacter species was isolated from the kidney of diseased rainbow trout (Oncorhynchus mykiss) reared on a trout farm. Biochemical characterization and phylogenetic analysis were performed for bacterial identification. Sequencing of the 16S rRNA gene and five housekeeping genes indicated that the strain belongs to the Citrobacter genus. However, multilocus sequence analysis, a comparison of average nucleotide identity, and genome-to-genome distance values revealed that strain SNU WT2 is distinct and forms a separate clade from other Citrobacter species. Additionally, the phenotype characteristics of the strain differed from those of other Citrobacter species. Quinone analysis indicated that the predominant isoprenoid quinone is Q-10. Furthermore, strain virulence was determined by a rainbow trout challenge trial, and the strain showed resistance to diverse antibiotics including β-lactams, quinolone, and aminoglycosides. The complete genome of strain SNU WT2 is 4,840,504 bp with a DNA G + C content of 51.94% and 106,068-bp plasmid. Genome analysis revealed that the strain carries virulence factors on its chromosome and antibiotic resistance genes on its plasmid. This strain represents a novel species in the genus Citrobacter for which the name C. tructae has been proposed, with SNU WT2 (=KCTC 72517 = JCM 33612) as the type strain.

Vibrio coralliilyticus (V. coralliilyticus) is a pathogen that causes mass mortality in marine bivalve hatcheries worldwide. In this study, we used a bacteriophage (phage) cocktail to prevent multiple-antibiotic-resistant (MAR) and phage-resistant (PR) V. coralliilyticus infection in Pacific oyster (Crassostreagigas) larvae. To prevent the occurrence of phage-resistant strains and decrease the effect of mono-phage treatment, we prepared a phage cocktail containing three types of V. coralliilyticus-specific phages and tested its prophylactic efficacy against MAR and PR V. coralliilyticus infection. The results of the cell lysis test showed that the phage cocktail showed an excellent bactericidal effect against the MAR and PR variants in contrast to the experimental group treated with two mono phages (pVco-5 and pVco-7). An in vivo test using Pacific oyster larvae also confirmed the preventive effect against MAR and PR variants. In conclusion, the application of the phage cocktail effectively prevented V. coralliilyticus infection in marine bivalve seedling production. Furthermore, it is expected to reduce damage to the aquaculture industry caused by the occurrence of MAR and PR V. coralliilyticus. Therefore, phage cocktails may be used for the control of various bacterial diseases.

Vibrio coralliilyticus is known as a coral pathogen that also infects marine bivalve larvae worldwide. It is considered to be one of the major constraints in artificial marine bivalve seed production as it causes mortality. In this study, we first isolated and characterized a high virulent of V. coralliilyticus designated as SNUTY-1 that was the cause of Pacific oyster larvae mortality in Korea. In the pathogenicity test, exposure to 2.14 × 105 CFU/mL for 24 h caused mortality to 88.65 ± 2.4% of the tested healthy Pacific oyster larvae. SNUTY-1 showed anti-microbial resistance to β-lactams, such as penicillins, cephalosporins, and carbapenems. We sequenced and assembled the complete genome of SNUTY-1 (5,842,676 bp), consisting of two chromosomes (Chr I and Chr II) and two plasmids (pSNUTY1 and pSNUTY2). The COG functional analysis confirmed that Chr I had more genes associated with basic cellular functions in comparison to Chr II. The results of the phylogenetic trees based on OrthoANI values indicated that the SNUTY-1 was closely related to V. coralliilyticus strains. SNUTY-1 had a unique plasmid (pSNUTY2), which could mean that the Korean isolate is different from other sequenced V. coralliilyticus strains from different geographical origins. Toxic proteins such as cytolysin/hemolysin and extracellular metalloprotease genes were encoded on Chr I and Chr II of SNUTY-1. These data facilitate the control of V. coralliilyticus infections in aquaculture by providing valuable insights into the biodiversity of this organism and valuable information for the study of virulence factors.

Harmful effects of heavy metals are myriad. Lead (Pb) from soil and atmosphere contaminates water bodies and affects the aquatic animals. Our previous study confirmed the in vitro probiotic potential of Lactobacillus reuteri against Pb toxicity, but further investigation is necessary for gaining insights into the related protection mode. Therefore, in this study, we investigated the protective effects of the potential probiotic L. reuteri P16 against waterborne Pb exposure-induced toxicity in the freshwater fish Cyprinus carpio. Fish (average weight: 23.16 ± 0.73 g) were allocated to four groups (control, Pb only, Pb + L. reuteri P16, and L. reuteri P16 only) and Pb groups were exposed to waterborne Pb (1 mg L−1) for 6 weeks. L. reuteri P16 (108 CFU g−1) supplemented diet was provided twice daily. Growth performances, hemato-biochemical parameters, innate immune responses, intestinal microbiota, and Pb accumulation in tissues were measured at the end of the trial. When the fish were exposed to Pb, dietary supplementation of L. reuteri P16 effectively decreased mortality and accumulation of Pb in tissues, and improved the growth performance. Co-treatment with Pb and L. reuteri P16 alleviated Pb exposure-induced oxidative stress, reversed alterations in hemato-biochemical parameters, improved innate immune parameters, and restored intestinal enzymatic activities. Moreover, L. reuteri P16 supplementation reversed the changes in intestinal microbiota in Pb-exposed fish. Furthermore, Pb exposure decreased the expressions of pro-inflammatory cytokines (TNF-α, IL-1β). However, the expression of heat shock proteins (HSP70 and HSP90) increased, which might have increased the cellular stress. Interestingly, the Pb-induced alterations of gene expressions were reversed by L. reuteri P16 supplementation. Thus, dietary administration of the potential probiotic L. reuteri P16 had several beneficial effects on growth performance and immune responses, decreased Pb accumulation in tissues, and reversed alterations in hematological responses of C. carpio. Furthermore, it offered direct protection against Pb-induced oxidative stress. Therefore, L. reuteri P16 may be a novel dietary supplement for enhancing growth performance and preventing Pb-exposure-induced toxicity in fish in aquaculture and aquatic products.

Pseudomonas species are one of the most prevalent bacterial species globally distributed in forest soil, river water, and human or animal skin. Some species are pathogens or opportunistic pathogens in hospitalized patients, animals, and plants. Various Pseudomonas species, including Pseudomonas putida, P. plecoglossicida, P. aeruginosa, and P. fluorescens, are known fish pathogens; P. fluorescens and P. putida cause severe losses in rainbow trout farming. Therefore, we investigated and isolated the pathogen that is responsible for mortality in a rainbow trout farm in Korea. The isolated bacterium was a strain of P. tructae, which was recently classified in the P. putida group. We performed taxonomical analysis of the bacteria in our previous study. In this study, we investigated the pathogenicity and clinical symptoms of P. tructae and analyzed its genomic characteristics. The pathogenicity of the strain was tested via challenge experiments in healthy rainbow trout and histopathologic analysis of the infected fish. Genome sequence was analyzed to identify the bacterial genes that are involved in antibiotic resistance and virulence. This is the first study reporting P. tructae as an emerging pathogen that is responsible for mortality in rainbow trout fisheries and providing the genome sequence of P. tructae.

Infectious hematopoietic necrosis virus (IHNV), one of the most important pathogenic fish viruses, affects trout fisheries and causes considerable economic losses. Currently, in Korea, more studies on IHNV infection are being reported. However, relatively less data is available on Korean isolates than on those from other countries. Few studies have focused on gene sequence analyses of IHNV glycoprotein (G) gene and almost none have focused on other gene fragments. Therefore, considering the dearth of adequate phylogenetic and genomic studies on Korean IHNV strains because of the lack of data, our study aimed to provide sufficient relevant data by sequencing the complete genome of the IHNV strain SNU1, which was recently isolated from a Korean rainbow trout farm. Moreover, we focused on expanding the perspectives on the phylogenesis of IHNV isolates from Korea and other Asian countries. IHNV was isolated from pooled hematopoietic tissue samples using Epithelioma papulosum cyprinid (EPC) cells, and phylogenetic analysis and genome study were conducted using complete G, N, and nonvirion (NV) gene sequences. Our main achievements were the development of a phylogenetic analytical method based on the NV gene and complete genome sequence analysis of the IHNV strain SNU1, which was compared with other Asian isolate sequences.

Staphylococcal infections are extensively investigated in humans owing to the resistance of staphylococci to diverse antibiotics commonly used in hospitals. The resistance mechanism of methicillin-resistant Staphylococcus aureus has garnered the interest of researchers due to its risk to the global public health. Furthermore, the zoonotic potential of staphylococci has led to increased interest in their transmission mechanism via food, livestock, as well as domestic and wild animals. Although fish are globally consumed, there are only few studies on the potential threat of staphylococcal infection in aquatic animals. In this study, we present the first description of Staphylococcus xylosus infection and its pathogenicity in rainbow trout, which resulted in fish mortality and economic losses in trout fisheries. We focused on the pathogenic role of the bacterium and its influence on rainbow trout based on the clinical symptoms in the eyes. Staphylococcus xylosus infection induced exophthalmia and disrupted the primary immune barrier, which increased the possibility of other secondary bacterial infections in fish under poor conditions, resulting in continuous mortality.

Janthinobacterium spp. are normally considered non-pathogenic, and few pathogenesis-related studies have been reported. Here, we report the first isolation of Janthinobacterium lividum in Korea as a pathogenic bacterium infecting rainbow trout. Mass mortality was observed at one rainbow trout hatchery, and dead fish were necropsied. Gram-negative, nonmotile, rod-shaped bacteria that grew on Cytophaga agar were isolated. A specific violet pigmentation was observed after 7 days of cultivation, and the species were characterized on the basis of the analysis of the 16S rRNA gene. Because no research has focused so far on the pathogenicity of these bacteria, our study was directed to their pathogenic role based on infection-induced histopathology. Examination of stained tissue sections revealed severe renal bacteraemia and tubule degeneration. Other tissue sections, including sections from the liver and the spleen, were relatively clear. The measured half-maximal lethal dose (LD50) was approximately 3 × 105 colony-forming units/fish, suggesting that this bacterium may be an opportunistic pathogen in rainbow trout fisheries. Since the bacterium commonly dwells in soil and most water for rainbow trout fisheries in Korea is supplied from ground water, the bacteria may naturally flow into the aquatic environment. Therefore, recognition of any pathogenic role of J. lividum is important for the prevention of disease in aquaculture.

Red mark syndrome (RMS) is a fish disease caused by the infection of Rickettsial agents, especially affecting rainbow trout (Oncorhynchus mykiss). The disease is prevalent in many countries in Europe (France, Switzerland, Italy, and Slovenia), South America (Chile), North America (USA), and even Asia (Japan). However, it has not been reported in Korean aquaculture. In February 2019, rainbow trout presenting red spot lesions with swollen features on the lateral side of their body were observed at a hatchery in Korea. Fishes showing those clinical signs were fry weighing 25 ± 5 g. Moreover, the fish showing the red spot lesions were found dead, which suggests an outbreak of a mortality-causing disease. The symptoms were similar to those of RMS, and we identified the presence of Rickettsia-like organisms associated with this disease using polymerase chain reaction (PCR), sequencing, histopathologic examination, and transmission electron microscopy. The distinct features of this infection, compared to that in previous reports, were that RMS occurred in small-sized fish and accompanied mortality. Additionally, the presence of the Rickettsia agent was accompanied with outbreak of the disease. Therefore, this is the first report of RMS outbreak in rainbow trout fisheries in Korea.

Thiazolidinedione 49 (TD49), a newly synthesized algicide, shows strong toxicity at low concentrations of 0.1−2.0 μM. However, its potential effects on non-target species at the transcript level were not investigated. Differentially expressed genes (DEGs) in the gills of the bay scallop, Argopecten irradians, were accessed after treatment with 0.68 μM TD49 for up to 48 h. Following exposure, it was observed that 5214 genes were upregulated and 3497 were downregulated. Functional enrichment analysis revealed that the apoptosis pathway was activated. The extrinsic apoptosis pathway was activated and the survival factors related pathway was suppressed. Furthermore, gene expressions related to ATP-binding cassette, nuclear factor erythroid 2-related factor, B cell lymphoma-2 family protein, glutathione reductase, glutathione peroxidase, catalase, NADPH2:quinone reductase, and superoxide dismutase were decreased. Conversely, gene expressions related to FAS-associated death domain protein, glutathione S-transferase, caspase 6, 8, cytochrome P450 1A1, and 2C8 were increased. These results comprehensively demonstrated the toxicity of the novel algicide TD49, and should draw the attention of researchers to the importance of analyzing the potential impact of chemical compounds as algicides to control the proliferation of harmful algae, due to the secondary pollution caused by their application.

Cyprinid herpes virus 3 (CyHV-3) diseases have been reported around the world and are associated with high mortalities of koi (Cyprinus carpio). Although little work has been conducted on the molecular analysis of this virus, glycoprotein genes identified in the present study seem to be valuable targets for genetic comparison of this virus. Three envelope glycoprotein genes (ORF25, 65 and 116) of the CyHV-3 isolates from the USA, Israel, Japan and Korea were compared, and interestingly, sequence insertions or deletions were observed in these target regions. In addition, polymorphisms were presented in microsatellite zones from two glycoprotein genes (ORF65 and 116). In phylogenetic tree analysis, the Korean isolate was remarkably distinguished from USA, Israel, Japan isolates. These findings may be suitable for many applications including isolates differentiation and phylogeny studies.

To explore the feasibility of Musa acuminata (banana) peels as a feed additive, effects of banana peel flour (BPF) on the growth and immune functions of Labeo rohita were evaluated. Diets containing five different concentrations of BPF (0% [basal diet], 1% [B1], 3% [B3], 5% [B5], and 7% [B7]) were fed to the fish (average weight: 15.3 g) for 60 days. The final weight gain and specific growth rate were higher (P

In the present study, we investigated effects of compound kaempferol 3-a-L-(4-O-acetyl)rhamnopyranoside-7-a-L-rhamnopyranoside (SA) isolated from Dryopteris crassirhizoma during immune-related gene expression in Ctenopharyngodon idella head kidney macrophages (CIHKM). The expression of immune-related genes (IL-1β, TNF-α, MyD88, and Mx1) were investigated using real-time PCR at 2 h, 8 h, 12 h, and 24 h after incubation with 1, 10, and 50 μg mL−1 of SA. Furthermore, fish were injected intraperitoneally with 100 μL of SA, and immune parameters such as lysozyme activity, complement C3, SOD, phagocytic activity, and IgM level were examined at 1, 2, and 3 weeks after injection. The differential expression of cytokines was observed after exposure to SA. IL-1β genes displayed significant expression at 2 and 8 h after exposure to 1–10 μg mL−1 of SA. SA also induced gene expression of cytokines such as MyD88, Mx1, and TNF-α. Furthermore, enhanced immune parameters in grass carp confirmed the immunomodulatory activity of SA. Interestingly, this compound has no toxic effect on CIHKM cells as tested by MTT assay. In addition, fish immunised with 10 μg mL−1 of SA exhibited maximum resistance against Aeromonas hydrophila infection. These results suggest that SA has the potential to stimulate immune responses in grass carp.

Background5-hydroxytryptamine type 3 (5-HT3) receptor antagonists are effective and safe on postoperative nausea and vomiting (PONV). Palonosetron, the newest 5-HT3 antagonist, has potent antiemetic property. We hypothesized that a combination of palonosetron and dexamethasone could more decrease PONV than palonosetron alone.MethodsAmong the patients scheduled to undergo laparoscopic gynecologic surgery, mastoidectomy with tympanoplasty or thyroidectomy under general anesthesia, eighty four female patients with at least two PONV risk factors were enrolled in this study. They were received randomly 0.075 mg palonosetron and 4 mg dexamethasone (group C) or 0.075 mg palonosetron alone (group P). The severity of PONV using Rhodes index and the percentage of complete response during postoperative 24 hours were compared between groups.ResultsThe frequency of mild/moderate/great/severe PONV based on Rhodes index were 9.8%/0%/0%/0% and 9.3%/2.3%/2.3%/0% in group P and group C, respectively. Complete response for PONV was observed in 90.2% and 86% of patients in group P and group C, respectively. The overall incidence of PONV in group P and C was 9.8% and 14%, respectively. There was no significant difference between the two groups.ConclusionsThere were no differences between palonosetron monotherapy and combination therapy of palonosetron and dexamethasone in patients with high emetogenic risk.

Palmitoleic acid (PA) is an effective algicide against Alexandrium tamarense. However, the toxicological mechanism of PA exposure is unclear. The transcript abundance and differentially expressed genes (DEGs) in gills of bay scallop were investigated following 80 mg/L PA exposure up to 48 h using the Illumina HiSeq 4000 deep-sequencing platform with the recommended read length of 100 bp. De novo assembly of paired-end reads yielded 62,099 unigenes; 5414 genes were identified as being significantly increased, and 4452 were decreased. Based on gene ontology classification and enrichment analysis, the ‘cellular process’, ‘metabolic process’, ‘response to stimulus’, and ‘catalytic process’ with particularly high functional enrichment were revealed. The DEGs, which are related to detoxification and immune responses, revealed that acid phosphatase, fibrinogen C domain-containing protein, cyclic AMP-responsive element-binding protein, glutathione reductase, ATP-binding cassette, nuclear factor erythroid 2-related factor, NADPH2:quinone reductase, and cytochrome P450 4F22, 4B1, and 2C8-related gene expression decreased. In contrast, some genes related to glutathione S-transferase, C-type lectin, superoxide dismutase, toll-like receptors, and cytochrome P450 2C14, 2U1, 3A24 and 4A2 increased. The results of current research will be a valuable resource for the investigation of gene expression stimulated by PA, and will help understanding of the molecular mechanisms underlying the scallops’ response to PA exposure.

To reveal the molecular mechanisms triggered by okadaic acid (OA)-exposure in the detoxification and immune system of bay scallops, we studied differentially-expressed genes (DEGs) and the transcriptomic profile in bay scallop gill tissue after 48 h exposure to 500 nM of OA using the Illumina HiSeq 4000 deep-sequencing platform. De novo assembly of paired-end reads yielded 55,876 unigenes, of which 3204 and 2620 genes were found to be significantly up- or down-regulated, respectively. Gene ontology classification and enrichment analysis of the DEGs detected in bay scallops exposed to OA revealed four ontologies with particularly high functional enrichment, which were ‘cellular process’ (cellular component), ‘metabolic process’ (biological process), ‘immune system process’ (biological process), and ‘catalytic process’ (molecular function). The DEGs revealed that cyclic AMP-responsive element-binding proteins, acid phosphatase, toll-like receptors, nuclear erythroid 2-related factor, and the NADPH2 quinone reductase-related gene were upregulated. In contrast, the expression of some genes related to glutathione S-transferase 1, C-type lectin, complement C1q tumor necrosis factor-related protein, Superoxide dismutase 2 and fibrinogen C domain-containing protein, decreased. The outcomes of this study will be a valuable resource for the study of gene expression induced by marine toxins, and will help understanding of the molecular mechanisms underlying the scallops’ response to OA exposure.

Okadaic acid (OA) is produced by dinoflagellates during harmful algal blooms and is a diarrhetic shellfish poisoning toxin. This toxin is particularly problematic for bivalves that are cultured for human consumption. This study aimed to reveal the effects of exposure to OA on the immune responses of bay scallop, Argopecten irradians. Various immunological parameters were assessed (total hemocyte counts (THC), reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), lactate dehydrogenase (LDH), and nitric oxide (NO) in the hemolymph of scallops at 3, 6, 12, 24, and 48 h post-exposure (hpe) to different concentrations of OA (50, 100, and 500 nM). Moreover, the expression of immune-system-related genes (CLT-6, FREP, HSP90, MT, and Cu/ZnSOD) was also measured. Results showed that ROS, MDA, and NO levels and LDH activity were enhanced after exposure to different concentrations of OA; however, both THC and GSH decreased between 24–48 hpe. The expression of immune-system-related genes was also assessed at different time points during the exposure period. Overall, our results suggest that exposure to OA had negative effects on immune system function, increased oxygenic stress, and disrupted metabolism of bay scallops.

Palmitoleic acid (PA), an algicidal compound, is used against the toxin producing dinofagelate Alexandrium tamarense, however, its impact on the edible bay scallop (Argopecten irradians) is still unclear. Therefore, we investigated the impacts of effective algicidal concentrations (20, 40, and 80 mg/L) of PA on immune responses in A. irradians. Various immune parameters including acid phosphatase (ACP) activity, superoxide dismutase (SOD), lysozyme, phagocytic activity, total protein, malondialdehyde (MDA) level, and reactive oxygen species (ROS) production and the expression of immune-related genes (PrxV, CLT-6, MT, and BD) were measured at 3, 6, 12, 24, and 48 h post-exposure (hpe) to PA. Lysozyme activity was lower in scallops at 12–48 hpe to 80 mg/L. SOD, ACP activity, ROS production, the total protein, and MDA level was higher at 12 to 48 hpe with different concentrations of PA. Phagocytic activity increased at 6–12 hpe to 40–80 mg/L of PA, but decreased at 24–48 hpe. The expressions of genes PrxV, CLT-6, MT and BD down-regulated at 3 hpe were observed, while differential expressions from 6–48 hpe with different concentrations of PA. The present study demonstrated that immersing A. irradians in PA at effective concentrations could result in differential effects on non-specific immune responses and expressions of immune-related genes.

Objective Although several studies have reported successful fusion rates after oblique lumbar interbody fusion (OLIF) using allografts or dimerized bone matrix (DBM) instead of autografts, whether OLIF can achieve satisfactory solid fusion without the use of autografts remains unclear. This study investigated the real fusion rates after OLIF using allografts and DBM, which were evaluated using both dynamic radiographs and computed tomography scans. Methods We enrolled 79 consecutive patients who underwent minimally invasive OLIF followed by percutaneous pedicle screw fixation. All patients were treated with OLIF between L2 and L5 and underwent radiographic and clinical follow-ups at 12, 18, and 24 months after surgery. Radiographic assessment of fusion was performed using the modified BrantigaSteffee-Fraser (mBSF) scale, which was categorized as follows: grades I (radiographic pseudoarthrosis), II (indeterminate fusion), and III (solid radiographic fusion). Other radiologic and clinical outcomes were evaluated using the following parameters: vertebral slippage distance, disc height, subsidence, Oswestry Disability Index (ODI), and visual analogue scale (VAS). Results Clinical outcomes demonstrated significant improvements in the VAS scores for back pain, leg pain, and ODI after surgery. Subsidence was present in 34 cases (35.4%) at 12 months postoperatively, which increased to 47.9% and reached 50.0% at 1.5 years and 2 years after surgery, respectively. The solid fusion rate after OLIF was 32.3% at 1 year, increased to 58.3% at 1.5 years, and reached 72.9% at 2 years. Radiographic pseudoarthrosis was 24.0% at 1 year, which decreased to 6.3% at 1.5 years and 3.1% at 2 years. Conclusion OLIF is a safe and effective surgical procedure for the treatment of degenerative lumbar diseases. The mBSF scale, which simultaneously evaluates both dynamic angles and bone bridge formation, offers great reliability for the radiological assessment of fusion. Moreover, OLIF using allografts and DBM, which is performed on one or 2 levels at L2–5, can achieve satisfactory fusion rates within 2 years after surgery.