A Single-Atom Fe-N-C Catalyst with Ultrahigh Utilization of Active Sites for Efficient Oxygen Reduction.

Fe-N-C single-atom catalysts (SACs) are emerging as a promising class of electrocatalysts for the oxygen reduction reaction (ORR) to replace Pt-based catalysts. However, due to the limited loading of Fe for SACs and the inaccessibility of internal active sites, only a small portion of the sites near the external surface are able to contribute to the ORR activity. Here, this work reports a metal-organic framework-derived Fe-N-C SAC with a hierarchically porous and concave nanoarchitecture prepared through a facile but effective strategy, which exhibits superior electrocatalytic ORR activity with a half-wave potential of 0.926 V (vs RHE) in alkaline media and 0.8 V (vs RHE) in acidic media while maintaining excellent stability. The superior ORR activity of the as-designed catalyst stems from the unique architecture, where the hierarchically porous architecture contains micropores as Fe SAC anchoring sites, meso-/macro-pores as accessible channels, and concave shell for increasing external surface area. The unique architecture has dramatically enhanced the utilization of previously blocked internal active sites, as confirmed by a high turnover frequency of 3.37 s-1 and operando X-ray absorption spectroscopy analysis with a distinct shift of adsorption edge.

First Report of Enterocytozoon hepatopenaei Infection in Pacific Whiteleg Shrimp (Litopenaeus vannamei) Cultured in Korea.

The consumption of cultured crustaceans has been steadily increasing, and Pacific whiteleg shrimp (Litopenaeus vannamei) are major cultivated invertebrates worldwide. However, shrimp productivity faces a variety of challenges, mainly related to outbreaks of lethal or growth retardation-related diseases. In particular, hepatopancreatic microsporidiosis caused by the microsporidian parasite Enterocytozoon hepatopenaei (EHP) is an important disease associated with growth retardation in shrimp. Here, we report the detection of EHP through histopathological, molecular and electron microscopy methods in the hepatopancreas of Pacific whiteleg shrimp with growth disorder in a South Korean farm. Phylogenetic analysis showed a clade distinct from the previously reported EHP strains isolated in Thailand, India, China and Vietnam. An EHP infection was not associated with inflammatory responses such as hemocyte infiltration. Although EHP infection has been reported worldwide, this is the first report in the shrimp aquaculture in Korea. Therefore, an EHP infection should be managed and monitored regularly for effective disease control and prevention.

Naturally occurring substitution in one amino acid in VHSV phosphoprotein enhances viral virulence in flounder.

Viral hemorrhagic septicemia virus (VHSV) is a rhabdovirus that causes high mortality in cultured flounder. Naturally occurring VHSV strains vary greatly in virulence. Until now, little has been known about genetic alterations that affect the virulence of VHSV in flounder. We recently reported the full-genome sequences of 18 VHSV strains. In this study, we determined the virulence of these 18 VHSV strains in flounder and then the assessed relationships between differences in the amino acid sequences of the 18 VHSV strains and their virulence to flounder. We identified one amino acid substitution in the phosphoprotein (P) (Pro55-to-Leu substitution in the P protein; PP55L) that is specific to highly virulent strains. This PP55L substitution was maintained stably after 30 cell passages. To investigate the effects of the PP55L substitution on VHSV virulence in flounder, we generated a recombinant VHSV carrying PP55L (rVHSV-P) from rVHSV carrying P55 in the P protein (rVHSV-wild). The rVHSV-P produced high level of viral RNA in cells and showed increased growth in cultured cells and virulence in flounder compared to the rVHSV-wild. In addition, rVHSV-P significantly inhibited the induction of the IFN1 gene in both cells and fish at 6 h post-infection. An RNA-seq analysis confirmed that rVHSV-P infection blocked the induction of several IFN-related genes in virus-infected cells at 6 h post-infection compared to rVHSV-wild. Ectopic expression of PP55L protein resulted in a decrease in IFN induction and an increase in viral RNA synthesis in rVHSV-wild-infected cells. Taken together, our results are the first to identify that the P55L substitution in the P protein enhances VHSV virulence in flounder. The data from this study add to the knowledge of VHSV virulence in flounder and could benefit VHSV surveillance efforts and the generation of a VHSV vaccine.

RNA-seq transcriptome analysis in flounder cells to compare innate immune responses to low- and high-virulence viral hemorrhagic septicemia virus.

Viral hemorrhagic septicemia virus (VHSV) is a rhabdovirus that causes high mortality in cultured flounder. Viral growth and virulence rely on the ability to inhibit the cellular innate immune response. In this study, we investigated differences in the modulation of innate immune responses of HINAE flounder cells infected with low- and high-virulence VHSV strains at a multiplicity of infection of 1 for 12 h and 24 h and performed RNA sequencing (RNA-seq)-based transcriptome analysis. A total of 193 and 170 innate immune response genes were differentially expressed by the two VHSV strains at 12 and 24 h postinfection (hpi), respectively. Of these, 73 and 77 genes showed more than a twofold change in their expression at 12 and 24 hpi, respectively. Of the genes with more than twofold changes, 22 and 11 genes showed high-virulence VHSV specificity at 12 and 24 hpi, respectively. In particular, IL-16 levels were more than two time higher and CCL20a.3, CCR6b, CCL36.1, Casp8L2, CCR7, and Trim46 levels were more than two times lower in high-virulence-VHSV-infected cells than in low-virulence-VHSV-infected cells at both 12 and 24 hpi. Quantitative PCR (qRT-PCR) confirmed the changes in expression of the ten mRNAs with the most significantly altered expression. This is the first study describing the genome-wide analysis of the innate immune response in VHSV-infected flounder cells, and we have identified innate immune response genes that are specific to a high-virulence VHSV strain. The data from this study can contribute to a greater understanding of the molecular basis of VHSV virulence in flounder.

Methanol Tolerant Pt-C Core-Shell Cathode Catalyst for Direct Methanol Fuel Cells.

Methanol crossover is one of the largest problems in direct methanol fuel cells (DMFCs). Methanol passing from the anode to the cathode through the membrane is oxidized at the cathode, degrading the DMFC performance, and the intermediates of the methanol oxidation reaction (MOR) cause cathode catalyst poisoning. Therefore, it is essential to develop a cathode catalyst capable of inhibiting MOR while promoting the oxygen reduction reaction (ORR), which is a typical cathode reaction in DMFCs. In this study, a carbon-encapsulated Pt cathode catalyst was synthesized for this purpose. The catalyst was simply synthesized by heat treatment of Pt-aniline complex-coated carbon nanofibers. The carbon shell of the catalyst was effective in inhibiting methanol from accessing the Pt core, and this effect became more prominent as the graphitization degree of the carbon shell increased. Meanwhile, the carbon shell allowed O2 to permeate regardless of the graphitization degree, enabling the Pt core to participate in ORR. The synthesized catalyst showed higher performance and stability in single-cell tests under various conditions compared to commercial Pt/C.

Two short antimicrobial peptides derived from prosaposin-like proteins in the starry flounder (Platichthys stellatus).

Prosaposin (PSAP) is a precursor of saposin (SAP), which is present in lysosomal and secreted proteins. PSAP is a member of the SAP-like protein families, which comprise multifunctional proteins. In particular, their antimicrobial activity has been reported. We identified PSAP-like (PsPSAPL) sequences from starry flounder and analysed their expression and antimicrobial activity based on cDNA and amino acid sequences. PsPSAPL showed conservation of three saposin B type domains at high levels, and PsPSAPL mRNA was relatively abundantly distributed in the brain and gills of healthy starry founders. PsPSAPL mRNA showed significant expression changes in response to viral haemorrhagic septicaemia virus and Streptococcus parauberis. Synthetic peptides (PsPSAPL-1 and -2), prepared based on amino acid sequences, were used to confirm as well as analyse the antimicrobial activity against bacteria and parasites. Consequently, PsPSAPL-1 and -2 were found to significantly inhibit the growth of various bacteria and kill the Miamiensis avidus. In addition, bacterial biofilm formation was significantly inhibited. Safety was also confirmed by analysing cell haemolysis. These results indicate the immunological function of PsPSAP and the potential antimicrobial activity of the AMPs PsPSAPL-1 and -2.

Genome data of shrimp acute hepatopancreatic necrosis disease causative Vibrio parahaemolyticus strains isolated from South Korea aquaculture farms.

The Vibrio parahaemolyticus is a gram-negative bacterium, which is responsible for acute hepatopancreatic necrosis disease (AHPND) in shrimp and has various virulent factors. So, to intensify the knowledge on pathogenic mechanism, the heterogeneous V.parahaemolyticus strains genome are indeed. Here, genome of seven V.parahaemolyticus strains, which are virulent to shrimps were sequenced by PacBio platform and the virulence was confirmed through the presence of plasmid (∼69 Kb) with binary toxin genes (i.e., pirA and pirB) with PCR method.

Current use and management of commercial fish vaccines in Korea.

The aquaculture industry in Korea has grown rapidly since the 1960s, and it is a major food source. However, the expansion of aquaculture systems has increased the chances of infectious disease outbreaks, and vaccination plays an important role in commercial fish farming. This is the first comprehensive review of commercial fish vaccines in Korea. It not only provides an overview of commercially available fish vaccines and their associated approval processes and laws, but also some perspectives on research advances regarding fish vaccines in Korea. In Korea, fish vaccines are approved only after their safety and effectiveness have been verified according to the Pharmaceutical Affairs Act, and after approval, each vaccine lot must pass the national evaluation criteria. As of the end of 2019, 29 vaccines were approved for 10 fish pathogens, including both single and combination vaccines containing more than two inactivated pathogens. The approved fish vaccines consist of 2 immersion vaccines, as well as 1 intramuscular and 26 intraperitoneal vaccines, which require syringe injection. All the 29 vaccines are manufactured as formalin-inactivated vaccines; 1 is an adjuvant vaccine and 28 are non-adjuvant vaccines; 25 are bacterial vaccines, 2 are viral vaccines, 1 is a parasite vaccine, and 1 is a parasite and bacterial vaccine. In terms of the target fish species, 27 vaccines are used in the olive flounder (Paralichthys olivaceus), 1 in the starry flounder (Platichthys stellatus), and 1 in the red seabream (Pagrus major), striped beakfish (Oplegnathus fasciatus), and amberjack (Seriola quinqueradiata). This imbalance exists mostly because the olive flounder is the main farmed fish species in Korea. In 2018, 67.71 million vaccine doses were distributed following satisfactory performance in the national evaluation. They were used to vaccinate approximately 80.6% of farmed olive flounders.

Whole-genome next-generation sequencing and phylogenetic characterization of viral haemorrhagic septicaemia virus in Korea.

Whole-genome next-generation sequencing was used to investigate the local evolution of viral haemorrhagic septicaemia virus, a serious pathogen affecting economically important fish such as rainbow trout and turbot in Europe and olive flounder in Asia. Sequence analysis showed that all isolates were genotype IVa, but could be classified further into four subgroups (K1-K4). In addition, genomic regions encompassing the nucleoprotein, phosphoprotein, matrix protein and non-virion protein genes, as well as the seven non-coding regions, were relatively conserved, whereas glycoprotein and RNA-dependent RNA polymerase genes were variable in the coding region. Taken together, the data demonstrate that whole-genome next-generation sequencing may be useful for future surveillance, prevention and control strategies against viral haemorrhagic septicaemia.

Molecular genetic characterisation and expression profiling of calpain 3 transcripts in red sea bream (Pagrus major).

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.

Molecular characterization and gene expression data of liver expressed antimicrobial Peptide-2 (LEAP-2) isolated from rock bream (Oplegnathus fasciatus).

Antimicrobial peptides (AMPs) are known to play a role as a first line of defence against microbial invasion. Liver Expressed Antimicrobial Peptides-2 (LEAP-2) is one of the AMPs. LEAP-2 includes four highly conserved cysteine residues and belongs to a cysteine-rich peptides group. We identified and characterized the molecular properties of LEAP-2 in rock bream. The expression levels of rock bream LEAP-2 (RbLEAP-2) in the 12 different tissues of healthy fish and the RbLEAP-2 expression pattern after infections with Edwardsiella piscicida (E. piscicida), Streptococcus iniae (S. iniae) and red seabream iridovirus (RSIV) were examined. This data provide that RbLEAP-2 plays an important role in innate immunity when rock bream is infected with a pathogen.

Efficacy and safety data of ceftiofur antibiotics against Streptococcus parauberis PH0710 infection in starry flounder (Platichthys stellatus).

This article provides efficacy and safety data of ceftiofur antibiotics against streptococcal infection in starry flounder. Ceftiofur, which is a veterinary antibiotics, is effective against fishery bacteria. Ceftiofur can be prescribed and sold by veterinarians. However, it is illegal in South Korea for fishery disease managers to prescribe and sell ceftiofur. Therefore, in order to utilize available antibiotics and prevent illegal use of veterinary antibiotics, it is necessary to perform research to determine the recommended effective dose and administration methods of antibiotics for fisheries. In this article, the appropriate concentration and injection method of antibiotics to treat starry flounder infected with S. parauberis PH0710 were provided. In addition, histopathological examination results were provided to confirm the effect of antibiotics on the host tissue. Accordingly, these data could be used as basic data for the application of ceftiofur antibiotics in disease management for fisheries.

The atypical chemokine receptor 4 in red sea bream (Pagrus major): Molecular characterization and gene expression analysis.

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.

Data on CXC chemokine ligand 10(CXCL10) expression and activation in red sea bream during bacterial and viral infection.

CXCL10 plays an important role in angiogenesis and inhibits the differentiation of endothelial cells into capillaries. It also plays an important role in the generation and transmission of effector T cell responses and the recruitment of T cells to inflammatory sites. In this article, we constructed cDNAs to identify and analyse the CXCL10 domain, and performed multiple alignments and a phylogenetic analysis to determine homology with other animals. Real-time PCR was performed to confirm construction and expression after bacterial and viral infection.

Data on molecular characterization and expression profiles of the NF-κB repressing factor gene in red sea bream (Pagrus major).

Nuclear factor-kappaB (NF-κB) repressing factor (NKRF) specifically inhibits the transcriptional activity of NF-κB protein. The PmNKRF cDNA is composed of 757 amino acid residues. Alignment analysis revealed that the G-patch and R3H domains are conserved in different organisms. We aimed to analyse red sea bream NKRF (PmNKRF) gene expression after infection with pathogens [Streptococcus iniae or red sea bream iridovirus (RSIV)] and in healthy individuals. In healthy individuals, PmNKRF was ubiquitously expressed in all 12 tested tissues, predominantly in the head kidney and spleen. Expression of PmNKRF was significantly up-regulated in the gills, kidney, liver and spleen after RSIV infection. After S. iniae infection, PmNKRF expression was significantly down-regulated in the gills and significantly up-regulated in the kidney, liver and spleen.

Characterization of gene expression profiles and functional analysis of peptidoglycan recognition protein 2 from rock bream (Oplegnathus fasciatus).

Peptidoglycan recognition protein 2 (PGRP2) is a Zn2+-dependent peptidase that plays important roles in binding to microbial components of the cell membrane, inducing phagocytosis and antimicrobial activity. Rock bream (Oplegnathus fasciatus) PGRP2 (RbPGRP2) was identified in the intestine by next generation sequencing (NGS) analysis. The open reading frame (ORF) the RbPGRP2 cDNA (470 amino acid residues) contains a peptidoglycan recognition protein domain (residues 300 to 446). Alignment analysis revealed that RbPGRP2 shares 37.6-53.5% overall sequence identity with the PGRP2s of other species. Phylogenetic analysis revealed that RbPGRP2 clustered together with PGRP2s from teleosts. In healthy rock bream, RbPGRP2 was found to be ubiquitously expressed in all of the examined tissues, especially in the liver. RbPGRP2 expression was significantly upregulated in all of the examined tissues of rock bream after infection with Edwardsiella piscicida, Streptococcus iniae and red sea bream iridovirus (RSIV) compared with the control. Purified rRbPGRP2 interactions with bacteria and inhibited the growth of bacteria in the presence of Zn2+. These results indicate that RbPGRP2 plays an important role in the innate immune response against bacterial infection.

Complete genome sequence and phylogenetic analysis of spring viremia of carp virus isolated from leather carp (Cyprinus carpio nudus) in Korea in 2016.

Spring viremia of carp (SVC) is listed as a notifiable viral disease by the World Organization for Animal Health (OIE). In 2016, the first official SVC outbreak was detected in the city of Gyeongsan, Korea. The present study reports the first complete genome analysis of SVC virus (SVCV, ADC-SVC2016-5) isolated from leather carp (Cyprinus carpio nudus). The results revealed that ADC-SVC2016-5 has a 11,029-bp genome containing five genes: N, P, M, G, and L. Phylogenetic analysis indicated that ADC-SVC2016-5 (accession number MG663512), isolated from leather carp, was closely related to genogroup Ia isolates of the Asian clade. This report provides additional information for studying the molecular epidemiology and evolution of spring viremia of carp virus.

Temperature-dependent immune response of olive flounder (Paralichthys olivaceus) infected with viral hemorrhagic septicemia virus (VHSV).

Olive flounder (Paralichthys olivaceus) is one of the most economically important aquaculture fish. However, its production is often affected by various diseases, especially viral hemorrhagic septicemia virus (VHSV) that cause serious economic losses. In this study, we sequenced the whole transcriptome of the P. olivaceus using Illumina RNA-sEq. De novo assembly of control and virus-infected cDNA libraries of head kidney at 13 and 20 °C was accomplished with 2,007,532,438 raw reads, resulting in 244,578 unigenes with an average length of 533 bp and found 65,535 candidate coding unigenes with homology to other species by BLAST analysis. DEG analysis among control and virus-infected head kidney samples of 13 and 20 °C revealed that 1290 up-regulated and 162 down-regulated genes (p ≤ 0.01), linked to metabolism, virulence factors, adhesion and immune-response. We constructed an expressed gene catalog for the P. olivaceus to serve as a resource for marine environmental genomic and immuno-genetic/genomic studies focused on uncovering the molecular mechanisms underlying the responses of P. olivaceus to VHSV under different temperature.

Publisher Correction: A molecular cross-linking approach for hybrid metal oxides.

In the version of this Article originally published, Liban M. A. Saleh was incorrectly listed as Liban A. M. Saleh due to a technical error. This has now been amended in all online versions of the Article.

A molecular cross-linking approach for hybrid metal oxides.

There is significant interest in the development of methods to create hybrid materials that transform capabilities, in particular for Earth-abundant metal oxides, such as TiO2, to give improved or new properties relevant to a broad spectrum of applications. Here we introduce an approach we refer to as 'molecular cross-linking', whereby a hybrid molecular boron oxide material is formed from polyhedral boron-cluster precursors of the type [B12(OH)12]2-. This new approach is enabled by the inherent robustness of the boron-cluster molecular building block, which is compatible with the harsh thermal and oxidizing conditions that are necessary for the synthesis of many metal oxides. In this work, using a battery of experimental techniques and materials simulation, we show how this material can be interfaced successfully with TiO2 and other metal oxides to give boron-rich hybrid materials with intriguing photophysical and electrochemical properties.