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Interleukin 17D (IL-17D), a pro-inflammatory cytokine, is a signature cytokine of T helper 17 (Th17) cells. However, studies characterizing the functions of IL-17D in teleost are scarce. Therefore, we aimed to characterize the properties of IL-17D in Amphiprion clarkii. We performed spatial and temporal expression, AcIL-17D-mediated antibacterial and inflammatory gene expression, NFκB pathway-related gene expression analyses, and bacterial colony counting and cell protection assays. We found that AcIL-17D contains a 630 bp coding sequence and encodes 210 amino acids. The spatial expression analysis of AcIL-17D in 12 tissues showed ubiquitous expression, with the highest expression in the brain, followed by blood and skin. Temporal expression analysis of AcIL-17D in blood showed upregulated expression at 6 and 24 h (polyinosinic: polycytidylic acid and lipopolysaccharide), 12 h (all stimulants), and 48 h (polyinosinic: polycytidylic acid and Vibrio harveyi). AcIL-17D expression in the blood gradually decreased at later hours in response to all the stimulants. After treatment of fathead minnow (FHM) cells with different recombinant AcIL-17D concentrations, the downstream gene expression analysis showed increased expression of antimicrobial genes in the FHM cells, namely [NK-Lysin (NKL), Hepcidin antimicrobial peptide-1 (HAMP-1), Defensin-β (DEFB1)] and some inflammatory genes such as IL-1β, TNF-α, IL-11, and STAT3. Further nuclear factor κB (NFκB) subunits (NFκB1, NFκB2, RelA, and Rel-B) showed upregulated gene expression at 12 and 24 h. The bacterial colony counting assay using FHM cells showed lower bacterial colony counts in rAcIL-17D-treated cells than in control. Furthermore, the Water-Soluble Tetrazolium Salt (WST -1) assay confirmed the ability of rAcIL-17D in the protection of FHM cells from bacterial infection and conducted the Hoechst 33342 staining upon treatment with rAcIL-17D and rMBP. Therefore, our findings provide important insights into the activation of IL-17D pathway genes in FHM cells, the protective role of AcIL-17D against bacterial infection, and host defense mechanisms in teleost.

Semisulcospira gottschei is an Asian endemic species inhabiting Korea and China. However, genetic structure analysis of the resource management of this species has not been performed. To investigate the genetic diversity among populations, microsatellites can be used to determine the geographic origins of marine and freshwater species. This study investigated the genetic structures of the Korean and Chinese populations of S. gottschei based on mitochondrial DNA (mtDNA) Cytochrome oxidase subunit I (COI) and polymorphic microsatellite loci developed from Semisulcospira coreana. Analysis of the mtDNA COI sequence revealed 43 haplotypes, which indicated no gene flow between the Korean and Chinese populations. To further elucidate the genetic structures of the Korean and Chinese populations, the population genetics of S. gottschei were analyzed using nine microsatellite markers. The genetic diversity analysis showed an average of 5.25 alleles per locus, with an average allelic richness of 4.02. Excessive homozygosity was found at all loci, which was expected to be due to the presence of null alleles at all loci. Populations of S. gottschei formed two separate clusters according to pairwise FST and AMOVA. Also, the UPGMA tree, PCA, STRUCTURE, and GeneClass indicated separation of the 11 populations into two clusters: Korea and China. These results have potential use in the management, restoration, and distinction of the origin country of populations.

A Gram-stain-negative, strictly aerobic, non-motile and rod-shaped bacterial strain, MYP1-1T, was isolated from the intestine of a stalked sea squirt (Styela clava) of the South Sea in the Republic of Korea. The neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that strain MYP1-1T clustered with the type strains of Halocynthiibacter species and Pseudohalocynthiibacter aestuariivivens . Strain MYP1-1T exhibited 16S rRNA gene sequence similarity values of 97.0–97.6 % to the type strains of Halocynthiibacter namhaensis , Halocynthiibacter arcticus and P. aestuariivivens . The phylogenetic tree based on genomic sequences showed that strain MYP1-1T formed a distinct branch separating it from the type strains of two Halocynthiibacter species and P. aestuariivivens and other taxa. The DNA G+C content of strain MYP1-1T from its genomic sequence was 55.0 mol%. Strain MYP1-1T contained Q-10 as the predominant ubiquinone and C18 : 1 ω7c as the major fatty acid. The major polar lipids of strain MYP1-1T were phosphatidylcholine, phosphatidylglycerol, one unidentified lipid and one unidentified aminolipid. The differences in fatty acid and polar lipid profiles and other differential phenotypic properties made it reasonable to distinguish strain MYP1-1T from the genera Halocynthiibacter and Pseudohalocynthiibacter . On the basis of the polyphasic taxonomic investigations, we conclude that strain MYP1-1T constitutes a new genus and species within the class Alphaproteobacteria , for which the name Paenihalocynthiibacter styelae gen. nov., sp. nov. is proposed. The type strain is MYP1-1T (=KCTC 82143T=NBRC 114355T).

Korean freshwater snails of the genus Semisulcospira are widely distributed across East Asia. It has been a very popular nutritional food in Korea, and is an ecologically important water quality indicator because it lives only in clean water. However, no microsatellite markers have been generated to study the population genetic diversity of this genus. In the present study, we developed and characterized 18 novel microsatellite loci from Semisulcospira coreana genomic DNA. The microsatellites were isolated using 454 GS-FLX titanium sequencing and 18 markers were used for genotyping in S. coreana. In addition, we also tested the cross-species transferability of the microsatellite markers in four additional Semisulcospira spp. We identified 18 polymorphic loci and the number of alleles per loci, and their polymorphism information content values ranged from 2 to 17 and 0.203 to 0.902, respectively. The observed and expected heterozygosities of the loci ranged from 0.063 to 0.924 and 0.226 to 0.924, respectively. According to the analysis of the cross-species transferability of these markers, four species, S. forticosta, S. gottschei, S. tegulata, and S. libertina, showed a very high transferability (80%–85%). These results show that this set of nuclear markers could be useful for population genetics studies of this species and closely related species.

The early growth response protein 1 (Egr-1) is a widely reported zinc finger protein and a well known transcription factor encoded by the Egr-1 gene, which plays key roles in many aspects of vertebrate embryogenesis and in adult vertebrates. The Egr-1 expression is important in the formation of the gill vascular system in flounders, which develops during the post-hatching phase and is essential for survival during the juvenile period. However, the complete details of Egr-1 expression during embryo development in olive flounder are not available. We assessed the expression patterns of Egr-1 during the early development of olive flounders by using reverse transcription polymerase chain reaction (RT-PCR) analysis. Microscopic observations showed that gill filament formation corresponded with the Egr-1 expression. Thus, we showed that Egr-1 plays a vital role in angiogenesis in the gill filaments during embryogenesis. Further, Egr-1 expression was found to be strong at 5 days after hatching (DAH), in the development of the gill vascular system, and this strong expression level was maintained throughout all the development stages. Our findings have important implications with respect to the biological role of Egr-1 and evolution of the first respiratory blood vessels in the gills of olive flounder. Further studies are required to elucidate the Egr-1-mediated stress response and to decipher the functional role of Egr-1 in developmental stages.

Continuous monitoring of the present genetic status is essential to preserve the genetic resource of wild populations. In this study, we sequenced regional Pacific abalone Haliotis discus samples from three different locations around the Korean peninsula to assess population structure, utilizing Genotyping-by-Sequencing (GBS) method. Using PstI enzyme for genome reduction, we demonstrated the resultant library represented the whole genome region with even spacing, and as a result 16,603 single nucleotide variants (SNVs) were produced. Genetic diversity and population structure were investigated using several methods, and a strong genetic heterogeneity was observed in the Korean abalone populations. Additionally, by comparison of the variant sets among population groups, we were able to discover 26 Korean abalone population-specific SNVs, potentially associated with phenotype differences. This is the first study demonstrating the feasibility of GBS for population genetic study on H. discus. Our results will provide valuable data for the genetic conservation and management of wild abalone populations in Korea and help future GBS studies on the marine mollusks.

In this study, a multiplex PCR detection method was developed to identify the country of origin of Corbicula japonica (clams), a commercially important bivalve in Asia. Specific primer sets that have a single nucleotide mismatch at the 3′ terminus were designed after sequencing the mitochondrial 16S rRNA gene of clams identified as C. japonica originating from Korea, China, and Japan. Using this method, each origin was clearly identified based on the PCR products: three bands for Korean C. japonica (100, 283, and 384 bp), one band for Chinese C. japonica (384 bp), and two bands for Japanese C. japonica (384 and 100 bp). These results indicate that the 16S rRNA gene, which is usually used to identify species, can distinguish the country of origin within C. japonica. Our multiplex PCR assay should be a useful tool for the fair trade of the species.

Differentiation of the genus Anguilla is important for phylogenetic studies, ecological monitoring, and food forensics. Although various methods have been developed to identify these species, current methods are time-consuming and limit the number of species that can be detected. The aim of this study was to develop a rapid and convenient method to identify the genus Anguilla. To differentiate among seven commercially important species of Anguilla (A. japonica, A. anguilla, A. rostrata, A. celebensis, A. pacifica, A. marmorata, and A. bicolor pacifica), fluorescence melting curve analysis (FMCA) with peptide nucleic acid (PNA) probes were used. One primer set was designed to amplify the mitochondrial cytochrome b gene, and seven PNA probes were designed to identify each species from the cyt b gene. The PNA probes were labeled with four different fluorescent reporter dyes (FAM, HEX, Texas Red, Cy5) for multiplex analysis using two tubes. Based on FMCA, each PNA probe showed the highest Tm value when it was 100% complementary to the target sequence. In conclusion, the PNA-based FMCA method is suitable for differentiating among seven species of Anguilla and should be applicable in various fields, such as global marketing and scientific research.

The increased international trade and worldwide consumption of seafood has increased the possibility of economic fraud. Particularly, the increased development of processed seafood has restricted the application of classical identification methods. DNA matabarcoding is a rapid method for identification of multiple species from an environmental sample. In this study, two universal markers were designed in the mitochondrial cytochrome oxidase subunit I region, and the metabarcoding analysis of processed seafood products was done using these markers. A total of 11 seafood products were analyzed, and 56 and 32 species within 36 families between them were identified by each primer set, respectively. Comparing the identified species with each primer set, only 12.8% of the species were identified by both primer sets. In addition, the species on the label when identified were not observed in some products. Although the analysis was done on the same gene region, different results can be obtained according to the primer set. Based on these results, it is advantageous to use more than one primer set to identify various species from seafood products using DNA metabarcoding analysis.

Lectins belong to the pattern-recognition receptors (PRRs) class and play important roles in the recognition and elimination of pathogens via the innate immune system. Recently, it was reported that lily-type lectin-1 is involved when a pathogen attacks in the early immune response of fish. However, this study is limited to information that the lectin is involved in the innate immune response against viral infection. In the present study, the lily-type lectin-2 and -3 of Oplegnathus fasciatus (OfLTL-2 and 3) have been presented to be included B-lectin domain and two D-mannose binding sites in the amino acid sequence that an important feature for the fundamental structure. To investigate the functional properties of OfLTLs, the tissue distribution in the healthy rock bream and temporal expression during early developmental stage analysis are performed using quantitative real-time PCR. OfLTL-2 and 3 are predominantly expressed in the liver and skin, but rarely expressed in other organ. Also, the transcripts of OfLTLs are not expressed during the early developmental stage but its transcripts are increased after immune-related organs which are fully formed. In the challenge experiment with RBIV (rock bream iridovirus), the expression of OfLTLs was increased much more strongly in the late response than the early, unlike previously known. These results suggest that OfLTLs are specifically expressed in the immune-related tissues when those organs are fully formed and it can be inferred that the more intensively involved in the second half to the virus infection.

Glutathione S-transferases (GSTs, EC 2.5.1.18) are categorized as phase II enzymes, which form an important multifunctional family associated with a wide variety of catalytic activities. GSTω, GSTρ, and GSTθ are cytosolic GSTs which have been extensively studied in a variety of organisms; however, few studies have focused on teleosts. Those paralogs from black rockfish (Sebastes schlegelii; RfGSTω, RfGSTρ, and RfGSTθ, respectively) were molecularly, biochemically, and functionally characterized to determine their antioxidant extent and protective aptitudes upon pathogenic stress. RfGSTω, RfGSTρ, and RfGSTθ, contained open reading frames of 717bp, 678bp, and 720bp respectively, which encoded respective proteins of 239, 226, and 240 amino acids in length. In silico analysis revealed that all RfGSTs possessed characteristic N-terminal domains bearing glutathione (GSH)-binding sites, and C-terminal domains containing substrate-binding sites. Recombinant RfGSTω (rRfGSTω) catalyzed the conjugation of GSH to dehydroascorbate (DHA), while rRfGSTθ and rRfGSTρ catalyzed to the model GST substrate 1-Chloro-2,4-dinitrobenzene (CDNB). Kinetic analysis revealed variation in Km and Vmax values for each rRfGST, indicating their different conjugation rates. The optimum conditions (pH and temperature) and inhibition assays of each protein demonstrated different optimal ranges showing their wide range of activity as an assembly. RfGSTω and RfGSTθ paralogs demonstrated their antioxidant potential towards H2O2 and heavy metals (Cd, Zn, and Cu) in vitro, while RfGSTρ had an antioxidant potential only towards heavy metals (Zn and Cu). Though all the paralogs were ubiquitously expressed in different magnitudes, RfGSTω was highly expressed in blood, whereas RfGSTρ and RfGSTθ were highly expressed in liver. The mRNA expression of RfGSTω and RfGSTθ, upon Streptococcus iniae and poly I:C stimulation, revealed a significantly up-regulated expression, whereas RfGSTρ mRNA expression was significantly down-regulated. Collectively, our findings suggest that RfGSTω, RfGSTρ, and RfGSTθ paralogs are potent in detoxifying xenobiotic toxics, capable of protecting cells from oxidative stress generated by both H2O2 and heavy metals, and finally, yet importantly, stimulated under pathogenic stress signals.

Pufferfish (Takifugu spp.) are economically important edible marine fish. Mistakes in pufferfish classification can lead to poisoning; therefore, accurate species identification is critical. In this study, we used the mtDNA cytochrome c oxidase subunit I gene (COI) to design specific primers for six Takifugu species among the 21 domestic or imported pufferfish species legally sold for consumption in Korea. We rapidly and simultaneously identified these pufferfish species using a highly efficient, multiplex polymerase chain reaction (PCR) system with the six species-specific primers. The results showed that species-specific multiplex PCR (multiplex species-specific polymerase chain reaction; MSS-PCR) either specifically amplified PCR products of a unique size or failed. MSS-PCR yielded amplification fragment lengths of 897 bp for Takifugu pardalis, 822 bp for T. porphyreus, 667 bp for T. niphobles, 454 bp for T. poecilonotus, 366 bp for T. rubripes, and 230 bp for T. xanthpterus using the species-specific primers and a control primer (ca. 1,200 bp). We visualized the results using agarose gel electrophoresis to obtain accurate contrasts of the six Takifugu species. MSS-PCR analysis is easily performed and provides identification results within 6 h. This technique is a powerful tool for the discrimination of Takifugu species and will help prevent falsified labeling, protect consumer rights, and reduce the risk of pufferfish poisoning..

To develop a promoter capable of driving transgene expression in non-model fish, we identified and characterized the muscle-specific alpha-actin gene in olive flounder, Paralichthys olivaceus (PoACTC1). The regulatory region of PoACTC1 includes putative regulatory elements such as a TATA box, two MyoD binding sites, three CArG boxes, and a CCAAT box. Microinjection experiments demonstrated that the regulatory region of PoACTC1, covering from -2,126 bp to +751 bp, just prior to the start codon, drove the expression of red fluorescent protein in developing zebrafish embryos and hatching olive flounder. These results suggest that the regulatory region of PoACTC1 may be useful in developing a promoter for biotechnological applications such as transgene expression in olive flounder.

The complement system serves conventional role in the innate defense against common invading pathogens. Complement factor D (CfD) is vital to alternative complement pathway activation in cleaving complement factor B. This catalytic reaction forms the alternative C3 convertase that is crucial for complement-mediated pathogenesis. In this study, rock bream (Oplegnathus fasciatus) CfD (OfCfD) was characterized and OfCfD mRNA expression was investigated. OfCfD encodes 277 amino acids (aa) for a 30-kDa polypeptide. A domain analysis of the deduced OfCfD aa sequence showed a single serine protease trypsin superfamily domain, a serine active region, three active sites, and three substrate-binding sites. Pairwise sequence comparisons indicated that OfCfD has the highest identity (84.5%) with Oreochromis niloticus CfD. The phylogenetic tree revealed a common ancestral origin of CfD members, with fish CfD distinct from other vertebrate orthologs. The structural arrangement of the OfCfD gene (2451 bp) contained five exons interrupted by four introns. A spatial transcriptional analysis indicated that OfCfD transcripts constitutively expressed in all of the examined rock bream tissues, and that they were highest in the spleen and liver. In addition, OfCfD transcripts were immunologically upregulated by lipopolysaccharide (LPS) (12 h p.i.), Streptococcus iniae (12 h p.i.), rock bream iridovirus (RBIV) (6-12 h p.i.), and poly I:C (6 h p.i.) in spleen tissue. OfCfD is a trypsin protease and its recombinant protein showed strong protease activity similar to that of trypsin, indicating its catalytic function in the alternative pathway. Together, our findings suggest that OfCfD might be involved in immune responses in rock bream.

Thioredoxin domain-containing protein 12 (TXNDC12) is a small, disulfide-containing protein that belongs to the thioredoxin (TXN) superfamily. In the present study, we identified and characterized a TXNDC12-like gene, designated OfTXNDC12, from rock bream, Oplegnathus fasciatus. OfTXNDC12 consists of seven exons interrupted by six introns. Comparative genomic structural analysis revealed that the TXNDC12 of vertebrates is a structurally conserved gene. The coding sequence of OfTXNDC12 comprises 522 bp, which encodes 173 amino acid residues with the conserved thioredoxin active site motif, CGAC, and a probable C-terminal ER retrieval motif, GDEL. Transcriptional analysis of OfTXNDC12 showed the highest concentrations of the mRNA transcript in the liver, implying that it has a significant role in the liver under normal physiological conditions. In comparison, injection of lipopolysaccharide, Edwardsiella tarda, Streptococcus iniae, polyinosinic:polycytidylic acid (poly[I:C]) and rock bream iridovirus mostly triggered greater upregulation of OfTXNDC12 transcript levels in liver than in gill tissue, supporting its potential functional importance in the liver. Insulin disulfide reduction assay showed that the recombinant fusion protein (rOfTXNDC12) possesses significant thioredoxin activity. Treatment of LNCaP cells with the recombinant protein along with H2O2 revealed that rOfTXNDC12 increased the viability of cells and further supported its putative antioxidant capacity. Taken together, the results from our study suggest that OfTXNDC12 encodes for a potent antioxidant involved in redox regulation that shows significant responses to immune stimuli.

Thioredoxin (TXN) superfamily proteins are identified by the presence of a thioredoxin active site with a conserved CXXC active motif. TXN members are involved in a wide range of biochemical and biological functions including redox regulation, refolding of disulfide containing proteins, and regulation of transcription factors. In the present study, a thioredoxin domain-containing protein 12 was identified and characterized from black rockfish, Sebastes schlegelii (RfTXNDC12). The full length of RfTXNDC12 consists of a 522-bp coding region encoding a 173-amino acid protein. It has a 29-amino acid signal peptide and a single TXN active site with a consensus atypical WCGAC active motif. Multiple sequence alignment revealed that the active site is conserved among vertebrates. RfTXNDC12 shares highest identity with its Epinephelus coioides homolog. Transcriptional analysis revealed its ubiquitous expression in a wide range of tissues with the highest expression in the ovary. Immune challenges conducted with Streptococcus iniae and poly I:C caused upregulation of RfTXNDC12 transcript levels in gills and peripheral blood cells (PBCs), while lipopolysaccharide injection caused downregulation of RfTXNDC12 in gills and upregulation in PBCs. Similar to TXN, RfTXNDC12 exhibited insulin disulfide reducing activity. Interestingly, the recombinant protein showed significant protection of LNCaP cells against apoptosis induced by H2O2-mediated oxidative stress in a concentration dependent manner. Collectively, the present data indicate that RfTXNDC12 is a TXN superfamily member, which could function as a potential antioxidant enzyme and be involved in a defense mechanism against immune challenges.

Lectins play significant roles in the innate immune responses through binding to pathogen-associated molecular patterns (PAMPs) on the surfaces of microorganisms. In the present study, tissue distribution and expression analysis of olive flounder lectins were performed after viral hemorrhagic septicemia virus (VHSV) challenge. Fish egg lectin and serum lectin were found to be predominantly expressed in the gills and liver, these results indicate that the transcript expression of olive flounder lectins is concentrated in immune-related tissues. Following a VHSV challenge, an overall increase in the transcript levels of the genes was observed and the expression patterns were distinctly divided into early and later responses during VHSV infection. In conclusion, olive flounder lectins are specifically expressed in immune-related organs and induced in both the immediate and long-lasting immune responses to VHSV in the olive flounder. These results indicate that lectins may be play important roles in the host defense mechanism and involved in the innate and adaptive immune response to viruses in fish.

Galectins, a family of β-galactoside-binding lectins, are pattern recognition receptors that recognize pathogen-associated molecular patterns and are subsequently involved in the opsonization, phagocytosis, complement activation, and killing of microbes. Here, we report a novel galectin related protein (GRP) identified from rock bream (Oplegnathus fasciatus), designated OfGal like B. The cDNA of OfGal like B is 517 bp with an open reading frame (ORF) of 438 bp, encoding 145 amino acids, with a single carbohydrate recognition domain (CRD). However, only two of the seven critical residues responsible for carbohydrate recognition were identified in the CRD. There was no signal peptide identified in the OfGal like B protein. The genomic structure of OfGal like B, determined using a bacterial artificial chromosome (BAC) genomic library, consists of four exons and three introns. Homology assessment, multiple sequence alignment, and phylogenetic analysis indicated that OfGal like B is an evolutionarily conserved lectin that is closely related to the proto-type galectins. OfGal like B mRNA was constitutively expressed in a wide range of tissues in healthy rock breams. When challenged with bacterial or viral stimulants, OfGal like B was up-regulated in the gills and spleen of rock breams, indicating that it likely plays an important role during bacterial and viral infections. Furthermore, recombinant OfGal like B (rOfGal like B) lacked carbohydrate-binding activity but was able to recognize and agglutinate bacteria, including Streptococcus iniae, Listeria monocytogenes, Vibrio tapetis, Escherichia coli, and Edwardsiella tarda, and a ciliate parasite, Miamiensis avidus. These results collectively suggest that OfGal like B is involved in pathogen recognition and plays a significant role(s) in the innate defense mechanism of rock bream.

The olive flounder (Paralichthys olivaceus) is one of the most important aquaculture species in Korea. Previous studies focused on the morphological changes and only analysed digestive enzyme expression patterns of certain digestive systems. A comprehensive analysis of the pancreatic and gastric digestive enzymes of the olive flounder in its early developmental stages has not been performed. In this study, we determined the mRNA expression levels of pancreas and stomach digestive enzymes by extracting total RNA from the whole body of olive flounders from hatching to post-metamorphosis and conducting real-time PCR analysis with gene-specific primers for each isoform. The pancreatic digestive enzymes were initially and strongly expressed from the first feeding period to pre-metamorphosis. The expression of trypsinogen 3 was detected from the early stage of development to metamorphosis, whereas trypsinogen 2 was significantly increased only in the post-metamorphosis period. The mRNA expression of pepsinogen was only detected at metamorphosis and corresponded to stomach differentiation. The lipid digestive-related enzymes had already reached a certain level at the beginning of hatching, then increased during the early developmental stage and gradually decreased before metamorphosis. These results suggest that food ingestion is exclusively digested by pancreatic digestive enzymes and trypsinogen 3 during the early developmental stage until pre-metamorphosis, and it then fully switches to digestion by pepsinogen and trypsinogen 2 in mid-metamorphosis. In conclusion, understanding the expression profiles of digestive enzymes in the pancreas and stomach during the early developmental stages is an important consideration when developing formulated larval diets for aquacultured olive flounder.

Takifugu rubripes is more expensive than other species of the genus because of its high protein content and special flavor. However, it is easily confused with imported T. chinensis and T. pseudommus because they have similar morphological characteristics. We identified single nucleotide polymorphism (SNP) markers of T. rubripes by genotyping-by-sequencing (GBS) and evaluated their ability to distinguish among T. rubripes, T. chinensis, and T. pseudommus. In all, 18 polymorphic SNPs were subjected to phylogenetic analyses of the three Takifugu species. Additionally, we subjected a second set of samples to Sanger sequencing to verify that the polymorphic SNPs could be used to evaluate the genetic variation among the three Takifugu species. A phylogenetic tree that included the analyzed sequence of set A, which is referred to as the reference sequence, and a validation sequence of set B with 18 SNPs were produced. Based on this phylogenetic tree and STRUCTURE analyses, T. rubripes, T. chinensis and T. pseudommus have low genetic variation and should be considered the same gene pool. Our findings suggest that further studies are needed to estimate the genetic association of the three Takifugu species.

The rock bream (Oplegnathus fasciatus) is one of the most economically valuable marine fish in East Asia, and due to various environmental factors, there is substantial revenue loss in the production sector. Therefore, knowledge of its genome is required to uncover the genetic factors and the solutions to these problems. In this study, we constructed the first draft genome of O. fasciatus as a reference for the family Oplegnathidae. The genome size is estimated to be 749 Mb, and it was assembled into 766 Mb by combining Illumina and PacBio sequences. A total of 24,053 transcripts (23,338 genes) are predicted, and among those transcripts, 23,362 (97%), are annotated with functional terms. Finally, the completeness of the genome assembly was assessed by CEGMA, which resulted in the complete mapping of 220 (88.7%) core genes in the genome. To the best of our knowledge, this is the first draft genome for the family Oplegnathidae. Machine-accessible metadata file describing the reported data (ISA-Tab format)

반수체(haploid)는 세포당 하나의 유전체 또는 염색체조가 존 재하는 것으로, 자성발생성이배체(gynogenesis diploid) 또는 웅성발생성이배체(androgenesis diploid) 유도 기술에 의해서 생산되어 왔다. 이들은 자외선에 의해서 유전물질이 불활성화 된 정자 또는 난자를 이용하여 유도됨으로써, 오로지 난자 또는 정자의 유전물질만으로 발생하게 된다(Tanaka et al., 2004; Yi et al., 2009). 경골어류의 반수체에 대한 연구는 금붕어(goldfish, Carassius auratus), 송사리(medaka, Oryzias latipes) 및 제브라피 쉬(zebrafish, Danio rerio)에서 보고된 바 있다(Walker, 1999; Araki, 2001; Luo and Li, 2003). 이들의 연구 결과 경골어류 의 반수체는 일반적으로 해로운 열성치사 유전자 존재 또는 유 전자 산물의 부족 때문에 부종(edema), 왜소증(dwarfism), 소 두증(microcephaly) 및 소안구(microphthalmia) 등과 같은 이 형적인 특징이 관찰되었고, 부화 전후 또는 난황 흡수 후 모두 사망하는 것으로 보고되어 왔으며(Felip et al., 1999; Luo and Li, 2003), 이러한 반수체의 특이적인 이상발생 현상은 반수 체 증후군(haploid syndrome)으로 명명되어 왔다(Tvedt et al., 2006). 그러나 반수체는 한 개의 염색체조만을 가짐으로써 우 성 유전자형 또는 열성 유전자형에 대한 표현형을 모두 관찰할 수 있기 때문에 효율적인 유전자 분석 및 검색의 방법론으로 이 용되고 있다(Yi et al., 2009). 이에 제브라피쉬는 반수체 배아의 반수체 넙치(Paralichthys olivaceus)의 발생학적 특성 분석

The complement components C1r and C1s play a crucial role in innate immunity via activation of the classical complement cascade system. As initiators of the pathogen-induced signaling cascade, C1r and C1s modulate innate immunity. In order to understand the immune responses of teleost C1r and C1s, Oplegnathus fasciatus C1r and C1s genes (OfC1r and OfC1s) were identified and characterized. The genomic sequence of OfC1r was enclosed with thirteen exons that represented a putative peptide with 704 amino acids (aa), whereas eleven exons of OfC1s represented a 691 aa polypeptide. In addition, genomic analysis revealed that both OfC1r and OfC1s were located on a single chromosome. These putative polypeptides were composed of two CUB domains, an EGF domain, two CCP domains, and a catalytically active serine protease domain. Phylogenetic analysis of C1r and C1s showed that OfC1r and OfC1s were evolutionary close to the orthologs of Pundamilia nyererei (identity = 73.4%) and Oryzias latipes (identity = 58.0%), respectively. Based on the results of quantitative real-time qPCR analysis, OfC1r and OfC1s transcripts were detected in all the eleven different tissues, with higher levels of OfC1r in blood and OfC1s in liver. The putative roles of OfC1r and OfC1s in response to pathogenic bacteria (Edwardsiella tarda and Streptococcus iniae) and virus (rock bream iridovirus, RBIV) were investigated in liver and head kidney tissues. The transcription of OfC1r and OfC1s was found to be significantly upregulated in response to pathogenic bacterial and viral infections. Overall findings of the present study demonstrate the potential immune responses of OfC1r and OfC1s against invading microbial pathogens and the activation of classical signaling cascade in rock bream.

Chemokines are small, structurally related chemotactic cytokines characterized by the presence of conserved cysteine residues. In the present study, we identified the cDNA of a CXC chemokine from Oplegnathus fasciatus, designated as OfCXCL12. An open reading frame of 297 bp encoded a 98 amino acid peptide with a putative signal peptide of 23 amino acids. The CXC family-specific small cytokine domain (SCY), which is highly conserved among vertebrates, was located between residues 29 and 87. The characteristic conserved cysteine residues in the CXC motif of OfCXCL12 were separated by tyrosine (Y). Similar to other vertebrate CXCL12 proteins, OfCXCL12 also lacked the ELR motif and hence belongs to ELR − subfamily. Phylogenetic analysis revealed two distinct clades, consisting of fish and tetrapod CXCL12 homologs. Constitutive expression with significantly higher levels of OfCXCL12 mRNA transcription was detected in immune-related organs, including the head kidney, spleen, and kidney. Infection with bacterial and viral agents led to significant upregulation of mRNA expression in both the head kidney and spleen, in a stimulant-specific manner. Stimulation of peripheral blood leukocytes by the mitogen concanavalin-A significantly induced OfCXCL12 transcription. Results from the present study suggest an important role for OfCXCL12 in immune defense against bacterial and viral infection in rock bream.

Pathogenic infections and environmental factors cause a variety of stresses in fish including oxidative stress by rapid elevation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Transcriptional activation and expression of antioxidant enzymes are essential for reducing the oxidative stress. In this study, we present the molecular characterization, immune responses and ROS scavenging activity of mitochondrial peroxiredoxin 3 from Oplegnathus fasciatus (RbPrx3). Coding sequence (CDS) of RbPrx3 contains 248 amino acids polypeptide which consists of highly conserved peroxiredoxin super family domain and two cysteine residues. Pairwise sequence comparison revealed that RbPrx3 has the greatest identity (94.8%) to Sparus aurata Prx3. Transcriptional analysis of RbPrx3 indicated the ubiquitously expressed mRNA in wide array of organs showing the highest expression in the liver of rock bream. Upon immune challenge of Edwardsiella tarda, Streptococcus iniae, rock bream iridovirus (RBIV) and lipopolysaccharide (LPS), RbPrx3 mRNA level was up-regulated in immunocompetent liver tissues compared to unchallenged fish. Purified recombinant RbPrx3 treated THP-1 cells showed higher survival rate against H2O2 induced oxidative stress and significantly reduced the level of intracellular ROS. Overall results from our study suggest that RbPrx3 may be involved in broader functions such as regulating oxidative stresses by scavenging ROS and activating immune responses in rock bream.

Superoxide dismutase is a family of important antioxidant metalloenzymes and catalyzes the dismutation of toxic superoxide anions into dioxygen and hydrogen peroxide. A recent study identified the partial superoxide dismutase (SOD) gene in olive flounder (Paralichthys olivaceus). The same study reported that it strongly induced benzo[a]pyrene and that it was an indicator of aquatic oxidative stress responses. However, its transcriptional response against viral infection has not been investigated. In the present study, the spatial and temporal expression profiles were analyzed to investigate the function of Of-SOD in the antiviral response. The Of-SOD transcripts were ubiquitously detected at various levels in diverse tissues in a real-time PCR. The expression of Of-SOD was significantly higher in the muscles, liver, and brain but extremely low in the stomach and spleen. Following a VHSV challenge, the expression of Of-SOD increased within 3 h in the kidneys and decreased to the original level 2 days postchallenge. In muscle, liver, and brain, Of-SOD mRNA was similarly up-regulated at 3?6 h postchallenge and then decreased to the basal level. Although the expression pattern and induction time differed slightly depending on the tissue, the transcript of Of-SOD consistently increased in the acute infection response, but the expression was low in the chronic response. The expression of Of-SOD was induced after the VHSV infection, and Of-SOD was probably involved in the immune response against the viral challenge. These results suggest that SOD may play important roles in the immune defense system of P. olivaceus and perhaps contribute to the protective effects against oxidative stress in olive flounder.

【Cytogenetic analysis was conducted to obtain basic information for chromosome manipulation of starry flounder Platichthys stellatus. Nuclear surface area and volume of erythrocyte were $7.60{\pm}0.93{\mu}m^2$ and $12.80{\pm}1.75{\mu}m^3$ , respectively. The haploid DNA content of the species was 0.66 pg/haploid cell which correspond to 93% of olive flounder Paralichthys olivaceus. A karyotype analysis was also carried out with the species using conventional staining and Ag-NOR banding techniques. It was consisted of 48 acrocentric chromosomes and inter-sex or intra-individual polymorphism was not detected in all specimens analyzed. The NOR regions, appearing a terminal position of the short arm of the smallest acrocentric pairs.】

Fish larvae are immediately exposed to microbes from hatching to maturation of their lymphoid organs, therefore effective innate mechanisms is very important for survival. However, the knowledge of the development of immune system in fish is limited and in demand now. In vertebrates, recombination-activating gene 1 (RAG-1) and immunoglobulin M (IgM) have been considered as very useful markers of the physiological maturity of the immune system. In this study, the expression of the both genes was assessed throughout the early developmental stages of olive flounder larvae (5-55 dph) and used as markers to follow the development of immune system. RAG-1 and IgM mRNA expression was detectable at 5 dph and remained so until 55 dph. These patterns of expression may suggest that the olive flounder start to develop its function around 5 dph. Tissue distribution was found that both genes mRNAs are only expressed in the immune-related organ such as spleen, kidney and gill. The early detection of IgM mRNA led to the investigation of its presence in oocytes. Both RAG-1 and IgM mRNA transcripts were detected in unfertilized oocytes, suggesting that they are maternally transferred. The biological significance of such a phenomenon remains to be investigated.

The immune system in teleost fish is not completely developed during embryonic and larval stages, therefore effective innate mechanisms is very important for survival in such an environment. However, the knowledge of the development of immune system assumed to be restricted. In many species, lysozymes have been considered as important genes of the first line immune defense. The early detection of lysozyme mRNA in previous reports, led to the investigation of its presence in oocytes. As a result, c-type lysozyme mRNA transcripts were detected in unfertilized oocytes indicating maternal transfer. Therefore, we investigated the expression patterns of lysozymes in flounder, including the matured oocyte. In our results, c-type lysozyme mRNA was first detected in unfertilized oocyte stage, observed the significantly decreased until hatching stage, and was significantly increased after hatching stage. On the other hand, g-type lysozyme mRNA transcripts were first detected at late neurula stage, and the mRNA level was significantly increased after 20 dph. It may be suggest that maternally supplied mRNAs are selectively degraded prior to the activation of embryonic transcription. This study will be help in understanding the maturation and onset of humoral immunity during development of olive flounder immune system.

Cardiovascular system is the primary organ to develop and reach a functional state, which underscores the essential role of the vasculature in the developing embryo. The vasculature is a highly specialized organ that functions in a number of key physiological works including the carrying of oxygen and nutrients to tissues. It is closely involved in the formation of heart, and hence it is essential for survival during the hatching period. The expression of genes involved during vascular development in the olive flounder (Paralichthys olivaceus) in the days after hatching is not fully understood. Therefore, we examined the expression patterns of genes activated during the development of flounder. Microscopic observations showed that formation of blood vessels is related to the expression of the vimentin gene. Also, the temporal expression patterns of this vimentin-like gene in the developmental stages and in the normal tissues of olive flounder. The purpose of this study was to examine the expression patterns of vimentin in normal tissues of the olive flounder and during the development of the vascular system in newly hatched olive flounders and HIF-1 plays a vital role in the formation of blood vessels during development. Vimentin expression was strong at the beginning of the development of blood vessels, and was present throughout all developmental stages. Our findings have important implications with respect to the roles of vimentin and HIF-1 in the development and evolution of the first blood vessels in olive flounder. Further studies are required to elucidate the vimentin-mediated hypoxic response signal transduction and to decipher the functional role of vimentin in developmental stages.

Myostatin (MSTN), a negative regulator of skeletal muscle development, is the major gene of interest for improving animal breeding productivity, including for aquaculture. We introduced a CRISPR/Cas9 system to disrupt Paralichthys olivaceus MSTN (PoMSTN) using microinjection. Cas9 mRNA and sgRNAs targeting the first exon of the PoMSTN gene were co-injected into embryos of P. olivaceus. On-target mutations on the PoMSTN locus were generated in somatic tissues with 75.6% efficiency, and founders harboring germline mutations were produced in the F0 generation. In the F1 generation, restriction fragment length polymorphism analysis was applied to select biallelic mutants, and heterozygous biallelic mutants with PoMSTN disruption were obtained. PoMSTN-disrupted P. olivaceus exhibited greater body thickness and increased condition factor, indicating the enhancement of muscle mass with muscle hyperplasia. Expression of PoMSTN mRNA and protein was significantly reduced in the muscle of PoMSTN-disrupted P. olivaceus, and the mRNA expression of major myogenic regulatory factors (myogenin, MyoD, and Myf5) was differentially affected in PoMSTN-disrupted mutants. These results suggest that the establishment of a CRISPR/Cas9 system in P. olivaceus provides powerful tools for related genetic studies and breeding.

The innate immune response is fundamental defense response of vertebrates and invertebrates. Especially, the innate immune response important for larvae that lack of resistance to infectious diseases in the early stages. Galectin is one of the kinds of lectin and presents in the fish mucous that involves innate immune response. Galectin have been studied from various fishing species, but expression analysis of galectin is still unclear during early developmental stage in olive flounder. In this study, we investigated gene expression of galectin-1 from various developmental stage and tissues. We excised several tissues including the muscle, fin, eye, gill, brain, stomach, intestine, kidney, spleen and liver from adult olive flounder and confirmed gene expression of galectin-1 using RT-PCR and quantitative real-time PCR. Expression of galectin-1 was significantly higher in muscle, stomach and intestinal tissue than other tissue in adult fish (5 and 29 months). Also, galectin-1 gene was detected from 0 DAH and gradually increased to 35 DAH and since then decreased after stomach development period. Induction of galectin-1 during the early developmental stage suggest that muscle, fin and eye tissue is formed and begins the secretion of galectin this period. In addition, increased expression levels at 35 DAH suggest that due to complete formation of stomach and intestine, increase of secretion and activation of enzyme. This study shows that expression of galectin-1 during early developmental stages and adult period in olive flounder and can be expect that galectin-1 play essental role in the innate immune system throughout the whole life time. Galectin-1 is primary barrier such as skin and digestive tissue against pathogen infection, also digestive tract developmental period is important for pathogen invasion can be expected that it will serve. Mass mortality due to the disease in seed production is continuing damage, therefore these result will be meaningful about infectious disease during early developmental stages as a basic data for the study.

The purpose of this paper is to compare and analyze family variations for growth-related traits of Pacific abalone, Haliotis discus hannai. Genetic parameters and breeding values were estimated using all measurement data like shell length, shell width, and total weight as 18-month-old growth traits of 5,334 individuals of selected third generation's Pacific abalone produced in 2011. Family variations of 865 individuals of the upper 10 families with the largest number were inspected. Overall mean in phenotypic traits of 18-month-old Pacific abalone which was investigated in this study showed 54.5 mm of shell length, 36.8 mm of shell width and 21.3 g of total weight respectively. And, variation coefficient of total weight was 51.0%, so variability of data was shown to be higher than 21.1% of shell length and 20.7% of shell width. The family effects showed significant difference by each family (p

The seven mitochondrial DNA regions (ND2, ND5, ND4, ND4L, ND6, ND1 and 12SrRNA) of Haliotis discus hannai were examined to estimate the availability as a genetic marker for the study of population genetic. The region with the highest genetic variation was ND4 (Haplotype diversity = 1.0000, Nucleotide diversity = 0.0108). On the other hand, ND2 and ND1 regions have significantly appeared genetic divergence between clusters (divergence of 90% and 87%). Also, pairwise F ST between clusters within ND2 and ND1 regions showed high values; 0.4061 (P = 0.0000), 0.4805 (P = 0.0000) respectively. Therefore we can infer that it is the most efficient and accurate way to analyze the region of ND4 with the highest variation in addition to the regions of ND2 and ND1, which formed clusters with high bootstrap value, for study of population genetic structure in this species. Keywords: mitochondrial DNA, genetic diversity, Haliotis discus hannai 서 론 전 세계의 전복류는 약 70여종이 알려져 있으며 열대지역을 비롯하여 온대 및 아열대지역의 연안에 많이 서식하고 있다 (Lindberg, 1992). 우리나라에서도 5종 (

The innate immune system is the only defense weapon that invertebrates have, and it is the fundamental defense mechanism for fish. The innate immune response is important in newly hatched flounders because it is closely involved in the initial feeding phase, which is why it is essential for survival during the juvenile period. The expression analysis of genes involved in the innate immune response in the olive flounder (Paralichthys olivaceus) in the days after hatching is incomplete. Therefore, we have begun to examine the expression patterns of genes specifically induced during the development of the innate immune system in newly hatched flounders. Microscopic observation showed that pronephron formation corresponded with the expression of perforin-encoding gene. These results suggest that perforin plays a vital role in the innate immunity of the kidney during developmental stages. Perforin expression was strong at the start of the development of the innate immune response, and continued throughout all the development stages. Our findings have important implications with respect to perforin’s biological role and the evolution of the first defense mechanisms in olive flounder. Further studies are required to elucidate the perforin-mediated innate immunity response and to decipher the functional role of perforin in developmental stages.

TCR subunits are members of membrane-bound receptors which allow the fast and efficient elimination of the specific fish pathogens have regulated function in adaptive immunity. Sequence structure of TCR subunits have been reported for various teleosts, but the information of each TCR subunit functional characterization through expression analysis in fish was unknown. In this study, we examined the gene expression of TCR subunits in the early developmental stages and observed transcript levels in various tissues from healthy adult olive flounder by RT-PCR. The mRNA expression of alpha subunit was already detected in the previous hatching step. But the transcripts of another TCR subunit were not observed during embryo development and increased after hatching and maintained until metamorphosis at the same level. It was found that all TCR subunits mRNAs are commonly expressed in the immune-related organ such as spleen, kidney and gill, also weak expressed in fin and eye. TCR alpha and beta subunit were expressed in brain, whereas gamma and delta were not expressed same tissue. The sequence alignment analysis shows that there are more than 80% sequence homology between TCR subunits. Because it has a high similarity of amino acid sequence to expect similar in function, but expression analysis show that will have may functional diversity due to different time and place of expression.

The effect of three different diets (formulated diet, FD; Undaria pinnatifida, UP; Laminaria japonica, LJ) on growth in the Haliotis discus hannai for 90 days was investigated. The shell length of UP ( mm) and LJ ( mm) were significantly faster than those of FD ( mm) (P

Olive flounder (Paralichthys olivaceus) is one of the commercial important flatfish species in Korea. The ocular signal transduction pathway is important in newly hatched flounders because it is closely involved in the initial feeding phase thus essential for survival during the juvenile period. However, the study of gene expression during ocular development is incomplete in olive flounder. Therefore we examined the expression analysis of specifically induced genes during the development of the visual system in newly hatched flounders. We searched ocular development-involved gene in the database of expressed sequence tags (ESTs) from olive flounder eye and this gene similar to arrestin with a partial sequence homology. Microscopic observation of retinal formation corresponded with the time of expression of the arrestin gene in the developmental stage. These results suggest that arrestin plays a vital role in the visual signal transduction pathway of the retina during ocular development. The expression of arrestin was strong in the ocular system during the entirety of the development stages. Our findings regarding arrestin have important implications with respect to its biological role and evolution of G-protein coupled receptor (GPCR) signaling in olive flounder. Further studies are required on the GPCR-mediated signaling pathway and to decipher the functional role of arrestin.

This study was conducted to estimation the selection response for growth-related traits in 31-month old of Pacific abalone, Haliotis discus hannai were born in 2008. In overall mean of surveyed traits and standard deviation showed 76.31 ± 7.247 mm of shell length, 49.48 ± 5.307 mm of shell width and 40.96 ± 6.80 g of total weight. The effect of sex and maturity were statistically significant in all traits include out a condition factor (p < 0.01). And In effect of sex, female were higher than male in all traits excepting condition factor, significantly. In correlation between breeding value and phenotypic value by each traits, showed rank correlation coefficient and simple correlation coefficient, which represented low positive correlation. A hopeful genetic improvement to the next generation showed 6.96 mm of shell length, 4.47 mm of shel width and 12.93 g of total weight. Therefor, It is considered that if considering properly selection intensity and selection ratio, efficient improvement could be made.

We examined the genetic population diversity of the wild Pacific abalone, Haliotis discus hannai and H. discus discus in Korea and Japan using microsatellite DNA markers. High levels of genetic diversity were detected in all populations, as indicated by the high levels of heterozygosity (observed heterozygosity: H Obs = 0.703–0.812; expected heterozygosity: H Exp = 0.761–0.846) and allelic diversity (mean number of alleles per locus: A Obs = 11.7–14.2; allelic richness: A Rich = 11.0–13.6). The genetic structure of the 14 populations was separated into three groups (group 1: all except two H. discus hannai populations (K7 and K8) from the Korea East Sea; group 2: two H. discus hannai populations (K7 and K8) of the Korea East Sea; group 3: all H. discus discus populations). Significant genetic differences were observed not only between H. discus hannai and H. discus discus populations, but also within H. discus hannai . The genetic differentiation observed in H. discus abalone suggests that they have evolved as semi-independent evolutionary units and may have developed local adaptations to their respective habitats. The genetic differentiation within H. discus hannai populations is thought to have occurred due to characteristic differences of geographical marine environments. The findings of the present study will be useful in the management and conservation of Pacific abalone resources.

Angiotensinogen (AGT) is the precursor of the renin-angiotensin system and contributes to osmoregulation, acute-phase and immune responses. A full-length cDNA of the AGT (2004 bp with a 1389 bp coding region) was isolated from rock bream (Rb), Oplegnathus fasciatus . The encoded polypeptide of 463 amino acids had a predicted molecular mass of 51.6 kDa. RbAGT possessed a deduced signal peptide of 22 residues upstream of a putative angiotensin I sequence ( 23 NRVYVHPFHL 32 ). RbAGT possessed a specific domain profile and a signature motif which are characteristics of the serpin family. Sequence homology and phylogenetic analysis indicated that RbAGT was evolutionarily closest to AGT of Rhabdosargus sarba . The mRNA expression profile of RbAGT was determined by quantitative RT-PCR and it demonstrated a constitutive and tissue-specific expression with the highest transcript level in the liver. Significantly up-regulated RbAGT expression was elicited by systemic injection of a lipopolysaccharide, rock bream iridovirus (RBIV) and bacteria ( Edwardsiella tarda and Streptococcus iniae ), revealing its pathogen inducibility. RbAGT manifested a down-regulated response to systemic injury, contemporaneously with two other serpins, protease nexin-1 ( PN- 1), and heparin cofactor II ( HCII ). In addition, a synchronized expression pattern was elicited by RbAGT and RbTNF-α in response to injury, suggesting that TNF-α might be a potential modulator of AGT transcription.

Olive flounder Paralichthys olivaceus is one of the most widely cultured fish species in Korea. Although olive flounder receive attention from aquaculture and fisheries and extensive research has been conducted eye morphological change in metamorphosis, but little information was known to molecular mechanism and gene expression of eye development- related genes during the early part of eye formation period. For the reason of eyesight is the most important sense in flounder larvae to search prey, the screening and identification of expressed genes in the eye will provide useful insight into the molecular regulation mechanism of eye development in olive flounder. Through the search of an olive flounder DNA database of expressed sequence tags (EST), we found a partial sequence that was similar to crystallin beta A1 and gamma S. Microscopic observation of retinal formation correspond with the time of expression of the crystallin beta A1 and gamma S gene in the developmental stage, these result suggesting that beta A1 and gamma S play a vital role in the remodeling of the retina during eye development. The expression of crystallin beta A1 and gamma S were obviously strong in eye at all tested developing stage, it is also hypothesized that crystallin acts as a molecular chaperone to prevent protein aggregation during maturation and aging in the eye.

This study was performed to obtain the basic data on physiological responses of low water temperature stress of the cultured Pacific abalone, Haliotis discus hannai . Abalones were exposed at low water temperatures of 7℃ and 4℃. We have investigated survival rate, superoxide dismutase (SOD) activity and total protein (TP) in the abalone by the exposure times (0, 3, 6, 12, 24, 72, 120, 168 and 216 hours). Survival rate of the abalone at 7℃ experiment was 90.8%, whereas at 4℃ experiment was 0% after exposure 10 days. SOD activity was significantly increased until 12 hours after exposure to 4℃, and then was recovered to starting level after 24 hours. However, there was no significant difference between control (12℃) and 7℃ experiments. TP was significantly increased until 216 hours after 24 hours at 4℃ experiment, but 7℃ experiment showed no significant differences compared to control (12℃) experiment. Therefore, H. discus hannai was acclimated in low water temperature stress at 7℃, but at 4℃, all abalone died possibly because they exceed the limits of defense ability to too low temperature.

Black scraper is a commercially important oceanodromous fish in Korea. The commercial catch of this fish has decreased continuously since 1990. However, its genetic characteristics have never been studied. For population genetic analysis to assist effective aquaculture and stock management efforts, we isolated and characterized 19 microsatellite loci using an microsatellite-enrichment method based on magnetic/biotin capture of microsatellite sequences from a size-selected genomic library. To characterize each locus, 30 individuals from a natural T. modestus population in southern Korea were genotyped. All loci except two, KTm213 and KTm284, were polymorphic, with an average of 15.18 alleles per locus (range, 2–41). The mean observed and expected heterozygosities were 0.67 (range, 0.33–0.97) and 0.79 (range, 0.40–1.00), respectively. A significant deviation from Hardy-Weinberg equilibrium was observed at six loci (KTm142, KTm145, KTm158, KTm24, KTm221, and KTm250). This high variability indicates that these microsatellites may be useful for high-resolution studies of population genetics.