Flounder Research Articles

Behavior-dependent selectivity of yellowtail flounder (Limanda ferruginea) in the mouth of a commercial bottom trawl

Behavior-dependent selectivity of yellowtail flounder (Limanda ferruginea) in the mouth of a commercial bottom trawl

LED 파장에 따른 강도다리 Platichthys Stellatus 성장특성

LED 파장에 따른 강도다리 Platichthys Stellatus 성장특성

Expression Pattern of Early Growth Response Gene 1 during Olive Flounder (Paralichthys olivaceus) Embryonic Development.

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.

Kudoa septempunctata-induced gastroenteritis in humans after flounder consumption in Japan: a case-controlled study.

Raw fish consumption is increasing worldwide. Since around the year 2000, western regions of Japan have reported a foodborne disease of unknown cause that occurred after the consumption of flounder. In October 2010, a particularly large outbreak was reported in these regions among individuals who consumed flounder fish that had been raised in aquaculture systems. The median incubation period was 5 h (range, 4-19 h), and the most frequently reported symptom was diarrhea (80%). The risk estimate of the consumption of flounder was significantly higher than that of the development of symptoms (odds ratio=9.50; 95% confidence interval, 1.59-∞). According to a trace-back investigation, all of the flounder responsible for the outbreak were raised in aquaculture systems. Microscopic examination revealed that the median amount of Kudoa septempunctata present in the muscle of flounder fish from the aquaculture farm was 4.5×10(3) spores/g (range, 1.0×10(3)-9.6×10(6) spores/g). The number of K. septempunctata spores required for the development of illness, as estimated using the Monte Carlo simulation, was 7.2×10(7) spores/g; therefore, thus this might be the minimum ingestion threshold for the development of gastrointestinal symptoms. As a public health measure, the current study results should be referred to for the prevention of the gastrointestinal symptoms related to the consumption of flounder; the national public health authority has disseminated these results. We concluded that K. septempunctata-contaminated flounder fish were associated with the gastrointestinal symptoms of this recent outbreak.

식물근권에서 분리한 세균의 어류질병세균에 대한 항균활성 효과

Olive flounder (Paralichthys olivaceus) is an important aquaculture fish species in Jeju Island, South Korea. Due to the intensification of flounder fish farming, huge amounts of chemical antibiotics are used against several fish diseases. This has many harmful side effects on fish, as well as human consumers. Hence, an alternative to chemical antibiotic agents is needed for disease control. In this study, three strains of rhizobacteria (BRH433-2, TRH415-2, and THJ609-3) were isolated from the rhizosphere of plants. Assays of their antibacterial activity against fish pathogens, such as S. iniae, S. parauberis, V. anguillarum, and E. tarda, were performed with untreated broth culture (without cell separation), supernatant, and precipitated pellets separated by centrifugation. Among these, the cell suspension prepared from the precipitated pellet showed significant antimicrobial activity when compared with that of the untreated broth culture and centrifugal supernatant. These results indicate that the three isolated rhizobacterial strains exhibit antibacterial activity. Analysis of the 16S rDNA sequences of the BRH-433-2, THJ609-3, and TRH415-2 strains showed the highest similarity to Burkholderia gladioli (99.5%), Pseudomonas baetica (97.7%), and P. koreensis and P. baetica (98.4%), respectively. We suggest that the strains hold promise in disease management of fish.

Molecular responses of European flounder (Platichthys flesus) chronically exposed to contaminated estuarine sediments

Molecular responses to acute toxicant exposure can be effective biomarkers, however responses to chronic exposure are less well characterised. The aim of this study was to determine chronic molecular responses to environmental mixtures in a controlled laboratory setting, free from the additional variability encountered with environmental sampling of wild organisms. Flounder fish were exposed in mesocosms for seven months to a contaminated estuarine sediment made by mixing material from the Forth (high organics) and Tyne (high metals and tributyltin) estuaries (FT) or a reference sediment from the Ythan estuary (Y). Chemical analyses demonstrated that FT sediment contained significantly higher concentrations of key environmental pollutants (including polycyclic aromatic hydrocarbons (PAHs), chlorinated biphenyls and heavy metals) than Y sediment, but that chronically exposed flounder showed a lack of differential accumulation of contaminants, including heavy metals. Biliary 1-hydroxypyrene concentration and erythrocyte DNA damage increased in FT-exposed fish. Transcriptomic and 1H NMR metabolomic analyses of liver tissues detected small but statistically significant alterations between fish exposed to different sediments. These highlighted perturbance of immune response and apoptotic pathways, but there was a lack of response from traditional biomarker genes. Gene-chemical association annotation enrichment analyses suggested that polycyclic aromatic hydrocarbons were a major class of toxicants affecting the molecular responses of the exposed fish. This demonstrated that molecular responses of sentinel organisms can be detected after chronic mixed toxicant exposure and that these can be informative of key components of the mixture.

Flounder

Flounder

Phenotypic traits, virulence-associated gene profile and genetic relatedness of Edwardsiella tarda isolates from Japanese eel Anguilla japonica in Korea

Edwardsiella tarda is the predominant bacterium in farm-cultured eel in Korea. Here, we evaluated the heterogeneity of 37 E. tarda isolates derived from Japanese eel with various origins (olive flounder, common carp and ornamental fish) between 2003 and 2010. Regardless of origins, the biochemical characteristics of E. tarda isolates were homogenous except hydrogen sulfide production, citrate utilization and mannitol fermentation. Based on the phylogenetic analysis of 16S rRNA, E. tarda isolates could be classified into two subgroups and displayed a close relation with Edwardsiella ictaluri and Edwardsiella hosinae lineages, suggesting that the subgroup I has been a predominant type in the Jeonnam and Jeonbuk provinces. I-CeuI-based pulsed-field gel electrophoresis (PFGE) typing showed that the isolates from Japanese eels belonged to 11 pulsotypes, indicating that the presence of highly genomic diversity. Additionally, two isolates, ET-060 and ET-191, showed a high frequency of virulence genes (100%) and caused 90% and 60% mortality in Japanese eel, respectively. This finding suggests a substantial congruence of virulence gene profiles and pathogenicity. Our results demonstrate that the intraspecific diversity within E. tarda strains from Japanese eel has been in prior existence. Based on the biochemical characteristics, the phylogenetic property of the 16S rRNA gene and PFGE types of Edwardsiella tarda, we could identify the intraspecific diversity of isolates from Japanese eel, Anguilla japonica in Korea. In addition, this study describes the strong congruence of virulence-related genes and pathogenicity, suggesting that the virulence profile may be useful tool for prediction of pathogenicity.

The Growth, Innate Immunity and Protection against H2O2-Induced Oxidative Damage of a Chitosan-Coated Diet in the Olive Flounder Paralichthys olivaceus

We demonstrate enhanced growth, innate immunity and protection against hydrogen peroxide (H2O2)-induced protein oxidation and cellular DNA damage in olive flounder Paralichthys olivaceus fed a chitosan-coated moist pallet (MP) diet. A chitosanbased biopolymer coated MP as the experimental diet and a non-coated MP (control) was fed to olive flounder fish. Growth, including the average weight gain (g/fish), weight gain (%) and feed intake (g) of the fish group fed a chitosan-coated MP diet increased significantly. The survival rate was reported as 100% throughout the experimental period. Immunological parameters indicated higher mucus lysozyme activity and significantly higher fish skin mucus total protein content was observed in fish fed the chitosan-coated MP diet compared to the control. A blood plasma analysis revealed attenuation of cellular DNA and protein oxidative damage caused by H2O2-induced oxidative stress in the fish fed the chitosan-coated MP diet compared to the control group. Moreover, blood serum biochemical analysis revealed health-promoting effects, including significantly higher hemoglobin and total cholesterol levels in the fish fed the chitosan-coated MP diet compared to the control group. In conclusion, growth, in nate immunity and protection against oxidative stresses were improved by feeding of the chitosan-coated MP diet to olive flounder reared in aquaculture.

Effects of rotifer, Brachionus rotundiformis in enhancing some digestive enzyme activities into glucose on somatic growth, RNA/DNA contents and some digestive enzyme activities of olive flounder Paralichthys olivaceus larvae

We investigated the effects of enzyme enhanced rotifer (EER), Brachionus rotundiformis on growth, RNA/DNA contents and digestive enzyme activities in olive flounder Paralichthys olivaceus larvae. Digestive enzyme activities of rotifer were enhanced by putting glucose in culture medium, and then rotifers (NR, rotifer not supplied the glucose during culture, and EER) was supplied to 10 rotifers/ml in larval rearing tank twice daily. The length-daily growth rate (DGR) showed a sudden decrease at 7 days post hatch (dph), and the weight DGR showed two times decreasing at 5 and 8 dph. The larvae in the NR treatment underwent two times the decrease of daily growth rate of body weight, while those in the EER treatment underwent only the first decrease of that. The DNA content for both treatment increased constantly. The RNA content increased in the larvae measuring up to 3.7 mm in the NR treatment. However, the RNA content of the EER treatment increased in the larvae until the end of the experiment. Therefore, supplement of rotifer enhanced the digestive enzyme activities for early olive flounder larvae prevented the decrease of RNA contents related with a protein synthesis and body weight growth after 7 dph, because NR is not enough for early larvae. Key words: Enzyme enhanced activity, nucleic acid content, somatic growth, critical period, flounder larvae, Paralichthys olivaceus, rotifer.

Sperm Attractant in the Micropyle Region of Fish and Insect Eggs1

In some animals, such as fish, insects, and cephalopods, the thick egg coat has a narrow canal-a micropyle-through which spermatozoa enter the eggs. In fish, there is no indication that spermatozoa are attracted by eggs from a distance, but once spermatozoa come near the outer opening of the micropyle, they exhibit directed movement toward it, suggesting that a substance exists in this defined region to attract spermatozoa. Since Coomassie Blue (CB) binds preferentially to the micropyle region in flounder, herring, steelhead, and other fish, it probably stains this sperm guidance substance. This substance-a glycoprotein based on lectin staining-is bound tightly to the surface of the chorion, but can be removed readily by protease treatment. Although fertilization in fish (flounder) is possible after removal of this substance, its absence makes fertilization inefficient, as reflected by a drastic reduction in fertilization rate. The sperm "attraction" to the micropyle opening is species specific and is dependent on extracellular Ca(2+). Eggs of some insects, including Drosophila, have distinct micropyle caps with CB affinity, which also may prove to assist sperm entry. Our attempts to fertilize fly eggs in vitro were not successful.

Purification and determination of two novel antioxidant peptides from flounder fish (Paralichthys olivaceus) using digestive proteases

We investigated the effects of bioactive-peptides from hydrolysates of flounder fish muscle (FFM) on antioxidant activity. The hydrolysates were prepared by enzymatic reactions of FFM using eight commercial proteases such as papain, pepsin, trypsin, neutrase, alcalase, kojizyme, protamex, and α-chymotrypsin. The α-chymotrypsin hydrolysate showed the strongest antioxidant activity among the eight enzymatic hydrolysates. Further separation of the α-chymotrypsin hydrolysate was performed by ultrafiltration, gel filtration, and reverse-phase high performance liquid chromatography. Consequently, two novel peptides with high antioxidant activity were purified, and their amino acid sequences were determined (Val-Cys-Ser-Val [VCSV] and Cys-Ala-Ala-Pro [CAAP], respectively). The two peptides showed good scavenging activity against the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical (IC50 values, 111.32 and 26.89μM, respectively) and high cytoprotective activities against 2,2-azobis-(2-amidino-propane) dihydrochloride (AAPH) without cytotoxicity and scavenged total reactive oxygen species in Vero cells. In particular, apoptotic bodies produced by AAPH dose-dependently decreased following treatment with the CAAP peptide. These results revealed firstly the two peptides with strong antioxidative effects from FFM.

Catabolic Signaling Pathways, Atrogenes, and Ubiquitinated Proteins Are Regulated by the Nutritional Status in the Muscle of the Fine Flounder

A description of the intracellular mechanisms that modulate skeletal muscle atrophy in early vertebrates is still lacking. In this context, we used the fine flounder, a unique and intriguing fish model, which exhibits remarkably slow growth due to low production of muscle-derived IGF-I, a key growth factor that has been widely acknowledged to prevent and revert muscle atrophy. Key components of the atrophy system were examined in this species using a detailed time-course of sampling points, including two contrasting nutritional periods. Under basal conditions high amounts of the atrogenes MuRF-1 and Atrogin-1 were observed. During fasting, the activation of the P38/MAPK and Akt/FoxO signaling pathways decreased; whereas, the activation of the IκBα/NFκB pathway increased. These changes in signal transduction activation were concomitant with a strong increase in MuRF-1, Atrogin-1, and protein ubiquitination. During short-term refeeding, the P38/MAPK and Akt/FoxO signaling pathways were strongly activated, whereas the activation of the IκBα/NFκB pathway decreased significantly. The expression of both atrogenes, as well as the ubiquitination of proteins, dropped significantly during the first hour of refeeding, indicating a strong anti-atrophic condition during the onset of refeeding. During long-term refeeding, Akt remained activated at higher than basal levels until the end of refeeding, and Atrogin-1 expression remained significantly lower during this period. This study shows that the components of the atrophy system in skeletal muscle appeared early in the evolution of vertebrates and some mechanisms have been conserved, whereas others have not. These results represent an important achievement for the area of fish muscle physiology, showing an integrative view of the atrophy system in a non-mammalian species and contributing to novel insights on the molecular basis of muscle growth regulation in earlier vertebrates.

Cryopreservation of flounder Paralichthys adspersus spermatozoa

To optimize the techniques of captive breeding of flounder Paralichthys adspersus, a methodology was developed for the cryopreservation of spermatozoa of this species. The effect on sperm motility post-thawing, using three different concentrations (1.0; 1.5 and 2.0 M) of DMSO as cryoprotective agent and five different freezing rates -7.5; -10; -12.5; -20 and -30°C min-1, with an automatic programmable freezer was evaluated. The highest percentages of post-thawing sperm motility were obtained by freezing sperm at -10°C min-1, no significant differences (P cryoprotectant solution including DMSO at three different concentrations adding 10% VHG v/v. The highest percentages of sperm motility (71.71 ± 13%) were obtained at the freezing rate of -10°C min-1 without significant differences between the three concentrations of the cryoprotectant solution in which the sample was incubated sperm (P

Artemia 공급 단계에서 은어(Plecoglossus altivelis), 조피볼락(Sebastes schlegeli ), 감성돔(Acanthopagrus schlegeli ) 및 넙치(Paralichthys olivaeus)의 소화효소 활성

We compared the nutritional requirements of whole larvae of the black seabream Acanthopagrus schlegeli, sweet fish Plecoglossus altivelis, olive flounder Paralichthys olivaeus and rock fish Sebastes schlegeli. The larvae were 20, 30, 14 and 5 DAH (or spawning) of black seabream, sweet fish, olive flounder and rock fish, respectively. Specific <TEX>${\alpha}$</TEX>-amylase activity (mU/mg protein) was highest (8,324.9 mU/mg protein) in rock fish larvae (P<0.05). Specific trypsin-like protease activity was highest (11,330.1 mU/mg protein) in black seabream larvae (P<0.05), which also exhibited the highest activity, 685.5 mU/mg dry weight (P<0.05). The specific activities per mg protein and mg dry weight of black seabream were the highest (187.4 mU/mg protein and 11.3 mU/mg dry weight, respectively) (P<0.05). A/P, P/L and A/L ratios of rock fish were 1.47, 90.3 and 133.1, respectively (P<0.05). We present here basic larval digestive enzymatic nutritional requirement data.

Towards a System Level Understanding of Non-Model Organisms Sampled from the Environment: A Network Biology Approach

The acquisition and analysis of datasets including multi-level omics and physiology from non-model species, sampled from field populations, is a formidable challenge, which so far has prevented the application of systems biology approaches. If successful, these could contribute enormously to improving our understanding of how populations of living organisms adapt to environmental stressors relating to, for example, pollution and climate. Here we describe the first application of a network inference approach integrating transcriptional, metabolic and phenotypic information representative of wild populations of the European flounder fish, sampled at seven estuarine locations in northern Europe with different degrees and profiles of chemical contaminants. We identified network modules, whose activity was predictive of environmental exposure and represented a link between molecular and morphometric indices. These sub-networks represented both known and candidate novel adverse outcome pathways representative of several aspects of human liver pathophysiology such as liver hyperplasia, fibrosis, and hepatocellular carcinoma. At the molecular level these pathways were linked to TNF alpha, TGF beta, PDGF, AGT and VEGF signalling. More generally, this pioneering study has important implications as it can be applied to model molecular mechanisms of compensatory adaptation to a wide range of scenarios in wild populations.

Gynogenetic induction in southern flounder (&lt;I&gt;Paralichthys lethostigma&lt;/I&gt;) by cryopreserved sperm of &lt;I&gt;Lateolabrax japonicas&lt;/I&gt;

Female southern flounder( Paralichthys lethostigma) grow larger than males.Therefore,all-female production will maximize profit potential for the culture of this species.It may be effective to develop protocols to produce all-female southern flounder through induction of meiotic gynogenesis with the cryopreserved heterologous sperm of Lateolabrax japonicas.To test methods for inducing diploid gynogenesis in southern flounder using heterogenous sperm,the UV was used to inactivate sperm and pressure shock was used to prevent extrusion of the second polar body.The results of experiments showed that gynogenetic diploid can be induced by inactivated heterogenous sperm because that hybrid would die before hatching.Diploid gynogenesis was induced by activating egg development with UV irradiated sperm( 80 mJ/cm2) 4-5 min after fertilization ( 18 ℃) ,and then 65 MPa pressure treatment for 6 min.Flow cytometry and microsatellite DNA analysis were used to demonstrate that the gynogenetic fry are diploidy.These results indicate that the use of UV irradiated sperm from Lateolabrax japonicas for activation of flounder eggs and pressure shock for polar body retention is an effective method to produce gynogenetic diploid in southern flounder.

Processing and Degradation of Lipovitellin During Embryonic and Larval Development of the Winter Flounder (Pleuronectes-Americanus)

Processing and Degradation of Lipovitellin During Embryonic and Larval Development of the Winter Flounder (Pleuronectes-Americanus)

Growth of the Frog Flounder in the Harima Nada

Growth of the Frog Flounder in the Harima Nada

From the Editors: Dos and Don'ts

The old saying that “you only have one chance to make a first impression” is one that applies to submitting papers to a journal. We have seen so many papers flounder on this first step that we want to share our list of dos and don'ts.