Black Sea Bream Acanthopagrus Schlegeli Research Articles

Phytase in soybean meal diet improves phosphorus availability of hybrid, female red sea bream Pagrus major × male black sea bream Acanthopagrus schlegeli

Phytase in soybean meal diet improves phosphorus availability of hybrid, female red sea bream Pagrus major × male black sea bream Acanthopagrus schlegeli

Suitable Dietary Protein/Lipid Ratio for Hybrid, Female Red Sea Bream Pagrus major and Male Black Sea Bream Acanthopagrus schlegeli in the Juvenile Stage, Compared with Red Sea Bream

To determine a suitable dietary protein/lipid (CP/CL) ratio in the early juvenile stages of hybrid porgy (F1), female red sea bream (RSB) × male black sea bream, five diets with various CP/CL ratios—60/7, 55/12, 51/17, 46/23, and 41/28—were prepared and provided to juveniles in triplicate. At the smaller juvenile stage, F1, weighing 0.32 g, a significantly higher specific growth rate (SGR) and feed efficiency (FE) were seen with 60/7 and 55/12 diets. However, in RSB weighing 0.26 g, SGR and FE were higher with the 60/7 diet than the other diets at 21°C. At the larger juvenile stage, F1, weighing 3.7 g, there was no significant difference in SGR or FE among the diets, but RSB weighing 4.0 g fed 60/7, 55/12, and 51/17 diets had higher SGR and FE than 46/23 and 41/28 diets at 24°C. Moreover, survival and apparent nutrient retention of F1 at both stages were significantly higher than those in RSB. These results indicate that both F1 and RSB weighing ca. 0.3 g require a higher dietary CP/CL than those weighing ca. 4 g. Additionally, F1 in both trials showed the suitability of a lower dietary CP/CL than RSB, indicating that mass production of F1 juveniles will be more economical than RSB.

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.

Effects of two different ozone doses on seawater recirculating systems for black sea bream Acanthopagrus schlegeli (Bleeker): Removal of solids and bacteria by foam fractionation

Foam fractionators, with and without additional ozonation, were evaluated for their effect on solids removal (suspended solids, SS; volatile suspended solids, VSS; dissolved organic carbon, DOC), particle size distribution of the foam in seawater recirculating systems during a 44-day experimental period. The effect of ozone on heterotrophic bacteria was also quantified in the entire system. Three separate but identical recirculating systems (4.5m3 system volume) with foam fractionators (300mm in diameter, 3m in height) were used in this study. One system (Control: CS) did not receive ozone, while the other two systems were ozonated at a rate of either 20g ozone/day (T 20) or 40g ozone/day (T 40) per kg of feed applied, respectively. A total of 107kg of black sea bream Acanthopagrus schlegeli (Bleeker) with an average weight of 334.5g was stocked into each system. Daily feeding rate was 1% of total body weight. The solids enrichment factor (EF=Cc/Ci, where Cc=concentration in foam condensate, Ci=concentration in inlet water) in T 40 was 10 times more dilute than the factors in CS and T 20. However, due to the higher volume of the foam (>10 times) in T 40, the removal rates of SS, VSS and DOC were the highest in T 40, but were not significantly different from T 20 (P>0.05). The mean particle sizes at the 90% cumulative removal point decreased with ozonation, 71.2±15.9, 57.9±10.2 and 48.0±10.2μm in CS, T 20 and T 40, respectively. The overall mean particle diameter of solids in the foam decreased as ozonation increased, with values of 29.4±4.4, 23.9±3.8 and 20.5±3.7μm in CS, T 20 and T 40. Numbers of heterotrophic bacteria in the inlet were 6.21±4.93×105CFU/mL, 0.29±0.19×105CFU/mL and 0.30±0.29×105CFU/mL in CS, T 20 and T 40, declining sharply with the addition of ozonation. As the number of the bacteria in the inlet decreased, the bacteria in the foam and the removal rate greatly decreased with increasing ozonation. However, EFs in T 20 (76.4) and T 40 (14.5) were higher than that in CS (12.2), and the T 20 showed significantly higher EF (P<0.05). Therefore, based on the EF, ozonation improved the removal efficiency of heterotrophic bacteria, even at the lowest concentration.

Copper uptake kinetics and regulation in a marine fish after waterborne copper acclimation

The uptake kinetics and regulation of copper in a marine predatory fish, the black sea bream Acanthopagrus schlegeli after acclimation to waterborne Cu were examined, using radiotracer techniques. The dissolved Cu uptake followed a linear pattern during the time of exposure, and the calculated uptake rate constant was 6.24 L kg −1 day −1. The efflux rate constant was 0.091 day −1 following dietary uptake of Cu, and the dietary assimilation efficiency (AE) of Cu varied between 1.7% and 10.9% after the fish were fed with three types of prey (oysters, clams and brine shrimp). After the fish were acclimated at a nominal concentration of 50 μg Cu L −1 for 14 days, the Cu uptake rate and efflux rate constant did not change significantly, but the Cu body concentrations and metallothionein (MT) concentrations in fish tissues increased significantly. Subcellular Cu distributions were also modified. Significant MT induction was observed in response to increased Cu tissue concentrations, indicating that MT rather than the uptake kinetics may play a primary role in Cu regulation during waterborne Cu acclimation in this marine fish. Moreover, the high Cu efflux may also be important in Cu regulation during long-term exposure. Our modeling calculations indicated that dietary uptake was likely to be the main route for Cu bioaccumulation in the fish, and the relative contribution of waterborne and dietary uptake depended on the bioconcentration factor (BCF) of the prey and ingestion rate of fish.

음향 텔레메트리 기법을 이용한 자연산과 양식산 감성돔의 행동특성 비교

Acoustic telemetry technique is one of useful tools to get behavioral information of the free-swimming fish. In this study, we conducted acoustic telemetry using coded acoustic transmitters to compare behavior characteristics between wild and cultured black seabream Acanthopagrus schlegeli, one of target species to promote resource in the marine ranching area. Two wild fish and five cultured fish were released in the marine ranching area after tagging surgically. Three of cultured fish were domesticated using the remote acoustic conditioning system for 3 weeks before being released. Two wild fish stayed at the released point for 2 hours and 9 days, respectively. One of wild fish was found about 10.8km away from the released point after 5 months. Two cultured fish stayed at the released point for 6 days and 75 days, respectively. One of acoustic conditioned fish stayed at the released point for 131 days and then was found about 10.1km away from the released point after 25 days. Others stayed at the released point during this study period(159 days).

Effects of replacement of dietary fish oil by soybean oil on growth performance and liver biochemical composition in juvenile black seabream, Acanthopagrus schlegeli

A 9-week feeding experiment was carried out on juvenile black seabream Acanthopagrus schlegeli to evaluate the effects of dietary replacement of fish oil by soybean oil on fish growth and liver biochemical composition. Fish in triplicate were fed four diets, in which 0% (FO as control), 60% (60SO), 80% (80SO) and 100% (100SO) of fish oil was replaced by soybean oil. The weight gain of fish fed 60SO or 80SO diet was similar to that of fish fed the control diet, but a total replacement of fish oil by soybean oil significantly reduced fish growth. Although the inclusion of soybean oil resulted in an increase in the crude lipid content of the liver, the level of fish oil replacement did not significantly alter the hepatosomatic index, feed conversion ratio, condition factor and liver proximate composition. The inclusion of soybean oil in seabream diets increased hepatic α-tocopherol concentrations, but reduced thiobarbituric acid-reactive substances and plasma cholesterol. Linoleic acid and linolenic acid significantly increased in fish fed soybean oil diets, but docosahexaenoic acid, eicosapentaenoic acid and the ratio n−3/n−6 were significantly reduced by the inclusion of dietary soybean oil (P<0.05). Our results indicated that the inclusion of soybean oil increased the hepatic α-tocopherol content and reduced lipid peroxidation in fish. However, complete substitution of fish oil with soybean oil reduced growth efficiency. Thus, 60–80% replacement of fish oil by soybean oil is recommended in diet formulation for black seabream.

Cloning and bioactivity analysis of a CXC ligand in black seabream Acanthopagrus schlegeli: the evolutionary clues of ELR+CXC chemokines

BackgroundThe ELR+CXC chemokines are multifunctional mediators that are mainly responsible for the recruitment of leucocytes to sites of inflammation and infection. Because of their high sequence identity with mammalian IL-8, fish IL-8-like CXCs have been named as piscine 'IL-8' and included in the ELR+ subgroup, even though there is no reliable functional or evolutionary evidence to support this classification.ResultsIn this investigation, a homologue of piscine 'IL-8' from black seabream (Acanthopagrus schlegeli), called BS CXC, has been cloned and analyzed. The results revealed that BS CXC has a high gene similarity and tertiary structure similarity with piscine and mammalian CXC chemokines, both ELR-CXC and ELR+CXC, although it has a lower identity with ELR-CXC, compared with ELR+CXC chemokines. Like other piscine IL-8, BS CXC has only an incomplete ELR motif, which is essential for the mammalian ELR+CXC ability to attract granulocytes. Bioactivity assay demonstrated that the BS rCXC produced in E. coli significantly stimulated migration of fish neutrophils and macrophages, but had no effect on rat neutrophils and macrophages, whereas hrIL-8 induced strong chemotaxis of fish neutrophils but did not affect fish macrophages. BS CXC seems show some structural and functional properties of the intermediate between ELR-CXC and ELR+CXC.ConclusionAs an incomplete ELR+CXC chemokine from a modern fish, BS CXC provides some clues on the evolution from ancient ELR-CXC to ELR+CXC by retaining some properties of the intermediate stage in evolution, and it may be more appropriate to call this molecule 'piscine CXC with an incomplete ELR', instead of terming it fish 'IL-8'.

Development of polymorphic microsatellite from RAPD bands of black sea bream Acanthopagrus schlegeli

AbstractEight pairs of simple sequence repeat markers were developed from random amplified polymorphic DNA product in black sea bream Acanthopagrus schlegeli. Twenty microsatellites were selected for designing microsatellite primers, of which eight gave working primer pairs. They had between three and seven alleles. Observed and expected heterozygosities varied from 0.65 to 0.90, and from 0.58 to 0.82, respectively. Eight additional fish species assessed for cross‐species amplification revealed between two and five positive amplifications and between zero and three polymorphic loci per species.

Size‐dependence of the potential for metal biomagnification in early life stages of marine fish

We investigated the bioaccumulation of metals (Cd, Se, and Zn) in different juvenile sizes of black sea bream Acanthopagrus schlegeli by applying a biokinetic model. A series of experiments were conducted to determine the physiological kinetic parameters, including uptake rate constant of waterborne metals, ingestion rate, assimilation efficiency of dietary metals, efflux rate constant, and specific growth rate as a function of fish size. Body concentration of metals as a function of body size was then simulated by the kinetic model and compared with the actual measurements. The uptake rate constants decreased with increasing fish size, with an allometric exponent (b) of 0.615 to 0.662. Ingestion rate was also negatively correlated with the fish size (b = -0.604). Assimilation efficiencies of Cd were independent of body size, whereas those of Se and Zn increased with fish size. In contrast, efflux rate constants and growth rate constants for metals were comparable in different sizes of fish. Predicted concentrations of Cd and Zn were comparable to actual measurements and were negatively correlated with fish size. Ingestion rate was the most important parameter accounting for the size-dependent bioaccumulation of metals, followed by dietary assimilation. We further showed that the trophic transfer potentials of Se and Zn were > 1 in smaller fish but then reduced to < 1 in larger ones, suggesting that trophic transfer potentials are highly size dependent in marine fish.

Seabream ghrelin: cDNA cloning, genomic organization and promoter studies

Recent studies have indicated that ghrelin stimulates growth hormone release from the pituitary via the growth hormone secretagogue receptor (GHSR). We have previously isolated two GHSR subtypes from the pituitary of the black seabream Acanthopagrus schlegeli. In the present study, we have cloned and characterized ghrelin from the same fish species at both the cDNA and gene levels. The full-length seabream ghrelin cDNA, isolated from sea-bream stomach using a novel approach by exploiting a single conserved region in the coding region, was found to encode a prepropeptide of 107 amino acids, with the predicted mature ghrelin peptide consisting of 20 amino acids (GSSFLSPSQKPQNRGKSSRV). Embedded in this full-length cDNA is a putative fish orthologue of the recently reported mammalian obestatin peptide. The ghrelin gene in black seabream, obtained by genomic PCR, was found to encompass four exons and three introns, possessing the same structural organization as in tilapia and goldfish, but different from that in rainbow trout. In addition, a 2230-bp 5'-flanking region of the seabream ghrelin gene was obtained by genome walking. Sequence analysis revealed that, as in the case of the human ghrelin gene, there is neither a GC box nor a CAAT box present in the isolated 5'-flanking region. However, a number of putative transcription factor-binding sites different from the human counterpart were found in the 5'-flanking region of the seabream ghrelin gene, suggesting that different cis- and trans-acting elements are involved in controlling their gene expression. Functional activity of this 5'-flanking region was examined by cloning it into the pGL3-Basic vector upstream of the luciferase reporter gene and transfected into various cell lines. Positive promoter activity could only be recorded in the colon-derived Caco-2 cells, suggesting that the cloned 5'-flanking region represents the functional promoter of the seabream ghrelin gene, which exhibits tissue-specific promoter activity. Using reverse transcriptase PCR analysis, expression of ghrelin was detected only in the seabream stomach, but not in the other tissues examined, including the brain, gill, intestine, kidney, liver and spleen. This stomach-specific expression of ghrelin in seabream is subject to regulation, as administration of growth hormone or ipamorelin to the fish in vivo was demonstrated to enhance its expression. Reminiscent of the homologous upregulation found in the transcriptional control of the seabream GHSR gene, a similar homologous regulatory mechanism might also exist in controlling the expression of seabream ghrelin. The identification of both GHSR and ghrelin from a single fish species would facilitate our subsequent studies on the elucidation of the physiological functions of the ghrelin/GHSR system in teleost. The possible existence of obestatin in teleost opens up new research avenues on the somatotropic axis in fish.

Ontogeny of tolerance to and avoidance of ultraviolet radiation in red sea bream Pagrus major and black sea bream Acanthopagrus schlegeli

Ontogenetic changes of tolerance to, and avoidance of, ultraviolet-B radiation (UV-B) were examined in red sea bream Pagrus major and black sea bream Acanthopagrus schlegeli. In the tolerance experiment, larvae and juveniles (age 13–46 days) were put in beakers, and were exposed to one of five different levels of UV-B radiation (1.8, 1.1, 0.2, 0.1, and 0 W/m2) for one hour. Their survival rates were calculated either 12 or 24 h later. In the avoidance experiment, fish (age 3–49 days) were put in a long experimental tank, half of which was covered with UV-blocking film and placed under two levels of UV-B radiation (1.1 and 0.2 W/m2), and their avoidance indices were calculated. Black sea bream had significantly better survival compared to red sea bream for most ages. Only black sea bream of ages 37 and 49 days showed significant avoidance of UV radiation under the higher level of UV-B, whereas both species did not show avoidance on any days at the lower level. The present results suggest that black sea bream are significantly better adapted to habitats with high UV-B radiation, than red sea bream, reflecting that back bream live in shallower waters through their early life stages.

Effects of Zn pre-exposure on Cd and Zn bioaccumulation and metallothionein levels in two species of marine fish

Zinc is an essential trace metal but also a potential toxicant to aquatic organisms. In this study, two juvenile marine fish species, the black sea bream Acanthopagrus schlegeli and the grunt Teraponjarbua, were pre-exposed to Zn either from waterborne (0.74–170 μg L −1) or dietary (39–5926 μg g −1) Zn for 1 or 3 weeks. The concentrations of Zn and metallothionein (MT) in the whole body of the black sea bream and in the gills, viscera and carcass of the grunt were then measured during this pre-exposure. Following the pre-exposure, both fish species were then exposed to 109Cd and 65Zn labeled food or water to quantify the dietary assimilation efficiency (AE) and the uptake rate of dissolved Cd and Zn. Zn concentrations in both fish species were enhanced after pre-exposure, but the increases were much less than the increase of ambient Zn pre-exposure concentration. Following Zn pre-exposure, MT concentrations in the viscera and carcass were significantly elevated, whereas the MT levels were not significantly elevated in the gills. Waterborne and dietary Zn exposure enhanced the uptake rates of dissolved Cd and Zn in both fish. The maximum increases of uptake rate constants of dissolved Cd and Zn were up to 1.9–2.8 and 2.1–2.6 times, respectively, in the seabream and grunt. In contrast, dietary assimilation efficiency of Cd and Zn was not significantly enhanced following Zn pre-exposure. A positive linear relationship was found between the uptake rate constants of dissolved metals and Zn or MT concentrations in the fish. The results suggested that Zn pre-exposure increased the potential of metal uptake from ambient water, but had little effect on dietary metal uptake. Furthermore, the Zn body concentration and metal uptake from the dissolved phase were significantly dependent on the fish body size.

Stimulation of growth hormone secretion from seabream pituitary cells in primary culture by growth hormone secretagogues is independent of growth hormone transcription

The action of a number of growth hormone secretagogues (GHS) on growth hormone (GH) secretion and gene expression was studied in a primary culture of pituitary cells isolated from the black seabream Acanthopagrus schlegeli. The peptide GHS employed included growth hormone-releasing peptide (GHRP)-2, ipamorelin, and human ghrelin. The nonpeptide GHS employed included the benzolactam GHS L692,585 and the spiropiperidine GHS L163,540. Secreted GH was measured in the culture medium by an enzyme-linked immunosorbent assay (ELISA) method using a specific antibody against seabream GH. The GH mRNA content in the incubated cells was assessed by reverse transcription polymerase chain reaction (RT-PCR) using a pair of gene-specific primers designed from the cloned black seabream GH cDNA sequence. A dose-dependent stimulation of GH release was demonstrated by all the GHS tested, except human ghrelin, with EC 50 values in the nanomolar range. Simultaneous measurement of GH mRNA levels in the incubated seabream pituitary cells indicated that the GHS-stimulated increase in GH secretion was not paralleled by corresponding changes in GH gene expression. In contrast to the situation previously reported in the rat, no change in GH gene expression was noticed in the seabream pituitary cells even though the time of stimulation by GHS was increased up to 48 h, confirming that the GHS-stimulated GH secretion in seabream is independent of GH gene transcription.

Isolation and characterization of the 5′-flanking region of the growth hormone secretagogue receptor gene from black seabream Acanthopagrus schlegeli

Ghrelin, the recently discovered endogenous ligand for growth hormone secretagogue receptor (GHSR), is widely expressed and involved in regulating diverse physiological functions in addition to stimulation of growth hormone (GH) secretion. Previous studies have demonstrated the functional significance of the ghrelin/GHSR system, yet the transcriptional regulation of the ghrelin and GHSR genes are poorly understood. We have recently cloned the GHSR cDNA from the pituitary of black seabream Acanthopagrus schlegeli. In the present study, we have isolated a 2.1 kb 5′-flanking region of the GHSR gene from the same species and have investigated, for the first time, the transcriptional regulation of GHSR from a non-human species. The 5′-flanking region of the seabream GHSR gene was found to contain a number of unique putative transcription factor-binding sites different from the human counterpart. Functional characterization of the 5′-flanking region in several cell lines indicates that the region between −1423 and +19 contains sufficient elements for promoter function. Moreover, progressive 3′-deletion analysis suggests the presence of negative regulatory element(s) and essential cis-acting element(s) at −514/+19 and −928/−515, respectively. Furthermore, we have shown that the promoter activity is significantly enhanced by a GHSR agonist in a cell line stably expressing the seabream GHSR, and this stimulatory effect could be completely blocked by a GHSR antagonist. These results suggest that homologous up-regulation plays an important role in the transcriptional control of the teleostean GHSR gene. This is in big contrast to the human situation in which a homologous down-regulation of the GHSR gene transcription by its own ligand has been previously demonstrated.

Dietary effects of eicosapentaenoic acid and docosahexaenoic acid on lipid metabolism in black sea bream

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were fortified at a level of 1.5% in a composed diet. The effects were confirmed in 0-year black sea bream Acanthopagrus schlegeli in terms of lipid metabolism and physiological activity. The EPA group was high in EPA in muscle, liver, intraperitoneal fat body (IPF), eye and brain. The levels of DHA in liver, eye, brain and heart were also high in the EPA group, suggesting that conversion of EPA to DHA occurred in those organs. Fortification of DHA increased the levels of DHA in organs except the eye, but did not affect EPA levels. Both the EPA and DHA groups showed smaller adipocytes or lower levels of lipid content than the control group. The starvation followed by feeding experiment caused marked body weight loss in the control group by consumption of muscle protein and lipids in IPF. Fortifications of EPA and DHA induced less mobilization of muscle protein and IPF lipids as energy. Liver function and resistance to air-dipping were improved by both EPA and DHA fortifications. The present results implied conversion of EPA to DHA in the fish with regard to parameters, such as lipid metabolism and physiological vitality.

Genetic divergence and population structure of black sea bream Acanthopagrus schlegeli inferred from microsatellite analysis

Four highly variable microsatellite loci, Acs1*, Acs3*, Acs4* and Acs9*, were isolated and then used to investigate genetic diversity and population structure in black sea bream, Acanthopagrus schlegeli, collected from wild populations of six locations (western Japan and southern Korea), and hatchery stock and post-stock populations from Hiroshima Bay. When allelic segregation of each microsatellite locus was examined using the single spawning pair and their progeny, all loci were well fitted to the Mendelian manner of inheritance. The genetic variations at these loci in the eight populations revealed high levels of variability. In the wild populations the mean number of alleles per locus was 10.8-13.5, and the mean observed hetrozygosity was 0.755-0.828. In contrast, these values in hatchery stock population were 10.0 and 0.776, respectively. Genetic distance indicates the existence of geographic divergence between western Japan and south Korea, and little genetic differentiation among populations in western Japan.

Effect of dietary vitamins C and E fortification on lipid metabolism in red sea bream Pagrus major and black sea bream Acanthopagrus schlegeli

: To determine the effect of vitamins C and E on lipid metabolism and interactions between them, L-ascorbyl-2-monophosphate-Mg (APM) and α-tocopherol acetate (TA) were fortified to a commercially based diet and fed to 0-year red sea bream Pagrus major and 1-year black sea bream Acanthopagrus schlegeli. Fortification of APM and TA, respectively, increased ascorbate (ASC) and α-tocopherol (α-Toc) contents in the organs. In addition, APM fortification increased α-Toc accumulation in both fishes, although TA fortification did not significantly affect the ASC content. Fortification of APM caused a depression in lipid accumulation in the intraperitoneal fat body and liver in red sea bream. Furthermore, a decrease in the serum thiobarbituric acid value in black sea bream and a reduction of the adipocyte diameter in the APM-fortified groups of both fishes were observed. However, fortification of TA did not affect these parameters as significantly as did fortification of APM. The shortest recovery time to air-dipping was found in the APM + TA-fortified group, followed by the APM-fortified group in red sea bream. The results implied an effect of vitamin C on lipid metabolism, and acceleration of vitamin E absorption and/or suppression of vitamin E degradation.

Effect of dietary ascorbate fortification on lipolysis activity of juvenile black sea bream Acanthopagrus schlegeli

: Hatchery-reared black sea bream Acanthopagrus schlegeli juveniles averaging 0.05 g in body weight were fed either a control diet (commercial diet) or an experimental diet in which the commercial diet was fortified with 50 mg l-ascorbyl 2-monophosphate Mg (APM)/100 g diet for 50 days. Calcium ascorbate supplemented as a vitamin mixture in the control diet was completely destroyed during storage. Fortification with APM significantly increased the ascorbic acid levels in the muscle, liver, brain and eye. Although APM fortification did not influence growth, survival or fish body composition, adipocyte diameter in the intraperitoneal fat body (IPF) was significantly reduced. After the feeding experiment, the fish were kept for 39 days without feeding. Fortification with APM resulted in high survival, high muscle protein retention and low body weight loss. The results suggested the necessity of fortification with an adequate amount of ascorbate in the diet. While fatty acid compositions of the IPF, muscle and liver were not significantly influenced by APM fortification, characteristic changes in the fatty acid profile were found after starvation. Vitamin C and highly unsaturated fatty acids seemed crossly interactive in relation to lipolysis activity in black sea bream juveniles.

Susceptibility of Various Marine Fish Species to Viral Hemorrhagic Septicemia Virus Isolated from Japanese Flounder

Susceptibilities of six species of marine fish to a flounder isolate KRRV-9601 (a European genotype) of VHSV were examined by intraperitoneal injection. Mortalities were induced in Japanese flounder Paralichthys olivaceus (100%), black sea bream Acanthopagrus schlegeli (90%), red spotted grouper Epinephelus akaara (70%) and rockfish Sebastes schlegeli (10%), but not in marbled sole Pleuronectes yokohamae and red sea bream Pagrus major. VHSV was recovered from dead and moribund fish and the surviving red spotted grouper at 60th day after the virus injection. The neutralizing antibody against VHSV was detected in the sera of surviving rockfish, but not in other surviving fishes. Histopathological features in the affected fish for each species were generally similar to each other, although the severity of hemorrhage varied among fish species.