A pathological study was performed on wild spiny lobsters with cardiac disease found in captured and stored groups of such lobsters in the Minami-Izu region of Shizuoka Prefecture. The present study evaluated the microbiology and histopathology of 39 lobsters including animated and weakened individuals.
Histopathological examination revealed that all the lobsters examined had cardiac lesions showing degeneration and necrosis of muscle fibers with haemocyte infiltration. No microorganisms were detected in the cardiac lesions on which histological and cultivating examinations were performed. From the results, it was considered that a disease characterized by degeneration and necrosis of cardiac muscles resulting in myocarditis would prevail in a cluster of free-living wild spiny lobsters.

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Ammonia oxidation activities were compared across 5 kinds of plastic filter media and one type of earthenware ball filter medium in submerged biological filters.
With the progress of ammonia oxidation, the pH and alkalinity of the recirculating seawater decreased. Ammonia oxidation was inhibited when the pH and alkalinity reached 6.0 and 0.5 meq./l, respectively. A significant linear relationship was observed between the amount of biologically oxidized ammonia and the decrease in alkalinity. Among well-conditioned biological filters with 6 types of filter media, the filters with a net or fibriform filter media showed higher ammonia oxidation. There was no significant linear relationship between the ammonia oxidation rate in the filter and the surface area of the filter medium. Daily loading of an organic substance for 92 days reduced the ammonia oxidation rates in the filters by 28 to 52%. The maximum ammonia oxidation rate (0.55g-N/m²/day) after loading the organic substance was obtained in the filter with a net filter medium.

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Inlet and outlet spawners of rainbow trout Oncorhynchus mykiss were tagged in Lake Huechulafquen in the 1990 spawning season. In the fishing season, 8.3% and 10.0% of the spent trout tagged from the inlet and oulet, respectively, were recaptured in the lake by sport anglers. This demonstrated that outlet spent adults also migrated in the lake as well as inlet spawners. The monthly distribution of the tag-recovery locations showed that the spent adults dispersed throughout the lake one month after the spawning season, and they started migrating toward their spawning streams three months before the next spawning. A few tags from the inlet were also recovered 25km downstream from the lake. In the 1991 spawning season, 8.6% and 10.0% repeat homing to the inlet and outlet, respectively, were observed. A few stray homers were observed, but most repeat spawners returned to their home spawning streams.

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The time course change of 13, 14-dihydro-15-keto-prostaglandin F_2α levels in holding waters of the cobitid loach, Misgurnus anguillicaudatus was studied during the ovulatory process initiated by an intraperitoneal injection of human chorionic gonadotropin (hCG). The control fish were injected with Ringer's solution. The 13, 14-dihydro-metabolite contents in the holding water were analyzed by high pressure liquid chromatography at 4 hour-intervals for 16 hours after the injections. In the non-ovulated status, levels of the 13, 14-dihydro-metabolite were only barely detectable in the holding water even in the hCG-injected females. When the hCG-treated females ovulated, the release of the 13, 14-dihydro-metabolite reached maximum levels ranging from 6.71 to 14.38 μg/fish, tending to decrease thereafter. Levels of the 13, 14-dihydro-metabolite were barely detectable in the holding water of the control fish through the experiment. Levels of prostaglandin F_2α were also monitored and although individual release rates varied, a similar trend in release pattern was observed. Thus, the present results clearly show that in synchrony with ovulation, 13, 14-dihydro-15-keto-prostaglandin F_2α which would be one of the postovulatory sex pheromones, was discharged into the environmental water by female loach.

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The site of vitellogenin synthesis in the freshwater prawn Macrobrachium nipponense was examined immunocytochemically using antibodies raised against lipovitellin purified from mature M. nipponense ovaries. The molecular weight of purified lipovitellin was estimated to be 350 kDa by gel filtration. The antiserum cross-reacted with vitellogenin in the hemolymph of the mature female prawn, and could therefore be used to demonstrate the possible site of vitellogenin synthesis immunocytochemically employing the peroxidase-anti-peroxidase (PAP) reaction. Hepatopancreas, sub-epidermal tissue, muscle, and ovary were fixed with periodate-lysine paraformaldehyde solution after which paraffin sections were made. In mature females, oocytes at the yolk globule stage, the hepatopancreas and the sub-epidermal tissue of the lateral somites showed positive PAP reactions. However, the sub-epidermal tissue of the ventral somites, follicular cells of the ovary and muscles did not. No positive reaction was observed in males and immature females. These results suggest that vitellogenin is synthesized in the hepatopancreas and at the sub-epidermal tissue in females at the exogenous vitellogenesis stage.

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We have studied the effect of water temperature on brain-pituitary-gonadal axis in male honmoroko, with particular focus on gonadotropin-releasing hormone (GnRH) contents in the brain and pituitary. Mature fish in the spawning season were exposed to long photoperiod (15L9D) combined with high (30°C) or low (15°C) water temperature for a period of 30 days. Salmon GnRH (sGnRH) contents in the brain and pituitary increased and maintained high levels at 15°C coinciding with the high levels of plasma testosterone and an increase in GSI. No marked changes in sGnRH content were observed at 30°C while GSI values and plasma testosterone levels decreased. These results indicate that the activities of GnRH neurons were associated with the gonadal activities. They may not, however, be involved in gonadal regression caused by high water temperature.

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Immunoglobulin in the eggs of carp was analyzed by SDS-polyacrylamide gel electrophoresis and Western blotting, using affinity purified antibodies against carp immunoglobulin M (IgM). Carp eggs were confirmed to contain IgM. However, gel filtration patterns revealed that egg IgM was of notably lower molecular weight than plasma IgM. Therefore, the egg IgM was considered not to be a tetramer, although the exact molecular weight could not be determined. Moreover the molecular weight of the heavy chain of egg IgM (68 kDa) was smaller than that of plasma IgM (75 kDa). Differences in IgM molecular weight may be due in part to the differences in the polypeptide composition of the heavy chain. The presence of egg type IgM was clearly demonstrated in the mature ovary, and was also faintly detected in immature ovaries possessing early yolk globule stage oocytes. These observations suggest that the accumulation of IgM occurs in conjunction with the accumulation of vitellogenin in the oocytes.

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The change of rigidity which accompanies the sol-gel transition of fish paste was analyzed using a kinetic approach. The enthalpy change, ΔH^≠, and the entropy change, ΔS^≠ of activation were 23.1 kJmol^-1 and -67Jmol^-1 K^-1, respectively. On the other hand, the enthalpy change, ΔH of the transition reaction was estimated to be 8.5 J (g of protein)^-1 using differential scanning calorimetry, which converts to 25.6 k Jmol^-1 based on the protein content. If the mol of ΔH is considered to be due to crosslinking in the gel, then the coincidence of ΔH^≠ and ΔH could be reasonable.

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A 42-day feeding trial was conducted with young yellowtails (163.6g) for the purpose of improving undesirable hematological characteristics caused by feeding a soy protein concentrate (SPC) diet (moist type pellet). Zero, 50, 100, 250, 500, and 1000mg of iron proteinate (Fe-P; 10-13% Fe) were respectively added per each 100g of the SPC diet, containing 20g SPC, 45g brown fish meal, and 166mg Fe-P. A reference diet of hundred grams contained 65g of brown fish meal and 166mg Fe-P and used as a control.
Although no meaningful effects of dietary Fe-P supplements on growth performances and Fe accumulation in the liver and spleen were found in the dietary groups, significantly lower red blood corpuscle count, hematocrit value, hemoglobin concentration, and serum Fe saturation rates were detected in fish fed a control diet without the Fe-P supplementation. There were no marked differences in desirable hematological characteristics and serum Fe saturation rates between groups fed diets with above 250mg of supplemental Fe-P and the reference diet.
These results suggest that undesirable hematological characteristics in yellowtails fed the SPC diet could be improved by preparing dietary Fe-P content, above 400mg per 100g of SPC diet.

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The component fatty acids of lipids from four species of flatfish (flathead flounder Hippoglossoides dubius, scalyeye plaice Acanthopsetta nadeshnyi, pointhead flounder Cleisthenes pinetorum herzensteini, and Korean flounder Glyptocephalus stelleri) caught in the Sea of Japan and Funka Bay, Hokkaido were examined using open-tubular gas-liquid chromatography.
About sixty fatty acids were observed. Tetracosahexaenoic acid was present as an unusual fatty acid, and the structure was determined as all-cis-6, 9, 12, 15, 18, 21-tetracosahexaenoic acid (24:6n-3) by spectrometric analyses.
In the flatfish examined, the lipids of flathead flounder captured in the Sea of Japan were found to be particularly rich in 24:6n-3 (6-9% of total fatty acids in the flesh, 3% in the liver, and 6% in the viscera). This acid was abundantly found in the triacylglycerols rather than the phospholipids.
The results of this study suggest that 24:6n-3 was primarily incorporated into flatfish tissues through their diets.

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Distribution of all visceral (muscular, liver, heart, and gonads) lipids, phospholipids, and fatty acid compositions of phospholipid in migratory, coastal and reef dwelling white-flesh fish was analyzed. Seventeen midwater to surface dwelling fish, eight of which were migratory species and the remaining nine coastal and reef fishes, sixteen demersal fish and seven squids caught around Japan and northern Pacific were used for analysis.
Total lipid content in the muscle of the fish examined were less than 10% except for blackthroat seaperch and channel rockfish. Liver lipid showed wide variations among fish species, and lipid contents were relatively higher in demersal fish than migratory fish.
(n-3) Polyunsaturated fatty acids (C20:5 and C22:6) constituted the predominant component exceeding 50% of the total fatty acids in the phospholipids in all fish species examined. C22:6n-3 was the most abundant in muscle phospholipid of squids and salmonids.

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The effects of p-chloromercuribenzoic acid (PCMB), one of the inhibitors of transglutaminase (TGase), on the elasticity of suwari gel from Alaska pollack frozen surimi paste were investigated in order to clarify the role of TGase in the setting of the paste. The amount of monodansylcadaverine incorporated to muscular proteins in the paste became zero when more than 0.5% PCMB was added to the paste. The breaking force and breaking strain of the suwari gel decreased to about 65%, the amount of its expressible water increased slightly, and its viscosity decreased with the addition of 0.5% PCMB. Furthermore, in the sodium dodecylsulfate-polyacryl amide gel electrophoresis pattern for the paste, the strengthening of crosslinked myosin heavy chain band and concomitant weakening of the myosin heavy chain band during the setting were suppressed by the addition of PCMB. From the results, it is presumed that the setting still occurs even if TGase does not act at all, although the elasticity of the resulting gel is somewhat weak.

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The effects of N-ethylmaleimide (NEM), a powerful SH reagent, and N-ethylsuccinimide (NES), not an SH reagent but an analogue of the former, on the physico-chemical properties of suwari gel from Alaska pollack surimi were investigated in order to clarify the effect of transglutaminase (TGase) on the setting of surimi paste. TGase was completely inactivated by the addition of more than 0.075% NEM to the paste, but the suwari gel was formed at 30°C even from such a paste. By the addition of this amount of NEM, the breaking force and SH content of muscle proteins decreased to about 65 and 60%, respectively, and the polymerization of myosin heavy chain (MHC) to crosslinked myosin heavy chain (CMHC) was suppressed. On the contrary, the addition of the same amount of NES did not influence the breaking force, SH content, or polymerization of MHC. These findings suggest that the gelation of the paste and the polymerization of MHC occur during setting even in the absence of TGase and that the combined contribution of the formation of CMHC and that of the SS bond to the breaking force of the suwari gel is about 35%.

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Nidamental glands of the squid Illex argentinus contain mucosubstance which forms jelly-like egg masses after spawning. In this study, a sulfated glycoprotein was prepared from the mucosubstance by solubilization with mild alkaline treatment (0.4 N NaOH, 4°C, 4h), followed by precipitation with ethanol (50%), and was characterized with respect to its chemical composition and macromolecular properties. The glycoprotein accounted for about 35% of the mucosubstance by weight and comprised 22.6% protein, 73.0% carbohydrate, and 4.4% ester sulfate. A large part of the glycoprotein was isolated after actinase digestion as a long, asymmetric, protease-resistant fragment having a molecular mass of about 1400 kDa. The protein backbone of the fragment accounted for 18.7% by weight and was composed virtually of Thr, Pro, and Ile in the molar ratio of 2:1:1. All Thr residues, comprising 45% of the total amino acids, were considered to link to GalNAc residues of oligosaccharides consisting mainly of Gal, Fuc, GalNAc, and an unidentified amino sugar. These combined results strongly suggest that the sulfated glycoprotein is heavily O-glycosylated and defined as a mucin. The Thr-GalNAc linkages, however, were resistant to β-elimination (0.5 N NaOH, 25°C, 24h). The mucin molecules were assumed to be mainly responsible for the viscous and gel-forming properties of the nidamental gland mucosubstance.

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20-hydroxy-4, 8, 13, 17-tetramethyl-4, 8, 12, 16-eicosatetraenoic acid was isolated from a highly unpalatable brown alga Turbinaria ornata as a feeding deterrent for another herbivorous gastropod Omphalius pfeifferi. The compound was confirmed to be a feeding inhibitor for the herbivorous green snail Turbo marumoratus found in the subtropical sea, as well.

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Feeding experiments were conducted at 20°C with diets containing 0, 12, 25, 37, and 50% of feather meal to examine the potential of feather meal as a substitute for fish meal in the diet of Japanese flounder. Juvenile fish, about 3g in initial body weight, were fed on each diet to satiation twice a day for 6 days a week for 8 weeks.
The weight gain of fish fed on the diets containing 12 and 25% of feather meal did not differ from that of fish fed on the control diet containing 80% of white fish meal, however, fish fed on the 37 and 50% feather meal diets gained less weight. The feed conversion efficiency and protein efficiency ratio of fish fed on the 12% feather meal diet were almost the same as in the control group, however, these efficiencies decreased as the proportion of feather meal in the diet increased from 25, 37 to 50%. Supplements of crystalline amino acids to the feather meal diet improved its nutritive value slightly. There was little difference in the proximate composition of the whole body together with the hematological and hematochemical parameters among the dietary groups tested.
The present study showed that 12 to 25% of feather meal is an appropriate substitute for fish meal in the diet of juvenile Japanese flounder.

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Changes in some chemical components of Alexandrium catenella (Whedon et Kofoid) Balech and Scrippsiella trochoidea (Stein) Loeblich III (Dinophyceae) during their growth cycles were examined. Results clearly showed that the cellular content of carbon and nitrogen gradually increased during lag and early exponential phases of growth. Thereafter, they decreased and became nearly constant from mid exponential phase to the end of the experiment. Changes in cellular phosphorus and cellular ATP content of these dinoflagellates showed the same general patterns as those of carbon and nitrogen. It was observed that after cellular content of ATP remarkably increased and reached a maximum level, cell number increased rapidly. Glutamic acid, glycine, and alanine were the predominant components of amino acids in both dinoflagellates. The mean values of nitrogen content in total amino acids in A. catenella and S. trochoidea throughout the growth cycle were higher than 40 and 60% of total cellular nitrogen, respectively. Since the changes in pattern of cellular amino acid content followed the same pattern as that of cellular nitrogen, it could be concluded that cells accumulated nitrogen compounds mainly in the form of amino acids. Relative abundance of arginine in S. trochoidea was nearly stable throughout the growth cycle, whereas, the relative abundance of arginine in A. catenella dramatically increased from the beginning of the stationary phase to the end of the experimment. It could be suggested that changes in cellular amino acid composition played an important role in the growth processes of this marine dinoflagellate.

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Carotenoid content and composition of commercial black tiger prawns Penaeus monodon exhibiting different body color were determined. A consistency was observed between the depth of body color of prawns and the carotenoid content of 2.3-33.1mg/100g in their exoskeleton. Astaxanthin was the major component in all the prawns, amounting to 86-98% of total carotenoids. Three forms of astaxanthin, namely diester, monoester, and free ones, were found. Cultured black tiger prawns accumulated preferentially astaxanthin monoester in their exoskeleton, when the total carotenoid content exceeded about 8mg/100g. Thus the external coloring in carotenoid-rich prawns may be due to interaction between the color of astaxanthin esters and that of carotenoprotein.

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The effects of storage temperature on postmortem changes in the contents of ATP and its related compounds were investigated in the adductor muscle, mantle, gill, and body trunk of the oyster Crassostrea gigas in relation to freshness. The K, K', and A. E. C. values taken for freshness indices were calculated from the contents of ATP and its related compounds.
In the adductor muscle, a marked decrease in ATP was observed together with the accumulation of AMP and IMP. The rates of ATP degradation during storage were on the order of 0>10>5°C storage. AdR was detectable only in the adductor muscle. In the other three tissues the level of AMP increased along with a slow decrease in the ATP level. The accumulation of IMP was not so marked as in the adductor muscle. The rates of ATP degradation during storage were on the order of 10>5>0°C storage in the body trunk, and 10>5=0°C storage in the mantle and gill. Although the K value remained low during the acceptable stage in all four tissues, the K' value in the adductor muscle and the A. E. C. value in the other three tissues changed rapidly and continuously from the beginning of storage at all storage temperatures examined (0, 5, 10, 15, and 25°C). The change rates of K' and A. E. C. values were higher at higher storage temperatures. The K' value obtained on the adductor muscle and A. E. C. values obtained on the other three tissues appeared to be useful as freshness indices for oysters.

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Free carnitine, acid-soluble total carnitine, and long-chain acylcarnitines in fish tissues were determined by high-performance liquid chromatography (HPLC) equipped with a Cosmosil 5C₈ or 5C₁₈-AR column. Free and acid-soluble total carnitine was extracted from such tissues as ordinary muscle, liver, kidney, heart tissue, and plasma of rainbow trout with 6% perchloric acid containing 20mM 2-mercaptoethanol. Acetylcarnitine and short-chain acylcarnitines (C₃-C₁₀) in the extract were hydrolyzed to free carnitine by alkaline to analyze acid-soluble total carnitine. Long-chain acylcarnitines (C₁₂<) in the tissues were extracted from the precipitated residue of the free and acid-soluble total carnitine extract and hydrolyzed to free carnitine by alkaline. Coenzyme A (CoASH) was formed stoichiometrically from carnitine and acetylcoenzyme A by carnitine acetyltransferase. The formed CoASH was determined by HPLC. CoASH was successfully isolated from other compounds by each column. The standard curve for carnitine vs the peak area of the CoASH was clearly in proportion from 0.1 μM to 100 μM. Recovery of free carnitine added to the homogenate of ordinary muscle tissue from rainbow trout was 98.9±4.7% (1 μmol/g added) and 99.8±6.2% (0.05 μmol/g added).

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Fingerling rainbow trout were fed experimental diets having different protein levels for 10 days to determine the sulfur amino acid metabolism involving taurine biosynthesis in fish. Either egg white albumin or casein was employed as a sole dietary protein source. Maximum body weight gain was obtained at about 40% crude protein level in both dietary groups. However, further increase in dietary protein did not improve the growth rate of the fish. Specific activity of the hepatic cysteine dioxygenase (CDO) [EC 1. 12. 11. 20] in the fish fed the egg white albumin diets increased exponentially as dietary protein level increased, whereas no clear effect on enzyme activity was noted in the casein dietary group. Judging from the difference in the sulfur amino acid contents between egg white albumin and casein, the hepatic CDO activity of rainbow trout seems to be closely related to dietary sulfur amino acid levels rather than protein levels. The accumulation of cystathionine in the fish fed a high egg white albumin diet suggests that the capacity of the transsulfuration pathway in rainbow trout is limited.

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