This paper examines the differences in the features of sounds produced by yellowtails and amberjacks of different size during swimming and bait-eating activities in a net pen. Recorded underwater sounds were analyzed by the one-third octave band method.
The overall underwater ambient noise levels in the Tarumizu and Furue waters were 108.6 dB and 106.4 dB, respectively. The sound levels of yellowtail were 102.8-116.0 dB during swimming and 113.4-124.8 dB during bait-eating. The sound levels of amberjack were 109.4-110.2 dB in the swimming activity and 115.3-121.9 dB in the bait-eating activity. The sound level in the bait-eating activity was higher than that in the swimming.
Graphs of one-third octave band analysis of the underwater sounds in the two activities could be classified in four specific patterns. The curve patterns indicated some relationship with sizes of the fish. Frequencies at the minimum sound level in a concave part of the pattern and at the maximum level in the swimming and bait-eating activities were higher for the small-sized fish and vice versa. Both frequencies of the amberjack sounds were lower than those of the yellowtail sounds in the respective sizes and activities.

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The influence of stocking density and dietary factors on branchial, urinary and epidermal N losses was assessed in goldfish. Water, skin mucus and urine samples were collected for analyses of ammonia, urea and free amino acids (FAA). Results indicated that postprandial ammonia (NH₄-N) excretion rates per unit body weight were significantly affected by stocking density. Stocking density also had a significant effect on urea excretion and FAA concentrations in the branchial plus urinary excreta. No correlation was detected between dietary amino acid pattern and the FAA profiles in the mucus. The concentration of taurine was high (>40 μmole/g dry matter) in mucus. In the urine of unfed fish, total amino acid levels (>2 mmole/ι) were ten-fold higher than in fed fish. The concentration of taurine in the urine of unfed fish represented > 95% of total FAA. Owing to the high concentrations of taurine in skin mucus and urine and the variations found, the effects of waterborne taurine on swimming orientation of goldfish were tested and compared to those of alanine, at three concentrations (10^-6, 10^-5, 10^-4M). Unlike alanine, highest attraction response was observed for taurine even at the lowest concentration tested.

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This study examined the behavioral characteristics of juvenile Japanese surf clam Pseudocardium sachalinensis in response to sand erosion and deposition under laboratory conditions, then estimated the fluid conditions critical to wash the clams out of the sand. The juveniles started burrowing downward into sand when their burying depth decreased to less than 1.5 times the shell length due to erosion, and moving upward when the depth increased to more than 2.5 times the shell length due to deposition of sand. Burrowing and climbing actions of the juvenile continued until the depth reached 1.7-2.1 times the shell length once again. The burrowing and climbing speeds were about 1.8 times higher than the speed of erosion or deposition of sand. It was concluded that the juveniles would maintain their position actively in order to avoid being washed out or buried too deeply by adapting their behavior to the dynamic conditions of sand movement. The juveniles were washed out of the sand when the erosion speed exceeded 3.5 mm/min, and such erosion occurred when oscillatory water flow speeds over a sandy bottom with median particle diameter of 0.3 mm exceeded more than 45 and 55 cm/s at periods of 4 s and 8 s, respectively.

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In order to determine the stock structure of the cresthead flounder Pleuronectes schrenki around Hokkaido, stocks were separated by morphometric characters and tagging experiments. The twenty morphometric characters of cresthead flounder (male: 543, female: 464) collected from ten locations between October 1993 and November 1994 were measured. Measurements were standardized to all male and female mean body length. When canonical discriminant analysis was applied to eleven morphometric characters which were selected by stepwise discriminant analysis, the cresthead flounder stocks were classified into two groups, 1 i.e. the sea group and the lake group.
Tagged cresthead flounders of 1, 011 individuals were released from Abashiri Bay and the Sea of Okhotsk off Saroma Lake between 1993 and 1995. A total of 40 recaptures of individuals released off Saroma Lake were caught in the tagging area between April 1993 and September 1995. A total of 43 recaptures of those released in Abashiri Bay were caught in the northwestward region from Abashiri Bay and the Japan Sea coast of Hokkaido between April 1995 and December 1996. Tag recaptures were compared with the results of the canonical discriminant analysis.

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Age and growth of the anglerfish Lophiomus setigerus were examined using vertebral centra from specimens collected in the East China Sea during the period from March 1991 to February 1996. Monthly changes in the frequency of appearance of a translucent band on the outer margin of the centrum and in the marginal increments indicated that ring marks form once a year, primarily from November through December. The body proportional hypothesis method was used to estimate the back-calculated total lengths. Male specimens possessed 1-8 ring marks while females had 1-11 ring marks. Using the back-calculated total lengths, growth of male anglerfish was expressed as TL_t=379.2 (1-e^{-0.193(t-0.300)}) (t_??_8) and TL_t=528.4 (1-e^{-0.140(t-0.264)}) (t_??_11) for females. Our results suggested that females grow faster and live longer than males.

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The validity of age determination of the Japanese charr Salvelinus leucomaenis using scale readings was examined by the mark and recapture method in a Japanese mountain stream from 1986 to 1989. When recaptured within a year, all of the 3 (1 growth and 2 resting) scale zone fish were found to still have 3 zones on their scales. One year after marking, they had 4 (2 growth and 2 resting) or 5 (3 growth and 2 resting) zones on their scales and after 2 years, they still had 4 or 5 zones. Fish with 1 resting zone, i.e., 1 annulus, were regarded as age 1⁺ and fish with 2 annuli were regarded as age 2⁺. Consequently, age determination of the Japanese charr using scales might be reliable to 1⁺ age but doubtful for 2⁺ and older.

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Full-length cDNA for a 71 kDa constitutively expressed heat-shock-cognate protein (HSC71), a member of the HSP70 family, was isolated from a Japanese flounder embryo cDNA library. It has a single ORF of 1950bp that encodes a protein of 71. 2 kDa. Japanese flounder HSC71 contains a EEVD (Glu-Glu-Val-Asp) peptide motif at the C-terminal end which is a common feature of cytosolic HSC proteins in the HSP70 family. Japanese flounder HSC71 is 96.0%, 93.9%, 93.5%, and 93.4% identical in primary structure to rainbow trout HSC71, bovine HSC71, rat HSC71, and human HSC71, respectively. These results suggest that the HSC71 amino acid sequence has been highly conserved among vertebrates. Northern blot analysis showed that HSC71 mRNA was expressed constitutively in the Japanese flounder cells in early passage regardless of heat shock treatment.

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Growth and maturation of Sargassum macrocarpum C. Agardh were studied in Fukawa Bay facing to the Sea of Japan, Yamaguchi Prefecture, at the depth of 8 m, from June 1993 to July 1994. New main branches on perennial stem had been apparently observed in June, and grew increasingly through July to March in the next year, then reached the maximum length and dry weight of the branches in March and May, respectively. Thalli with three or more growth rings in holdfast matured and formed receptacles through March to June. The release of oospores and embryos was observed only in June. The number of main branches was almost the same among adult thalli and did not show variation throughout the year. The minimum and maximum standing crops were 257.6gm^-2 in August 1993 and 1155.7gm^-2 in May 1994, respectively.

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Introns may accumulate much higher genetic variation than exons. Universal primers were designed from the conservative nucleotide sequences of exons to amplify the flanking intron. Length variations in the S7 ribosomal protein (RP) gene intron 1 and mitochondrial creatine kinase (CK) gene intron 6 of the swordfish Xiphias gladius were found. Single or two banded fragment patterns in each individual were observed by agarose gel electrophoresis. Nucleotide sequence analysis revealed that highly polymorphic fragment patterns observed in the RP gene intron 1 were due to different numbers of a TG repeat (microsatellite). The length of the CK gene intron 6 was dimorphic, in which presence or absence of a 24 bp block was responsible for longer or shorter introns. Additional minor nucleotide insertion/deletions were observed independent of the RP microsatellite and the CK 24 bp block regions. The results of this investigation indicate that introns may be good sources of intraspecific genetic variation for population genetic studies and that the same set of primers can be used to amplify homologous intron regions even among distant species. Further, the conserved exon primed PCR strategy may be useful to prevent appearance of priming site polymorphism (null allele).

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Using the stable isotope technique and assuming a δ¹⁵N enrichment of 3-4‰ per trophic level, Japanese anchovy Engraulisjaponicus were found to increase in trophic position by a half of one trophic level as they grew from 14mm to 30mm in standard length (SL) and by a further third to one half from 30mm to 70-80mm SL, ranging over a total δ¹⁵N of 3.5‰ and δ¹³C of 1.6‰ from recruitment to the fisheries ground to adulthood, during October 1993 in Sagami Bay, Central Japan. Based on the δ¹⁵N shift, a similar increase in trophic position with growth was observed in January, March, August and September. Light N, derived from river runoff during the rainy season in August, is thought to have been rapidly incorporated into lower levels of the food chain since a sudden drop in δ¹⁵N was observed in anchovy larvae of two size ranges, 19-21mm and 29-31mm SL. Japanese sardine Sardinops melanosticta were found to increase in trophic position more rapidly than Japanese anchovy in the larval life history stage. The isotopic signatures of the larger fish taken from the shirasu (anchovy larvae) fishing nets in August 1994 were suggestive of heavy reliance on anchovy larvae as a food source. The stable isotope technique was found to be effective in estimating ontogenetic change in trophic position in the Japanese anchovy.

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Reconstituted myoglobin of bonito showed a single endothermic peak with higher transition temperature, reflecting a two-state process of structural unfolding. Such a denaturation profile was found to be different from the multi-state process of its holomyoglobin. On the other hand, the denaturation profiles of both holo- and reconstituted myoglobins of sperm whale showed a similar two-state process. The Soret absorbance of both holo- and reconstituted myoglobins of bonito gave rise to similar temperature dependence, but decreased to with a larger extent than that of sperm whale holomyoglobin. The heme pocket environments of both holo- and reconstituted myoglobins of bonito are therefore recognized to be more labile than that of sperm whale holomyoglobin. Also, conformational stability of the tertiary fold of both holo- and reconstituted myoglobins of bonito observed from the temperature dependence of tryptophan fluorescence intensity was found to be considerably lower than that of sperm whale holomyoglobin. The differences in the thermal perturbation profiles of the globin structure between bonito and sperm whale myoglobins could explain the low thermal stability of fish myoglobins.

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The combination effects of perilla and of either Yuzu peel or young leaf of Japanese pepper on the masking of odor were studied in boiled sardines by sensory evaluation, gas chromatography and gas chromatography-mass spectrometry.
The combination of Japanese pepper leaf-perilla (1:1) had the highest suppressing effect, followed by perilla and Yuzu-perilla (1:1) respectively. Eight fishy volatiles identified in boiled sardines without spice were also detected in the boiled sardine to which the above-mentioned spices were separately added, and the composition of the fishy volatiles in the boiled sardine with spices was the same as that of the boiled sardine without spice. On the other hand, when the aroma components identified in each spice were compared, perillaldehyde, 3 components (α-pinene, citronellal and 2-undecanone) and γ-terpinene were the main or characteristic components of perilla, young leaf of Japanese pepper and Yuzu, respectively. In additional tests using authentics, it was found that perillaldehyde greatly contributed to the masking of the odor of boiled sardines when perilla was added independently. The higher suppression of young leaf of Japanese pepper-perilla was attributed to the combination of citronellal and perillaldehyde, and the combination effect of γ-terpinene-perillaldehyde was a cause of the lower suppression of Yuzu-perilla.

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The effect of the administration of various steroid hormones on the breakdown of myofibrillar proteins and collagen was examined in association with some protease activities to specify the protease implicated in the breakdown of these proteins. The administration of estradiol-17β remarkably increased the content of free 3-methylhistidine (3-MeHis), a specific constituent of myofibrillar proteins, in female fish, but decreased it in male fish. Administration of an androgen, testosterone, increased the free 3-MeHis contents both in male and female fish. Cathepsin L activity assayed as a hydrolyzing activity on benzyloxycarbonyl-Phe-Arg-7-(4-methyl)coumaryl-amide was correlated with the change in the free 3-MeHis content induced by hormone administration in the case of female fish. Although not significantly, testosterone showed increasing effects on the content of free hydroxyproline, a specific constituent of collagen, in male and female fish, respectively. The result suggested that these hormones promoted the breakdown of collagen. However, the induction of a specific protease correlated with the collagen breakdown was not detected in the present study.

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We isolated and characterized wax esters from some species of myctophid fish, which are rich in wax esters, i.e., Stenobrachius leucopsarus, Stenobrachius nannochir and Lampanyctus regalis, through TLC, HPLC, GC and mass spectrometry. Wax esters with carbon chain lengths ranging from 30 to 44 were the major constituents among the above three species, always accounting for more than 90% of the total wax esters. The predominant molecules in the wax esters were 34:1 (16:0-18:1, alkoxyacyl) in S. leucopsarus, 34:1 (16:0-18:1), 40:2 (22:1-18:1) and 38:2 (20:1-18:1) in S. nannochir, and 40:2 (22:1-18:1), 42:2 (22:1-20:1, 20:1-22:1) in L. regalis, respectively. The molecular patterns in the above species coincided well with the random prediction.

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In birnaviruses, the viral capsid proteins VP2 and VPS, and the protease NS are translated as a polyprotein. In this study, the complete polyprotein gene was sequenced and the deduced amino acid sequence was analyzed for the marine birnavirus (MABV) strain Y-6. Comparison of VP2 region with infectious pancreatic necrosis virus (IPNV) strains revealed that the central part of VP2 contained a variable region whereas the N- and C-terminal parts appeared conserved among the MABV and IPNV strains. In the VPS gene, hydrophilic residues were concentrated around the C-terminal region, suggesting that this region was exposed to the outside of the molecule. The N-terminal of NS appeared variable, however, the C-terminal appeared conserved. This result was similar to previous reports of other IPNV strains. The VPS open reading frame (ORF) was found in 5'-end of the plyprotein ORF. Considerable variation was found in this region compared to other proteins. The amino acid composition of VPS indicated a high, rich concentration of arginine suggesting that VP5 is a basic protein that may function in RNA binding. This is the first report of the complete analysis of the MABV polyprotein gene.

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The heat-induced gelling properties of carp actomyosin sol containing 90 mg protein per g of sol at 0.5 M NaCl and pH 7.0 were investigated by dynamic rheological measurements, breaking strength measurements, and SDS-PAGE analyses. The results indicated that the sol was characterized by poor gel forming ability caused by the inherent properties of carp actomyosin, no setting response, and relatively strong non-proteolytic gel weakening (modori) around 53°C. Furthermore, at slow heating rate, it was found that myosin heavy chain was cleaved by a myofibril-bound proteinase(s).
The addition of microbial transglutaminase could induce setting response to actomyosin sol; the extent of the response and resulting gel strength increased markedly with an increase in the transglutaminase activity level. The non-proteolytic modori was not reduced by the addition of transglutaminase.

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Various gelatinolytic activities in phosphate-buffered saline extracts of yellowtail skin, muscle, gill, heart, liver, spleen, stomach, pyloric caeca, intestine, and caudal fin were revealed by gelatin zymographic analysis. Most active bands were demonstrated at larger than 50 kDa in all tissues tested, but the additional active bands smaller than 50 kDa were also detected in the pyloric caeca. An active band at 80 kDa sensitive to leupeptin (acetyl-L-leucyl-L-leucyl-L-argininal) was commonly detected in all tissues. Active bands sensitive to leupeptin at 140 kDa and 80-100 kDa in the gill and at 110 kDa in the pyloric caeca and at 120 kDa in the intestine were distributed specifically in these tissues. Intensive active bands between 25-80 kDa in the pyloric caeca were also sensitive to leupeptin. However, these active bands sensitive to leupeptin were not affected by E-64 ([L-3-trans-carboxyoxirane-2-carbonyl]-L-leucyl-agmatin) except for those at 110 kDa in the pyloric caeca and at 120 kDa in the intestine, suggesting that most active bands sensitive to leupeptin were derived from serine-proteinases. Active bands sensitive to 1, 10-phenanthroline were detected in the following tissues: skin, muscle, heart, liver, spleen, stomach, and caudal fin at 80 kDa, all tissues at 60 and 55 kDa, in the skin, gill, spleen, and caudal fin at 85 kDa, spleen at 70 kDa, and skin, gill, and caudal fin at 65 kDa, suggesting gelatinolytic metalloproteinase activities were widely distributed in yellowtail tissues. p-AminophenyImercuric acetate induced various latent serine-proteinase activities only in the gill.

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Effects of calcium agonists (A23187, caffein, ryanodine, and thapsigargin) on estradiol-induced vitellogenin (VTG) induction were examined in primary hepatocyte culture in the rainbow trout Oncorhynchus mykiss. These agonists are effective in depleting calcium in various calcium stores. Hepatocytes were precultured for 2 days and then estradiol-17β (E₂, 2×10^-6M) and the agonists were simultaneously added to the incubation medium. The hepatocytes were cultured for 7 more days and then spent medium was analyzed by SDS-PAGE. The relative rate of VTG production was evaluated by measuring the integrated optical density of the main VTG band and was expressed as the percentage of VTG to total proteins including the VTG. The addition of A23187 (10^-7_??_10^-6M), caffein (10^-4_??_10^-2M) or thapsigargin (10^-7_??_10^-6M) to the incubation medium specifically reduced VTG production by hepatocytes in a concentration-dependent way. Ryanodine also reduced the production to about 60% of the control at a concentration of 10^-4M. These results suggest that the synthesis of VTG is more susceptible to intracellular sequestered calcium, at least to calcium in the endoplasmic reticulum, than are other hepatocyte-derived proteins in rainbow trout.

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Apparent and true availabilities of amino acids from white fish meal (FM), defatted soybean meal (SBM), malt protein flour (MPF), corn gluten meal (CGM), extruded SBM (ExSBM), and extruded MPF (ExMPF), were determined by an indirect method for fingerling rainbow trout Oncorhynchus mykiss, common carp Cyprinus carpio, and red sea bream Pagrus major.
Apparent protein digestibilities (APD) of FM (89 to 94%), SBM (90 to 93%), and MPF (81 to 84%) were almost identical in the three species tested. However, the APD of CGM in carp (76%) and bream (79%) were lower than that in trout (95%). Individual apparent amino acid availabilities (AAAA) approximated the APD. The APD of ExSBM and ExMPF were two to four percent higher than the unextruded SBM and MPF, respectively, without any negative influences on individual AAAA. This finding suggests that the extrusion processing is an effective method to improve availabilities of amino acids in SBM and MPF. On the other hand, relatively large differences were recognized between the true amino acid availabilities (TAAA) and the AAAA among certain amino acids. Thus, determination of TAAA may be necessary for more accurate and economical feed formulation.

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A cDNA clone encoding troponin-T of ezo-giant scallop Patinopecten yessoensis striated adductor muscle has been isolated and sequenced. The cDNA is composed of 1, 939 bp with a translational region of 975 bp at the nucleotide positions 111-1, 085. It deduced 325 amino acid residues with a molecular weight of 38, 438. Ezo-giant scallop troponin-T showed high homology with akazara scallop troponin-T (92%). However, it possesses 11 amino acid residues more than akazara scallop troponin-T and substitutions of 26 residues. According to sequence comparison with rabbit troponin-T, the residues 39-126 and 180-233 of ezo-giant scallop troponin-T appears to be tropomyosin-interacting regions and the residues 206-210 to be troponin-I-interacting region. Moreover, ezo-giant scallop troponin-T was assumed to have close phylogenetic relations to troponin-Ts of akazara scallop, nematode Caenorhabditis elegans, and fruit fly Drosophila melanogaster.

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Carotenoids in the integuments of the red tileflsh Branchiostegus japonicus were investigated. Two new keto carotenoids, 4-ketolutein D [(3S, 3'S, 6'S)-3, 3'-dihydroxy-β, ε-caroten-4-one] and 4-ketolutein F [(3S, 3'R, 6'S)-3, 3'-dihydroxy-β, e-caroten-4-one] have been isolated along with the 19 known carotenoids. Astaxanthins (35.8% of the total carotenoid) and tunaxanthins (34.5%) were found to be major components. However tilefishxanthins I, II, III, and IV have not been found in our analysis.

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The polysaccharide produced by a marine Pseudomonas sp. No. 42 strain was found to be a highmolecular-weight glycosaminoglycan composed of N-acetyl-D-glucosamine (D-GlcNAc), D-glucuronic acid (D-GlcUA), and L-glutamic acid (L-Glu) in a molar ratio of 2:1:1. Structural analysis, employing a combination of chemical and NMR techniques, established that the polysaccharide was composed of linear repeating units having the following structure:
The native polysaccharide contained α-D-GlcNAc residues possessing free hydroxyl groups at 3 and 4 positions, an acetyl group at 3 positions, and 4 positions, respectively, in a ratio of 1:2:1.

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Postprandial changes in plasma free amino acid concentrations and nitrogen contents of the gastrointestinal digesta of rainbow trout Oncorhynchus mykiss fed different protein sources were examined. Three experimental diets containing either white fish meal (FM), defatted soybean meal (SBM) or malt protein flour (MPF), were fed to triplicate groups (initial mean weight; 63 g) for two weeks at 15°C. After 48 hours of fasting, the fish were fed again the respective diets to satiation. Blood samples were taken at 3, 6, 9, 12, 15, 18, 21, 24, and 48 hours after the last feeding.
Plasma concentrations of individual amino acids reached peak levels at 12±3 hours post-feeding in the FM group, and at 21±3 hours in the SBM and MPF groups. Evacuation of gastric digesta was faster in the FM and SBM groups than the MPF group. However, the 0.9% NaCl insoluble nitrogen levels (%) in the gastric digesta of the SBM and MPF groups seemed relatively stable until 21 hours compared with the decreasing trend observed in the FM group. The insoluble nitrogen contents (mg/100g BW) in the intestinal digesta were highest in the MPF group, intermediate in the FM group, and unexpectedly lowest in the SBM group throughout the sampling periods.
These findings suggest that peak levels of plasma free amino acids in the SBM and MPF groups occurred later than the FM group due in part to different protein digestive processes in the gastrointestinal tract.

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The changes in content of ATP and its related compounds, free amino acids, organic acids and opines were investigated in the muscle of B. striatissimum during storage at 0°C and 5°C. Immediately after shelling, the total amount of ATP and its related compounds were 2.8μmol/g. ATP, ADP and AMP accounted for 98% of the total ATP and its related compounds. ATP reached the highest level on the 1st day at 0°C, then decreased slowly. ATP degraded faster at 0°C than at 5°C. AMP was decomposed to inosine through both pathways, since IMP and adenosine were detected. Hypoxanthine, xanthine and uric acid increased with the decrease of ATP. Immediately after shelling, the total amount of free amino acids in the muscle were 1, 719 mg/100 g. Taurine, arginine, proline, alanine, glutamic acid and glycine were major free amino acids and accounted for 87% of the total amount of free amino acids. Acetic acid increased rapidly during storage, but octopine and alanopine increased slowly.

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About 100, 000 individuals of masu salmon Oncorhynchus masou were released into Ukai River in Noto Peninsula. Then the released fish were collected in the river and coastal zone of the peninsula, and the hepatic enzyme activities were determined to investigate the metabolic response in the liver during the migration from river to sea. The activities of amino acid degrading enzymes (alanine aminotransferase and aspartate aminotransferase) and gluconeogenic enzyme (fructose-1, 6-diphosphatase) were significantly higher in the fish caught in the sea than in those caught in the river, whereas no remarkable difference in the lipogenic and glycolytic enzyme activities was found between the fish caught in the river and those caught in the sea. These results suggest that amino acid degradation and gluconeogenesis in the liver of masu salmon were enhanced in the early period of seawater migration.

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