Development of bones in the mouth parts and changes of gut contents were investigated in early red snapper Lutjanus argentimaculatus larvae reared with naturally-occurring zooplankton as food. Larvae immediately after initial mouth opening possessed incomplete bony components in the mouth parts. However, the bony elements grew rapidly in size on the day of initial mouth opening, day 0, during which they started feeding. Acartia sinjiensis nauplii of 0.10-0.15mm in total length (TL) were major food organisms at this stage. From day 1 to 2, no conspicuous changes occurred in the size and type of food organisms ingested, although some skeletal elements were added in the mouth part. Many new skeletal elements developed from day 3 to 4, as the size of food organisms in gut increased abruptly. The larvae started feeding on Oithona dissimilis copepodids (0.20-0.50mm TL) and the weight percentages of the copepodids ingested increased thereafter. Early red snapper larvae acquired initial feeding ability by growing the size of a limited number of bony elements in the mouth parts. Further increase in feeding ability was achieved by differentiation of additional bony elements from day 3 to 4.

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To investigate the physiological mechanism of homing, the abalone Haliotis diversicolor supertexta was individually accommodated in a 2m basin. Abalone, and a disc on which a shelter was fixed, were set centrally, and a luminous rod on the animal's shell was monitored to trace the locomotion path in dark conditions at night-time. The effects of shelter removal with the disc and angular displacement of a substrative sheet were examined.
The locomotion path seemed to consist of three fundamental components: peripheral, central and petaled rounds. The homing path was almost straight and not the route previously drawn. Near or after the real time of sunrise, most abalone homed or passed the shelter and settled peripherally. Without the shelter, the homing abalone wandered in the central bottom area. The abalone compensated or biased its locomotive direction against horizontal rotations of the substratum. The homing may be realized by a mechanical memory of locomotive directions during dead-reckoning.

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We tried to culture the resident peritoneal macrophage (RPM) of red sea bream (RBS) and obtained transferable cultured cells, when cultivated using RPMI1640 supplemented with 0.4% NaCl and 20% fetal bovine serum at 30°C in 5% CO₂. The cells had phagocytic activity against Latex beads and had acid phosphatase and nonspecific esterase activities, both of which are principal characteristics of RBS RPM. Electron microscopically, the cells had slender microvilli, micropinocytic vesicle-like vacuoles, and microfibrils, similar to RSB RPM. The cells had receptors for RSB IgM on the cell surface. The cultured cells migrated to 10^-8M N-formylmethionyl leucocyl phenylalanine (FMLP) and the supernatants of the cultured cells. The results suggest that resident peritoneal macrophages produce and release chemotactic factor-like substance (s) in the abdominal cavity.

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Ovarian development e. g. gonadosomatic index, oocyte diameter, fecundity, histology, and related steroid hormones e. g. testosterone (T), estradiol-17β (E₂), 17α, 20β-dihydroxy-4-pregnen-3-one (DHP), were examined in captive female catfish Clarias macrocephalus during an annual cycle to establish the optimum season for its artificial propagation. Results showed that captive C. macrocephalus had a group-synchronous pattern of ovarian development, as indicated by the presence of oocytes at all stages of development throughout the annual cycle. Mean gonadosomatic index (GSI; 11-13%), oocyte diameter (1.54-1.56mm), fecundity (80-110 eggs/g body weight), and serum T levels (36-37 ng/ml) were lowest in January-April, suggesting that it is not the optimum season to induce C. macrocephalus to spawn during these months. Serum E₂ levels were lowest in January (7 ng/ml), and highest in December (20 ng/ml). Serum DHP levels were below detectable limits (<0.02 ng/ml) throughout the year, supporting the observation that final maturation and ovulation do not occur in this species under captive conditions. Changes in various reproductive parameters and steroid hormone levels indicate that January-March, April-June, July-September and October-December correspond to the refractory, preparatory, spawning and post-spawning periods, respectively, of the annual cycle. The results of the present investigation can be used as a guide for the controlled breeding and commercial aquaculture of C. macrocephalus in the Philippines.

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Precocious males first appear in the second year in sockeye salmon, whereas in masu salmon they appear in the first year. In underyearling male masu salmon, precocious maturation is accelerated under short photoperiod with an increase in salmon gonadotropin-releasing hormone (sGnRH) and pituitary gonadotropin subunit (GTH Iβ and GTH IIβ) contents, suggesting that the brain-pituitary-gonadal axis is already completed. In this study, the development of the brain-pituitary-gonadal axis in underyearling male sockeye salmon was investigated by manipulating photoperiod in order to clarify the relationship between its development and initiation of precocious maturation. Fish were divided into short (8L-16D) and long photoperiodic (16L-8D) groups in June and were reared for 4 months until October. sGnRH contents in the brain and pituitary, and GTH Iβ and GTH IIβ contents in the pituitary were measured. sGnRH contents in the hypothalamus and the pituitary, and GTH Iβ contents in the pituitary increased under short photoperiod, although gonadal maturation was notinduced under either photoperiod. However, pituitary GTH IIβ contents did not increase in either photoperiodic group. These results suggest that in contrast to masu salmon, the brain-pituitary-gonadal axis is not completed in underyearling male sockeye salmon. This species-specific difference in the development of the brain-pituitary-gonadal axis may underlie differences in the initiation of precocious maturation.

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Feeding experiments were conducted to evaluate meat meal (MM) as an alternative protein source for fish meal in the diet of Japanese flounder. The diet containing 80% of white fish meal as a sole protein source was the control, and 20, 40, 60, 80, and 100% of fish meal protein were replaced by MM protein in experimental groups. Juvenile fish of about 3g in initial body weight were fed on each diet to satiation twice a day, 6 days per week for 8 weeks at 20°C.
Survival rates of fish ranged from 93 to 100% and were not significantly different among all dietary groups tested. The final body weight, weight gain, feed efficiency, and protein efficiency ratio of fish fed diets containing MM up to 60% substitution levels were statistically identical to those of fish fed the control diet, except that the feed efficiency in the 60% substitution diet was lower. Feed performances in diets replacing 80 and 100% of fish meal protein were significantly inferior to those in the control group. Supplements of crystalline amino acids to the MM diet did not seem to improve the nutritive value of the diet. Since substitution up to 60% did not adversely affect the hematological and hematochemical parameters as well as the body composition, it is considered thatabout 60% of white fish meal protein can be replaced by MM in the diet of juvenile Japanese flounder.

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An 8-week feeding experiment was conducted to develop a semipurified diet for the red sea urchin Pseudocentrotus depressus. Casein, casein hydrolysate and crystalline amino acids were tested in an attempt to find an adequate source amino acid for the urchin diet. In addition, two binders, sodium alginate and Curdlan, were compared. The growth in test diameter and body weight, and feed efficiency became higher as the amino acid chain length increased. Urchins fed a diet containing casein showed the highest values of body protein content, protein efficiency ratio and apparent net protein utilization. The energy availability and digestibility of the diet having crystalline amino acids showed the lowest values. The diet with casein and sodium alginate showed a higher growth rate, lower feed efficiency and lower protein retention than the diet with casein and Curdlan. These results indicated that casein is the most suitable of the three amino acids sources tested in this experiment. The choice of binder can be changed depending on the objective, that is, growth or diet efficiency.

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Age and growth of anglerfish Lophius litulon were examined using vertebral centra from specimens collected in the East China and Yellow Seas during January 1991 to April 1996. Monthly changes in the percentage frequency of a translucent band on the outer margin of centrum and the marginal increments indicated that ring formation occurred once a year mostly in April. Back-calculated total lengths for each sex were calculated by the regression method using a standardized ring radius. The initial growth trend based on monthly collected young fish (_??_250mm in total length) were compatible with the mean back-calculated total lengths from vertebral centra for males and females at the first and second ring marks. Growth of anglerfish was expressed as TL_t=1130 (1-e^{-0.080(t+0.401)}) (t_??_8) for males and TL_t=1547 (1-e^{-0.064(t+0.345)}) (t_??_13) for females using the back-calculated total lengths. Our results suggested females grow faster and live longer than males.

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Salinity response in F₁ hybrids of the guppy was measured as survival time after subjecting mature fish to 35 ppt artificial seawater. The amount of heterosis was expressed by the difference between the means of the F₁ hybrids and the parental strains. The mean survival times of the F₁ hybrids were higher than the mid-parent values, indicating heterosis. The amount of heterosis differed among strain combinations. A positive correlation was observed between the survival times of the F₁ hybrids and the female parents but not between the F₁ hybrids and the male parents, indicating maternal effects. These results suggest that the heterosis observed in the F₁ hybrids is attributable to two components: the first is the non-maternal component induced by strain combinations and the second is the maternal effects of strain populations.

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An identification of the causative bacterium strain 12-N, which was isolated from coelomic fluid of diseased sea urchin Strongylocentrotus intermedius, was undertaken based on its cultural and biochemical properties, DNA base composition, and DNA-DNA homology. The strain 12-N was an aerobical Gram-negative filiform, which formed bright yellow pigmented colony and showed slightly gliding motility without flagella. Its morphology gradually changed from filiform to short rods during incubation in liquid medium. Its optimum growth temperature was considered to be between 25°C and 30°C and no growth was observed above 37°C or below 10°C. The strain required seawater for its growth and could not degrade agar, cellulose or chitin. The G+C mol% of DNA from the strain was 40.5. On the basis of these characteristics, it is considered that the strain 12-N belongs to the genus Flexibacter and closely resembles F. maritimus. However, the strain differed from F. maritimus in serological property and DNA-DNA homology.

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We investigated mitochondrial DNA divergence for amphidromous and landlocked forms of ayu Plecoglossus altivelis to describe their genetic status and search for genetic markers discriminating the two forms. The first half of the control region was sequenced for 60 fish, 15 individuals from each of 2 amphidromous and 2 landlocked populations. These sequences were found to be highly variable, suggesting their utility for the analysis of intra-specific divergence. The landlocked form was genetically more homogeneous than the amphidromous form in terms of the number of polymorphic sites and the magnitude of nucleotide diversity. Intra-form net nucleotide substitutions were 0.024% in the landlocked and 0.062% in the amphidromous, showing that intra-form genetic differentiations were small. In contrast, inter-form net nucleotide substitutions were considerably higher, 0.241-0.527%, indicating some genetic heterogeneity in the mitochondrial genome between the two forms. Nearly 80% of fish were distinguishable as amphidromous or landlocked by the nucleotide substitutions at hyper-variable sites.

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The control region of mitochondrial DNA, known to be the most variable in the genome, was analyzed so as to assess its suitability for examining genetic variability and population structure in the Japanese flounder. A total of 424 nucleotide sites, including the proline transfer RNA gene and the first half of the control region, was sequenced from 55 specimens from Niigata, Honshuand Sado Island, off the north-western coast of Honshu. Out of 350 nucleotide sites on the control region, 126 (36.0%) were variable, 54 haplotypes being found. Differences between nucleotide sequences ranged between 0 and 8.3% with an average (=nucleotide diversity) of 4.33%, indicating that the control region of the mitochondrial DNA in the Japanese flounder is characterized by extremely high variability. The frequency in occurrence of specific nucleotides in 2 sites in the Niigata sample differed significantly from that in the Sado Island sample. This result accorded with previous studies which suggested Japanese flounder populations in Niigata and Sado belong to different local populations.

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We consider the optimal harvesting policy, that is maximizing the yield, under sustainable fisheries including the age of first capture and seasonal harvesting. To obtain this policy, we analyze mathematical and numerical methods using spawning per recruit (SPR) and yield per recruit(YPR) simultaneously. We use data on a chub mackerel population in the Pacific Ocean off eastern Japan. We consider three cases of seasonal fishing, fishing throughout the year, half year after the spawning season and variable fishing season, defined as the policy that varies the beginning and the end of fishing season. Under a variable fishing season, the optimal fishing season includes the fishing season of the two major types of chub mackerel Scomber japonicus fisheries, the dip-net and the purse-seine fisheries. We conclude that (1) the maximum sustainable yield is unlikely to be in pulse fishing, (2) The optimal yield under a fixed fishing season policy is close to that under a variable fishing season, (3) In any case, the fish should be preserved until the end of the first spawning season.

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The reproductive biology of the starspotted dogfish Mustelus manazo from Tokyo Bay was examined. The specimens attained their first maturity at 687mm TL (age 3) for malesand 701mm TL (age 3) for females. All specimens over 780mm TL (age 5) for males and over 820mm TL (age 6) for females were fully mature. The gonad index for males reached its minimum during June and July, and maximum ova diameter was the largest in May and June. The fertilized eggs were foundin the uteri by early July, and the largest embryos occurred between May and June. It was assumed thatthe mating, fertilization and parturition occurred during May and June, therefore, the gestation period was estimated at 11-12 months. The litter size increased with total length of the mothers and the fecundity ranged from 2 to 13 embryos. A predominance of males in total number of embryos was observed, but yearly variations were found.

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The feeding apparatus of the Paralithodes camtschaticus, P. brevipes and P. platypus during the transition zoea, glaucothoe and first juvenile stages were analyzed. The mandibles of zoeal larvae are well adapted for grinding of food. The mandibles of the glaucothoe are uncalcified and rudimentary, and the mandibular lateral lobes are apparently incapable of giving support to the masticatory movement. The setae of endopods and endites of the maxillae and endopods of the first and second maxillipeds are substituted for minute setae or denticles. The third maxilliped appear to be apparently developed, but the crista dentata on the ischium is still not formed. The first juvenile has well calcified mandible. The crista dentata on the third maxilliped is completely formed.
The setose zoeal foregut has two chambers distinctively separated by a heavily setose cardiopyloric valve. The pyloric stomach has a well developed filter press. The glaucothoe hasthe foregut chambers and the cardiac pyloric valve unarmed or with few small setae present. The gastric mill and lateral teeth appear for the first time in the juvenile foregut. These observations indicate changing in the feeding of lithodids, in which they abstain from feeding during the glaucothoe stage.

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An individual's growth opportunity may be influenced by the date on which it wasborn. To examine the effects of birth date on growth in juvenile (Age 0+ ) white-spotted charr Salvelinus leucomaenis, individual birth dates were identified by counting the daily growth increments in the otolith. Significant linear relationships were found between fork length at catch and birth date; early-born individuals tended to be larger than late-born ones at a given time. About one quarter or half of the variability observed in fork length could be explained by birth date variation. Differences of birth date among individuals within a cohort may have a significant influence on later stages of life history, such as age at seaward migration.

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Carp which have received an intraperitoneal injection of κ-carrageenan show a high survival rate after being challenged with pathogenic bacteria. In order to elucidate the mechanism underlying the immunoenhancement, we investigated its effects on the non-specific defense system of carp. κ-Carrageenan had little influence on the activity of the alternative complement pathway or on the phagocytic and respiratory burst activities of head kidney phagocytes (HKP), yet it greatly elevated the migration of HKP to the peritoneal cavity. Since the migrated HKP (especially macrophages) showed a high phagocytic activity, it is highly probable that the early elimination of challenge bacteria by such mobilized and activated phagocytes was responsible for the high survival rate of the κ-carrageenan-injected fish. It was also found that the phagocytic activity of the migrated head kidney macrophages was elevated not by resident peritoneal cells, but by leukocytes which had migrated to the peritoneal cavity. This indicates that the migrated leukocytes produced and secreted a factor (s) with macrophage activation potency.

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An extract was prepared with trichloroacetic acid from the inks of neon flying, boreal clubhook, and boreo pacific gonate squids and free amino acids, trimethylamine oxide, 5'-ATP and related compounds, betaines, and other extractive components were analyzed. The squid inks were rich in taurine and hydroxyproline. Higher amounts of aspartic acid, glutamic acid, alanine, leucine, and arginine were detected in the boreal clubhook and boreo pacific gonate squid inks. Each free amino acid of the neon flying squid ink was lower than those of the boreal clubhook and boreo pacific gonate squid inks. A small amount of trimethylamine oxide and large amounts of homarine and glycinebetaine were detected in three squid inks.
Ethanol extract was prepared to determine the extraction capability. There were some composition similarities between ethanol and trichloroacetic acid extracts. Ethanol was inferior in extraction of inorganic ions, even in the case of the hot-ethanol extraction. The hot-water extract showed that amounts of glycine, α-aminobutyric acid, Cl^-, and PO₄^3- were higher than those of the trichloroacetic acid extract of the neon flying squid ink.

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The content and composition of diacyl glyceryl ethers (DAGE) of the pyloric cecal and ovarian lipids of the asteroids Solaster paxillatus and Asterias amurensis were investigated.
In both species, the pyloric cecal lipids contained a relatively high percentage of DAGE. On the other hand, the ovarian lipids of S. paxillatus had an abundance of these compounds but were relatively low percentages in A. amurensis. The unsaponifiable matter isolated from the tissue neutral lipids consisted of remarkably high levels of glyceryl ethers and small amounts of alkenyl types. Among the different tissues examined, glyceryl ethers originated from DAGE were in general similar in composition; the most predominant component was 18:0 alcohol followed by 20:1 and 16:0 alcohols. The fatty acid compositions of DAGE and/or triglyceride classes of the different tissue lipids of the above two asteroid species were also discussed.

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The fish muscles stored as a fillet and a round were compared. At 3h, the I-band disappeared in stressed fish fillet, while it disappeared or remained slightly narrow in the muscle as a round. Both types of unstressed fish muscles began to contract slowly and showed large breaking strength. At 10h, both types of stressed fish muscles were tenderized, weakening pericellular connective tissue since the contraction continued. In the muscle as a round, the I-band became narrow. In unstressed fish muscle stored as a round, the restraint of bony structure induced myofibrillar bendings during contraction and weakened pericellular connective tissue. As a result, the round was more tenderized than the fillet. At 48h, in stressed fish muscle as a fillet the contracted state continued, but in this muscle as a round the original length of the I-band was restored. However, these muscles showed similar small breaking strength since the weakening of pericellular connective tissue was in the similar extent. Unstressed fish muscle as a round was more tenderized than this muscle as a fillet due to the bony-structural resistance against contraction. The maintenance of full rigor index occurred in the process where the internal structure was adapted to contractile tension after the disappearance of ATP, as in the case of the restoration of the I-band in the round.

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A growth experiment was conducted to compare the relative efficacy of L-ascorbyl-2-polyphosphate (C2PP) and L-ascorbyl-2-sulfate (C2S) in supplying the dietary vitamin C requirement for juvenile grass shrimp Penaeus monodon. Purified diets with 6 levels of either supplemental C2PP (0, 120, 200, 800, 2000 and 4000mg/kg diet) or C2S (0, 30, 50, 200, 500 and 1000mg/kg diet) were fed to P. monodon (mean weight 0.79±0.08g) for 8 weeks. Each diet was fed to three replicate groups of shrimp. Results indicated that shrimp fed diets containing _??_22.81mg of C2PP/kg or _??_72.41mg of C2S/kg diet had significantly (p<0.05) higher weight gain than shrimp fed the unsupplemented control diet. Feed conversion ratio (FCR) was poor in shrimp fed the diet lacking supplementary vitamin C. Shrimp fed diets supplemented with 126.90 and 292.84mg of C2PP/kg or _??_72.41mg of C2S/kg diet had a higher survival than shrimp fed the unsupplemented control diet. Ascorbic acid concentration in hepatopancreas was higher in shrimp fed diets supplemented with C2PP and C2S than those fed the unsupplemented control diet, and the concentrations were generally proportional to the level of as-corbic acid supplementation in the diet. Weight gain analyzed by broken-line regression indicated that the dietary level of ascorbic acid from each source for juvenile P. monodon is 29.27mg of ascorbic acid/kg diet for C2PP and 73.83mg of ascorbic acid/kg diet for C2S suggesting that C2S is about 40% as effective as C2PP in meeting the vitamin C requirements

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So far, the dietary requirements of the ten amino acids arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine have been proved in fish and the quantitative requirements have been determined in several fishes. However, each essential amino acid requirement determined by different laboratories does not correspond with each other, not only among species but also even within species, because of the differences of experimental conditions. Therefore, some researchers have applied a new method based on the idea that there shoud be a correlation between whole body amino acid pattern and the dietary amino acid requirement: i.e., only one amino acid requirement is determined by growth data and the other nine are estimated as being propotional to the whole body amino acid pattern. There would be little difference in the patterns of requirement by this new method among species, because body amino acid patterns are almost identical among species. On the other hand, when the A/E ratios of amino acid requirements based on growth assay are compared, close similarities were noted between carp and catla in the family Cyprinidae, and among chinook salmon, chum salmon and coho salmon in the family Salmonidae, suggesting the existence of specificity in requirements among fish species or family.

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The utilization of stearic acid (SA) and corn starch (Cs) or dextrin (Dx) as energy sources for Macrobrachium rosenbergii (de Man) juveniles, and the effect of increasing dietary SA and digestible energy levels on weight gain, survival, lipid class and fatty acid profiles of the whole body of prawns were determined in a 60-day feeding experiment in a randomized complete block design. The diets contained fixed amounts of carbohydrate (30%) and protein (35%), and increasing levels of SA (0, 2, and 7%) which resulted in an increase of gross energy (14.4, 15.3, 17.2 MJ/kg diet).
Regardless of SA level, Cs and Dx were both utilized effectively for energy by M. rosenbergii juveniles. Regardless of carbohydrate sources, increase in dietary amount of SA resulted in significantly higher content of SA and 18:1 n-(9+11) in the body of prawns, both in the neutral and polar lipid fractions. Weight gains of the prawns were higher in the diets with 2%, then 0%, followed by 7% SA. This indicated that SA were utilized for growth but the contribution was low as energy sources.
The result of the present study showed that M. rosenbergii juveniles utilized SA as an energy source but the contribution of SA as energy source was lower than that of carbohydrates.

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Myosin was purified from retractor smooth muscle of whelk, Neptunea polycostata.
Ca-, Mg-, and EDTA-ATPase profiles of whelk myosin were studied under various conditions, and compared with those of other myosin, especially Abalone Haliotis discus retractor smooth muscle myosin. The properties of whelk myosin ATPase were almost similar to those of abalone and scallop myosin, though the following differences were observed.
1. At neutral pH and 25°C, enzymatic activities of whelk myosin were lower than those of abalone and scallop myosin.
2. Ca-sensitivity of whelk myosin was higher than that of scallop myosin.
3. In the absence of Ca²⁺, Mg-ATPase activity did not depend on KCl concentration in contrast to rabbit skeletal muscle myosin, scallop myosin and abalone myosin.
4. The pH dependent activity curves under the low ionic condition (0.05M KCl) were different from those of abalone myosin.
5. Arrhenius plots of whelk myosin ATPase activities showed no bending in the temperature range between 5°C and 30°C, which were similar to the case of abalone myosin, but different from scallop myosin. The activation energies were higher for whelk myosin than those for abalone myosin.

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The structure of a mucopolysaccharide from a marine Pseudomonas WAK-1 strain has been investigated, by carboxyl-reduction, partial hydrolysis, periodate oxidation, and 2D NMR spectroscopy. This polysaccharide was shown to have the repeating unit:

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Synthesis and secretion of the protein with molecular weight 196 K on SDS-polyacrylamide gel electrophoresis was induced in immature Japanese eel hepatocytes by pharmacologically high concentration of estradiol-17β (E₂), 10^-4M, during 4 days culture, but it was not induced by 10^-5M and 10^-6M E₂ during the same or more days culture. The protein with the same molecular weight was observed in the plasma of the eel into which E₂ was injected intraperitoneally.
Vitellogenin, a very-high-density lipoprotein with density in the range of 1.27 to 1.30g/ml, was isolated from the plasma of female silver eel and also from that of E₂ treated immature eels by density gradient ultracentrifugation. This lipoprotein was further purified by a DEAE-Toyopearl column and characterized to consist of a major apolipoprotein with 196 K. These results in dicate that the 196 K protein that appeared in the culture medium of hepatocytes is the apolipoprotein of vitellogenin.
Hepatocytes prepared from the preliminarily E₂-injected eel secreted the vitellogenin after 3 days culture with 10^-6M E₂, but did not secrete the vitellogenin after the same or more days culture without E₂.

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Apparent availabilities of amino acids and minerals from white fish meal (FM), defatted soybean meal (SBM), malt protein flour (MPF), and corn gluten meal (CGM) were determined for fingerling rainbow trout Oncorhynchus mykiss. Groups of forty fish (mean weight; 13 g) were each allotted to one of six round tanks for collecting feces. A test diet containing one of the protein sources at approximately 35% crude protein level was fed to duplicate groups at 15°C, and the feces were collected. Availability was determined by an indirect method using chromic oxide.
Apparent protein digestibility of CGM was the highest (96%), with FM and SBM being slightly lower (94%), and the lowest was MPF (86%). Apparent availabilities of individual amino acids within each protein source were similar and almost approximated to the protein digestibility value. Apparent availabilities of phosphorus from FM and MPF per se were higher than those from SBM and CGM. The copper and zinc availabilities for SBM showed the highest values.
These results suggest that the apparent protein digestibility value is indicative of the amino acid availability from a protein source with a high protein digestibility such as FM, SBM, and CGM in fingerling rainbow trout. On the contrary, individual mineral availability values should be assessed to formulate efficient and economical fish feeds.

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A feeding trial was conducted to determine the adequate level of dietary vitamin B₆ (pyridoxine, PN) for juvenile tilapia Oreochromis niloticus x O. aureus fed diets containing different dietary protein concentrations. Purified diets with eight levels of PN (0, 2, 4, 8, 12, 20, 50, 100mg/kg diet) at either 28 or 36% protein concentration were each fed to three replicate groups of tilapia (mean weight: 0.73±0.01g) for 8 weeks. Results indicated that in the 28% protein group, fish fed 4mg PN/kg diet had a more significant (p<0.05) weight gain than fish fed 0 and 100mg PN/kg diet; feed efficiency ratio (FER) of fish fed 4mg PN/kg diet was higher than fish fed 0 and 8-100mg PN/kg diets. In the 36% protein group, fish fed 12-50mg PN/kg diets had higher weight gain than fish fed 0, 100mg PN/kg diets and fish fed 20mg PN/kg diet had higher FER than fish fed 0-4mg PN/kg diets. Hepatic alanine aminotransferase (ALT) activity generally increased with increasing dietary vitamin B₆ and leveled off at 12mg PN/kg and 20mg PN/kg in the 28% protein and 36% protein groups, respectively. Tilapia fed 100mg PN/kg diet at 28% protein concentration showed normocytic normochromic anemia symptoms. Weight gain and ALT activity analyzed by broken-line regression indicated that the optimum dietary vitamin B₆ requirement in juvenile tilapia were 1.7-9.5mg PN/kg and 15.0-16.5mg PN/kg diet in 28% and 36% protein diets, respectively.

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cDNA encoding fast skeletal muscle light meromyosin (LMM) predominantly expressed in carp acclimated to a cold temperature of 10°C was inserted into an Escherichia coli expression vector pET-11a. The resulting plasmid pET10 produced non-fused carp 10°C-type LMM, yielding 10% of the total proteins in E. coli. The 10°C-type LMM was purified by altered dialyses against high- and low-ionic-strength buffers and ion-exchange chromatography. An apparent molecular mass of the purified LMM was about 74, 000 on SDS-PAGE, which was slightly larger than that previously reported for LMM isolated from carp acclimated to 10°C. Transition temperatures (Tm) were 30.2 and 34.9°C for the present 10°C-type LMM on DSC analysis. This LMM exhibited a typical pattern of α-helix in CD spectroscopy with two minima at 222 and 208 nm, and its α-helical content at 20°C was about 70%. The maximal decreasing rate derivative at 35°C of the mean residue ellipticity of carp LMM per unit change of measuring temperature well reflected Tm values observed in DSC analysis.

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Naturally fertilized bluefin tuna Thunnus thynnus eggs which were obtained from 7-year-old broodstock in a net cage were incubated until hatching at 27°C. No conspicuous changes were found in egg moisture and amounts of total nitrogen and phospholipid during the embryonic development. Egg protein gradually increased, but free amino acid decreased with the development. Triacylglycerole (TG), a main egg constituent of 420mg/g dry egg at the stage of early cleavage, rapidly decreased after the stage of late gastrula and reached 140mg/g dry egg just before hatching. Activities of aspartate aminotransferase, alanine aminotransferase, creatine kinase, and lactate dehydrogenase fell between the stages of early cleavage and Kupffer's vesicle and rose thereafter. Activities of alkaline phosphatase remained high until embryo formation but fell rapidly thereafter. These results indicate that TG plays an important role as a main energy fuel, and that the differentiation and formation of organs are prompted immediately before or after the stage of Kupffer's vesicle during the embryonic development of bluefin tuna.

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Microbial population in kusaya gravy from Niijima Island was analyzed by grouping of functional characteristics and genetic identification from 16 S rRNA genes (16 S rDNA). Viable conunts in TSSY medium supplemented with 0.1% thioglycolate and 0.3% agar using the MPN method were determined as 10¹¹/ml, which was the highest value compared with previous reports on kusaya gravy. Each of denitrifying, nitrate reducers, sulfate reducers and proteolytic bacteria were estimated as about 10⁹/ml, and starch hydrolyzing and lactic acid producing bacteria were estimated as lessthan 10³/ml. Viable counts on TSA medium, which were superior to BPG and B₆P₆G media, were 10⁸ CFU/ml. The 16 S rDNA were amplified from kusaya gravy by PCR without cultivation of baceria, cloned, and sequenced. Sequence analysis of the cloned partial 16 S rDNA indicated that the major bacteria in kusaya gravy were Bacteroides-Cytophaga group bacteria, wall-less spirochaeta-like bacteria, unidentified bacteria, and so on. The results of genetic identification did not coincide with those of cultural methods; i.e., most of the above bacteria have not been isolated by plate methods so far, and Corynebacterium and Peptococcuceae which were representative organisms in the plate surface method under aerobic or anaerobic conditions, respectively, were not detected by the PCR method. These results indicated that there are diverse organisms which are unknown and unculturable in kusaya gravy.

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The application of the Flow cytometry (FCM) technique for rapid determination of cell number of viable bacteria suspended in seawater is described. A fluorescein diacetate was used to distinguish between viable cells and dead cells for various bacteria. The FCM technique was also used to discriminate between Gram-positive and Gram-negative bacteria using the LIVE BacLight^TM Bacterial gram stain kit. A difference in the fluorescence scattergram between the two bacterial groups was observed. The FCM method provided rapid determination of cell number of viable bacteria in seawater. A good correlation was observed between the values determined by the FCM method and the colony counting method in the range of 10⁵-10⁹ cells/ml. One FCM assay could be completed within 60 s and the total assay time including the preparation of bacteria was within 35min.

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The effects of carbon dioxide on the growth of food spoilage and pathogenic bacteria, Pseudomonas aeruginosa, P. fluorescens, Escherichia coli, Salmonella typhimurium, Vibrio parahaemolyticus, nonagglutinating (NAG) vibrio, Staphylococcus aureus, Bacillus cereus, B. subtilis, B. macerans, B. licheniformis, Weissella (Lactobacillus) viridescens, Enterococcus faecalis, and Clostridium perfringens were investigated on solid media at 30°C. Growth of the bacteria on the surface of Plate Count Agar (PCA) packaged with different concentrations of carbon dioxide (0, 20, 40, 60, 80, 100% in N₂ gas) was evaluated after 24h incubation at 30°C. Growth of P. aeruginosa, P. fluorescens, E. coli, S. typhimurium, V. parahaemolyticus, NAG vibrio, and S. aureus was inhibited by carbon dioxide in proportion to the increase in the ratio of carbon dioxide in N₂ gas mixtures. Particularly, a significant growth inhibition was observed for two species of Pseudomonas, S. aureus, and NAG vibrio. Growth of 4 species of Bacillus (B. cereus, B. subtilis, B. macerans, B. licheniformis) was not inhibited by carbon dioxide. Growth of 2 species of lactic acid bacteria (W. viridescens, E. faecalis) and a species of obligate anaerobic clostridia (C. perfringens) was stimulated by CO₂.

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The effects of dietary stearic acid (SA) and crude protein (CP) levels on the utilization of SA as an energy source by freshwater prawn Macrobrachium rosenbergii (de Man) were determined by feeding and tracer experiments.
Feeding experiments showed that M. rosenbergii juveniles fed diet 2 (2% SA+35% CP) gave significantly higher (p<0.05) weight gain, feed conversion efficiency (FCE), and protein efficiency ratio (PER) than those fed diet 4 (7% SA+50% CP), which provided the lowest weight gain, FCE, and PER. Diet 2 tended to give higher weight gain than diets 1 (0% SA+35% CP) and 3 (7% SA+35% CP), but no significant difference existed among the 3 dietary groups. The higher weight gain of prawns fed diet 2 (2% SA) compared with diet 1 (0% SA) indicated the positive contribution of SA as an energy source. Significantly higher SA and oleic acid levels were observed in prawns fed diets with 7% SA than those fed with 2% SA, indicating that dietary SA affected body fatty acid profile. Prawns fed diets containing 35% CP had significantly higher PER than those fed 50% CP diets.
Tracer experiments showed that M. rosenbergii juveniles utilized SA as an energy source as evidenced by expired ¹⁴CO₂ after feeding with [¹⁴C] SA. Expired ¹⁴CO₂ accounted for half of ingested radioactivity 48 h after feeding with labelled diets. The prawns fed diets containing 35% CP expired much more ¹⁴CO₂ than those fed diet containing 50% CP, but no significant difference was detected (p>0.05).

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