Two feeding trials were performed on carp to investigate phosphorus (P) and nitrogen (N) excretion during their growth span. Trial I was conducted under laboratory conditions by feeding 3.9 g carp an experimental diet (crude protein 34.8%, total P 1.41% and available P 0.67%) for 280 days under controlled conditions. Trial II was performed with 72.8 g carp, feeding them a commercial diet (CP 35.8%, total P 1.62% and available P 0.75%) for 180 days on a practical scale. Fish grew throughout the experiment in trial I, whereas they stopped growing in trial II when the water temperature fell below 15°C. In both trials, P and N content in fish body increased with increasing weight until it plateaued when fish were between 500 and 600 g. The retention rates of the two elements also followed a similar pattern, but decreased beyond the size range mentioned above. In both trials, P and N loading increased with an increase in fish size, but such a pattern was less evident until a bodyweight of 600 g, the trend being more pronounced in trial II. The results of the present study indicate that excretion is higher during the slow-growing stage of carp and is, hence, influenced by fish size.

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Larval and juvenile ayu from seven year-groups (1986, 1987, 1992, 1995, 1996, 1999 and 2000) were collected in the Shimanto Estuary and adjacent coastal waters. The present study focuses on the variation among year-groups in the hatching period estimated by age determination using the otolith. The hatching period of the dominant cohorts in the 1986, 1987 and 1992 year-groups occurred from late October to mid-November. A delay of the hatching period of the dominant cohort was observed from the 1995 year-group, which occurred in late November to early December, and the dominant periods in the 1996, 1999 and 2000 year-groups were observed from early to late December. It appears that the delay of the hatching period of dominant cohorts was not due to a delay of spawning, but a high mortality of early hatched larvae. The water temperature in autumn in the coastal waters adjacent to the Shimanto River has tended to rise over the past 20 years and this trend was especially notable in the late 1990s. The delay in the hatching period of the dominant cohort observed from the 1995 year-group was likely to be related to the rise in seawater temperatures in autumn.

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The species composition of demersal fish was studied in nearshore waters (33-116 m depth) of south-eastern Hokkaido, the coldest area around the Japan Archipelago due to the influence of the cold Oyashio Current, using bottom gillnet samples collected during October 1996, August 1997, May 1998 and September 1999. The water temperature just above the sea bottom in the study area was lowest (<2°C) during May and then rose through autumn (>14°C). Cottids were the most abundant family in terms of both overall biomass and number, but their gravimetric dominance decreased from May (84%) through October (14%), whereas pleuronectids and stichaeids increased. Of the 57 fish species sampled, plain sculpin Myoxocephalus jaok was the dominant species in terms of overall biomass, accounting for 29.0% of the total biomass, followed by horned sculpin Enophrys diceraus (19.5%), Kamchatka flounder Atheresthes evermanni (6.5%) and blackline prickleback Acantholumpenus mackayi (4.9%). Plain sculpin dominated during May and September, but its predominance was low during October (9.6%), when witch flounder Glyptocephalus stelleri (22.7%) and blackline prickleback (10.8%) became important. This seasonal change appears to reflect the annual life cycle events of the fish, such as spawning.

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The present study estimated the age and growth of the silky shark Carcharhinus falciformis in the Pacific Ocean. Samples and biological data were collected from Japanese tuna longline and purse seine fisheries from 1992 to 1999. Vertebra centra were picked from 145 males and 153 females for age determination. The number of annual rings observed for males and females was 0-8 and 0-13, respectively. Combined sex von Bertalanffy growth equations were obtained as follows: L_t=216.4(1-e^{-0.148(t+1.76)}) where L_t is precaudal length in cm at age t. A mature size for males was considered to be approximately 135-140 cm (precaudal length), with an estimated age of 5-6 years, whereas corresponding values for females were 145-150 cm and 6-7 years, respectively. Birth size ranged from 48 to 60 cm. There was no remarkable difference in growth, birth size and age at maturity between the Pacific and Atlantic Oceans. The life history parameters of the silky shark are approximately the same in both oceans.

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In the present study, we compared the advantage of marine protected areas (MPA) to the reduction of the fishing mortality coefficient (F). We accomplished this by comparing the yield per recruitment (YPR) and spawner biomass per recruitment (SPR) under two controls. This was accomplished using a mathematical model. We used the following five measures as comparisons: (i) the condition of the fishery where the increase in YPR is possible; (ii) the increase in YPR or SPR obtained by allocating half the fishing ground as an MPA and by reducing F by half; (iii) the maximum YPR obtainable when the fishing mortality coefficient or the proportion of MPA in the fishing ground is completely controlled; (iv) the proportion of the MPA and the reduction ratio of F required for attaining 30% SPR; and (v) the YPR obtainable while maintaining 30% SPR. Our results show that the MPA has a minor disadvantage in terms of the first measure. The MPA is advantageous in increasing SPR in the second measure, with a low migration rate of fish. The MPA is also advantageous in increasing YPR in the second measure, with some intermediate migration. The MPA is disadvantageous in the third measure. The MPA is advantageous in the fourth measure, with a low migration rate. The MPA is disadvantageous in the fifth measure.

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Predation by invertebrates may be one of the major factors influencing the mortality of released flounder juveniles in the field. We developed a polymerase chain reaction (PCR)-based technique for the detection of Japanese flounder material from the gut contents of potential predators in the field. The PCR primers used here are flounder specific and encompass a 153 bp region from the right domain of the mitochondrial control region. With these oligonucleotide primers, PCR reactions yielded specific amplification products from the gut contents of some putative predators, including Matuta lunaris, Portunus gladiator, Sepioteuthis lessoniana, Suggrundus meerdervoorti, Platycephalus sp. and Rhyncopelates oxyrhynchus. Many animals with gut contents of unidentified fish material showed indication of predation on the flounder after release of hatchery reared flounder juveniles. The technique developed in the present study is useful not only for the survey of predation on the flounder by known species, but also for the search for novel potential predatory species in the field.

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An apparatus to measure the locomotor activity of aquatic benthic organisms at variable low light levels was developed and the diurnal behavioral pattern of the abalone Haliotis discus discus was measured at various low light intensities. During the experiment, abalone were exposed to 12 h light-dark cycles of complete darkness, 0 μmol/m²/s throughout the 12 h dark cycle and, during periods I (days 1-8) and III (days 19-26), the 12 h light cycles were set at 10 μmol/m²/s. During period II (days 10-17), abalone were exposed to a light level during the 12 h light cycles of 1×10^-5, 1×10^-6, 1×10^-7 or 1×10^-8 μmol/m²/s and the changes in locomotor activity assessed. At daytime levels of 1×10^-5 μmol/m²/s, typical behavioral patterns were observed of high locomotory activity during the night-time cycle. However, at lower light intensities, the distinction between day and night activity patterns became less clear and, at intensities lower than 1×10^-7 μmol/m²/s, the difference between activity during the light and dark cycles became negligible. Based on this, we conclude that the threshold of light level perception in relation to locomotor activity is approximately 1×10^-7 μmol/m²/s. The significance of these results in relation to the entrainment of behavior in abalone is discussed.

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The present study was undertaken to assess the lipid composition and deposition in muscle at three anatomical locations in cultured yellowtail and to investigate the effect of lipid composition and deposition on meat texture. Lipid deposition in muscle was studied by histochemical staining of lipid with Sudan dye. Lipid class composition analysis showed that neutral lipids were the main constituents of lipid in cultured yellowtail and accounted primarily for the variation in muscle lipid content with the anatomical location of meat, as well as with season, whereas the polar lipid content remained almost constant. Furthermore, muscle neutral lipid content was correlated negatively with meat breaking strength; however, no correlation was observed between muscle polar lipid content and meat breaking strength. The histochemical study revealed that, in yellowtail muscle, lipid is preferentially deposited in the myosepta and, with increases in muscle lipid content, additional fat is deposited along sparsely distributed thin connective tissue. It was also observed that the greater the lipid deposition in collageneous connective tissue, the lower the meat breaking strength; presumably, higher lipid deposition in the connective tissue resulted in weakening of the muscle structure.

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The annual reproductive cycle, including the first maturity of ovarian development and plasma levels of testosterone (T) and estradiol-17β (E2), was examined in female Japanese catfish Silurus asotus reared under natural conditions. In addition, the possible period that final oocyte maturation and ovulation can be induced by human chorionic gonadotropin (hCG) injection were investigated. Results showed that female Japanese catfish matured 1 year after hatching under reared conditions. The beginning of vitellogenesis was in March and ovarian development and plasma T and E2 levels peaked in June. Thereafter, the gonadosomatic index gradually decreased to October and regression of oocytes at the tertiary yolk globule stage was observed. Female Japanese catfish could be induced to final oocyte maturation and ovulation by hCG treatment during the period from June to September. In addition, the fertilization rates were relatively high and stable during this period. These results suggest that yearling female Japanese catfish can be used as brood stock for seed production. This is the first study to investigate the annual reproductive cycle in Japanese catfish. These data will provide useful information regarding brood stock management and seed production.

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The Yatsushiro Sea and Shibushi Bay are, respectively, located on the western and south-eastern coast of Kyushu, southern Japan. The Yatsushiro Sea is a shallow semi-enclosed inland sea, whereas Shibushi Bay is an open-type bay with a deep and wide mouth facing the open sea. The size at sexual maturity and spatiotemporal patterns of reproduction of the kuruma prawn Marsupenaeus japonicus (Decapoda, Penaeidae) were examined and compared between these two regions. In the Yatsushiro Sea, the size at sexual maturity was estimated to be 131 mm body length. However, the estimated size at sexual maturity was considerably larger (154 mm) in Shibushi Bay. The spawning season of M. japonicus was estimated to continue from April to September in the Yatsushiro Sea, whereas it was estimated to be longer in Shibushi Bay, from March to November. It is believed that the warm water temperature due to the strong effect of the Kuroshio Current prolonged the spawning season of M. japonicus in Shibushi Bay. The spawning grounds were estimated to be in areas deeper than 10 m in the Yatsushiro Sea and deeper than 20 m in Shibushi Bay. In Shibushi Bay, body size distribution of mature females was considered to be less affected by water depth in comparison with the Yatsushiro Sea, although older mature females larger than 200 mm body length also spawned outside of the bay.

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Tropical minute rotifer strains (SS-type) induce mixis at 30-35°C but sexual reproduction and resting egg formation do not proceed well due to rapid environmental change. The present study examined the effect of temperature regulation on rotifer Brachionus rotundiformis (Langkawi strain, SS-type) resting egg formation in small (500 mL in culture volume)- and large-scale (500 L in culture volume) experiments. Rotifers were cultured at 30°C in 15-17 p.p.t. seawater with an initial density of 1 individual (ind.)/mL. After 4 days, when cultures were in exponential growth stage with active mixis induction, the culture temperature of the experimental rotifers was changed to 25°C. Control rotifers were cultured at 30°C throughout the experiment. Fresh or frozen Nannochloropsis oculata and condensed freshwater Chlorella vulgaris were used as the rotifer diets in the small- and large-scale experiments, respectively. Significantly higher resting egg production was observed with the experimental rotifers (30→25°C) versus the control rotifers. In the large-scale trial, experimental rotifers produced 2.6×10⁶ resting eggs during a 9-day experiment, which was 1.6-fold more than the control rotifers. Moreover, the efficiency of resting egg formation was found to increase by a factor of 1.8. The present study indicates that decreasing culture temperature from 30 to 25°C after active mixis increased resting egg formation in B. rotundiformis (SS-type).

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In order to simplify the food chain in a closed ecological recirculating aquaculture system, raw Spirulina platensis cultivated in 50-L photobioreactors were fed to tilapia Oreochromis niloticus as a uni-feed from the onset of exogenous feeding. The feasibility of using tilapia grown on raw Spirulina (body weight: 155.4±3.9 g, standard length: 16.2±0.2 cm; n=3) was investigated for 30 weeks for sashimi (sliced raw meat). Some of the rheological properties of the flesh were measured to clarify the obtained results of sensory evaluations of texture and fatness. The elastic modulus of flesh of the Spirulina-fed fish was significantly higher than that of the control fish (body weight: 168.9±5.8 g, standard length: 17.8±0.5 cm; n=3) that were fed commercial diets. In addition, the viscosity of the flesh of the Spirulina-fed fish was significantly lower than that of the control fish. There was no significant difference in the rupture strength between the two treatments. The rheological parameters in the muscle were found to coincide with the results of the sensory assessment. These results suggest that tilapia fed solely on raw Spirulina have a high flesh quality that is suitable for sashimi. The muscle lipid of the raw Spirulina-fed fish had lower levels of non-polar lipids such as triglycerides and partial glycerides, but higher levels of polar lipids such as phosphatidylcholine and phosphatidylethanolamine. The fatty acid profile of the raw Spirulina-fed fish muscle, especially in the polar lipid fraction, was characterized by an abundance of ∑n-6 highly unsaturated fatty acids (20:3n-6, 20:4n-6, 22:4n-6, 22:5n-6).

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The presented model involves the application of chaos theory to generate fish movements resulting from environmental stimuli. The model uses three steps within a model neural network such as input stimuli, central decision making and response output resulting in fish movements. The stimuli in the first step include the main abiotic and biotic factors, which could be quantified as an intensity parameter that was then normalized as a ratio between 0 and 1. The decision-making process can be generated using chaos dynamics with the stimuli parameters. The response of fish movements from the output signal representing movement speed and direction of fish can be re-regulated as main movement pattern depending on physiological state or life cycle by third response filtering. The simulation results seen as a movement pattern for sea bream and flounder using this neural chaotic model fitted very well to the observations of fish tracked in the sea by ultrasonic tracking methods. It was also revealed that the fish movement components generated as movement velocity and direction when in tidal flow had similar patterns to those patterns seen in field observations with similar irregular and chaotic variations with time.

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Two newly designed microparticle diets (MD), with two kinds of peptide (C700 and C800) as a protein source were developed. Microparticle diet Q (MD-Q) contained C700 (molecular weight -30000 Da) and C800 (molecular weight 1000-2000 Da); in contrast, microparticle diet T (MD-T) contained C700 only. Two separate trials, representing larvae from different hatches, were conducted. Japanese flounder Paralichthys olivaceus larvae were fed newly designed MD or a combination of them with live food (LF) between 3 and 10 days after hatching (d. a. h.) in experiment I, or between 11 and 20 d. a. h. in experiment II, and compared them to LF and a commercial diet (CD) feeding groups. The growth and survival rates in both experiments were the highest in the LF treatment. But in the microparticle treatment larvae fed MD-Q had a higher survival rate and better growth than those fed MD-T, either alone or in combination with LF. First-feeding larvae fed on MD-Q had a 20.5% survival rate and 1.12 mm gain by 10 d. a. h. Unfed larvae died within 6 d. a. h. These results indicate that using a mixture of different molecular weight peptides is good protein sources and also this type of microparticle diet can be applied to flounder from larval to juvenile stages.

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Because blood vitellogenin (Vg) has been considered a biomarker for environmental estrogens, the basal levels of Vg and 17β-estradiol (E₂) were determined in male Japanese whiting reared under natural conditions. Serum levels of Vg and E₂ were measured and gonadal development was assessed by gonadosomatic index (GSI) and histological observation in 8-10 male fish at monthly intervals throughout the annual reproductive cycle. Serum E₂ was <60 pg/mL throughout the study period. In contrast, serum Vg exhibited seasonal changes: serum levels of Vg gradually increased from April to May (mean 63±13 ng/mL and 124±48 ng/mL in April and May, respectively), and then reached a peak value (mean 352±68 ng/mL) in June. Thereafter, serum Vg gradually decreased, reaching undetectable levels (<50 ng/mL) in October. Serum levels of Vg tended to increase in the male fish in which the GSI was >1%. Histological observation revealed that testes in such male fish were in active spermatogenesis and then all of the testes of male fish in which serum Vg decreased to ND levels were regressed. These results suggest that Vg productive potency (sensitivity to estrogens) may increase in the spermatogenic stage, resulting in production of Vg in response to very low levels of natural or xenobiotic estrogens.

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The aim of the present paper was to provide some information on the distribution pattern and feeding habits of juvenile and young Lutjanus johnii in the Matang mangrove estuary on the west coast of Peninsular Malaysia. Sampling was carried out at five sites using otter trawl nets from October 1998 to January 2000. Ninety-three individuals of juvenile and young L. johnii were collected during the research period. The range in total length varied from 3.4 to 21.1 cm, and the gonads of all fish were at the immature stage. Fish were caught at the river mouth and neighboring sites in Matang at a water depth of 1.6-7.5 m, salinity of 12.4-28.3, and temperature of 27.3-31.6°C. Individuals fed mainly on Natantia and Mysidacea, although the type of food varied with size. Large-sized individuals fed mainly on Natantia, and small-sized individuals on Mysidacea.

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Young red-spotted grouper Epinephelus akaara with an average total length of 3.4 cm were divided into five groups in floating net-cages, and reared under satiated conditions with different feeding frequencies (0.5, 1, 2, 4 and 8 times per day) for 40 days. Total food intake increased with feeding frequency. Feeding four times per day resulted in the highest growth and food conversion efficiency. Total lipid accumulation in the muscle, liver and intraperitoneal fat body (IPF) increased with feeding frequency. Red-spotted grouper were found to contain a high proportion of docosahexaenoic acid (DHA) in the muscle. Fish fed 0.5 times per day were characterized as having a high proportion of DHA in triglycerides (TG) in muscle (80%), liver (69%) and IPF (18%). Increasing saturated fatty acids and a relative reduction of DHA were observed in the muscle TG as the feeding frequency increased. Frequent feeding accelerated the accumulation of eicosapentaenoic acid and saturated acids in the liver and IPF. Low saturated acids and a subsidiary proportional increase in DHA were the result of the low lipid reserves. A possible role for DHA and saturated acids are discussed with regard to lipid reserves.

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Age and growth of Sebastes vulpes collected from the coastal waters of western Hokkaido were studied. Observation of the otolith margin verified that annuli (outer margins of the opaque zone) were produced chiefly from July to August. This period was associated with parturition and the birth season. The maximum age estimated by the surface method was 12 years but the oldest fish was aged at 35 years by the cross-section method. The surface method was inadequate for aging of S. vulpes older than 6 years because of the underestimation of age. No significant difference was found in the parameters of the growth equations between both sexes. The von Bertalanffy growth curve combined for both sexes was as follows: SL_t=358.6(1-exp^{-0.156(t+0.820)}), where SL_t is standard length (mm) at age t (after parturition in years). It seems likely that S. vulpes grows slowly and lives longer than previously thought.

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Fish swim by undulatory contractions of the axial trunk musculature. It has been presumed that a descending signal from the brainstem activates central pattern generators in the spinal cord to make the swimming rhythm. In the carp the electrical or chemical stimulation of a mesencephalic nucleus, the nucleus fasciculi longitudinalis medialis (Nflm), could initiate swimming. However, it has not been established what signals originate from the Nflm in order to make the fish swim. The activity of the Nflm neurons was therefore examined electrophysiologically during fictive swimming in paralyzed carp. Three types of neuronal activities closely related to the swimming rhythms were obtained. The first type was a continuous tonic firing throughout an episode of fictive swimming. Neurons involved in this tonic activity may project to the spinal cord and contribute to the activation of spinal neurons to initiate fish swimming. The second type was accompanied by continual phasic firings occurring in rhythm with the activity of spinal motoneurons. Supposing that the swimming rhythm originates in the spinal cord, the synchronous activity in the brain neurons may suggest that in the nucleus there is a relay neuron conveying the rhythm information from the cord to other neurons there or in the brain. The third type exhibited reduced firing rates during fictive swimming. It is possible that the neurons engaged in this activity may be inhibitory and suppress the activities of other neurons in the nucleus and spinal cord during rest or during decelerating swimming.

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The fatty acid composition in horse mackerel caught off Nagasaki, off Tsushima Island, and in the middle of the East China Sea was investigated. The ratios of monoenoic and polyenoic acids to the total fatty acids in the Nagasaki and bull trawl catch specimens had a negative correlation. The docosahexaenoic acid (DHA; 22:6n-3) ratios of total fatty acids in summer-caught specimens were lower than those in winter-caught specimens, and this tendency was significantly clearer in smaller-sized fish, while DHA levels in tissues varied little throughout the year. Consistently high levels of DHA were found in various fishing areas, which suggests that horse mackerel offers a stable source of DHA.

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Seasonal changes in levels of chemical constituents in the abdominal muscle of male and female mud crab Scylla serrata were investigated. The gonadosomatic index in the female crab was higher in October and August, of which the muscle yield, glycogen, and total amount of adenosine 5'-triphosphate (ATP)-related compounds (ARC) in the October sample were the highest throughout the year, but the total amount of free amino acids (FAA) was the lowest. The total FAA and individual FAA such as glycine, alanine, and arginine increased in the August and November female samples, while that in the male specimens was higher in January, March, and August. The total ARC in both crabs was lower in the samples collected from winter than in other seasons whereas glycinebetaine was higher in winter and early spring. Glutamic acid, glycine, alanine, arginine, glycinebetaine, and adenosine monophosphate might be responsible for the taste of mud crab. Their level together was relatively higher in the August and January male samples, and in the August and November female specimens. However, the correlation between the taste component content and degree of gonad maturation was low.

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Formaldehyde (FA)-induced denaturation of myofibrillar proteins and its prevention were investigated by means of measuring the solubility, adenosine triphosphatase (ATPase) activity, and thermal gel formability of myofibrils and surimi proteins in the presence and absence of free amino acids and glutathione, reduced form. The addition of FA decreased the solubility of myofibrils in 0.5 M NaCl at pH 7.0 and 0°C depending on its concentration and incubation time. The solubility decrease was completely inhibited by the presence of equal, twofold, and threefold amounts of cysteine (Cys), glutathione, and histidine (His) to the amount of FA, respectively. Myofibrillar Ca-ATPase was markedly activated at the initial phase and then decreased later by the addition of FA. The K-ATPase was inactivated with an increase in the amount of FA. The FA-induced changes in both ATPase activities were inhibited in the presence of Cys and His. Thermal gel formability of surimi paste increased only in a short period after the addition of a low concentration of FA. Practically, FA inhibited the thermal gelation and setting effect through the inactivation of transglutaminase. In the presence of Cys, His or glutathione, a strong elastic surimi gel was produced because FA-induced detrimental effects were inhibited.

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The cytochrome P450 (CYP) represents a large group of microsomal monooxygenases that catalyze drugs as well as a host of lethal environmental contaminants such as dioxins, leading to either detoxification and excretion from the animal or generation of carcinogenic intermediates. In the present study two forms of cDNA were cloned (Eu MC1 and Eu MC2) for European eel CYP1A genes by polymerase chain reaction (PCR) techniques. The cDNA of Eu MC1 was 3368 bp long coding 521 amino acid residues, and that of Eu MC2 was 2464 bp long coding 517 amino acid residues. Identities of deduced amino acid sequences between Eu MC1 and Japanese eel CYP1A1 and that between Eu MC2 and the second form of Japanese eel CYP1A were 98% and 97%, respectively, showing decisively that Eu MC1 and Eu MC2 are orthologous to Japanese eel CYP1A1 and the second form of CYP1A, respectively. A striking difference between the two eel species was that the Eu MC1 peptide was two amino acid residues longer than that of the Japanese eel CYP1A1. Existence of two loci of CYP1A in Japanese and European eels may suggest that the two forms of CYP1A exist widely among the eel species, because the divergence between the two eel species has been shown to be close to the basal divergence among eels. The identities in CYP1A may help to estimate genetic distance between European and Japanese eels.

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Glucose has been implicated in functioning as a form of carbon translocated from symbiont zooxanthellae to the host coral cell. The present paper describes the lipid biosynthesis from [¹⁴C]-glucose in the coral tissue. To study the incorporation of [¹⁴C]-glucose into lipids, the branch tips of the coral Montipora digitata were incubated with [¹⁴C]-glucose or another radiolabeled substrates. The lipid biosynthesis from [¹⁴C]-glucose was dependent on light, and was decreased by dark conditions or by photosystem II inhibitor, 3-(3, 4-dichlorophenyl)-1, 1-dimethylurea. Of the lipid classes, the light dependency was more pronounced with the biosynthesis of triacylglycerols (TG) and wax compared with phospholipids. Examination of [¹⁴C]-label distribution in the glycerolipids suggested that [¹⁴C]-glucose supplied mainly the fatty acid moiety of newly synthesized TG, while [¹⁴C]-glucose provided evenly the fatty acid moiety and the glycerol skeleton of phospholipids. The comparison of [¹⁴C]-labeling of lipid from host coral tissue and symbiont zooxanthellae suggested that [¹⁴C]-glucose entered the coral cell and was processed in parallel in the zooxanthellae and host cells. Furthermore, the coral cells used various [¹⁴C]-labeled sugars for lipid synthesis with similar lipid labeling profile as was the case for glucose. The current study thus supports the view that the low-molecular-weight compound, sugars and amino acids, once translocated from zooxanthellae to host cell were metabolized toward lipogenesis as well as glycerol.

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A method of introducing protease inhibitors into fish muscle through the bulbus arteriosus was developed using an in situ perfusion technique. Perfusion efficiency was initially tested using eosin and [³⁵S]-methionine. Visible fluorescence was observed in the gill, liver, intestine and dorsal muscle of the eosin-treated tilapia, and the occurrence of eosin in the blood vessels of the dorsal muscle was confirmed under a fluorescence stereoscopic microscope with ultraviolet light. The radioactivity of [³⁵S]-methionine was taken into the dorsal muscle and liver at a concentration of 7.8 Bq/g and 70.2 Bq/g, respectively, after perfusion with 1000 Bq/mL solution. Using the perfusion technique with four kinds of protease inhibitors dissolved in physiological saline, the type of proteases implicated in the post-mortem muscle softening in tilapia (867±195 g, n=10/protease inhibitor) was investigated. After the perfusion of leupeptin (serine and cysteine protease inhibitor), benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-fmk; caspase inhibitor), chymostatin (serine protease inhibitor) and O-phenanthroline (metalloprotease inhibitor), the breaking strength of the perfused muscle was measured as a parameter of the meat toughness and compared with that of the control fish, which were perfused with physiological saline only. The reduction of breaking strength during storage was inhibited by the perfusion of leupeptin and Z-VAD-fmk.

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Four steroidal ketones were isolated from the holdfast of cultivated Laminaria japonica. The structures were characterized as ergosta-4, 24(28)-diene-3-one (1), ergosta-4, 24(28)-diene-3, 6-dione (2), stigmasta-4, 24(28)-diene-3-one (3) and stigmasta-4, 24(28)-diene-3, 6-dione (4), by spectral data. Compounds 2 and 4 were shown to be cytotoxic against the MCF-7 human breast cancer cell, and the growth of MCF-7 was inhibited by 96% and 79%, respectively, at 10 μg/mL. It is the first report on the isolation of cytotoxic steroidal ketones from the kelp in the genus of Laminaria.

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The liver oils of five dominant shark species, Alopias superciliosus, Carcharhinus falciformis, C. longimanus, Prionace glauca, and Sphyrna lewini, in the Indian Ocean were studied for their lipid classes, fatty acid and triacylglycerol (TAG) molecular compositions, in order to understand and identify the inter species changes and possible utilization avenues. The livers showed 26.1-60.1% oil content regardless of the gender or species of shark. Triacylglycerol was the predominant lipid class (65.2-86.1%) in all species followed by sterol esters (2.9-12.7%), hydrocarbons (2.5-11.6%) and diacylglyceryl ethers (1.0-3.8%). The major fatty acid in total lipid and TAG was docosahexaenoic acid (C22:6n-3; DHA), which in male S. lewini was at remarkable levels (43.4%). The predominant fatty acid combinations of TAG molecules in all shark species were palmitic, DHA and oleic acids (PDO 12.5-19.9%), and palmitic, DHA and palmitic acids (PDP; 8.4-15.4%). Tridocosahexaenoin was found in considerable levels in S. lewini (male).

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