The behavior of the cuttlefish Sepia esculenta near basket traps was observed in the field and in the laboratory in order to analyze the capture process of basket traps. In the field, cuttlefish spawned both during the day and the night and mainly outside the traps. This finding negates the conventional idea that the entry of cuttlefish into traps is motivated by spawning. Cuttlefish entered and exited from the trap in a straight movement with the arms first, as in feeding. No cuttlefish touched the trap during these movements, which means that the reaction of cuttlefish to traps is mediated by vision. Cuttlefish inside the trap moved very slowly, not evasively, and they remained inside for at least 2 days. This behavior indicates the existence of an attractive stimulus within the trap. In laboratory tanks, individuals repeatedly entered the trap. Because the average length of stay of six cuttlefish in the trap in the first entry (6 h 18 min) was less than in the sixth entry (8 h 19 min), exploratory behavior cannot explain the behavior of cuttlefish entering basket traps.

抄録全体を表示

The sensory basis of the behavior of cuttlefish towards basket traps explains in part the mechanism of capture by the gear. Previous studies have shown that the reaction of cuttlefish Sepia esculenta to basket traps is mediated mainly by vision. In this study, visual factors that attract cuttlefish to basket traps were examined in the laboratory. The reaction of cuttlefish was divided into three processes of recognition, approach, and entry; the frequency and the duration of each process indicated the strength of the reaction. Cuttlefish were most attracted to a basket trap that contrasted most strongly with the background. When the dismantled components of the basket trap were presented as visual targets to cuttlefish, all the components were approached by the cuttlefish, which remained in the internal space. Cuttlefish have a habit of occupying the internal space of a structure and this habit seems to be the main motivation for entry into a trap. Another experiment was carried out to examine the social attraction between individuals inside and outside a trap. Social interference between males and females seems to be part of the mechanism of capture of cuttlefish by basket traps.

抄録全体を表示

Bimonthly field investigations of the seasonal foraging activity of the sea urchin Strongylocentrotus nudus were carried out in Oshoro Bay of Hokkaido, Japan. Migration of the marked sea urchins transplanted to a fixed 9 m square site (81 divisions, each 1 m square) on coralline flats with the brown alga Laminaria religiosa set in the center division was monitored. The highest foraging activity was observed in July when the gonads of the sea urchins were in the growth stage, and high water temperature was 19.9-20.7°C. No foraging behavior was observed in September and November due to their maturation and spawning, while the sea urchins migrated actively. In January, neither foraging nor migration occurred due to the low water temperature of 4.0-5.0°C. A little foraging activity was observed in March when the gonads were again in the growth stage. In May 1992, when the gonad index was higher than that in July of the previous year, foraging activity was low, while active migration was observed. It is considered that the time when S. nudus forage actively, during spring and summer, alters due to annual fluctuations in their gonadal development attributable to the biomass of the algal community on which they feed.

抄録全体を表示

The present study was carried out to reduce the total phosphorus loading (T-P) from carp by replacing dietary fish meal with alternate proteins (blood meal and defatted soybean meal). The experimental diets were formulated according to the Lake Kasumigaura Standard (crude protein < 35%, digestible energy > 3.5 kcal/g) and contained fish meal at the levels of 10, 15, 20, 25, and 30%. The dietary total phosphorus (P) contents were between 0.9 and 1.4%, and water extractable P (available P for carp) ranged from 0.55 to 0.70%. Duplicate groups (n=50) of carp (average weight 2.2 ± 0.3 g) were fed one of the five experimental diets to satiation, three times a day for 12 weeks, at 20.0 ± 1.6°C. T-P from each group was determined based on water extractable P and the rate of P absorbed and retained in carp. The growth performance was highest in fish fed the diet containing 25% fish meal followed by 30%, although there was no marked difference between the treatments except for the 10% fish meal group. The feed gain ratio ranged between 0.96 and 1.14. The values for T-P (kg/t carp production) were effectively reduced by decreasing dietary fish meal levels, and ranged from 5.9 for the 10% fish meal diet to 9.6 for the 30% fish meal diet. However, low fish meal diets with high amounts of alternative proteins resulted in high nitrogen loading, therefore, a suitable level of fish meal in carp diet was estimated to be 20-25%, under the present feeding conditions, substituted by a combination of blood meal and defatted soybean meal.

抄録全体を表示

Allozyme variation of diploid loach Misgurnus anguillicaudatus was examined in samples collected from 44 localities in Japan. Genetic differentiation was estimated based on allele frequencies of 12 enzyme loci. Nine loci (36.9%) were polymorphic (< 0.95 in major allele frequency) and average heterozygosities were unusually high (Ho=0.110 ± 0.051, He=0.131 ± 0.052). The coefficient of gene differentiation (Gst=0.774) suggested high genetic differentiation among populations. Based on the unweighted pair-group method using arithmetic averages (UPGMA) dendrogram, loach populations were grouped into six clusters. The population of Memanbetsu, Hokkaido (group 1) was remarkably different from others (D=0.286). Populations distributed in Niigata, Nagano, Tochigi, Saitama, Chiba and Shizuoka Prefectures (group 6) were also genetically distinct from other loaches (D=0.192). These results suggest genetic differentiation among groups 1, 6, and other loaches may be inter-subspecies level. Other loaches could be separated to four clusters (groups 2-5) at D=0.100-0.065. Genetic differentiation among them seems to be at local race level.

抄録全体を表示

In order to elucidate the regulation of gonadotropin (GTH) gene expression by gonadal sex steroids, the effects of ovariectomy and sex steroid administration on pituitary mRNA levels of GTH subunits were examined in goldfish. Ovariectomy caused a marked increase in GTH Iβ mRNA levels, and steroid hormone replacement (testosterone, T; estradiol-17β, E₂; and 11-ketotestosterone, KT) suppressed the elevated levels in sexually early recrudescent and mature females. Pituitary mRNA levels of α and GTH IIβ were not affected by ovariectomy and steroid hormone treatment. When sex steroids (T, E₂, and KT) were administered to sexually immature juvenile fish, GTH Iβ mRNA levels were suppressed as observed in adult fish. However, GTH IIβ mRNA levels were observed to increase by sex steroids (T and E₂ but not KT) unlike that observed with adult fish. These results indicate that sex steroids exert an inhibitory effect on GTH Iβ mRNA levels from the time goldfish are immature to the time they are mature. However, sex steroids (T and E₂) have a stimulatory effect on GTH IIβ mRNA levels in juvenile goldfish and the effect becomes less pronounced when they become adult.

抄録全体を表示

This paper estimates the age and growth of the alfonsino Beryx splendens in the waters around the Izu Islands off the Pacific side of Japan. The samples consist of 250 fish of the landings of the offshore longliners from December 1995 to November 1996 and 10 fish of the coastal longliners in February of 1995. By the surface method using a microscope, a reader counted the number of hyaline and opaque zones on the sagittal otoliths, judged whether the edge was hyaline, and measured the radii from the focus to the outer edge of each hyaline zone. In order to estimate the parameters of the von Bertalanffy's growth equation representing the overall ages, the age and fork length data and the mean length at 1 year old. In a previous study were used for the maximum likelihood approach. From the results, the rate of readability of the otolith from the offshore samples was 97.6% and that from the coastal samples was 100%. The monthly changes in the frequency of the opaque edge showed that the hyaline and opaque zones were laid down once a year. The hyaline zone began to form from May to July (peaking in August). The ages of the offshore samples for both the sexes ranged from 2 to 23 years, and those of the coastal samples 2 to 5, respectively. The estimated growth curves were expressed by l(t)=44.4[1-exp{-0.132(t+3.45)}] for males and l(t)=45.0[1-exp{-0.150(t+2.08)}] for females, where l (t) and t denote the fork length (cm) and the age in years, respectively. The issues to be resolved in the future were discussed.

抄録全体を表示

A specific lot of sodium chloride (NaCl) has a contaminant toxic to the growth of Nannochloropsis oculata. This toxic effect was markedly reduced by co-culture with Flavobacterium sp., and such detoxifying ability was specific to this bacterial strain. Bioassays of the NaCl after heat treatment and ultrafiltration indicated that the NaCl was contaminated with heat-labile organic compounds of low molecular weight. Chemical analysis indicated that one contaminant in NaCl had analogous structure to a fungicide tridemorph. Commercially available tridemorph showed a toxic effect on N. oculata, and it was reduced by co-culture with Flavobacterium sp. These results indicate that the tridemorph-like substance is a causative factor for the growth inhibition of N. oculata, and that Flavobacterium sp. has an ability to detoxify the contaminant as well as tridemorph. The detoxifying ability of Flavobacterium sp. has the potential to be widely applicable for removing the trace pollutants affecting the growth of microalgae.

抄録全体を表示

The present study proposes a method for calculating and estimating relative biomass of recruits of fish stock using catch and effort data. The relative biomass of the recruits is defined by the product of the absolute biomass of recruits and the catchability coefficient. Assumptions are that the catch per unit of effort (CPUE) is proportional to the total biomass of the recruited stock, that the recruitment suddenly occurs just before the beginning of the fishing season, and that such biological parameters as natural mortality coefficient and growth coefficient are small in magnitude. From these assumptions, an approximation equation for calculating the relative biomass of recruits, which uses only the CPUE and the effort, was derived. The maximum likelihood procedure was proposed for the parameter estimation. The accuracy of the equation was examined by the simulations. The method was applied to the data of the setline fishery exploiting the Pacific halibut, Hippoglossus stenolepis. The results showed that the extent of the discrepancy of the equation was small and that the annual changes in the recruitment biomass of the halibut was periodical. The interpretation of the results and the issues to be solved in the future are discussed.

抄録全体を表示

We generated 196 expressed sequence tags (EST) from a Japanese eel Anguilla japonica spleen cDNA library. Of these, 90 EST (46%) showed no homology to known genes, while 106 EST (54%) showed homology to known genes and transcripts. Of the 106 homologous EST, 13 were homologous to 12 different immune-related genes, 46 were homologous to 33 different ribosomal proteins, three were homologous to the 28S rRNA gene, 10 were homologous to eight different mitochondrial genes and the remaining 34 encoded 28 different identified genes. Six identified EST are similar to previously reported EST of Japanese flounder Paralichthys olivaceus spleen cDNA. These analyses demonstrate the utility of EST and sequence-tagged clones in comparative studies of gene expression in the fish spleen.

抄録全体を表示

The morphological and physiological characteristics of Pythium sp. isolated from Wando, Korea, were compared by the general mycological characteristics, behaviors to environmental conditions (e.g. temperature, pH, and salinity) and nutritional requirements for growth with those isolated from Fukuoka, Miyagi and Aichi, Japan. The number of hyphal swelling per visual field (31 mm²) of the isolate from Wando was significantly higher (P < 0.05) than those of the Japanese isolates. The other morphological characteristics of the four isolates differed slightly. The four isolates grew at between 5 and 30°C, and at between pH 5 and 8.5. The optimal seawater concentration for growth of the isolates from Wando and Fukuoka was 80%, while those from Miyagi and Aichi was 50%. Growth responses of mycelium were high on bovine serum and laver extract in the isolates from Wando and Fukuoka, and on bovine serum and yeast extract in the isolates from Miyagi and Aichi. Growth responses for the carbon and nitrogen source of mycelium were the highest on starch and DL-methionine in the isolate from Wando, and on D-glucose and L-aspartate in the isolates from Fukuoka and Aichi, and on D-glucose and DL-methionine in the isolate from Miyagi, respectively. It is apparent that nutritional requirements of the four isolates differed slightly. Since the morphological and physiological characteristics of four isolates resemble each other well, the isolate from Wando seems to be Pythium porphyrae.

抄録全体を表示

The productive structure and productivity of a Sargassum macrocarpum C. Agardh population were studied from June 1993 to July 1994 in Fukawa Bay facing the Sea of Japan, Yamaguchi Prefecture. S. macrocarpum formed a dense population at a depth of 8 m in the study area. Using the stratified clip technique, monthly changes in the productive structure from 1993 to 1994 were clarified. The dry weight of leaves and main branches increased with the elongation of branches. Thalli in the middle to high stratum began to bear receptacles from March 1994 and the dry weight of receptacles was approximately one-third of the standing crop in June. The loss of leaves increased from April to June 1994, and the loss of main branches and receptacles from June to July 1994. Productivity of branches and receptacles reached maxima of 4.67 g dry wt/m² per day from February to March and 5.33 g dry wt/m² per day from April to May, respectively. Productivity of the leaves, however, was almost constant at approximately 2 g dry wt/m² per day from July 1993 to March 1994. Therefore, maximum productivity of the S. macrocarpum population of 7.17 g dry wt/m² per day occurred from February to March. Annual net production of newly sprouting branches in June 1993 was 1600.1 g dry wt/m² per year based on the summation method, which was calculated from the monthly changes in the productive structure.

抄録全体を表示

Two puerulus larvae of the spiny lobster Panulirus longipes were successfully obtained through the rearing of newly hatched phyllosoma larvae fed with diets of Artemia and gonads of the mussel, Mytilus galloprovincialis, in the laboratory. Their durations of phyllosoma were 281 and 294 days, respectively, at 26.0°C during initial 110 days of rearing and thereafter 24.5°C. The numbers of instars in their phyllosoma phase were estimated at 21 and 23. Based on the morphological features of 55 specimens, the phyllosoma phase of P. longipes was divided into 10 stages. The present study provides a description and illustration for each stage. Body length in stage I was 1.78 mm, an average (n=4), and in stage X it was 34.6 mm (n=1). The present study cannot show the morphological differences between phyllosoma larvae of P. longipes and Panulirus japonicus.

抄録全体を表示

Positive taxis toward turbid seawater (turbiditaxis) is a well-known key factor in the formation of Shirasu (Japanese anchovy larvae, Engraulis japonicus) fisheries in coastal waters. The physical characteristics of turbid seawater, including color, particle size, underwater light intensity, and scattered light intensity, were studied to examine the mechanism by which turbidity lures the larvae using four food colors, polishing powder, and five water colors. The results of taxis tests comparing turbid materials with different characteristics, led to the conclusion that the scattered light intensity of turbid seawater was the key factor causing positive turbiditaxis in anchovy larvae.

抄録全体を表示

To assess the number of mitotic divisions in fish spermatogonia, an easy method was devised which can estimate the number of mitotic divisions by only counting the cells in the cross-section of a cyst at its largest diameter. Using clay to simulate spermatogonial cysts, we obtained results which related the number of cells in a cross-section of a cyst at its largest diameter to the total number of cells in the same cyst. The results were then compared to the number of mitotic divisions observed in seven species. The number of divisions estimated from the simulation experiment coincided exactly with the observed values in all species with spherical shaped cysts. However, the counts determined in fish with elliptical shaped cysts differed from the expected values. As a result, it is clear that the obtained values from the simulation experiment are valid for the estimation of the number of mitotic divisions.

抄録全体を表示

To estimate the debility and death of a harbor seal Phoca largha stranded on the coast of Toyama Bay, Sea of Japan, on 3 March 1998, histopathological studies on the visceral organs were carried out. Abnormalities were found in four of the organs examined: considerable proliferation of actively phagocytic macrophages in the lymph node; heavy inflammation of the jejunum villi; a benign cortical adenoma in nodules present in the kidney; and a signet ring cell carcinoma (adenocarcinomatous mucocellulare) associated with a marked scirrhous cancer developed in the stomach. The mucocellular carcinoma seemed to have been a main factor in the death of the seal.

抄録全体を表示

To estimate the quantitative adequacy of amino acids in practical dietary proteins, free amino acid (FAA) levels in various tissues of rainbow trout Oncorhynchus mykiss fed different protein sources were compared. Four diets, the proteins of which were derived mainly from fish meal (FM diet), soybean meal (SBM diet), malt protein flour (MPF diet), and the combination of SBM and MPF (COMB diet), were fed to duplicate groups (30 fish/group, 10 g/fish) for 6 to 9 weeks at 15°C, until each treatment group reached the weight of the FM diet group attained in 6 weeks. The fish for FAA analysis were sampled 12 h after the last feeding. The body weight of the FM group was attained in 7 weeks by the COMB diet group, and in 9 weeks by the SBM and the MPF diet groups. Concentrations of free threonine, methionine, and lysine in most of the tissues of the COMB diet group, as well as the SBM and the MPF diet groups, were quite lower than those of the FM diet group. Levels of these amino acids between the four diets and most of the tissues examined were highly correlated. Although the threonine content in the COMB diet was slightly lower than the FM diet, these findings suggest that not only methionine and lysine but also threonine is still insufficient in the COMB diet.

抄録全体を表示

The zero-year red sea bream Pagrus major were fed for 41 days on dry pellets containing 1% Teaflan (60% catechin) or Spirulina supplement. The effects of catechin and Spirulina on ascorbate absorption, lipid metabolism, and collagen synthesis were compared in relation to vitamin C nutrition. Total ascorbate concentrations in the serum and liver were increased significantly in the catechin-fed groups relative to the control, but Spirulina increased in value only in liver. Feeding with catechin and Spirulina depressed non-esterified fatty acid and total lipid in serum, respectively. Liver lipid was depressed by feeding catechin and Spirulina. Hepatic free carnitine and long-chain acylcarnitine contents were markedly higher in both catechin- and Spirulina-fed groups than in the controls. Hepatic carnitine palmitoyltransferase activity was markedly elevated in the Spirulina-fed group. In contrast, glucose-6-phosphate dehydrogenase and fatty acid synthase activities were not different among the groups. The collagen fraction soluble at 20°C was lower and the insoluble collagen fraction (not soluble at 70°C) was higher in catechin- and Spirulina-fed groups. These results suggest that dietary supplementation with catechin, as well as Spirulina, improved vitamin C metabolism in young red sea bream.

抄録全体を表示

This paper describes a method of evaluating virtual codend selectivity with covernet selectivity when the mesh size of the covernet is not small enough to retain all the fish that enter the covernet. If the covernet mesh size is not small enough, small fish can escape through the covernet mesh after passing through the codend, and then their body length proportion retained in the codend will be overestimated. We developed a model in which covernet selectivity can be estimated at the same time as accurate codend selectivity. The validity of the method was examined with data from a covered-codend experiment on the Patagonian grenadier Macruronus magellanicus collected in the southwest Atlantic. The model fits the data well even though the plots of proportion retained were U-shaped. For both the codend and covernet selectivity estimated in the model, fish of length close to 100% selectivity had a girth close to mesh perimeter. This supported that both the codend and covernet selectivity estimated in the model were reasonable. The analysis proposed in the present study would be useful to obtain accurate estimates of codend selectivity by evaluating the effects of covernet selectivity on the data.

抄録全体を表示

Matrix metalloproteinases (MMP) are widely distributed in vertebrate tissues. One of the well-characterized gelatinases from higher vertebrates is MMP-2, named gelatinase A or 72 kDa type IV collagenase, which is active for the cleavage of denatured collagens, type IV collagen, type V collagen, and other matrix proteins. To investigate the primary structure and properties of MMP-2 from teleost as lower vertebrates, a cDNA library was prepared from mRNA of rainbow trout fibroblast and screened. Using polymerase chain reaction and degenerate oligonucleotide primers, which are specific for two highly conserved sequences found in MMP of higher vertebrates, a resultant cDNA fragment was used as a probe. A cDNA clone 3.0 kb long was isolated and found to contain an open-reading frame coding for a polypeptide of 655 amino acids. The rainbow trout polypeptide was 73% identical, at the level of amino acid sequence, to human proMMP-2 with the greatest degree of similarity occurring in the propeptide and catalytic domains and was denoted as rainbow trout proMMP-2. Then the isolated cDNA was expressed in Escherichia coli and the recombinant protein was found to degrade gelatin and human type V collagen, providing support to the hypothesis that the cDNA codes for the authentic rainbow trout proMMP-2. In contrast to human proMMP-2, rainbow trout proMMP-2 was not activated by 4-amino-phenylmercuric acetate. This is the first report of cDNA for fish proMMP to our knowledge.

抄録全体を表示

The reason why bitterness of the autolytic extract is enhanced by shaking during autolysis was investigated from the viewpoint of improving the taste of the extract from fish wastes. Two kinds of extract were prepared from the head-viscera mixture of frigate mackerel after autolysis with (S1) and without shaking (S2). A comparison of the two extracts showed significant differences in their organoleptic and chemical properties. More brown in color, S1 tasted much more bitter than S2, while S1 gave lower contents of free amino acids, higher thiobarbiturate (TBA) values and a smaller ratio of polyunsaturated fatty acids to the total ones. This indicates that lipid oxidation occurred more vigorously in S1 than in S2. Furthermore, it was found that the increase in the bitterness and in the loss of free amino acids was correlated with the increase in TBA values of the extract. In conclusion, lipid oxidation accelerated by shaking during autolysis contributed to the enhanced bitterness and brown discoloration and to the loss of free amino acids of the autolytic extract from fish wastes.

抄録全体を表示

The amino acid sequences of myosin rod containing subfragment-2 (S2) and light meromyosin (LMM) were determined by cDNA cloning for walleye pollack fast skeletal myosin heavy chain. While S2 and LMM were composed of 442 and 656 amino acid residues, a total of 1937 amino acid residues accounted for the whole myosin heavy chain molecule with previously determined sequence for the subfragment-1 heavy chain region of this fish. Both regions for S2 and LMM showed a seven-residue repeat pattern characteristic to fibrous proteins with a coiled-coil structure of two α-helices, displaying a, b, c, d, e, f, and g where positions a and d were frequently occupied by hydrophobic amino acids and c and g often contained charged residues. The occurrence of a 28-residue unit with repetitive sequence was also strongly suggested, when one and three skip residues were adopted into S2 and LMM, respectively. Thus, walleye pollack S2 and LMM consisted of 17 and 24 zones with a 28-residue repeat rearrangement. There were several amino acid substitutions which might account for a low thermal stability of walleye pollack myosin heavy chain in comparison with the sequences of higher vertebrate counterparts. However, it seemed difficult to interpret such low stability only from the comparison in the 28-residue repeat arrangement at the primary structure.

抄録全体を表示

A lipoxygenase was found in the crude enzyme solution from the gills of carp, Cyprinus carpio. It oxidized arachidonic acid (AA) more efficiently than linoleic acid, eicosapentaenoic acid and docosahexaenoic acid. Lipoxygenase activity was constantly detected in the gill microsomes and was found to be optimum at pH 7.2. It was not stimulated by reduced nicotinamide adenine dinucleotide phosphate and was not inhibited by SKF525A, a cytochrome P450 inhibitor. The oxygenated products extracted from the reaction mixtures of crude enzyme solution and AA were purified by reverse-phase and straight-phase high-performance liquid chromatography (HPLC). The major metabolite was identified as 12 (S)-hydroxyeicosatetraenoic acid (12 (S)-HETE) by ultraviolet spectrophotometry, gas chromatography-mass spectrometry and chiral phase HPLC. In addition, 12-hydroxyeicosapentaenoic acid (12-HEPE) and 13-hydroxyoctadecadienoic acid (13-HODD) were also found in the reaction products as minor components. Similar results were obtained by the analysis of the reaction products of AA and carp gill microsomes. These results confirm the presence of 12-lipoxygenase in carp gill microsomes.

抄録全体を表示

The present study was aimed at a physique index which enabled to evaluate the fat mass in fish body by using the data of standard body length (BL) and body weight (BW) for cultured sea bream at various growth stages. The relationships between BL and BW and between BL and lean body mass weight (LBM) were (BW/BL^2.840)×10³=52.65 and (LBM/BL^2.819) × 10³=49.74, respectively. Then, we gave a definition to the relationship between BL and BW as (BW/BL^α)×10³=physique index, evaluated the correlation coefficient between the physique index value to several power values of α and fat content in each part of fish body. The α value attained to the maximum level on the correlation coefficient was 2.548 for the muscle part, 2.775 for the visceral part, 2.916 for the dorsal ordinary muscle, and 2.823 for the whole body. The α value of 2.823 in the whole body was closely similar to 2.819 of the α value between BL and LBM. Moreover, the correlation coefficient at 2.823 of the α value gave a significantly high level of P<0.001, not only in the case of the fat content of the whole body, but also in any case of the muscle part, visceral part, and dorsal ordinary muscle. Therefore, we named this physique index, (BW/BL^2.823)×10³, the TM index, and proposed it as an index to reflect the amounts of the whole body fat.

抄録全体を表示

As a means of effective utilization of fish water-soluble proteins (FWSP), which are mostly discarded into the waste water of seafood processing plants, the development and characterization of edible films from FWSP of blue marlin meat were investigated. The film-forming solutions were prepared from 3% FWSP solutions at pH 10 with 1.5% glycerol as a plasticizer, followed by heating at 70°C for 15 min. Edible films were successfully prepared by drying the film-forming solutions at 25°C for 20 h. It was revealed that FWSP had to be denatured somehow to unfold the protein structure, and the interaction of FWSP molecules, particularly through disulfide linkages, was attributed to the formation of films. Transparent edible films thus formed had better flexibility and lower water vapor permeability compared with most of the other protein films.

抄録全体を表示

In order to clarify the effects of habitat temperatures on crustacean myofibrillar ATPase activities, the activities were measured in the muscle of American lobster Homarus americanus and Japanese spiny lobster Panulirus japonicus. Magnesium (Mg²⁺)-ATPase activities of the Japanese spiny lobster in the presence and absence of calcium (Ca²⁺) were lower than the corresponding activities of the American lobster. The American lobster lost Ca²⁺ sensitivities in myofibrillar Mg²⁺-ATPase activities over 35°C, while the Japanese spiny lobster lost sensitivities over 40°C. Inactivation profiles in Mg²⁺- and Ca²⁺-ATPase activities showed that myofibrillar thermal stability of the American lobster was lower than that of the Japanese spiny lobster. No seasonal change in Mg²⁺-ATPase activity was observed in either species. These results suggest that the myofibrils of both lobster species would adapt to their habitat temperatures.

抄録全体を表示

Bluefin tuna (Thunnus thynnus) meat, wrapped with or without polyethylene film, was stored at 4°C and relative humidity of 100%. Decrease in Hunter's ‘a’ and increase in ‘L’ were observed in both samples during 120 h storage. Metmyoglobin (metMb) reductase activity of both samples decreased, while the metMb increased with the duration of storage. The nicotinamide adenine dinucleotide (NADH) of tuna meat increased during the first 56-80 h of storage, but decreased again during the further storage. Although the nicotinamide adenine dinucleotide phosphate (NADPH) of both wrapped and unwrapped samples decreased with the duration of storage, the total amount of NADH and NADPH seemed to remain at a constant level during the first 80 h storage and then significantly decreased during further storage. The metMb reductase is an important factor affecting the accumulation of metMb of refrigerated tuna.

抄録全体を表示

As a first step in understanding the mechanism of vitellogenesis in the kuruma prawn Penaeus japonicus, biochemical characteristics of vitellin (Vt) were investigated. Vitellin was purified from vitellogenic ovary by gel filtration and ion-exchange chromatography, and an anti-Vt antiserum was raised in rabbits. The molecular weight of the purified Vt was estimated to be 530 kDa by native-polyacrylamide gel electrophoresis and gel filtration. Vitellin was composed of three polypeptide subunits of 91, 128, and 186 kDa in sodium dodecylsulfate-polyacrylamide gel electrophoresis. The 91 kDa subunit was further purified by reversed-phase high-performance liquid chromatography. A protein sequencer was used to analyze the amino-terminal amino acid sequence of the 91 kDa subunit; residues up to position 29 were identified, except for two residues at positions 10 and 14. Positive immunohistochemical reaction against the anti-Vt antiserum was observed in the cytoplasm of oocytes at endogenous and exogenous vitellogenesis stages.

抄録全体を表示