The small semelid bivalve Theora lubrica, a selective deposit-feeder, predominated on the extreme surface of soft muddy sediment in the eastern area of Hiuchi-Nada, the Seto Inland Sea, where thermal stratification was formed in late smnmer, 1983.
At three main habitats suitable for the bivalve, which were separated mutually by the deeper basin of a depth more than 20m where benthic individuals seldom occurred, many planktonic larvae spawned by ceah own population had settled intermittently on the surface sediment and further grown up to be in adult-stage. The distribution of completely settled bivalve was basically controlled by the ambient dissolved oxygen concentration in summer. However, the juvenile bivalve immediately after settlement was frequently found in great numbers in various sediments different from the main habitats, but shortly thereafter died out under such severe enviro-mental conditions as dissolved oxygen decreased markedly at the bottom layer.

抄録全体を表示

Parameters of the Sakhalin surf clam Spisula sachalinensis stock in Sendai Bay were estimated by analyzing the fishery data to examine the management of fishery. The fishing has been greatly influenced by the fluctuation in recruitment, since the age structure has skewed to younger side, The average fishing mortality coefficient F and natural mortality coefficient M during 1980-84 were 0.6358±0.2735, and 0.5323±0, 0915, respectively. The catchability coefficient q was 3.164×10-5.
Since the natural mortality coefficient is high, we can expect higher yield per recruit from higher F and lower age of first capture. The most important problem in the management of the stock recruited intermittently by the strong year class, however, is to secure the minimum level of stock which could produce a lat of progeny if the circumstances might become favorable. Since it might be difficult to predict the recruitment from the stock-recruitment relationship, two models were proposed to follow successive stock density. Optimum fishing mortality coefficient is presumed to be between 0.5 and 0.6, which would be able to hold the stock at a level enough to produce recruits under deteriorated conditions.

抄録全体を表示

Calls of the scorpaenoid fish Sebasticus marmoratus were classified into single knock sound and a train of knock sounds each of which lasts for about 100-160 msec followed by a silent period of 200-500 msec. Each knock sound was made of a frequency component of less than 1 kHz. The fish emitted vigorous calls for about one or two h at dawn and dusk. Little remarkable seasonal variation in the occurrence of the sounds emitted was observed. The calls which were used maingy to threaten away invaders, were made by a contraction and relaxation of the sonic muscle, and amplified by the swim-bladder. The peak frequency of a call was decided mainly by the cycle of contraction and relaxation of the sonic muscle and secondly by the length of the swim-bladder.

抄録全体を表示

Progress in research on chromosome manipulation of aquatic animals. has been reviewed by one of the present authors. Along with the context, successful induction of gynogenesis in the pacific abalone was reported before. The present work attempted to induce triploid animals in the pacific abalone Haliotis discus hannai as a part of a series of genetic and breeding researches on the species.
Egg and sperm specimens, obtained through stimulating animas with sterilized and heated sea water, were used for insemination. Normal developmental processes of inseminated eggs were observed to determine praper times for starting the treatments of eggs for inducing triploid animals. Cold, hot, or hydrostatic pressure shock was applied to inhibit releases of first and/or second polar bodies. Ploidy status of zygotes was examined by karyotype observation as well as chromosome counts.
After examining sets of conditions of times, intensity, and duration of treatments, it became evident that treating eggs at 3°C of cold shock for 15 min 12 or 32 min after insemination, at 35°C of hot shock for 3 min or at 200kg/cm² of hydrostatic pressure shock for 5 min 7 or 22 min after insemination can inhibit release of first or second polar bodies and result in induction of thousands of triploid animals of the pacific abalone in quite a high frequency.

抄録全体を表示

Studies of age and growth of japanese flounder Limanda yokohamae in Su ?? -Nada of Seto Inland Sea were done about ten years ago. However, in recent years, CPUE of this stock is con-sidered to be on the decrease. Therefore, there is a possibility that age and growth of this species have changed in present time.
Using 4, 636 otoliths of japanese flounder, it was made clear that hyaline zone was formed once a year as an indication of full age from May to middle of December-March. Based on this result, standard body length and body weight in each full age were established until six years of age for both sexes of japanese flounder in Su ?? -Nada.
The growth of japanese flounder in Sendai Bay was better than in Su ?? -Nada. Furthermore, comparing the results that were reported on age and growth of this species in 1974 in Buzen-Kai, in spite of depletion of stock condition, the growth of this species has not become better yet.

抄録全体を表示

Age and growth are the most important parameters for stock assessment. These parameters of stone flounder Kareius bicoloratus in Buzen-Kai of the western part of Suo-Nada were reported in 1974. However, they were not representative of the growth of this species in Suo-Nada.
Using 3, 274 otoliths as materials which were sampled in Suo-Nada during the period of 1970-1974, the criterion of age determination and the growth of stone flounder in this area were clarified in this report.
Hyaline zone in otolith of stone flounder in Suo-Nada was formed from the beginning of May to the end of November-the beginning of January once a year.
Standazd body length and body weight at each full age for both sexes were established, and moreover, growth curves on standard body length and body weight for both male and female stone flounders were represented by von Bertalanffy growth equation.
As compared with the state of growth in 1974, a change of the growth of this species in Suo-Nada was not observed in the present condition.
It may be important that the criterion for reading of zones in otolith be unified and it is also necessary to develop an objectively counting method of age zones in it.

抄録全体を表示

Isolated scale melanophores of mosquitofish Gambusia affinis were examined to confirmwhether microtubules were concerned with pigment granule transport.
Single treatment of melanophores with keeping at room temperature after low temperature (-3 ?? -5°C) or with colchicine elicited rapid aggregation and dispersion in responses to epine-phrine and theophylline, respectively. The treatment of melanophores with low temperature blocked incompletely both melanosome aggregation and dispersion. Furthermore, these re-spouses were completely blocked by the combined treatment of the melanophores with low tem-perature-plus-colchicine. Under this combined treatment, the melanosomes remained in the fully dispersed state during the pretreatment. On the other hand, the same treatment to aggregated melanophores elicited incomplete dispersion of melanosomes during the pretreatment, indicating a dynamic function of microtubules in melanosome aggregation.
These results suggest that microtubules are essential to the transport of pigment granules also in mosquitofish melanophores.

抄録全体を表示

Behavioural studies of fish towards the slope are conducted in relation to a set-net. Ten individuals of crucian carp Carassrus auratus are tested in an experimentai tank which consists of a flat and a sloped area in Experiment I and the sides of a trap box attached to the slope in Ex-perimentII.
In equal conditions of illumination in Exp. I, the distribution of fish tends to be increased in the flat area, which indicates that fish keep away from the ascending sloped area of the larger gradient. The repellent effect is typically observed in the case of gradient over 14 degrees. When the tank is partly shaded with black roofing board, fish are attracted into the darkened area. In the experimental combinations of sloped gradient and lower light intensity the repellant reactions towards the sloped area is diminished in the smaller gradient under 14 degrees. These reactions are attributed to the relative differences of light intensity between the slope and flat areas in the tank and also to the degrees of sloped gradients.
In Exp. II three divided areas, i.e., flat, slope and trap, are also examined in numbers of fish distribution in combination of lighting canditions. Numbers of fish tend to increase in the dazkened trap, while it varies with complex reactions of fish in the case of darkened slope and lighted trap.

抄録全体を表示

Carp Cyprinus carpio (about 130g in body weight) were exposedto 2, 10 and 42 ppb Cd (CdCl₂⋅ 21/2H₂O) for 15, 29, 64 and 120 days. The water quality of control aquarium were as follows: water temperature, 21.3-25.2°C; dissolved oxygen concentration, 6.0-7.6mg/l; pH, 7.3-7, 5; water hardness, 60mg CaCO3/l.
The fish exposed to 42 ppb Cd consumed less food and grew less than control, 2 and 10 ppb.
Most of them died after 29 days. Fish affected by Cd were injured by pecking of other fish. There was little effect of Cd on red blood cell count, hemoglobin concentration, hematoclit value and serum levels or activities of Na, K, Mg, urea-N, triglyeeride, total cholesterol, LDH, AI-P and amylase. On the other hand, serum levels or activities of Ca, Cl, total protein, albumin, globulin, glucose and LAP inclined to decrease, while serum activities of GOT, GPT and LDH inclined to increase. As histopathological changes, swelling of gill epithelial cells, atrophy of hepatic and pancreatic cells, hyperplasia of hematopoietic cells, expansion of renal tubule and atrophy of
renal epithelial cells in kidney were observed. And Cd-exposed fish showed scoliosis mainly in 12-15th vertebra and damage of neural spine.
These hemochemical changes seem to be due to the changes of gill epithelial permeability and
the damage of hepatopancreas and renal tubule reabsorption. Activation of osteoclast and scoliosis which seem to be due to decrease of serum Ca concentration were also observed.

抄録全体を表示

As results of an attempt to discriminate an instrumental feeding response with a light stimulus in bluegills, stable discriminated response was established in all 4 experimental fish, even though a maximum of 43 training sessions each of which consisted of 9 trials were required. Regarding the response under presentation of the stimulus after establishment, responding rates in terms of number of responses per min correlated negatively to latencies which were elapsed time from onset of the stimulus until initiation of first responding (r=-0.70 to -0.79: P<0.01). Under presentation of stimulus, the fish started to respond witih latencies of less than 30s on 72 to 88% of total trials, whereas during periods between successive stimulations they did not emit response at all on 60 to 67% trials or, if they did respond, they initiated with it latencies of 60 s or more on 20 to 24% trials. These facts suggest to us that more frequent and faster responding of the fish during the stimulus presentation than during the inter-signal periods was based on relevancy of responding to the light stimulus which functioned as a discriminative one.

抄録全体を表示

The functional capacity of the immune system was studied in the young rock fish. Two month-old fish are able to mount an antibody response against sheep red blood cells (SRBC), while this capacity is lacking or very low, even if present, in fry aged 1 month. Following immu-nization at the age of 1 month, the fish failed to induce an anamnestic response on reimmunizationat 2.5 months after the first injection. Their reactivity to SRBC reached a similar level to that of the adult at the age of 3 months, although circulating antibody decreased more quickly than in adults. Fish as young as 1.5 months were capable of eliciting an allograft response in the same fashion as adults, measured by eye transplantation. Three month-old fish reject allografted scales more rapidly than adults. Comparison between normal and dwarf fish revealed that the immunol-ogical maturation was more dependent on the size rather than the age of the fish. The capacities of mount both allograft rejection and antibody production were correlated with the development of the lymphoid organs. From these results, it is possible to say that the onset of immunological maturation occurs at about 1.5 and 2 months after birth, for allograft rejection and antibody production respectively.

抄録全体を表示

In order to keeg the quality of shrimp during ice storage, a mixture of crushed ice, salt and some chemicals were employed. The quality of shrimp during storage was evaluated by means of the volatile base nitrogen (VB-N), extractive-nitrogen (AA-N), VB-N/AA-N ratio, indole, inosine monophosphate ratio (IMP ratio), bacterial count and sensory quality. It was found that using crushed ice containing 3 and 7% NaCl extended the shelf-life of shrimp by 8 and 6 days, longer than that in the case of crushed ice alone. When 0.1% K-sorbate, or 0.1% K-sorbate, 0.05% Na-polyphosphate and 0.05% Na-pyrophosphate were added to crushed ice, the microbial growth and autolysis of shrimp meat retarded significantly. Crushed ice muted with combination of 3% NaGl and 0.1% K-sorbate, or 3% NaCl, 0.1% K-sorbate, 0.05% Na-polyphosphate and 0.05% Na-pyrophosphates showed better effects extending the shelf-life of shrimp to 17 days. This dra-matic effect can decrease the post-harvest loss of shrimp.

抄録全体を表示

Amultielectrode enzyme sensor system was applied to determine the freshness indicator [K_I={(H_xR+H_x)/(IMP+H_xR+H_x)}×100]in some fish and the display of freshness pattemwas studied by a computer. Moreover, the exudate obtained by the heat and press-treatment ofthe fish muscle was examined to determine zhe freshness of the fish.
The apparatus used in this study consisted of multielectrode enzyme sensor, relay controller, A/D converter, microcomputer, floppy disk, monitor and printer. The output current of thesensor was read by the computer and converted to digital signals every s sec. This data wasstored in the floppy disk. The amounts of hypoxanthine(H_x), inosine(H_xR), inosine mono-phosphate(IMP)and K_I value were calculated by the computer on the basis of this data. Fresh-ness of fish was expressed as foillows; very fresh: K_I<10, fresh: K_I<40, not fresh:K_I>40. Fresh-ness pattern was depicted on the display screen in the shape of a triangle, the apexes were C₁/C₀, C₂/C₀ and C₃/C₀, where C₁, C₂ and C₃ are the concentration of H_x, H_xR and IMP, respectively.C₀ is the total amount of C₁, C₂ and C₃.
In order to avoid the tedious extraction procedure for the preparation of samples, fish muscleswere heated at 80°C for 5-10min and press-treated to obtain the exudates. The K_I values of the exudates were in fair agreement with those of the extracts which were prepared by the con-ventional extraction method. One assay including the preparation of sample required about15min.

抄録全体を表示

Distribution and generic composition of denitrifying bacteria in coastal and oceanic waters were investigated from 1980 to 1984.
Denitrifying bacteria were enumerated by the M. P. N. method; their number in the surface water ranged from less than 2.0×10^-1to 3.4×10² cells/ml.
Almost all (98.1%) of the isolated denitrifiers (264 strains) were asporogenous, gram-negative rods with polar flagella. Denitrifying bacteria capable of forming pigments on nutrient agar or producing gas in the medium containing glucose were not isolated. About 84.8% of the isolates required NaCi for growth. Pseudomonas was the most dominant genus of denitrifying bacteria in the water column.

抄録全体を表示

The autolysis of bacterial cells (strain V37) capable of producing lytic enzyme was investigated using the washed cells gown in polypepton-yeast extract medium.
Strain V37 cells grown in the medium containing 0.5M NaCl or KCl were conspicuously auto-lysed than those grown in the medium comprising 0.5M MgCl₂ or without addition of any in-organic salt. The optimum pH and temperature for the autolysis of strain V37 cells were 7 to gand 40°C, respectively. The autolytic activity slightly increased in the presence of 0.2-0.3M NaCl in 0.05M Tris-HCl buffer (pH 7.0), but was significantly inhibited by bivalent cations such as Ba²⁺, Ni²⁺, Co²⁺ and Mg²⁺. The presence of NaCl (0.4-0.9M) in the medium, enhanced then ability to autolyse.

抄録全体を表示

Gonads of sea urchin Strongylocentrotus nudus were salted with 10, 15, and 20% NaCl and stored at 5°C for about 27 weeks. During storage, composition of lipid of the salted gonads was analyzed. TBA value and contents of VBN, carbonyl, and oxo-acid were also determined,
The content of triglyceride, a principal component of non-polar lipids, of salted gonads decreased during storage, while that of free fatty acid increased. The changes in the contents of these lipid classes occurred noticeably in the sample with NaCl added at a higher concentration. The contents of phosphatidylcholine and phosphatidylethanolamine, major components of polar lipids, decreased, being accompanied with formations of lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine. A larger amount of LPC was accumulated in the sample with NaCl added at higher concentration.
Fatty acid composition of the total lipid in all samples remained almost unchanged during storage. However, percentages of C_20:4 and C_20:5 decreased in the polar lipid fraction, while it increased in the non-polar lipid fraction.
These results suggested that the lipid deterioration of salted gonads of sea urchin during storage was caused through a hydrolytic reaction rather than oxidative one.

抄録全体を表示

This paper deals with the effects of supplemental phospholipids (PL) on the assimilation and transport of [¹⁴C] tripalmitin in relation to the nutritional role of PL in diets of the prawn Penaeus japonicus. The prawns were fed on the diets containing [¹⁴C] tripalmitin with 3% soybean lecithin (diet A) and without supplemental PL (diet D), and then the incorporation of radioactivity into the organs and tissues was examined after 1, 3, and 6h of feeding. Supplemental soybean lecithin slightly accelerated the mobilization of dietary [¹⁴C] tripalmitin from the guts to the hepatopancreas but did not exert an influence upon the absorption rate (%) of [¹⁴C] tripalmitin under the conditions adopted in the present study. The inclusion of soybean lecithin in diets resulted in the increase of proportion of radioactive PL in the hemolymph, especially, phosphatidylcholine which may be used as the constituents of hemolymph lipoproteins. These results suggest that dietary PL possibly play an important role in the smooth transport of dietary lipids, especially cholesterol, in the body.

抄録全体を表示

The feeding trials were conducted to examine the effects of several protein sources and other factors on the weight gain, feed conversion efficiency (FCE), and protein efficiency ratio (PER) of Tilapia nilotica. As a protein source, casein-gelatin (3:1) and casein had a higher nutritive value than gelatin, albumin, and a mixture of casein and crystalline amino acids (1:1).
The effects of feeding rate, feeding frequency, stocking density, dietary vitamin level, and a bineer on growth of Tilapia were tested with 2 levels in a factorial design using an orthogonal array Ls. As for the weight gain, FCE, and PER, a significant difference (P<0.05) was detected only on the feeding rate. The weight gain was higher at 7.0% feeding rate than at 3.5% feeding rate; whereas the FCE and PER were higher at 3.5% feeding rate than at 7.0% feeding rate. The weight gain, FCE, and PER of Tilapia were not affected by the feeding frequency, stocking density, dietary vitamin level, and the binder under the experimental conditions adopted.

抄録全体を表示

Accumulation and retention of ¹²⁵Sb by short-necked clam Tapes japonica were investigated in order to elucidate the uptake mechanism of the nuclide in marine bivalves.
It was found that the accumulation of ¹²⁵Sb by the clam from the environmental water showed an initially relative rapid increase, followed by a gradual increasing pattern during the experimental period. The concentration factors for ¹²⁵Sb in the clam at the end of the experimental period were obtained as 1.2 for the soft part and 4.2 for the shell.
The loss of ¹²⁵Sb accumulated in the whole clam showed an initial decrease, followed by two slow elimination patterns. The long-lived biological half-life for ¹²⁵Sb in the clam was approximately 58 days.
Regarding the influence of chelating agent and co-existing element on the accumulation of ¹²⁵Sb by the clam, it was observed that the addition of stable antimony to the rearing sea watere enhanced the accumulation of ¹²⁵Sb by the soft part and shell of the clam to some extent; whereas, the accumulation of ¹²⁵Sb by the soft part and shell was not depressed in the presence of EDTA.
The accumulation of ¹²⁵Sb by the shell depends mostly on the surface adsorption phenomenon rather than that via metabolic process.

抄録全体を表示

Hemolysins were purified from whole bodies of the sea anemone Anthopleura japonica by acetone precipitation, ion-exchange chromatography on CM-cellulose, gel filtration on Sephadex G-75 and chromatofocusing. Two hemolysins (AJH-1 and 2) were detected and only AJH-2 was obtained in pure form as judged by analytical disc electrophoresis. AJH-2 exhibited a lethal activity in mice (LD₃₀ 78μg/kg, i, v. injection) as well as a hemolytic activity (106, 500 HU/mg against sheep erythrocytes). It was stable over a wide range of pH values from 2 to 11 but rather unstable to heat treatment. The molecular weight was determined to be 17, 800 by sedimentation equilibrium or 19, 500 by SDS-polyacrylamide gel electrophoresis, indicating that AJH-2 has no subunit structure. AJH-2 was a slightly basic protein (pI 8.0) and its amino acid composition was characterized by the absence of half-cystine. It was notable that these properties of AJH-2 were closely similar to those of parasitoxin, the major lethal hemolysin isolated from the sea anemone Parasicyonis actinostoloides.

抄録全体を表示

The authors isolated three bacteria from natural habitats which were able to produce β-1, 4-mannanase, β-1, 3-xylanase and porphyranase. They were cultivated in a fiuid media, stirring for 4 days at 25°C. Each enzyme produced was partially purified from the culture fluid by ammonium sulfate precipitation and chromatography on a Sephadex G-200 column.
The thallus of Porphyra yezoensis was treated with a 0.5% papain solution, and then it was put in a mixture solution of 0.1M acetate buffer, pH 6.0, 0.1 unit each of β-1, 4-mannanase, β-1, 3-xylanase and porphyranase, and 0.7M mannitol as an osmoticum. After 1 h-gentle shaking of the mixed solution, a number of protoplasts were released from the thallus. When the thallus was treated with the mixture solution which lacked in the above three enzymes, no protoplast was observed.
These results indicate that the bacterial enzymes obtained were quite useful to degrade the cell wall of red aigae, and an of β-1, 4-mannanase, β-1, 3-xylanase and porphyranase were essential for the release of protoplast from the thallus of P. yezoensis.

抄録全体を表示

Two attempts were conducted to examine the effect of fermentation on proximate composi-tion, POV, TBA, and VBN values of fish waste, and the effects of fermented and fermented-re-steamed scrap meals on the growth of red sea bream and feed efficiency. Fermentation by a combination of Aspergillus oryzae, Aspergillus sojae, Saccharomyces cerevisiae, and Bacillus sub-tills decreased the lipid content, POV, and TBA in fish waste, and increased VBN. However, VBN decreased by resteaming after fermentation. The growth and feed efficiency of fish fed on fermented scrap meal diet was superior to those of the nonfermented scrap meal diet group. How-ever, both groups were significantly inferior to white fish meal diet group. On the other hand, no significant difference was recognized between fermented-resteamed scrap meal diet group and white fish meal diet group in the growth and feed efficiency. These findings indicate that the removal of both toxic oxidized lipids and protein degenerates is essential in the utilization of fish waste as a dietary protein source and that fermentation and steaming are effective for the removal.

抄録全体を表示

The levels of mercury and selenium in twenty-four gonad specimens of five species of marlins, i. e., each seven individuals of blue marlin Makaira mazara, striped marlin Tetraguturus audax and sailfish Isotiophorus platyterus, two individuals of shortbill spearfish Tetraputurus angustirostris and one individual of sword fish Xiphias gladius, are presented.
Total mercury content (T-Hg) correlated significantly between gonad and muscle, and T-Hg in the gonad was about 30% to that in the muscle. The ratio of methyl mercury content (MeHg) to T-Hg in the gonad was small compared with that in the muscle.
Selenium content (Se) in the gonad was relatively high, and moreover the mean content of Se in the female was significantly high compared with that in the male. The molar ratio (Se/Hg) of Se to T-Hg in the gonad correlated negatively with T-Hg in the gonad. Furthermore, the ratio tended to get nearer to 1 with the increase in T-Hg.

抄録全体を表示

Contents of dimethyl sulfide(DMS)and dimethyl-β-propiothetin(DMPT)in various parts(gill, mantle, viscera, adductor, etc.)of 16 species of live shellfish obtained from Tokyo wholesalefish market and cultured oyster obtained monthly from Miyagi Prefecture throughout the yearwere determined by gas liquid chromatography.
In general, the contents of DMS and DMPT of shellfish were higher in the viscera than in the muscle. However, relationship between the concentration of DMS and those of DMPT in the shellfish was apparently not found.
Concentration of DMS in viscera, gill, mantle and adductor of the cultured oyster increased from spring to the beginning of summer and decreased from the end of summer to winter. Butseasonal variations of DMPT concentration in cultured oyster were not observed.
Concentrations of DMS in homogenate of viscera, gill and mantle of oyster increased about 3times during the incubation period at 30°C for 2 h. However, this increase was not found in homogenate of adductor of oyster. Then extract of oyster viscera was dialized against phosphate buffer and incubated with synthetic DMPT under various temperatures and pH. As a result, the highest activity in the formation of DMS from DMPT was observed at about 30°C with a pHvalue of 8.

抄録全体を表示

Administration of 17α-methyltestosterone (MT) to sexually immature chum salmon Oncorhynchus keta induced the nuptial coloration.
MT-treated chum salmon at the feeding migration stage in the North Pacific Ocean might correspond to those at the spawning migration stage as judged from the following changes: protein and lipid contents in muscle, high levels of muscle protease activity, colorations of muscle and blood serum. The relation between changes in muscle composition and sex steroid was suggested strongly.
It was proved that the androgen was trigger to the muscle deteriorations during spawning migration of chum salmon.

抄録全体を表示