To investigate iterative measurement of the morphometric characters of fish larva, the daily change in the body size of intensively reared larval fish, red sea bream snapper Pagrus major, olive flounder Paralichtys olivaceus and ayu Plecoglossus altivellis was monitored on the moribund state and over the subsequent preservation process of 15 days and the differentiation by formalin fixation was evaluated.
Throughout the trial period the size of the fish body frequently suffered significant shrinkage and/or weight loss immediately after fixation and then slightly but chronically in the fixative. Primarily the weight loss was more pronounced than the shrinkage in length. An Analysis of the covariance for the allometric equations, therefore, suggests that the treatment of fixed samples might be misleading when conducting morphometric studies of live fish stock. The changeability of physical body was dependent upon age, even though the somatic sizes were of an equivalent range when alive. Moreover, the variation in measurements over one hour or so mostly occurs irrespective of the formalin fixation. These facts suggest that iterative measurements of fixed fish larva are limited and alternative methods such as applying microscopic biophysics to the variations in the structure and tissues of larval fish in fixatives, or using optical and volumetric techniques for live measurements are required.

View full abstract

To obtain the fundamental information required to establish an artificial seed production technique for the marble goby Oxyeleotris marmoratus, the development of sense organs and mouth and the feeding of the larvae were observed. The larvae exhibited a S-posture and horizontal swimming at 2 days after fertilization (d AF) and commenced feeding on phytoplankton (species unknown) at 3 d AF when the eyes, the otic vesicle with ciliated epithelium, the free neuromasts on the head and the trunk, and the ciliated olfactory epithelium were functional. The first taste buds appeared in the oral cavity at 6 d AF after the onset of feeding on Brachinous spp. The larvae commenced feeding on Cyclops sp. at 7 d AF, Moina sp. at 10 d AF, and Artemia salina nauplii at 15 d AF. This change of feeding might be due to the development of the mouth and mobility of larvae rather than the development of sense organs. At 20 d AF, the larvae developed free neuromasts on the caudal fin. Twin cones and rods appeared in the ratinae at 30 d AF when the larvae changed in phototaxis from positive to negative. The larvae became benthic in habit at 35 d AF.

View full abstract

Hatching dates of larval Japanese flounder settling at Yanagihama Beach near Nagasaki in 1990 and 1991 were estimated by measuring daily increments of otolith of 1, 629 specimens (8.5-73.9mm SL). The spawning season of flounder was estimated to extend from late February or early January to the middle or end of April. Although spawning seems to have taken place every day, five prominent peaks appeared in the frequency distributions of hatching dates, mostly falling on spring tides. There are two alternative interpretations of this phenomenon; either there is a semilunar periodicity in spawning, or the larvae derived from eggs spawned during a spring tide have more chance of surviving and being carried to Yanagihama by some oceanographical conditions which previail during spring tides.

View full abstract

The effects of iron on oogonium formation of female gametophytes, growth rate and pigment syntheses of Lmninaria japonica Areschoug were investigated and compared in both soluble EDTA chelated iron (Fe (III) -EDTA) and solid amorphous hydrous ferric oxide (am-Fe (III)) media containing nitrate and phosphate. Soluble Fe (III) -EDTA [0.4-2 μM] and solid am-Fe (III) [2 μM] were found to strongly affect the oogonium formation of female gametophytes; most gametophytes in iron-free and reduced iron concentration media (<0.4 μM in Fe (III) -EDTA, <2 μM in am-Fe (III)) continued only vegetative growth without oogonium formation. The growth rate and chlorophyll-a (Chl-a) concentration of young sporophytes significantly increased with increased iron concentration in the culture media. The growth rate and Chl-a concentration of young sporophytes cultured in am-Fe (III) media were approximately one half lower than those in Fe (III) -EDTA media, possibly as a result of the lower iron uptake rate of young sporophytes observed in am-Fe (III) media. This lower iron uptake rate may be attributed to the low solubility and the slow dissolution rate reported for solid amorphous hydrous ferric oxide in seawater. Furthermore, iron was found to promote the syntheses of fucoxanthin, chlorophyll-c, β-carotene and Chl-a in adult sporophytes. This study clearly indicates that iron plays an important role in the oogonium formation, growth rate and pigment syntheses of L. japonica.

View full abstract

The effects of copper, zinc and cadmium on the growth rates (cell division day^-1) and photosynthesis (O₂ mgh^-1 10⁶ cells^-1) of Microcvstis aeruginosa (Cyanophyceae), Scenedesmus quadricauda (Chloro-phyceae), and Aulacoseira granulata (Bacillariophyceae) were determined. Then, the effective con-centration (EC₅₀) for growth and photosynthesis in each species of microalga was calculated. Of the three heavy metals tested, copper was found to be the most toxic element to the three experimental organisms. M. aeruginosa exhibited higher tolerance while S. quadricauda exhibited higher sensitivity. There were some differences between EC₅₀ for growth and photosynthesis in the three organisms. In copper, EC₅₀ values for growth obtained in the three microalgae were higher than their EC₅₀ values for photosynthesis. In zinc and cadmium, M. aeruginosa and A. granulate showed the same trend but in S. quadricauda, the EC₅₀ value for growth was lower than that for photosynthesis. The growthphotosynthesis response relationship showed that in copper, growth of the three test plants were less inhibited than their photosynthesis at lower exposure levels (0.001-0.1 μg l^-1). In zinc and cadmium, a proportional response existed between relative growth rates and relative photosynthesis in all microalgae.

View full abstract

We attempted to forecast the catch of post-larval stages of Japanese sardine with total length 19-35mm exploited each year by troll and beach seine fisheries in Sagami Bay, Japan, during March and April. In the forecasting system, the feed forward (layered) type of neural network was utilized. The system for forecasting the catch in Sagami Bay during March and April was developed on the basis of (a) predicted hydrographic conditions (occurrence rates of the Kuroshio path types and distance between the axis and Cape Iroh-zaki in March and April) as predicted in the previous paper, (b) hydrographic data from November (previous year) to February (current year) and (c) Japanese sardine catch data in various landing regions in the previous year. The predicted values of catches agreed well with the observed catches. Upon investigation of the weights and threshold values in the trained neural network, the distance between the Kuroshio axis and Cape Iroh-zaki was found to significantly affect the predictions. We also examined how the data length for learning of the neural net affects the prediction. It appears that the neural network is a practical tool for predicting the catch.

View full abstract

The facial lobe (FL) of the catfish Silurus asotus is composed of paired structures which are anteriorly tapered and posteriorly swollen longitudinal columns. Two longitudinal columns (lobules) extend caudorostrally in the anterior one-third of the lobe.
We studied the central projections of seven major taste peripheral rami into the FL with horseradish peroxidase (HRP) transganglionic labeling methods.
The facial afferent fibers of the maxillary barbel ramus terminate over a large area of the FL from anterior to posterior. Their terminal areas are distributed in the medial lobule of the anterior FL, ventral half of the intermediate FL, and lateral portion of the posterior FL. The maxillary and mandibular fibers project, respectively, to the most lateral portion and to the overall region of the caudal half of the FL. The recurrent facial fibers project to the dorsolateral lobule of the anterior FL. The facial fibers of the hyomandibular and ophthalmic rami project to the most lateral portions in the intermediate region of the rostrocaudal extent of the FL. The intermediate nucleus of the FL which develops as a longitudinal column throughout the caudal two-thirds of the ventromedial portion of the FL receives projections from the maxillary barbel, maxillary and mandibular rami. The present results show that each peripheral taste ramus projects in a precise topographic fashion to the ipsilateral Fl, and that the two lobules, one for maxillary barbel and the other for the trunk are present in the anterior one-third of the FL.
The trigeminal fibers of the maxillary barbel, maxillary and mandibular rami project to certain areas of the FL where the facial fibers of each ramus also project.

View full abstract

Seven α-globin genes (Nos. 1-7) have been isolated from a genomic library of the carp, Cyprinus carpio. In this study, the complete nucleotide sequences of Nos. 1 and 5 were determined. Globin genes Nos. 1 and 5 had three coding regions and two intervening sequences (IVS). The total length of the three coding regions was 432 bp, and that of the first and second IVS was 428/96 bp (No. 1) and 129/385 by (No. 5), respectively. In the 5'- and 3'-untranslated regions, sequences homologous with the consensus sequence of the signals for expression were observed. The homologies with the amino acid sequences predicted from the cDNA were 93.0% (No. 1) and 99.3% (No. 5). However, the first IVS of No. I and second IVS of No. 5 included 298 and 289bp palindromic sequences (palindromic sequence of carp α-globin genes Nos. 1 and 5: PCα-1, PCα-5), respectively. PCα-1 and PCα-5 were quite similar (homology 98.6%), and no modifications or specific sequences were observed in the IVS adjacent to either of them. In addition, eight repeats of palindromic elements “tTCGTAcgaattcgTACGAa” were observed in PCαs, and six of them constitute 80 by complementary sequences that form the stem and loop structures. Therefore, we presume that the PCas are repetitive sequences, and that they arose from insertion.

View full abstract

Nine statistical models with different probability distributions are introduced for the expanded DeLury's method with variable catchability coefficients according to such environmental factors as water temperature, lunar cycle, and the intensity of ocean waves. After being applied to the catch-effort data of spiny lobster gillnet fishery, statistical models are compared and discussed with AIC and the confidence intervals of the estimators. The AIC values indicate that the negative binomial model is the optimum model. This result adequately reflects the distributional nature of spiny lobster in the field which shows some aggregation, coupled with other fishing characteristics. Though the confidence intervals of the estimated parameters were rather broad in the negative binomial model, those calculated through simultaneous analysis using three-year data were narrower than those calculated using single-year data.

View full abstract

A method for estimating the suitable stock-recruitment equations based on a comparison of various statistical models is presented. Fourteen statistical models including the Ricker curve and Beverton-Holt curve were considered. Stock-recruitment relations were estimated by the maximum likelihood method and suitable models were selected using AIC. Thirty-five sets of stock-recruitment data derived from published papers were analyzed. The results show that the various statistical models selected as suitable models do not always coincide with the model used in the original papers. A detailed examination is needed to estimate the stock-recruitment relationship.

View full abstract

Interracial crosses between the small, diploid race (2n=48, 16m+22sm, st+10a) and the large, tetraploid race (4n=96, 32m+44sm, st+20a) of the spinous loach Cobitis biwae produced viable progeny with an intermediate karyotype (72 chromosomes, 24m+33sm, st+15a), that demonstrated a “hybrid” as well as a “triploid” nature. Intergeneric crosses between the diploid race of C. biwae and the loach Misgurnus anguillicaudatus (2n=50, lOm+4sm+36a) produced viable progeny which we identified as diploid hybrids, and had an intermediate karyotype (2n=49, 13m+13sm, st+23a) between the two species. The progeny from the intergeneric crossess between the tetraploid race of C. biwae and the loach had a karyotype which comprised the two sets from the tetraploid race of C. biwae and the other from the diploid loach Misgurnus anguillicaudatus (73 chromosomes, 21m+24sm, st+28a).

View full abstract

Studies were conducted to determine the mechanism of blood pressure- and cholesterol-lowering effects of funoran on rats fed with a saline solution and cholesterol diet. Clofibrate (COIB) was used as a reference hypolipidemic drug. Funoran caused significant reduction of systolic blood pressure (SBP). Funoran and CPIB significantly reduced serum total cholesterol (TC), free cholesterol (FC), triglyceride (TG), LDL-cholesterol (LDL), and atherogenic index (AI) levels in these rats. The increase of sodium, water excretion and sodium-potassium ratio in urine in the funoran group was more significant in the experimental rats than in the control group. Moreover, the ratio of Na and K in serum decreased with the funoran diet. The CPIB diet enhanced cholesterol level in the liver while the funoran diet suppressed the level, but in feces the former diet did not change the cholesterol level while the latter diet increased it. These results suggest that the enhanced ability to excrete sodium in urine by the funoran diet is an important factor for reducing blood pressure and that the antihyperlipidemic effect of funoran was not caused by the mobilization of peripheral cholesterol on the liver, but by the enhanced excretion of cholesterol into feces.

View full abstract

This paper investigates the effect of 0.05% acetic acid with brine on fish preservation. The main reasons for choosing acetic acid for this trial were its known antimicrobial activity, low cost and because it is generally recognized as safe (GRAS). Sardine were immersed in 4, 10, and 15% brine after adding acetic acid and stored at 15°C. Controls were run at O°C. The results of sensory evaluation and chemical changes in flesh (pH, VB-N, and K value) and microbial changes in the immersion brine are presented here. Based on the sensory evaluation, sardines immersed in 4% brine with acetic acid had a storage period of 5 days, which agrees with the VB-N and K values. All other samples were considered acceptable until the last day (7 th) of storage.
The results of microbial populations in 4% brine showed an increase of gram negative bacteria, and only minor changes in the 10% brine samples. In both cases Moraxella and Pseudoinonas were predominant. In 15% brine, gram positive bacteria increased and Micrococcus was observed as predominant.

View full abstract

In order to study the effect of different dietary arginine levels on the growth of red sea bream larvae, two types of diets were prepared: one group of five zein microbound diets with increasing levels of arginine, and one group of five microcoated diets with the same arginine levels as those in the microbound diets. All diets had a crude protein content (N×6.25) of 60%. Twenty-day-old red sea bream larvae were fed on these diets for 28 days, and at the end of the experiment, the amino acids in the diets and larvae were analyzed. Growth of red sea bream larvae was enhanced by increasing arginine levels to 2.5% of the diet. Further increase in arginine level did not improve the growth response. For practical purposes, at least 2.5% arginine in the diet is recommended for larval feeding of red sea bream.

View full abstract

Lysozyme activity in seven organs of the mussel Mytilus edulis was determined to evaluate seasonal variation. Although no correlation was detected between lysozyme activity of any organ and its constituents, two groups of organs showed positive correlation of variation in lysozyme activity with season. One group included the gill, mantle, body fluid, and foot, while the other the mid-gut gland, gonad, and adductor muscle. In the mussel lysozyme may be essential to defense against exogenous and endogenous bacteria in the two groups, respectively.

View full abstract

Tryptophan hydroxylase (5-monooxygenase) (EC 1. 14. 16. 4; Trp hydroxylase) in skipjack liver was extracted with Tris-acetate buffer solution and purified by acid treatment, ammonium sulfate fractionation, Sephadex G-150, DEAE-Sepharose CL-6 B, Butyl-Sepharose 4 B, and Toyopearl HW-55 F chromatography. The enzyme was purified 1, 500-fold with a 6.2% yield from skipjack liver. The apparent molecular weight was estimated to be 288, 000 by gel filtration on Sephadex G-150. The enzyme gave a single protein band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis which also revealed that the enzyme was composed of identical subunits with a molecular weight of 97, 000. The optimum temperature was 35°C and the enzyme was stable under 35°C. The optimum pH was 8.0 and the enzyme retained more than 80% of its original activity between pH 7.5 and 8.5 after incubation at 35°C for 30min. The enzyme was inhibited by Co²⁺, Mn²⁺, and Zn²⁺ ions. However, it can be activated by adding Fe³⁺, K⁺, and Li⁺ ions.

View full abstract

The effects of plant growth regulators (PGRs), organic acids, and sugars on the growth of tissues of the sea lettuce Ulva pertusa (Ulvaceae, Chlorophyta) were examined in cultures maintained on agar. The culture medium used was the artificial seawater ASS₁ supplemented separately with 5 PGRs (1-naphthylacetic acid, 3-indoleacetic acid, 2, 4-dichlorophenoxyacetic acid, kinetin, and trans-zeatin), 3 organic acids (2-ketoglutaric, malic, and citric acids) and 3 sugars (glucose, fructose, and xylose). The concentrations of PGRs, organic acids and sugars ranged between 0.1-100 μg, 0.01-100mg, and 1-8g/100ml, respectively. These media were solidified with 0.7% Difco Bacto Agar.
The PGRs and organic acids except citric acid enhanced growth. Sugars did not enhance growth significantly (p>0.05). The best relative growth rate (3.56) was observed with the treatment of zeatin at a concentration of 5μg/100ml, and a similar growth rate (3.24) was observed in 2-ketoglutaric acid at a concentration of 30mg/100ml. When the thalli were cultured in a liquid medium, zeatin (5μg/100ml) increased the photosynthetic pigment content (14%) but decreased the free amino acid content (-12%). 2-Ketoglutaric acid (30mg/100ml) increased the photosynthetic pigment content (15%) and the free amino acid content (36%).

View full abstract

Two feeding experiments were conducted to evaluate malt protein flour (MPF) as an alternative protein source for the diet of rainbow trout Oncorhynchus mykiss fingerlings. MPF is a new protein rich by-product from brewer's spent grain. Experiment 1 was conducted to clarify the suitable substitution level of MPF for white fish meal (WFM) in the diet. The control diet, containing WFM as the sole protein source, and isonitrogenous (40% crude protein) experimental diets, containing MPF substituted for 20 to 80% of WFM protein, were fed to fish with an average initial weight of 10g for 6 weeks. Weight gain and feed efficiency in fish fed the diet substituting MPF up to the 60% level were not different (p>0.05) from those in fish fed the control diet. There were no significant differences in protein and energy retention between 0 to 40% substitution level. In Experiment 2, crystalline essential amino acids (EAA) were supplemented in the diets containing MPF to simulate the EAA composition in the control diet. Consequently, no significant differences were detected in protein and energy retention between 0 to 60% substitution level. Thus, these results suggest that MPF is a promising alternative protein source for the diet of fingerling rainbow trout.

View full abstract

To clarify the role of endogenous enzymes and bacterial enzymes on post-mortem biochemical changes in scallop adductor muscle, the effects of chloramphenicol (CP) on these changes during storage at 5 and 10°C were investigated.
Both muscle with and without CP added showed the same ATP breakdown pattern; degradation to inosine (HxR) and hypoxanthine (Hx) was not inhibited by CP, therefore, degradation to HxR and Hx was mainly caused by endogenous enzymes. D-Lactic acid, an end product of glycolysis, increased to a certain level in both muscle with CP and muscle without CP in the early stage of storage. The acid level then remained constant in the muscle with CP, but increased markedly as decomposition progressed in the muscle without CP. D-Lactic acid thus forms due to both endogenous and exogenous enzymes. The final content of octopine, another end product of glycolysis, was higher in the muscle with CP than in the muscle without CP, and this difference is thought to be caused by D-lactic acid formation in the muscle without CP.

View full abstract

Molecular species of collagen in the mantle muscle and skin of the squid Todarodes pacificus were examined by biochemical techniques. A major collagen and a minor collagen which showed distinct patterns of SDS-polyacrylamide gel electrophoresis were isolated from the pepsin-solubilized collagen from both of the tissues by differential salt precipitation and phosphocellulose column chromatography. By peptide mapping, the major and minor collagens which existed in the mantle muscle were shown to be essentially identical to the major and minor collagens in the mantle skin, respectively. The major and minor collagens, termed Type SQ-I and SQ-II collagens (SQ: squid), respectively, in the muscle were demonstrated to be genetically distinct from each other by peptide mapping and amino acid analysis.

View full abstract

A slightly astringent and sour taste of skipjack meat is generally disliked. Skipjack is classed as the family Scombridae. Even among fishes belonging to the family Scombridae, the taste of the raw meat differs greatly from species to species. In this study, we attempt to compare the chemical composition of extracts of the ordinary muscle of fish of this family to clarify the peculiar taste of skipjack muscle. The compositions of free amino acids (FAA), organic acids (OA), and nucleotides (NUC) were compared among ten different species. The total FAA exceeded 1, 000mg/100g in the meat of skipjack and frigate mackerel, but was only 300-400mg/100g in the meat of Spanish mackerel. The imidazole compounds accounted for 57-96% of the total ninhydrin positive substances in all samples tested, but anserine was not detected in mackerel. Skipjack and frigate mackerel were richer in lactic and malic acids than other species. The total NUC content was 230-500mg/100g and the IMP content was 150-410mg/100g in the muscle of all species of the fish examined.
Our experiments show that skipjack and frigate mackerel meat generally thought to taste astringent contains large amounts of extractive components and small amounts of as yet unidentified OA and NUC. The astringency and sourness of the meat is therefore likely to be caused by some or a combination of such compounds.

View full abstract