Role of sodium bicarbonate on the initiation of sperm motility in the Japanese eel

ABSTRACT:   In order to find out the role of sodium bicarbonate (NaHCO₃) on the initiation of sperm motility in the Japanese eel Anguilla japonica , interactions were investigated between NaHCO₃ and various reagents (K⁺ channel blocker 4-aminopyridine [4-AP], ammonium chloride [NH₄Cl], sodium acetate and calcium chloride [CaCl₂]) that could regulate internal factors (intracellular K⁺, intracellular pH [[pH]_i] and intracellular Ca²⁺) in sperm motility. Contradictory effects of NaHCO₃ were observed (i.e. an inhibitory effect when 4-AP was absent and a promoting effect when 4-AP was present). Sodium bicarbonate inhibited the initiation of sperm motility in the Japanese eel. However, NaHCO₃ restored the motility of immotile sperm that 4-AP inhibited. The inhibitory effect of NaHCO₃ disappeared with the addition of NH₄Cl, which raised [pH]_i, but the promoting effect was not affected by [pH]_i. Although NaHCO₃ recovered motility in the presence of 4-AP, this recovery was also observed with the addition of CaCl₂ instead of NaHCO₃. In the initiation of sperm motility in the Japanese eel, two roles for NaHCO₃ are suggested: an inhibitory role relating to the regulation of [pH]_i and a promoting role relating to the uptake of another initiation factor, which could be Ca²⁺.     

Binding characteristics of the Zn-binding membrane protein from common carp

ABSTRACT:    This study incorporated the 43 kDa Zn-binding membrane protein isolated from common carp into liposome. The specificity and strength of the binding of ⁶⁵Zn to the 43 kDa protein-liposomes, and the binding of the ⁶⁵Zn-labeled 43 kDa protein-liposomes to laminin were studied. It was found that ⁶⁵Zn was bound to the external side of the 43 kDa protein-liposomes. Specific binding of ⁶⁵Zn to the protein-liposomes was detected. The binding parameter of Zn to the protein was found to be: maximum binding site (N_max), 76.7 pmole/µg protein (approx. 3 mole of Zn²⁺/mole); and equilibrium dissociation constant (Kd), 0.19 µM. Of the cations introduced (Ca²⁺, Cd²⁺,Co²⁺, Cr²⁺, Cu²⁺, Fe²⁺, Hg²⁺, Mg²⁺, Mn²⁺, Ni²⁺, Pb²⁺), only Co²⁺ competed significantly with Zn. The protein-liposomes were also found to bind specifically to laminin with a N_max of 1.1 pmole/µg laminin, and Kd of 4.79 µM. No significant protein-liposome binding occurred to other extracellular matrix proteins (fibronectin, fibrinogen or vitronectin). Furthermore, the binding was specifically inhibited by the Arg-Gly-Asp (RGD) peptide or GRGDSPG, while two other analogs (GRGESPG and GRADSPG) were without effect.     

Effects of Rhizopus extract administration on somatic growth and sexual maturation in lacustrine sockeye salmon Oncorhynchus nerka

ABSTRACT: The filamentous fungi Rhizopus , like many fungal species, possesses physiologically active substances. Rhizopus extract (RU) is reported to be effective for various aspects of growth and reproduction in many vertebrates. The effects of RU administration on body growth and plasma levels of steroid hormones were investigated in lacustrine sockeye salmon Oncorhynchus nerka . One-year-old fish were fed daily with RU (20 mg/kg feed) from July 1999 to October 2000 for 15 months. Fish were sampled every month and plasma levels of testosterone (T), 11-ketotestosterone (11-KT), estradiol-17β (E₂) and 17α,20β-dihydroxy-4-pregnen-3-one (DHP) were measured by time-resolved fluoroimmunoassay. Body growth of RU-fed fish of both sexes increased significantly in 1⁺ and 2⁺ October, and 2⁺ January–March and July. All RU-fed males and one female matured in 2⁺ October. RU-fed 1⁺ precociously mature males showed increased plasma levels of T, 11-KT and DHP in 1⁺ October. In 2⁺ males, RU significantly elevated plasma levels of T from May to June, 11-KT from June to July, and DHP in October. In sockeye salmon, administration of RU accelerated body growth of both sexes and sexual maturation in males, suggesting physiologically active substances present in RU enhance somatic growth and sexual maturation by sex-specific mechanisms.     

Preparation of algal-oligosaccharide mixtures by bacterial agarases and their antioxidative properties

ABSTRACT:   Algal-oligosaccharide-lysates (AOL), derived from six agars and four algal polysaccharide extracts (APE), were treated with 100–500 activity units (AU) of MA103-agarases or MAEF108-agarases, and their antioxidative properties evaluated. Soluble total polyphenols (TP) were between 462.2 ± 1.6 gallic acid equivalents (GAE, µg/mL) and 70.6 ± 17.4 GAE. The DPPH radical scavenging capacity of all AOL went from 68.3 ± 0.7% to 0.5 ± 0.1%. The ferrous ion chelating capacity of all AOL went from 93.1 ± 0.2% to 21.7 ± 0.9%. Evaluation of the H₂O₂ scavenging capacity of all AOL was between 35.9 ± 5.4% and 0.1 ± 0.2%. The reducing power of all AOL went from 51.3 ± 2.6 to 3.2 ± 6.8 expressed as µg/mL ascorbic acid. In DPPH radical scavenging capacity, ferrous ion chelating capacity and reducing power etc., the AOL derived from the APE of Porphyra dentate (digested by 500 AU of MAEF108-agarases) were highest, in all test sets. However, the AOL derived from the APE of Monostroma nitidum (digested by 500 AU of MAEF108-agarases) had the highest H₂O₂ scavenging capacity in all test sets. The order of antioxidative activity performance of all AOL treated in this experiment, by these four antioxidative methods, is as follows: ferrous ion chelating capacity > DPPH radical scavenging capacity > H₂O₂ scavenging capacity > reducing power; this may be related to their polyphenols, small molecular weight polysaccharides or simple sugar constituents. In this study, it is demonstrated that various agarases derived from algal oligosaccharide mixtures possess good potential for use as a health food, due to their antioxidative capacity.     

Characterization of 38 kDa and 42 kDa chitinase isozymes from the liver of Japanese common squid Todarodes pacificus

ABSTRACT: Characterization was investigated on the 38 kDa and 42 kDa chitinase (EC3.2.1.14) isozymes from the liver of Japanese common squid Todarodes pacificus . Optimum pH toward colloidal chitin was observed at pH 3.0 for the 38 kDa chitinase, and pH 3.0 and 9.0 for the 42 kDa chitinase. K _m and k _cat of the 38 kDa and 42 kDa chitinases toward a longer substrate, glycol chitin, were 0.071 mg/mL and 1.22/s, and 0.074 mg/mL and 0.196/s, respectively. Alternatively, strong substrate inhibition of both chitinases were observed toward a short substrate, N -acetylchitopentaose (GlcNAc₅). Both chitinases decomposed not only chitin but also chitosan (D. A. 95%). The cleavage pattern and reaction rate were investigated using N -acetylchitooligosaccharides (GlcNAc_n, n  = 2–6). Both chitinases hydrolyzed GlcNAc_n ( n  = 4,5, and 6). The release of GlcNAc was not observed. The speed of the reaction was observed to be in the following order: GlcNAc₄ > GlcNAc₅ > GlcNAc₆ for the 38 kDa chitinase, and GlcNAc₆ > GlcNAc₅ > GlcNAc₄ for the 42 kDa chitinase. Both the chitinases released p -nitrophenol from p -nitrophenyl GlcNAc_n ( n  = 2, 3, and 4). N-terminal amino acid sequences of the 38 kDa and 42 kDa chitinases were YLLSXYFTNWSQYRPGAGKYFPQNI and EYRKVXYYTNWSQYREVPAKFFPEN, respectively.     

Haematological responses in the European eel, Anguilla anguilla L., to sublethal infestation by Anguillicola crassus in a thermal effluent of the Swedish Baltic

Abstract. Haematological variations were studied in a European eel population, Anguilla anguilla L., naturally infested by the sanguivorous nematode Anguillicola crassus. This occurred off the Swedish Baltic coast in an area receiving heated cooling water from a nuclear power station. The erythrocyte count, haematocrit, leucocrit, haemoglobin concentration, mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentrations, the various cell types in peripheral blood, serum iron concentration, the amount of total serum protein, and scrum protein fractions α ₁ , β₁ , α ₂, β ₂ and γ were all measured. Each variable was correlated to: (1) the intensity of infestation, i.e. number of parasites per host; and (2) a parasitization index, i.e. the weight of parasites per somatic weight of the host. Most variables showed no or only minor reactions to the infestation. However, a marked increase in the γ -fraction of scrum proteins, reduced lymphocyte numbers and increased granulocyte numbers are indicative of a humoral and cellular immune response.     

A pharmacokinetic study of flumequine in sea bass, Dicentrarchus labrax (L.), after a single intravascular injection

The pharmacokinetic properties of flumequine following a single intravascular injection (10 mg kg^–1 fish) were studied in sea bass, Dicentrarchus labrax (L.), 120 g held at 18 °C. The absorption half life ( t _1/2α) and the elimination half life ( t _1/2β) of the drug were calculated to be 1.05 and 10.71 h, respectively. Tissue penetration of flumequine seemed to be moderate because both the apparent volume of distribution of the drug at steady-state ( V _d(ss)) and the extensive apparent volume of the central compartment ( V _c) were found to be small (1.51 and 0.626 L kg^–1). The mean residence time ( MRT ) was short (09.73 h) and the total clearance (CL_T) of the drug was rapid (0.156 L kg^–1 h^–1).     

Seasonality of serum levels of vitellogenin in male Japanese whiting, Sillago japonica, reared under natural temperature and photoperiod

ABSTRACT:   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.     

Development of an in vitro culture system for producing eel larvae from immature ovarian follicles in Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis>

To standardize conditions during the final maturation and ovulation of ovarian follicles from Japanese eel, we have developed a culture system for the production of fertilizable eggs from post-vitellogenic ovarian follicles in vitro. Post-vitellogenic ovarian follicles were incubated in culture medium supplemented with 17α,20β-dihydroxy-4-pregnen-3-one (DHP) with or without bovine serum albumin (BSA) to assess the effects of protein concentration. Eggs that ovulated during incubation were fertilized, and the remaining follicles were incubated in prostaglandin F_2α (PGF_2α) for a further 3 or 6 h before fertilization. Male eels were injected repeatedly with human chorionic gonadotropin. The quality of eggs obtained under the different culture conditions was evaluated after artificial fertilization in terms of hatching success. Hatching rates tended to decrease with increasing concentrations of BSA in the incubation medium in a dose-dependent manner. The addition of PGF_2α drastically increased the number of eggs that ovulated, but the rate of hatching was greatly decreased compared with eggs obtained earlier by DHP incubation alone. The larvae obtained from artificially fertilized eggs produced in vitro survived for 14 days without feeding. We conclude that in vitro culture systems thus have a great potential for the acquisition of good quality eggs under tightly controlled artificial conditions, culminating in the production of eel larvae.     

Kinetics of Nitrogen Excretion by Cultured Flounder Paralichthys olivaceus

This study was undertaken to quantify the rate of nitrogen excretion by the cultured Japanese flounder as a function of body weight and water temperature. Measurements of the did rate of nitrogen excretion for the cultured flounder were made at mean water temperature of about 16, 19, and 23 C. The excretion rate of nilmgen was estimated by adding the nitrogen excreted in the forms of ammonia and urea nitrogens. The diurnal pattern in the excretion rate of nitrogen was governed mainly by the feeding time. The proportions of excreted ammonia to total nitrogen were 77.9% at 16 C, 84.5% at 19 C, and 83.2% at 23 C. The average was 81.9%. The relationship between the body weight and excretion rate of nitrogen ( E_N , mg N/fish per h) is expressed as E_N =α,.W', where α, = nitrogen excretion rate at temperature 0 . The parameter α, is dependent on water temperature, such that α, =α₂₀ Q₀₁^(0–200) where α₂₀= nitrogen excretion rate at 20 C, and Q₀₁, = temperature coefficient. The values of the kinetics parameters for the cultured flounder were found to be γ = 0.57, α₂₀= 0.060, and Q₀₁= 1.12.     

Effects of temperature changes on the endogenous rhythm of oxygen consumption in the Japanese flounder <Emphasis Type="Italic">paralichthys olivaceus</Emphasis>

ABSTRACT:   The effects of temperature changes on the endogenous rhythm of oxygen consumption in the Japanese flounder Paralichthys olivaceus which were acclimated to 3, 14 or 20°C in advance were investigated. The oxygen consumption rate (OCR) of individuals (total length >28 cm) that were acclimated to 3°C, maintained a relatively low value of 6.9 ± 2.3 mL (mean ± SD) O₂/kg ww (wet weight)/h till 5.8°C, which is considered a 'minimum' rate. Thereafter, the OCR gradually increased up to 18.7 mL O₂/kg ww/h at the temperature of 10.6°C. The OCR of individuals acclimated to 14°C stabilized with 124.2 ± 24.1 mL O₂/kg ww/h, when tested at the relatively constant temperature of 14.4 ± 0.17°C. Maximum entropy spectral analysis revealed that the peak OCR occurred at 23.9 h intervals, which could be a circadian rhythm. The mean OCR showed a peak at 06.00–08.00 hours. For the temperature above 25°C in which the fish were acclimated to 20°C, the rhythmic patterns of OCR were observed until the experimental temperature reached 26.4°C. For the temperature above 28.4°C, the metabolic activity rhythm of the OCR was dampened and then the OCR abruptly rose again. It is assumed that the oscillator of the endogenous rhythm lost the governing of normal metabolic activity in Japanese flounders above 28.4°C. These results suggest that the temperatures of around 5.8, 26.4 and 28.4°C are the 'lower limit temperature', 'upper incipient lethal temperature', and the 'critical thermal maximum', respectively, for the endogenous rhythm of oxygen consumption in the Japanese flounder.     

Perception of light intensity by Haliotis discus discus based on locomotor activity patterns

ABSTRACT:   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.     

Effects of estradiol-17β and 17α-methyltestosterone on gonadal sex differentiation in the F2 hybrid sturgeon, the bester

The effects of giving oral estradiol-17β (E₂) and 17α-methyltestosterone (MT) on gonadal sex differentiation in the F₂ hybrid sturgeon, the bester ( Huso huso female ×  Acipenser ruthenus male), are investigated. Giving E₂ at 10 μg/g diet to fish from 14 months until 31 months of age induced incomplete feminization and resulted in approximately 40% abnormal ovary development in which oocytes were observed without ovarian lamellar structures and gonadal shape was similar to normal testis. Giving MT at 25 μg/g diet for the same duration failed to induce masculinization, and resulted in approximately 30% undeveloped gonads even at 30–37 months of age. In contrast, E₂ and MT at only 1 μg/g diet given from 3 to 18 months of age was sufficient to induce feminization and masculinization, respectively. In these fish, feminization and masculinization were observed at 9 months, when most putative ovaries and testes were histologically distinguishable by the shape of the gonadal surface. These results indicate that sex reversal can be induced in these fish by hormone treatment that is started at 3 months age, before morphological differentiation occurs on the stroma of the gonads.     

Pharmacokinetics of oxolinic acid in gilthead sea bream, Sparus aurata L.

This is the first study on the pharmacokinetic parameters of oxolinic acid (OA) in gilthead sea bream, Sparus aurata L. The kinetic profile of OA was studied after a single intravascular injection (20 mg kg⁻¹) in 100 g fish at 20 °C. The distribution half-life ( t _1/2α) and the elimination half-life ( t _1/2β) of the drug were found to be short (0.51 and 12.60 h, respectively). The drug penetration from the plasma to the tissues was adequate as the apparent volume of distribution of the drug at steady-state ( V _d(ss)) was found to be 2.11 L kg⁻¹. The mean residence time ( MRT ) of OA was short (14.25 h) and the total clearance rate ( Cl _T) of the drug was low (0.15 L kg⁻¹ h⁻¹). The bioavailability ( F %) of OA following oral administration (30 mg kg⁻¹) was also low (14%). Maximum values were observed for muscle at 0.5 h after injection, with levels declining as with subsequent sampling. At the first two time points (0.5 and 1 h) plasma levels of OA were higher than muscle, however, the reverse was evident for subsequent samples. Following oral administration, highest muscle levels were found at 16 h and, with the exception of the 24-h sampling, muscle OA concentrations were higher than plasma at all time points. The fast elimination of OA suggests short withdrawal times with reference to human consumption of treated fish.     

Hormone injections enhance the tolerance of land-locked ayu spermatozoa to cryopreservation

We evaluated the effects of maturation-stimulating hormones on the post-thaw motility of land-locked form ayu ( Plecoglossus altivelis ) spermatozoa. Male ayu were administered three intraperitoneal injections of either salmon pituitary extract (SPE; 0.2 or 0.6 mg g⁻¹ BW day⁻¹) or of 17, 20β-dihydroxy-4-pregnen-3-one (DHP; 2 or 10 μg g⁻¹ BW day⁻¹), the maturation-inducing steroid (MIS) in ayu. Before cryopreservation, the motility of spermatozoa of the SPE- and DHP-treated groups was significantly higher than that of the control group. Similarly, the comparative post-thaw motility (presented as a percentage of the motility obtained before cryopreservation) was significantly higher in the SPE group than in the control; however, there was no significant difference between the DHP group and the control. The effect of SPE and DHP on pre- and post-cryopreservation motility was not dose dependent. Our results suggest that the hormone(s) present in salmon pituitary are effective in enhancing the tolerance of ayu sperm cells to cryopreservation and that the MIS (DHP) is not involved in this process.     

Conditions for the induction of some selective enzymes from <Emphasis Type="Italic">Bacillus subtilis</Emphasis> and their hydrolysis ability against mackerel and gracilar (asparagus, <Emphasis Type="Italic">Gracilaria verrucosa</Emphasis>)

ABSTRACT:   This study was conducted to optimize the cultivation conditions for Bacillus subtilis to produce proteases, amylases and cellulase, and to further investigate the hydrolysis ability against mackerel and asparagus. The extracellular enzymes from B. subtilis after 2 and 4 days incubation in a modified medium, containing 1% skim milk, 1% soya meal, 0.25% starch, 0.25% K₂HPO₄, 0.5% NaCl and 0.05% MgCl₂ were collected for the hydrolysis of asparagus and minced mackerel, respectively. Except for the α,α-diphenyl-β-picrylhydrazyl (DPPH) scavenging ability of the hydrolyzed asparagus, the trolox equivalent antioxidation capacity and DPPH scavenging ability of both samples increased significantly ( P  < 0.05) after 1 h hydrolysis and further increased during elongated hydrolysis at 50°C. Sodium dodecylsulfate–polyacrylamide gel electrophoresis indicated severe degradation of muscle proteins during hydrolysis. Changes in reducing sugar, soluble proteins and peptides before/after hydrolysis suggested the extracellular enzymes from B. subtilis could effectively hydrolyze the mackerel or asparagus, and subsequently improve their antioxidation ability.     

Acoustic characterization of biological backscatterings in the Kuroshio-Oyashio inter-frontal zone and subarctic waters of the western North Pacific in spring

The acoustic characteristics of biological backscattering in the western North Pacific were studied to verify expert knowledge on species composition in the echosigns. The survey was conducted in the Kuroshio-Oyashio inter-frontal zone and the subarctic waters in April 2003. The species composition of backscatterings was identified by using midwater trawl, Isaacs-Kidd midwater trawl and Bongo net. The differences of mean volume backscattering strengths between 120 and 38 kHz (ΔMVBS₁₂₀₋₃₈) were calculated for the backscatterings. Six types of backscatterings were classified based on the results of net samples and the ΔMVBS₁₂₀₋₃₈. The ΔMVBS₁₂₀₋₃₈ of each group was as follows: copepods 13.7–17.3 dB, krill 11.6–15.3 dB, Japanese anchovy −1.6 to 1.1 dB, a myctophid, Diaphus theta −0.8 dB, sand lance 6.1 dB and larvae and juveniles of pelagic and mesopelagic fish −9.6 to −4.0 dB. The results suggest that biological backscatterings in the Kuroshio-Oyashio inter-frontal zone and subarctic waters of the western North Pacific in spring can be characterized by using ΔMVBS.     

Effect of Dietary Supplementation of Vitamins A, D3, E, and C on Yearling Rice Field Eel, Monopterus albus: Serum Indices, Gonad Development, and Metabolism of Calcium and Phosphorus

Abstract.— The objective of this study was to determine the effect of dietary vitamins A, D₃, E, and C on the gonad development, lipid peroxidation, and immune response of yearling rice field eel, Monopterus albus . A 6-wk feeding trial was designed according to an L₁₆(4⁵) orthogonal design, in which four vitamins, each at four supplementation levels, were arranged. Sixteen diets were mixed with the different vitamin levels and randomly assigned to 16 groups of fish. Increasing dietary vitamin E supplementation level significantly ( P  ≤ 0.05) increased the gonadosomatic index and lowered the serum content of malondialdehyde of rice field eel. Increasing dietary vitamin A and C levels also showed similar effect, but the differences were not statistically significant. Serum immunoglobulin M content increased significantly ( P  ≤ 0.01) as dietary vitamin C supplementation levels increased. The concentrations of calcium in bones showed significant ( P  ≤ 0.05) trend with vitamin D₃ and A supplementation levels, but the bone phosphorus content was not affected by the dietary vitamin levels.     

Effects of entrance design on catch efficiency of arabesque greenling traps: a field experiment in Matsumae, Hokkaido

ABSTRACT:   A field experiment was conducted in the Matsumae area of Hokkaido, Japan, during June and July 2002, to investigate the effects of different entrance designs on the catch efficiency of fish traps by fishing with commercial traps (entrance inclination angle [α] = 37°; funnel length of entrance [ L _f ] = 22 cm) and experimental traps. The experimental traps were of the same size and similar design as commercial traps, with different entrance inclination angles (trap E1: α = 46°; E2: α = 27°; E3: α = 0°; all L _f  = 22 cm) or funnel lengths (E4: α = 37°, L _f  = 8 cm). In total, 2200 fish during 200 trap hauls were captured. The catch was significantly higher using both traps E2 and the commercial trap than with trap E3 ( P  < 0.05), and the catch of trap E2 was higher than that of the commercial trap. There were no significant differences in mean fish body length or the frequency distributions of body length among trap types (E1, E2, E3 and commercial). The funnel length of the entrance also affected the catch of traps. Trap E4 had significantly higher catches than the commercial trap ( P  = 0.04) when traps were deployed for a 1-day soak time. Fish body length frequency distributions did not differ between trap E4 and the commercial trap. The results showed that catch can be greatly affected by trap entrance designs.     

Qualitative and quantitative changes of F<Subscript>o</Subscript>F<Subscript>1</Subscript>-ATPase in Japanese flounder and red sea bream associated with rearing temperatures

ABSTRACT:   Fast skeletal muscles of Japanese flounder Paralichthys olivaceus and red sea bream Pagrus major were examined for quantitative and qualitative changes of mitochondrial ATP synthase (F_oF₁-ATPase) in association with rearing temperatures. The specific activities of F_oF₁-ATPase from Japanese flounder reared at 10°C, 15°C and 25°C for 4 weeks were determined to be 81 ± 11, 74 ± 13 and 83 ± 11 nmol/min·mg mitochondrial protein, respectively. The corresponding activity from red sea bream reared at 8°C for 5 weeks was determined to be 65 ± 9 nmol/min·mg mitochondrial protein, which was higher than 33 ± 9 nmol/min·mg mitochondrial protein in fish reared at 23°C. The contents of α- and β-F₁-ATPase in total mitochondrial proteins were not significantly different between fish reared at different temperatures for the two fish species. However, the contents of β-F₁-ATPase in the total fast skeletal muscle extracts, prepared from Japanese flounder reared at 10°C, were 2.1- and 2.9-fold higher than those for fish reared at 15°C and 25°C, respectively. The corresponding content from red seabream reared at 8°C was 2.2-fold higher than that for fish reared at 23°C. Therefore, the changes in F_oF₁-ATPase depending on rearing temperatures were species-specific.