Molecular cloning of CD4 from ginbuna crucian carp <Emphasis Type="Italic">Carassius auratus langsdorfii</Emphasis>

ABSTRACT:   The clonal triploid ginbuna crucian carp Carassius auratus langsdorfii , a naturally occurring gynogenetic fish, is a useful model for studying T-cell-mediated immunity. CD4, a T-cell receptor (TCR) coreceptor, is a membrane-bound glycoprotein found on helper T-cells, and assists in the binding of major histocompatibility complexes. In the present study, full-length cDNAs encoding the CD4 molecule from the S3n strain of ginbuna crucian carp were cloned and characterized. 5'-rapid amplification of cDNA ends (RACE) and 3'-RACE yielded two distinct cDNA clones of CD4 homolog from the ginbuna, and these sequences share 95% identity at the amino acid level. These ginbuna CD4 molecules consisted of a signal peptide, immunoglobulin superfamily (IgSf) like domains, a transmembrane domain, and a cytoplasmic domain similar to other known CD4. A tyrosine protein kinase p56^lck binding motif is conserved in the cytoplasmic tail of ginbuna CD4. Phylogenetic tree analysis indicated that ginbuna CD4 sequences are closely related to CD4L-1 from other fish species. Expression of ginbuna CD4 mRNA was detected in the gill, thymus, head kidney, trunk kidney and peripheral blood leukocytes, indicating that its expression pattern is similar to that of ginbuna TCRβ mRNA. The results suggest that ginbuna CD4 sequences are useful as molecular probes for helper T-cells.     

Chemical composition of dried eyeballs from <Emphasis Type="Italic">Euphausia superba</Emphasis> and <Emphasis Type="Italic">Euphausia pacifica</Emphasis>

ABSTRACT:   Dried krill eyeballs were obtained from Euphausia superba and Euphausia pacifica by using a patented industry method and their chemical compositions were examined. Crude protein content was 77.7% and 80.8% of the dry matter of E. superba and E. pacifica , respectively. The dominating amino acids in both krill were glutamic acid, aspartic acid, glycine, arginine, leucine and tyrosine. Crude fat content was 10.9% and 5.4% of dry matter of E. superba and E. pacifica , respectively. The main lipid class of the extracted lipids was phospholipids at 88.5% in E. superba and 96.4% in E. pacifica . The dominating fatty acids in both krill were 22:6 ( n- 3), 20:5 ( n- 3), 16:0 and 18:1 ( n- 9). Astaxanthin (3, 3'-dihydroxy-β, β-carotene-4, 4'-dione) content of E. superba and E. pacifica was 566 mg/100 g and 252 mg/100 g of dry matter, respectively. Retinol of E. superba and E. pacifica was 153.0 mg/100 g (510 000 IU/100 g) and 57.6 mg/100 g (192 000 IU/100 g) of dry matter, respectively. The lipophilic extract of E. superba by using n -hexane contained 1923 mg/100 g of astaxanthin at approximately four times higher than the dried eyeballs.     

Difference in the level of paralytic shellfish poisoning toxin accumulation between the crabs <Emphasis Type="Italic">Telmessus acutidens</Emphasis> and <Emphasis Type="Italic">Charybdis japonica</Emphasis> collected in Onahama,Fukushima Prefecture

ABSTRACT:     The difference in paralytic shellfish poisoning (PSP) toxin accumulation in the crabs Telmessus acutidens and Charybdis japonica was investigated at Onahama, Fukushima Prefecture, from 2002 to 2005. The level of toxin accumulation in the hepatopancreas of T. acutidens corresponded to that of mussels when examined on a yearly basis. In 2003, some crabs had a high toxicity of approximately 1000 MU, which compares to one-third of the human minimum lethal dose. Therefore T. acutidens should be monitored as a vector species of PSP toxin. The toxin profile of T. acutidens was also investigated. Because an increase in highly toxic species of PSP toxins with a decrease in low toxic species, such as N -sulfocarbamoyl-11-hydroxysulfate toxins, was not clearly observed between consecutive samples, toxin transformation in T. acutidens was considered to have a minimal impact on toxicity. PSP toxins were also detected in several specimens of C. japonica , but the highest toxicity was only 7.4 MU/g in the hepatopancreas. Because C. japonica is widely distributed in the coastal waters of Japan, investigation of toxin accumulation in the crab should be continued, including its investigation in different areas of water from Onahama, where the causative dinoflagellates of PSP occur in different conditions.     

Morphological studies of peripheral blood cells of the Chinese sturgeon, <Emphasis Type="Italic">Acipenser sinensis</Emphasis>

The peripheral blood cells of one-year-old Chinese sturgeon (Acipenser sinensis) have been studied by light microscopy and transmission electron microscopy. The erythrocyte count was 84.86 × 10⁴ cell mm⁻³ in the peripheral blood of the fish and that of leukocytes was 2.24 × 10⁴ cell mm⁻³. The erythrocytes and four main types of leucocyte—thrombocytes, lymphocytes, granulocytes (including neutrophils and eosinophils), and monocytes, were identified in the peripheral blood. In addition to normal erythrocytes, reticulocytes and division of erythrocytes were observed. Thrombocytes were the most numerous among the leukocytes, and the number of neutrophils with lobated nuclei was larger than for other fish. The structures of the erythrocytes, lymphocytes, monocytes, granulocytes, and thrombocytes of the fish were studied. The erythrocytes were almost completely devoid of organelles, except for some mitochondria and granules. A large number of vacuoles and a few organelles were observed in cytoplasm of the monocytes. There were many microvilli on the membrane and pseudopodia-like cytoplasm bulge in the lymphocytes. The neutrophils were round or oval in shape with bilobed, trilobed, or multilobed nuclei whereas the eosinophils had big special granules, dark stained. There were many vesicles in some thrombocytes, which were related to its phagocytosis; some thrombocytes had almost no cytoplasm or organelles.     

Optimum temperature and salinity conditions for growth of green algae <Emphasis Type="Italic">Chlorella ellipsoidea</Emphasis> and <Emphasis Type="Italic">Nannochloris oculata</Emphasis>

ABSTRACT:   The effects of temperature and salinity on growth of green algae Chlorella ellipsoidea and Nannochloris oculata were determined to compare the optimum culture conditions. A four-temperature (15, 20, 25, and 30°C) × three-salinity (10, 20, and 30) factorial design with triplicates was applied. Specific growth rate (SGR), maximum density, and duration to reach maximum density of C. ellipsoidea were significantly affected by both temperature and salinity. The highest SGR was observed in C. ellipsoidea at 25°C and salinity 10, but the maximum density was very low. The highest maximum density was achieved in C. ellipsoidea at 15°C and 10. The slope constant of the linear relationship between semilogarithmic growth of C. ellipsoidea and day of culture was highest at 15°C and 10. The SGR and duration to reach maximum density of N. oculata were significantly affected by both temperature and salinity. However, maximum density of N. oculata was significantly affected by temperature, but not salinity. The highest maximum density was achieved in N. oculata at 25°C and 30, but SGR was significantly lower than that of N. oculata at 25°C and 10. The slope constant of the linear relationship between semilogarithmic growth of N. oculata and day of culture was highest at 25°C and 30. Based on these results, the condition of 15°C and salinity 10 seemed to be optimal for maximum density of C. ellipsoidea , and the condition of 25°C and 10 and 30 for SGR and maximum density for N. oculata , respectively.     

Proposal for stock-recruitment relationship for Japanese sardine <Emphasis Type="Italic">Sardinops melanostictus</Emphasis> in North-Western Pacific

ABSTRACT:   This study assessed the stock-recruitment relationship (SRR) for the Japanese sardine Sardinops melanostictus in the North-western Pacific. Of the 20 SRR models investigated, the Akaike information criterion (AIC) was the minimum (AIC = 551.2) when the data were separated into two groups (A and B) and the log-normal distribution was applied as the error term. Group A was constructed with SRR data from 1976–1987 and 1992–2004. Group B consisted of data from 1988–1991. The AIC minimum model was R  = 22.8 S  ×  e ^ε for Group A, where R , S , and ε denote the recruitment of sardine (individual number of 0-year old fish), spawning stock biomass (SSB), and error term, respectively. This model indicated that recruitment was proportional to the SSB and that no density-dependent effect operated over the range of SSB investigated (51 000–11.3 million t). Recruitment was markedly higher (lower) when the sea surface temperature (SST) of the Kuroshio Extension area in February was low (high). The essential SRR can simply be expressed as R  = 22.8 S  ×  e ^ε with the level of recruitment deviating from the model to a greater or lesser degree depending on the environmental conditions.     

Fortification of <Emphasis Type="Italic">niboshi</Emphasis> with histidine prepared from <Emphasis Type="Italic">katsuobushi</Emphasis> protein digest

ABSTRACT:   Free and total histidine contents in the muscle of various fishes and invertebrates caught in the Seto Inland Sea were estimated. These contents were higher in the muscles from skipjack, yellowfin tuna, yellowtail and mackerel than in those from lizard fish, sea bream and hairtail. Invertebrate muscles, except squid, contained low free and total histidine. Boiled and dried anchovy ( niboshi ) contained lower free histidine than that of dried anchovy (suboshi). To prepare free histidine-rich extracts, the waste residue of soup stock from smoke-dried and shaved skipjack ( katsuobushi ) was digested with proteases. The extract of the enzyme digest contained high free histidine and was used to fortify niboshi with free histidine. If taken, the fortified niboshi may suppress food intake, and prevent obesity.     

Size selectivity of escape holes in conger tube traps for inshore hagfish <Emphasis Type="Italic">Eptatretus burgeri</Emphasis> and white-spotted conger <Emphasis Type="Italic">Conger myriaster</Emphasis> in Tokyo Bay

ABSTRACT:   In Tokyo Bay, conger tube-trap fishers voluntarily deployed escape holes of at least 13 mm diameter to reduce the by-catch of young conger smaller than the marketable size of 35 cm total length. Comparative fishing experiments in Tokyo Bay were carried out using tube traps with seven hole diameters (3, 9, 13.5, 14, 15, 17, and 19 mm), to obtain the size-selectivity of the escape-hole size for inshore hagfish Eptatretus burgeri and white-spotted conger Conger myriaster . On the assumption of the geometrical similarity in the combination of body g and hole perimeter m at a given retention probability, a single master curve s ( R ) = exp(−13.52 + 11.31 R )/(1 + exp [−13.52 + 11.31 R ]) was estimated for the two species in terms of relative R  =  g / m using the Share Each LEngth's Catch Total (SELECT) process based on a multinomial distribution. Almost all conger and hagfish with a girth equivalent to the hole perimeter were able to pass through the hole. Thus, the two species have a high ability to escape through a narrow space by squeezing the body through the hole in the rigid PVC tube. Optimum escape-hole size is discussed from several objectives for conger tube-trap fishery management, e.g. reduction of hagfish by-catch. This study also specifies the conditions for pooling data when fishing experiments using more than two fishing gears are replicated.     

Induction of (<Emphasis Type="Italic">Z</Emphasis>)-8-heptadecene in marine green alga <Emphasis Type="Italic">Bryopsis maxima</Emphasis> by mechanical wounding

ABSTRACT:   After mechanical wounding of the marine green alga Bryopsis maxima in a phosphate buffer, one main organic component was released to the solution. The organic compound was characterized by a molecular ion at 238  m/z by gas chromatography–mass spectrometry (GC-MS) and was deduced as 8-heptadecene by the fragment pattern. To identify the stereochemistry of 8-heptadecene, synthetic ( Z / E )-8-heptadecene was coinjected to the solution of wounded B. maxima . Comparing retention times and mass spectra with the synthetic sample, the target hydrocarbon obtained from wounded B. maxima was coincident with ( Z )-8-heptadecene.     

Effects of heavy metals in river waters in Japan on immobility and mortality of <Emphasis Type="Italic">Daphnia magna</Emphasis> and <Emphasis Type="Italic">Oryzias latipes</Emphasis> larvae

ABSTRACT:   Samples of river waters containing high concentrations of zinc and other heavy metals but low concentrations of other anthropogenic contaminants were collected to investigate the relationship between toxicity of heavy metals and naturally present organic matters or hardness, as well as the effects of heavy metals on aquatic organisms. Acute toxicity tests were conducted for the water samples using Daphnia magna and medaka Oryzias latipes . Almost all the D. magna died in river waters containing high concentrations of zinc, but O. latipes in the same waters were hardly affected. Since the test organisms were not only exposed to zinc but also other heavy metals in the river waters, we examined the toxicity using toxic units composed of zinc, copper, lead, and cadmium. The results of a bioassay with the river waters showed that the mortality of D. magna did not depend solely on the total number of toxic units of heavy metals. The organic matters and the hardness of the river waters could decrease the acute toxicity of zinc and other heavy metals to D. magna .     

Hybridization success of three common European cyprinid species, <Emphasis Type="Italic">Rutilus rutilus,Blicca bjoerkna</Emphasis> and <Emphasis Type="Italic">Abramis brama</Emphasis> and larval resistance to stress tests

ABSTRACT:   Hybridization success at early developmental stages and larval resistance to osmotic, thermal and fasting tests in roach Rutilus rutilus , silver bream Blicca bjoerkna , common bream Abramis brama and their F1 hybrids were investigated. Results revealed that hybrid survival rates were similar to parents. At the eyed embryo stage, however, a maternal effect was observed as a general trend during hatchling and larval stages. After these stages, hybrids displayed a higher survival rate than their parents. Under stress tests, no survival was observed after 40 min for osmotic and thermal shocks and after 24 days for the prolonged fasting test in these species and their F1 hybrids. The median survivals of hybrids were intermediate between the two parents. For total mortality, hybrids were also affected by a maternal effect but to the advantage of the hybrids.     

Characteristics of burnt meat in cultured yellowtail <Emphasis Type="Italic">Seriola quinqueradiata</Emphasis>

ABSTRACT:   In order to understand the characteristics of burnt meat in cultured yellowtail Seriola quinqueradiata , fish were kept at two different temperatures (13 and 30°C) and slaughtered by either spinal cord destruction (SCD) or suffocation in air (SA). Early postmortem changes during storage at 32°C were analyzed by rheological, biochemical, and histological methods. The burnt meat (with lightness parameter, L* ≥ 55) was observed at 1-h storage in the SA 30°C group, at 2 h in SCD 30°C, and at 4 h in SA 13°C; meat was normal for the SCD 13°C group until 6 h of storage. Breaking strength scores were higher for the normal meat (200 g/cm²) than burnt meat (70 g/cm²) at 4 h of storage. Expressible water content was higher for the burnt meat than for the normal meat. Adenosine triphosphate concentrations for the SCD groups were higher than for the SA counterparts. Moreover, pH decrease was much faster in the 30°C groups, showing pH 5.6 at 2 h of storage. A negative correlation between the pH and lactic acid contents in muscle ( P  < 0.001) was found. Histological analysis evidenced a larger pericellular area (40%) in the burnt samples than in the normal samples (16%). It was confirmed that a higher fish-keeping water temperature and a stressful slaughter method (faster glycolytic process) were determinative factors that influence the occurrence of burnt muscle in yellowtail, and that the effect of the former is larger than the latter.     

Growth changes in bighand thornyhead <Emphasis Type="Italic">Sebastolobus macrochir</Emphasis> off the Pacific coast of northern Honshu,Japan

ABSTRACT:     The biomass of bighand thornyhead Sebastolobus macrochir was increased by the high recruitment success of the 1999–2002 year classes off the Pacific coast of northern Honshu, Japan. In this study, the growth of bighand thornyhead was examined over a 9-year period from 1996 to 2004 in this area. The growth of the 1999 year class and the 2000–2002 year classes was reduced at 3 and 2 years old, respectively, while the 1999–2002 year classes were smaller than the 1993–1998 year classes. In 2-, 3- and 4-year-old fish, the relationship between abundance and mean standard length was expressed by negative linear regressions, while fish became smaller when abundance of the year class was larger. Mean bottom temperatures were stable at depths of 350–900 m; variations in water temperature were small in the main distribution area of bighand thornyhead. We discuss the factors affecting the growth of bighand thornyhead via changes in the demersal fish community and feeding habits.     

Possibility for decreasing of mercury content in bluefin tuna <Emphasis Type="Italic">Thunnus orientalis</Emphasis> by fish culture

ABSTRACT:   The bluefin tuna tested were reared for 22 months from eggs before the beginning of the experiment, and sampling was performed every 3 months over the following year. The experimental results showed that the mercury concentration in the muscle ranged from 0.32 to 0.85 μg/g, which is lower than that found in wild bluefin tuna of a similar size. Increase in the mercury concentration corresponding to the increase in body weight was not shown, and it was quite different with wild bluefin tuna. Furthermore, no significant relationship was found between the lipid concentration and the mercury concentration in muscle. Among the internal organs of cultured bluefin tuna, the heart (0.32–0.66 μg/g), liver (0.43–0.99 μg/g) and spleen (0.59–1.0 μg/g) contained higher concentrations of mercury. It was estimated that the full-cycle cultured bluefin tuna had been fed small fish containing lower concentrations of mercury, and that the mercury concentration of tuna would be almost equal throughout the year because the effect of mercury accumulation would be weakened by body growth. Therefore, it was concluded that selecting diet fish species might decrease mercury contents in cultured bluefin tuna.     

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.     

Genetic comparison between torafugu <Emphasis Type="Italic">Takifugu rubripes</Emphasis> and its closely related species karasu <Emphasis Type="Italic">Takifugu chinensis</Emphasis>

Abstract:   Sequence analyses of mitochondrial (mt) and nuclear genes were performed for genetic comparison between two Takifugu pufferfish species: torafugu T. rubripes and karasu T.  chinensis . With a sequence coverage of 20% in mtDNA, 640, 308, 344, 522 and 697 bp encoding mt 16S ribosomal RNA (rRNA), adenosine triphosphatase 6 ( ATPase 6 ), nicotinamide adenine dinucleotide dehydrogenase subunit 4 ( ND4 ), ND5 and cytochrome b (cyt b ), respectively, among 24 wild torafugu, 24 wild karasu and six hybrid-like samples, 15% of the torafugu identified by external color patterns showed nucleotide sequences consistent with karasu. Meanwhile, sequences of 60% karasu were consistent with those registered for torafugu (AJ421455). As for the hybrid-like samples, two possessed karasu-specific sequences in some base positions while torafugu-specific sequences in others. The remaining hybrid-like samples possessed torafugu-specific sequences. On the other hand, the mt control region did not show such type of consistency. Analysis of nuclear melanocortin receptor genes ( MC1R , MC4R ) among 54 samples showed 99–100% inter- and intraspecific sequence identity. Partial nuclear 18S  rRNA, complete internal transcribed spacer 1 ( ITS1 ), partial 5.8S  rRNA and ITS2 genes showed similar levels of identity, indicating a very low level of variation in their respective gene fragments between the two Takifugu species.     

Effects of fish size and water temperature on the acute toxicity of boron to Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis> and red sea bream <Emphasis Type="Italic">Pagrus major</Emphasis>

ABSTRACT:     The acute toxicities of boron were examined for Japanese flounder Paralichthys olivaceus and red sea bream Pagrus major in terms of fish size and water temperature. Japanese flounder of 0.1–70.0 g and red sea bream of 0.6–20.3 g were exposed to different concentrations of boron for 96 h at 20°C under semi-static conditions. In both fish species, the median lethal concentration (LC₅₀) for 96 h of boron increased linearly with increasing fish size, ranging from 108 to 252 mg B/L for the flounder, and from 97 to 172 mg B/L for the sea bream. The effect of water temperature on acute toxicity was examined for Japanese flounder of 0.6 and 1.5 g at 10, 15, 20 and 25°C, and for red sea bream of 0.6 and 2.4 g at 12, 15, 20 and 25°C. The toxicity of boron for the flounder increased linearly with increasing water temperature. The 96 h LC₅₀ values ranged from 299 to 108 mg B/L for the 0.6 g flounder and from 350 to 113 mg B/L for the 1.5 g flounder. A similar trend was shown for the 2.4 g red sea bream; however, the relationship for the 0.6 g red sea bream was not significant.     

Multigenerational effects of 17β-estradiol and nonylphenol on euryhaline cladoceran <Emphasis Type="Italic">Diaphanosoma celebensis</Emphasis>

ABSTRACT:     The effects of parental exposure to 17β-estradiol (E2) and 4-nonylphenol (4-NP) on life history parameters of three successive generations of the euryhaline cladoceran Diaphanosoma celebensis were assessed under laboratory conditions. Less than 24-h-old neonates (P) were exposed to five sublethal concentrations of E2 (0.1, 1, 10, 100 and 1000 μg/L) and 4-NP (0.01, 0.1, 1, 10 and 50 μg/L) at 25°C. Age at first reproduction, reproductive period, fecundity and lifespan were investigated. Successive generations (F₁–F₃) were monitored further in the absence of toxicants. Results showed that cladocerans exposed to 10–1000 μg/L E2 produced more neonates at a younger age compared to the control. The same effects were also observed in the F₁ and F₂ but ceased in F₃. Cladocerans exposed to 1 μg/L 4-NP also produced significantly more neonates compared to the control, but this effect was not found in successive generations. The results suggest that vertebrate hormone can modify the reproduction of D. celebensis , and the effects are multigenerational.