Short-term evaluation of oxygen transfer from rice (Oryza sativa) to mixed planted drought-adapted upland crops under hydroponic culture

Mixed cropping is a cultivation method widely practiced in tropical regions. The newly developed close mixed planting technique mitigates the flood stress of drought-adapted upland cereal species by co-growing rice (Oryza sativa) plants under field flood conditions. We tested the hypothesis that O₂ was transferred from rice to upland crops using the model system of hydroponic culture. To confirm the hypothesis, the phenomena of O₂ absorption and release by plants were evaluated in a water culture condition without soil. Experiments were conducted in a climate chamber to estimate the amount of O₂ released from the roots of rice and pearl millet (Pennisetum glaucum) under both O₂-rich (20.0 ± .0% conc. in phase I) and O₂-free dark (.8 ± .0% conc. in phase II) conditions. The total O₂ change (between the two phases) in a single planting of rice and pearl millet was significantly higher than that of the mixed planting of rice and pearl millet, which indicated that O₂ was transferred from rice to pearl millet under a water culture condition. The result indicated that approximately 7 μM O₂ g fresh root weight^?1 h^?1 was transferred between the two plant species. O₂ transfer was confirmed between the two plant species in a mix cultured in water, implying its contribution to the phenomenon that improved the physiological status of drought-adapted upland crops under field flood conditions.     

冻结条件下冻藏温度对鲢鱼肉肌原纤维蛋白冷冻变性的影响

本研究探讨了不同冻结终温、冻结速率以及冻结贮藏温度下鲢鱼肉肌原纤维蛋白ATPase活性的变化。结果表明，冻结终温和冻结速率肌球蛋白变性的影响较小，即使在慢速冻结（从0℃经过72h冻结到－40℃）下，样品肌原纤维蛋白的Ca^2＋－、Mg^2＋－、EDTA－ATPase活性的变化都很小。在贮藏过程中，贮藏温度越低肌原纤维蛋白越稳定，而慢冻和快冻对于其后冻藏过程中肌原纤维蛋白变性的差异也不显著。与冻结速率和浆结终温相比，冻结贮藏温度的影响明显。     

Grey mullet roe contains yolk protein having IgE cross-reactivity to chum salmon roe major allergen (Onc k 5)

The major allergenic protein in grey mullet roe was immunologically characterized using rabbit IgG against the β′-component, which is a vitellogenin fragment and the major allergen in chum salmon roe, and the IgE cross-reactivity between salmon and mullet roe was examined using chum salmon roe-allergic patients' sera. Grey mullet β′-component was identified in the yolk protein and consisted of 16 and 30 kDa proteins that showed marked reaction with the anti-β′-component IgG and shared N-terminal amino acid sequence similarity with vitellogenin. The grey mullet β′-component consisted of six different isoforms generated from vitellogenin A and vitellogenin B, and they inhibited the IgE-binding reaction between chum salmon β′-component and a chum salmon roe-allergic patient’s serum. Thus, grey mullet roe may be an allergenic seafood capable of introducing IgE cross-reactivity to chum salmon roe through the β′-component.     

Production of triploid eastern little tuna,Euthynnus affinis (Cantor, 1849)

Herein, we developed a triploidization method using spawned eggs collected immediately after spawning of eastern little tuna (ELT), Euthynnus affinis. ELT broodstock induced the spawning by hormonal treatment in the tank, with the resulting spawned eggs being used for the triploidy induction. Under optimal conditions, the mean ± SEM triploidization and hatching rates were 97.2 ± 2.8% and 84.5 ± 10.3%, respectively. Although triploid ELT showed growth performance equivalent to that of diploids, the triploids died at a higher rate than the diploids during 2–4 weeks post‐hatching when triploids and diploids were reared in the same tank. Therefore, we propose that it would be necessary in a practical operation to use triploid‐only ELT seedlings to avoid selective cannibalism by the diploids. The ELT triploids exhibited an all‐female phenotype. Because previous studies have reported that female triploids show a greater probability of sterility than male triploids, this characteristic could be a major advantage. Since this triploidization method, using spawned eggs, can be performed without handling the broodstock, it is possible to avoid the physical damage caused by the process of artificial insemination, making it possible to repeatedly produce triploid populations without valuable broodstock loss. Thus, we have developed an efficient method to produce ELT triploids, although further study is essential to evaluate sterility of the triploid ELT.     

Effects of stocking density and water exchange regimes on growth and survival of juvenile spotted babylon, Babylona areolata (Link), cultured in experimental earthen ponds

The growth and survival of juvenile spotted babylon, Babylonia areolata , were determined at five stocking densities (100, 200, 300, 400 and 500 snails m⁻²) and three water exchange regimes (7-, 15- and 21-day intervals) in experimental earthen ponds over a 6-month experimental period. The results showed that the growth of spotted babylons was not significantly different among any density treatments ( P <0.05). At the end of the experiment, the average growth rates in body weights were 0.59, 0.59, 0.58, 0.42 and 0.41 g month⁻¹ respectively. Growth was significantly different among the different water-exchange treatments ( P <0.05). The higher body-weight gains were observed in snails held at water exchanges of 7- and 15-day intervals, when compared with those held at water exchange of 30-day intervals. At the end of the experiment, average body-weight gains were 4.22, 3.67 and 2.68 g for snails held in water-exchange treatments of 7-, 15- and 30-day intervals respectively. This study recommended that stocking densities ≤300 snails m⁻² and water exchange of 7–15-day intervals are suitable for cultured B. areolata juveniles in earthen pond.     

Habitat and prey selection of common minke,sei, and Bryde’s whales in mesoscale during summer in the subarctic and transition regions of the western North Pacific

This study represents the first quantitative analysis of the characteristics of the distribution areas and stomach contents of common minke whale Balaenoptera acutorostrata, sei whale B. borealis, and Bryde’s whale B. edeni in relation to oceanographic and prey environments in mid summer in the western North Pacific. Common minke whales were distributed within subarctic regions and the northernmost region of the transitional domain, coinciding with the main habitat of their preferred prey, Pacific saury Cololabis saira. Sei whales were mainly found in the northernmost part of the transition zone and showed prey preference for Japanese anchovy Engraulis japonica, which was significantly more abundant in the main distribution area of the whale than in its adjacent areas. “Hot spots” of Bryde’s whales were found in several regions of the transition zone between the subarctic boundary and the Kuroshio front. This whale species preferred Japanese anchovy as prey, for which the distribution density was significantly higher in the main distribution area of the whale than in the adjacent areas. These results indicate that the summer distributions of Pacific saury and Japanese anchovy greatly influence the distributions of these whale species, suggesting that the whales’ habitat selection is closely related to their prey selection.     

Identification of imported Chirimen at the genus level by a direct sequencing method using mitochondrial partial 16S rDNA region

ABSTRACT:   Quality control of imported fish products is a constant challenge for Customs officials. To help officials access the quality and integrity of imported fish products, and to enhance the effectiveness and accuracy of product screening, a method was developed to identify boiled and dried larval and juvenile sardines (Chirimen) at the genus level by direct sequencing using a partial sequence (606 bp) of mitochondrial 16S rDNA. A phylogenetic tree was constructed, based on nucleotide sequences of seven kinds of Chirimen imported from four countries with 16 standard samples belonging to the orders Clupeiformes and Salmoniformes. To identify the fish genera in imported Chirimen, bootstrap values and branch lengths of the phylogenetic tree as well as genetic distances were used. The data revealed that Chirimen imported from China and Korea contains species of the genus Engraulis . Regarding other imported Chirimen, the least that could be verified was that the sardine ingredients do not belong to regulated genera.     

Introduction: the coastal ecosystem complex as a unit of structure and function of biological productivity in coastal areas

Coastal seas are composed of relatively independent ecosystems, such as estuaries, rocky shores, mangroves, and coral reefs. Such individual ecosystems (IEs) are linked closely to each other by the dispersal and circulation of nutrients and organic matter and the movement of organisms, and form a coastal ecosystem complex (CEC). The CEC is understood as a unit of structure and function of coastal seas. It is characterized by a high degree of species diversity and it plays a large role in fishery and aquaculture production, as it provides important marine services for humans. This special volume compiles recent ecological studies of target species and IEs, to facilitate the conservation of coastal seas and the sustainability and production of their fisheries and aquaculture based on our understanding of the structure and function of the CEC in these environments.     

An assessment of genetic diversity in wild and captive populations of endangered Japanese bitterling <Emphasis Type="Italic">Tanakia tanago</Emphasis> (Cyprinidae) using amplified fragment length polymorphism (AFLP) markers

ABSTRACT:   The Japanese bitterling Tanakia tanago (Cyprinidae) is on the verge of extinction in the wild, placing great importance on captive breeding programs for current conservation of the species. However, the loss of genetic diversity during captive breeding is an ongoing matter of concern. Since some captive populations have been almost monomorphic in mitochondrial DNA (mtDNA), this hampers assessments of their genetic diversity during captive breeding. To more accurately assess their genetic diversity, one wild and three captive populations were examined using amplified fragment length polymorphism (AFLP) markers. Estimates of average heterozygosity and nucleotide diversity ranged 0.0479–0.1920 and 0.0023–0.0088, respectively, enabling comparison of genetic diversity among the wild and captive populations, and among year-classes of captive populations. Significant differences in numbers of amplified fragments and proportions of polymorphic fragments were observed among year-classes of all populations. The indices of genetic diversity calculated from AFLP seemed to be, however, less sensitive to weak bottlenecks. No continuous decrease in genetic diversity in nuclear DNA was detected in presently captive populations. This supports the possibility of re-introduction of the captive populations into the original habitats, although survival and reproductive ability in the wild must be taken into consideration.