Development of phototaxis in the early life stages of Pacific bluefin tuna <Emphasis Type="Italic">Thunnus orientalis</Emphasis>     

Yoshiaki Ina  Yoshitaka Sakakura  Yosuke Tanaka  Toshiyuki Yamada  Kazunori Kumon  Takeshi Eba  Hiroshi Hashimoto  Junpei Konishi  Toshinori Takashi  Koichiro Gen 《Fisheries Science》2017,83(4):537-542

We investigated the development of phototaxis in larval and early juvenile stages of Pacific bluefin tuna Thunnus orientalis to detail behavior development in relation to light. We observed the distribution of Pacific bluefin tuna in an illumination gradient tank from 1 to 26 days after hatching (DAH). Two long rectangular tanks (100 × 10 × 10 cm) were used for experiments; each tank was divided into four sections for observations and one tank was equally illuminated at 1.0 × 10³ lx as the control tank, and the other was at 4.0 × 10², 1.0 × 10³, 1.0 × 10⁴ and 7.0 × 10⁴ lx as the illumination gradient tank. Laboratory-reared larvae and juvenile were released into each tank and acclimatized for 10 min. Thereafter, the number of individuals in each section was counted for 5 times with 10-min intervals. Until 2 DAH (3.6 ± 0.1 mm BL), larvae distributed homogeneously in each section in both tanks. After 3 DAH (3.7 ± 0.1 mm BL) when the eyes of the larvae were pigmented, most fish moved into the 7.0 × 10⁴ lx section in the illumination gradient tank, while fish in the control tank maintained a uniform distribution during the experimental period (Chi-square test, P < 0.05). The results suggest that the post-larvae and juvenile stages show strong positive phototaxis.  相似文献   

Morphological identity of a taxonomically unassigned cytochrome c oxidase subunit I sequence from stomach contents of juvenile chum salmon determined using polymerase chain reaction     

Sakiko Orui Sakaguchi  Tetsuro Ikuta  Gen Ogawa  Kodai Yamane  Naonobu Shiga  Hiroshi Kitazato  Katsunori Fujikura  Kiyotaka Takishita 《Fisheries Science》2017,83(5):757-765

In a previous report, we analyzed the stomach contents of juvenile chum salmon Oncorhynchus keta by morphological observation and also by molecular identification using the mitochondrial cytochrome c oxidase subunit I (COI) region. However, one of the most frequently detected COI sequences could not be assigned to any specific taxon, even at the phylum level. In the present study, we conducted in situ hybridization (ISH) on the stomach contents of juvenile chum salmon using the COI sequence and polymerase chain reaction amplification of a 18S ribosomal RNA gene from the tissue sections where ISH signals were detected. As a result, the organism that was enigmatic at the phylum level was found to be an appendicularian. Moreover, Oikopleura longicauda collected from the bay where the juvenile chum salmon samples were obtained was shown to have the same COI sequences as this taxonomic “orphan” COI sequence from the stomach contents. The present results suggest that the COI sequences previously deposited in public databases for “Oikopleura” are actually derived from taxonomic groups other than appendicularians, and that this may have hampered our understanding of prey richness in the stomach or gut of certain marine animals based on DNA barcoding.  相似文献   

Effect of a Wheat Protein on pH-Dependent Water-Binding Capacity and Viscosity of Wheat Tailings Fractions     

Masaharu Seguchi  Machiko Hayashi  Hiroshi Matsumoto 《Cereal Chemistry》1997,74(4):384-388

Wheat flour was fractionated with acetic acid using a mortar and pestle method or a blender method. Higher pH-dependent water-binding capacity (WBC) and viscosity were obtained only in the tailings fraction. The higher pH-dependent WBC was rather stable at 5–37°C, however it decreased with salt addition. Pepsin or bromelain treatment stopped the pH-dependent changes in WBC and viscosity, which suggests that this characteristic of the tailings fraction is due to the presence of proteins. HPLC indicated that the M_r of the proteins associated with high WBC at low pH was >200 kDa.  相似文献   

Effects of Various Surfactants on Rheological Properties of Maize Starch Granules     

Masahiro Kurakake  Hiroshi Hagiwara  Toshiaki Komaki 《Cereal Chemistry》2004,81(1):108-114

In this study, the formation of complexes between surfactants and the helical chains of amylopectins was confirmed. Nonionic surfactants with hydrophobic and hydrophilic groups of appropriate size and chemical structure enhanced the swelling and gelatinization processes of starch granules. Hydrophobic groups form complexes with the amylose and linear chains of amylopectin by becoming inserted into the hydrophobic inner area of the helical structures. The hydrophilic groups help the approach of the hydrophobic groups into the hydrated molecular chains and thus aid the formation of the complex. Among the anionic surfactants tested, SDS and sodium n‐decyl benzenesulfate caused maximum swelling and gelatinization peaks. The average length of the amylopectin exterior chains is almost the same as that of the hydrophobic chains of SDS (16.9 Å) and of sodium decyl benzenesulfate (18.2 Å). This suggests that these anionic surfactants form rigid complexes with the exterior of the amylopectin by fitting their hydrophobic chains to the hydrophobic inside of the helical structures of these short exterior chains. This process was clarified by NMR analysis and by a decrease in the complex with the addition of iodine. The hydrophobic alkyl chains of anionic and cationic surfactants fix to the edge of the starch molecular chains by forming inclusion complexes with the helical chains of the amylopectin. Cationic ions interact with the starch molecular chains, causing a negative charge that results in a more rapid and efficient swelling of the starch granules. A decrease in setback value occurs due to the inhibition of rearrangement among the starch molecular chains. With SDS, the complex molecular chains become more extensively developed through the repulsion effects of the anionic ions resulting in a larger swelling power and gelatinization peak.  相似文献   

Dynamics of physicochemical properties and occurrence of fungal fruit bodies during decomposition of coarse woody debris of Fagus crenata     

Yu Fukasawa  Takashi Osono  Hiroshi Takeda 《Journal of Forest Research》2009,14(1):20-29

The pattern of changes in the physicochemical properties of wood, and its relationship with fungal succession during decomposition of coarse woody debris (CWD) of beech (Fagus crenata Blume) were investigated. In total, 47 snags and 66 logs were assigned to a system of five decay classes, and were used for analysis of the decomposition process. The decomposition process consists of two phases characterized by their dominant organic chemical constituents. In the first phase (decay class 1–3), acid-unhydrolyzable residue (AUR) and holocellulose decreased simultaneously. In the second phase (decay class 3–5), holocellulose decayed selectively. Fruiting bodies of ten fungal taxa occurred frequently on decomposing logs and/or snags. These fungi were divided into early and late colonizers according to their occurrence during CWD decomposition. The relationship between fungal community composition and the physicochemical properties of CWD was analyzed by canonical correspondence analysis (CCA). According to the Monte Carlo permutation test, decay class, water content, and type of CWD (log or snag) significantly affected the fungal community structure. Our results suggested that white-rot basidiomycetes, especially Omphalotus guepiniformis, play a central role in the simultaneous decomposition of AUR and holocellulose in the first phase of decomposition. On the other hand, fungal taxa occurring in the second phase of decomposition may not be responsible for the decomposition of holocellulose. Three possible mechanisms of holocellulose decomposition and AUR accumulation in the second phase of decomposition are proposed and discussed. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Overexpression of the Barley Nicotianamine Synthase Gene HvNAS1 Increases Iron and Zinc Concentrations in Rice Grains   总被引：1，自引：0，他引：1  

Hiroshi Masuda  Kanako Usuda  Takanori Kobayashi  Yasuhiro Ishimaru  Yusuke Kakei  Michiko Takahashi  Kyoko Higuchi  Hiromi Nakanishi  Satoshi Mori  Naoko K. Nishizawa 《Rice》2009,2(4):155-166

In humans, iron (Fe) and zinc (Zn) deficiencies result in major worldwide health problems. Transgenic technologies to produce Fe- and Zn-biofortified rice varieties offer a promising potential solution. Nicotianamine, the precursor of phytosiderophores, chelates Fe²⁺ and Zn²⁺ and plays an important role in transporting these metals to both vegetative and reproductive organs within the plant. Our objective was to increase Fe and Zn contents in rice grains by overexpressing the barley nicotianamine synthase gene HvNAS1. HvNAS1-overexpressing transgenic rice showed increased HvNAS1 expression and subsequent increases in endogenous nicotianamine and phytosiderophore content in shoots, roots, and seeds. Fe and Zn concentrations in polished T₁ seeds from transgenic plants increased more than three and twofold, respectively; Fe and Zn concentrations also increased in both polished and brown T₂ seeds. These results suggest that the overproduction of nicotianamine enhances the translocation of Fe and Zn into rice grains.  相似文献   

Effects of double harvesting on estimated total digestible nutrient yield of forage rice     

Hiroshi Nakano  Ikuo HattoriKenzi Sato  Satoshi Morita 《Field Crops Research》2009

We examined the effects of cultivar (Taporuri, Mohretsu, Tachiaoba, and Hinohikari) on estimated total digestible nutrient (TDN) yield of forage rice in double harvesting. The total estimated whole-plant TDN yield (i.e., of the first crop plus second crop) of Taporuri was the highest in double harvesting. In the first crop, the estimated whole-plant TDN yield of Taporuri was the highest. In the second crop, the estimated whole-plant TDN yield of Taporuri was almost the same as those of Mohretsu and Tachiaoba but higher than that of Hinohikari. We also examined the effects of cultivation method (double harvesting or single harvesting) on estimated TDN yield of forage rice. In Taporuri and Mohretsu, the total estimated whole-plant TDN yield was similar in double harvesting and single harvesting. However, in Tachiaoba and Hinohikari, it was lower in double harvesting than in single harvesting. It is important to maximize the amount of nutrition in leaf and stem rather than panicle because the grain is not digested well by cattle. In the double harvesting, the total estimated leaf blade (leaf) TDN yield of Taporuri was higher than that of Hinohikari and almost the same as those of Tachiaoba and Mohretsu. The total estimated leaf sheath plus stem (stem) TDN yield of Taporuri was the highest. In comparison of the total TDN yield of double harvesting with that of single harvesting, the total estimated leaf and stem TDN yields were higher in double harvesting than in single harvesting in all cultivars except for Hinohikari. Thus, double harvesting of Taporuri is an effective way of reducing the overall loss of nutrition from the crop.  相似文献   

Genetic identification and morphology of naturally spawned eggs of the Japanese eel Anguilla japonica collected in the western North Pacific     

Tatsuki Yoshinaga  Michael J. Miller  Kazuki Yokouchi  Tsuguo Otake  Shingo Kimura  Jun Aoyama  Shun Watanabe  Akira Shinoda  Machiko Oya  Sachie Miyazaki  Kei Zenimoto  Ryusuke Sudo  Tetsuya Takahashi  Hyojin Ahn  Ryotaro Manabe  Seishi Hagihara  Hiroshi Morioka  Hikaru Itakura  Masamichi Machida  Kazuyuki Ban  Mayu Shiozaki  Bunpei Ai  Katsumi Tsukamoto 《Fisheries Science》2011,77(6):983-992

Eggs of the Japanese eel Anguilla japonica collected in the western North Pacific were identified by onboard species-specific polymerase chain reaction (PCR) and DNA nucleotide sequencing after the cruise. Fish eggs of various species were collected by large plankton net tows at 12 stations along the southern part of the West Mariana Ridge on 19–25 May 2009. A total of 43 fish eggs were distinguished morphologically as possibly being of A. japonica. Thirty-one of those were analyzed by PCR, which included 15 eggs collected at 12°50–55′N, 141°15–20′E (in 5 tows) that showed positive results. The 16S ribosomal RNA (rRNA) gene sequences of eggs determined after the cruise indicated that 31 A. japonica eggs had been collected. The remaining eggs were of mesopelagic eel species (Serrivomeridae and Derichthyidae), or unidentified species. The morphological characteristics of the A. japonica eggs were consistent with those of artificially spawned eggs, except they had a slightly larger diameter. The egg diameter range did not overlap with those of mesopelagic eels of the Serrivomeridae, which often spawn in the same area as A. japonica. These results suggest that egg diameter and embryo shape can be used to morphologically identify naturally spawned A. japonica eggs.  相似文献   

Vortex flow produced by schooling behavior of arabesque greenling <Emphasis Type="Italic">Pleurogrammus azonus</Emphasis>     

Takashi Kitagawa  Takashi Nakagawa  Ryuji Kimura  Hiroshi Niino  Shingo Kimura 《Fisheries Science》2011,77(2):217-222

Arabesque greenling Pleurogrammus azonus form schools of 30,000–60,000 individuals to feed on mesozooplankton near the sea surface. The fish need to be close to the surface where mesozooplankton production occurs, but the food is not sufficiently dense there for the fish to grow optimally while avoiding predation by sea birds. Arabesque greenling use a unique method to optimize their feeding conditions while avoiding staying on the sea surface. When the school swims upward, water is pushed downward. Upward swimming of a school of 30,000 individuals generates a downward stream of about 0.8–1.1 m/s, resulting in a convergent flow near the surface. This convergence concentrates the mesozooplankton on the sea surface and transports them into deeper layers with a strong vortex about 3.0 m in diameter and 10–20 m long. Thus, schooling of this fish induces vortex flows that provide a rich feeding environment.  相似文献   

Genetic diversity and expression of carbon monoxide dehydrogenase from <Emphasis Type="Italic">Aeropyrum pernix</Emphasis>     

Hiroshi Nishimura  Nozomi Sato  Yoshiko Nomura  Eri Iwata  Yoshihiko Sako 《Fisheries Science》2011,77(1):135-141

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