論文 - 長野 直樹
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Use of an Antifungal Drug, Amphotericin B for Isolation of Thraustochytrids
Taoka Y., Nagano N., Okita Y., Izumida H., Sugimoto S., Hayashi M.
Journal of Bioscience and Bioengineering 110 ( 6 ) 720 - 723 2010年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Bioscience and Bioengineering
The inhibitory effect of amphotericin B (AMPH) on the growth of fungi during the isolation of thraustochytrids was examined. The growth of fungi was significantly inhibited by addition of AMPH, and therefore colonies of thraustochytrids were not overlaid with fungal mycelia, which resulted in increased efficiency of thraustochytrids isolation. © 2010 The Society for Biotechnology, Japan.
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Nagano N., Taoka Y., Honda D., Hayashi M.
Journal of Oleo Science 58 ( 12 ) 623 - 628 2009年11月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Oleo Science
The effects of carbon sources, seawater concentration and seawater component in a culture medium were investigated to optimize culture conditions for growth by a marine thraustochytrid Aurantiochytrium limacinum strain mh0186. Strain mh0186 could utilize D-glucose, D-fructose and D- mannose as carbon sources. Seawater concentrations between 12.5 - 200% were required for good growth, and a single omission of magnesium sulfate from the seawater reduced the growth of the cells. Jar fermentor trials were carried out for the purpose of docosahexaenoic acid (DHA) production by strain mh0186. The total fatty acid content of the cell was 466.5 mg/g dry cells, and biomass and DHA yield were estimated as 23.1 g/L and 4.3 g/L, respectively, at 26 h. The daily production of DHA by the strain was 4.0 g/L/d, suggesting that the higher DHA production rate of our strain mh0186 should be appropriate for industrial production of DHA. © 2009 by Japan Oil Chemists' Society.
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Taoka Y., Nagano N., Okita Y., Izumida H., Sugimoto S., Hayashi M.
Marine Biotechnology 11 ( 3 ) 368 - 374 2009年6月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Marine Biotechnology
The growth, lipid content, and fatty acid composition of Aurantiochytrium sp. strain mh0186 at different temperatures were investigated. Strain mh0186 grew well at 15-30°C, but weakly at 10°C. The biomass at 15-30°C was significantly higher than at 10 and 35°C, and the total lipid at 15-35°C was significantly higher than that at 10°C. The amount of DHA in the total fatty acid was highest at 10°C and decreased in response to temperature increase. The content of DHA (mg/g-dry cell weight) at 15-30°C were significantly higher than those at 35°C and those at 15-25°C were significantly higher than those at 10 and 35°C. The DHA yield at 15-35°C was significantly higher than those at 10 and 35°C. Unsaturation of fatty acid was regulated by temperature and was enhanced in response to temperature decrease. The ratio of DHA to DPA varied at different temperatures. © 2008 Springer Science+Business Media, LLC.
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Extracellular enzymes produced by marine eukaryotes, thraustochytrids
Taoka Y., Nagano N., Okita Y., Izumida H., Sugimoto S., Hayashi M.
Bioscience, Biotechnology and Biochemistry 73 ( 1 ) 180 - 182 2009年2月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Bioscience, Biotechnology and Biochemistry
Extracellular enzymes produced by six strains of thraustochytrids, Thraustochytrium, Schizochytrium, and Aurantiochytrium, were investigated. These strains produced 5 to 8 kinds of the extracellular enzymes, depending on the species. Only the genus Thraustochytrium produced amylase. When insoluble cellulose was used as substrate, cellulase was not detected in the six strains of thraustochytrids. This study indicates that marine eukaryotes, thraustochytrids, produced a wide variety of extracellular enzymes.
DOI： 10.1271/bbb.80416
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Taoka Yousuke, Nagano Naoki, Okita Yuji, Izumida Hitoshi, Sugimoto Shinichi, Hayashi Masahiro
Journal of Bioscience and Bioengineering 105 ( 5 ) 562 - 565 2008年
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：The Society for Biotechnology, Japan
Tween 80, KH<sub>2</sub>PO<sub>4</sub> and tomato juice were added to basal medium for the isolation of thraustochytrids. By the addition of Tween 80 and KH<sub>2</sub>PO<sub>4</sub>, the number of thraustochytrids isolated from seawater increased. KH<sub>2</sub>PO<sub>4</sub> and Tween 80 were considered to be useful for isolating thraustochytrids.<br>
DOI： 10.1263/jbb.105.562
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Osako K., Fujii A., Ruttanapornvareesakul Y., Nagano N., Kuwahara K., Okamoto A.
Fisheries Science 73 ( 3 ) 660 - 667 2007年6月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Fisheries Science
For the purpose of clarifying the differences of taste components between the testis and ovary of the sea urchin Anthocidaris crassispina, variations in free amino acid composition in gonadal extract during gonadal development were investigated using chemical and histopathological methods. Sea urchins were collected at Iki Island, Nagasaki, Japan between 30 April and 5 June 2003, and maturation stages and the free amino acid compositions were determined. The sweet amino acids threonine (Thr), glycine (Gly), and alanine (Ala), the umami amino acid glutamic acid (Glu), and the bitter amino acids lysine (Lys) and arginine (Arg) were the main constituents accounting for more than 80% of total free amino acids. In the testis and ovary, Gly levels were the highest among them and increased with gonadal development. The other free amino acids consisted mainly of bitter amino acids and either showed no variation or decreased with gonadal development. These variations in free amino acid composition were observed more clearly in the ovary than the testis. These findings indicate the possibility of differences in the flavor of sea urchin gonad by sex and gonadal development stages. © 2007 Japanese Society of Fisheries Science.
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Nagano N., Nagano N., Hozawa A., Fujiki W., Yamada T., Miyaki K., Sakakura Y., Hagiwara A.
Aquaculture Research 38 ( 2 ) 121 - 130 2007年2月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Aquaculture Research
The seven-band grouper, Epinephelus septemfasciatus (Thunberg), is currently recognized as a potential new species for aquaculture in Japan. This study describes normal and abnormal skeletal development of the jaw and vertebrae in cultured larvae and early juveniles of E. septemfasciatus. The ontogenetic stages at which skeletal deformities of jaw and vertebra developed were also described for this species. Osteological observations were made using a clearing and staining method for larvae and soft X-ray photographs for juveniles. A high incidence of skeletal deformities was observed in the jaws and vertebral column during the larval and juvenile stages. Most of the jaw deformities were explained by an abnormal maxilla curvature. Jaw deformities were visually evident from flexion stage after ossification of the deformed elements. Deformities in the vertebral column (mostly lordosis) were observed from the post-larval stage and became more evident as growth proceeded. The lordosis generally occurred on the positions of the 8-11th vertebra. These types of deformities are compared with those of other species, and possible causative factors of the skeletal deformities are discussed. © 2007 Blackwell Publishing Ltd.
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Yukino T., Yukino T., Hayashi M., Inoue Y., Imamura J., Nagano N., Murata H.
Nippon Suisan Gakkaishi (Japanese Edition) 71 ( 1 ) 74 - 79 2005年1月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Nippon Suisan Gakkaishi (Japanese Edition)
Nutritional fortification of Spirulina with docosahexaenoic acid (DHA) was attempted. Fish oil, DHA-ethyl and free DHA were supplemented into the culture of Spirulina as a source of DHA. Exogenous DHA in triglycerides and ethyl ester were not taken up into Spirulina cells. However, the cells took up the DHA in free form from the culture media. The cells without supplementation with DHA did not contain DHA in the cellular fatty acids. The DHA content of the cells was greatly increased by supplementation with DHA into the culture media. It reached to 70.2% of the total fatty acid in the cells. DHA was mainly incorporated into the neutral lipids such as monoglycerides and diglycerides in the cells. Free fatty acids were slightly detected in the DHA-fortified cells. A small amount of DHA was also incorporated into glycolipid and phospholipid fractions. Sulfoquinovosyldiacylglycerol in the DHA-fortified Spirulina contained 9.1 % of DHA in the total fatty acid. However, only 1-2% of DHA were incorporated into the other polar lipids.
DOI： 10.2331/suisan.71.74
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Nagano N., Decamp O., Decamp O.
Aquaculture Research 35 ( 5 ) 516 - 518 2004年4月
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A Technique to Enrich α-tocopherol in Clilorella and Marine Rotifers
NAGANO Naoki, HAYASHI Masahiro, YUKINO Tsugiyo, MURATA Hisashi
水産増殖 = The aquiculture 51 ( 4 ) 459 - 460 2003年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：日本水産増殖学会
α-Tocopherol (TOC) and various fatty acids were supplemented into the <I>Chlorella vulgaris</I> strain K-22 culture at 28°C for 24 h, and TOC content of the <I>Chlorella</I> cells was determined. The addition of TOC alone into the <I>Chlorella</I> culture medium did not give an increase of the cellular TOC content. However, the TOC contents in the <I>Chlorella</I> cells supplemented with TOC and various fatty acids were much higher than those supplemented with TOC alone. Moreover, the TOC content in the cells supplemented with a mixture of TOC and oleic acid was higher than those supplemented with a mixture of TOC and docosahexaenoic acid (DHA) . The TOC content of the rotifers fed on the TOC-enriched <I>Chlorella</I> was much higher than rotifers fed on unenriched <I>Chlorella</I>. On the other hand, rotifers could be easily enriched with TOC by feeding the TOC-enriched <I>Chlorella</I> cells.
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Nagano N., Iwatsuki Y., Okazaki Y., Nakata H.
Journal of Oceanography 57 ( 2 ) 155 - 163 2001年6月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Oceanography
Larval feeding and survival strategies are described on a Japanese sand lance, Ammodytes personatus Girard, collected in the vicinity of a thermohaline front in the Ise Bay, in comparison with those of other predominant larvae, Hexagrammos spp. and Sebastiscus marmoratus (Cuvier). First-feeding A. personatus larvae (3.1-3.9 mm NL) fed primarily on tintinnid ciliates, subsequently switching to copepod nauplii (4.0-7.9 mm NL larvae) and post-naupliar copepods (8.0-11.3 mm NL larvae). First-feeding Hexagrammos spp. larvae (6.5-6.9 mm NL) fed primarily on post-naupliar copepods, and first-feeding S. marmoratus larvae (<4.0 mm NL), mostly on copepod nauplii. The different food preferences of these species at first-feeding were related to their different mouth widths (0.15-0.19, 0.52-0.56 and 0.32-0.40 mm, respectively) and/or body size (3.1-3.9, 6.5-6.9 and 3.2-3.9 mm NL, respectively). Ciliate-feeding by first-feeding A. personatus larvae was strongly related to the convergence of the larvae and their prey near the thermohaline front, densities of both being greater on the inshore side of the frontal zone. In conclusion, the aggregation of ciliates near the thermohaline front may have improved feeding conditions and survival of first-feeding A. personatus larvae.
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Nagano N., Iwatsuki Y., Kamiyama T., Nakata H.
Hydrobiologia 432 ( 1-3 ) 149 - 157 2000年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Hydrobiologia
The contribution of ciliates as a food source to survival of first-feeding surgeonfish larvae, Paracanthurus hepatus, was examined in rearing experiments. The larvae were exposed to eight treatments; i.e. a tintinnid, Amphorellopsis acuta (1.0 × 104, 5.1 × 103 and 2.2 × 103 cells 1-1) and a naked ciliate, Euplotes sp. (1.3 × 104, 8.0 × 103 and 5.0 × 103 cells 1-1), plus two controls without ciliates. Highest survival of the larvae over the first 4-8 days was observed in the highest density of A. acuta. Rearing experiments also showed that the survivals of larvae fed with A. acuta were higher than those fed with Euplotes sp. Gut content analyses revealed loricae of A. acuta in the larvae. Although Euplotes sp. (lacking loricae) was never recognized in those larval guts, feeding on Euplotes sp. by larvae was confirmed using the ciliate labeled with fluorescent microspheres, implying that the feeding on naked ciliates by fish larvae has been overlooked. The results strongly suggested that both tintinnid and naked ciliates play important roles as alternative food sources to copepod nauplii by enhancing the survivability of fish larvae, especially those with a smaller mouth.
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Nagano N., Iwatsuki Y., Kamiyama T., Shimizu H., Nakata H.
Plankton Biology and Ecology 47 ( 2 ) 93 - 99 2000年
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Plankton Biology and Ecology
The survival from hatching to day 8 of larval grouper, Epinephelus septemfasciatus, was examined in two rearing experiments. In Experiment 1, the larvae were fed with aloricate ciliates, Euplotes sp. 1 or Euplotes sp. 2, at different concentrations. Significantly higher survival of the larvae was observed in the treatment with the highest density of Euplotes sp. 1 (1.4 x 104 cells l-1) on days 5 and 6 after hatching. Experiment 2 consisted of different prey concentrations of a loricate ciliate, Favella taraikaensis. Significantly higher larval survival was observed in the treatment having the highest density of F. taraikaensis (4.8 x 103 cells l-1) on days 4-6 after hatching. Larval gut content analyses failed to show any ciliates in Experiment 1, whereas hard body parts of F. taraikaensis were detected in Experiment 2. However, feeding on Euplotes by grouper larvae was confirmed by labelling the former with fluorescent microspheres. The lack of ciliate remains in Experiment 1 might be due to complete digestion by the larvae. The present experiments demonstrated that the higher ciliate densities enhanced larval survival until 4-6 days after hatching, suggesting the importance of ciliates as initial food for first-feeding E. septemfasciatus. It is likely that ciliates in the marine ecosystem may bridge the gap until grouper larvae can encounter foods such as copepod nauplii.
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Uye S., Nagano N., Shimazu T.
Journal of Oceanography 56 ( 4 ) 389 - 398 2000年
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Oceanography
We investigated the geographical variations in abundance and biomass of the major taxonomic groups of micro- and net-zooplankton along a transect through Ise Bay, central Japan, and neighboring Pacific Ocean in February 1995. The results were used to estimate their secondary and tertiary production rates and assess their trophic roles in this eutrophic embayment in winter. Ise Bay nourished a much higher biomass of both micro- and net-zooplankton (mean: 3.79 and 13.9 mg C m -3 , respectively) than the offshore area (mean: 0.76 and 4.47 mg C m -3 , respectively). In the bay, tintinnid ciliates, naked ciliates and copepod nauplii accounted for, on average, 69, 18 and 13% of the microzooplankton biomass, respectively. Of net-zooplankton biomass, copepods (i.e. Acartia, Calanus, Centropages, Microsetella and Paracalanus) formed the majority (mean: 63%). Average secondary production rates of micro- and net-zooplankton in the bay were 1.19 and 1.87 mg C m -3 d -1 (or 23.1 and 36.4 mg C m -2 d -1 ), respectively, and average tertiary production rate of net-zooplankton was 0.75 mg C m -3 d -1 (or 14.6 mg C m -2 d -1 ). Available data approximated average phytoplankton primary production rate as 1000 mg C m -2 d -1 during our study period. The transfer efficiency from primary production to zooplankton secondary production was 6.0%, and the efficiency from secondary production to tertiary production was 25%. The amount of food required to support the zooplankton secondary production corresponded to 18% of the phytoplankton primary production or only 1.7% of the phytoplankton biomass, demonstrating that the grazing impact of herbivorous zooplankton was minor in Ise Bay in winter.
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Uye S., Nagano N., Nagano N., Shimazu T.
Plankton Biology and Ecology 45 ( 2 ) 171 - 182 1998年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Plankton Biology and Ecology
We measured the abundance, biomass and production rate of micro- and net-zooplankton in Dokai Inlet, a heavily eutrophic and polluted embayment in northern Kyushu, in August 1996. This inlet nourished a much higher biomass of net-zooplankton (mean: 53.2 μg Cl-1) than microzooplankton (10.1 μg Cl-1). Mean contribution of tintinnid ciliates to the total microzooplankton biomass was largest (75%), followed, in order, by copepod nauplii (20%) and naked ciliates (5%). For net-zooplankton, the mean biomass of copepods (i.e. Acartia, Euterpina, Oithona and Paracalanus) was lower (43% of the total net-zooplankton biomass) than non-copepod taxa, such as chaetognaths and the larvae of bivalves and polychaetes. Mean secondary production rates of micro- and net-zooplankton in the inlet were 14.4 and 38.3 mg C m-3 d-1, respectively, and the mean tertiary production rate of net-zooplankton was 4.20 mg C m-3 d-1. The transfer efficiency from phytoplankton primary production to zooplankton secondary production was 28%, and the efficiency from secondary production to tertiary production was 7.9%. The amount of food required to support zooplankton secondary production was equivalent to 87% of the phytoplankton primary production, indicating that zooplankton, particularly net-zooplankton, are the major phytoplankton grazers in this extremely eutrophic inlet.
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Uye S., Nagano N., Tamaki H.
Journal of Oceanography 52 ( 6 ) 689 - 703 1996年12月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Oceanography
We measured abundance and biomass of 3 major groups of microzooplankton, i.e. tintinnids, naked dilates and copepod nauplii, at 21 stations in the Inland Sea of Japan in October 1993, January, April and June 1994. The average abundance of the microzooplankton over the entire Inland Sea of Japan ranged from 2.39 × 10 5 indiv. m -3 in January to 4.00 × 10 5 indiv. m -3 in April. Ciliated protozoans, i.e. tintinnids plus naked cilliates, numerically dominated the microzooplankton. The average biomass of the microzooplankton was exceedingly high in October (8.62 mg C m -3 ) compared to that in the other months (2.06, 2.79 and 2.68 mg Cm -3 in January, April and June, respectively). The ciliated protozoans also dominated in terms of biomass except in October, when copepod nauplii were more important. Estimated production rate of the microzooplankton was highest in October (average: 6.02 mg C m -3 d -1 ) and followed in order by June, April and January (1.94,1.14 and 0.54 mg C m -3 d -1 , respectively). Due to higher specific growth rate, the production rate by the ciliated protozoans far exceeded that by the copepod nauplii. The trophic importance of the microzooplankton in the pelagic ecosystem of the Inland Sea of Japan was assessed by estimating carbon flow through the microzooplankton community.