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論文
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奥村, 真子 ; 三木, 理 ; 上野, 聡浩 ; 小杉, 知佳 ; 吉村, 航 ; 加藤, 敏朗 ; Okumura, Chikako ; Miki, Osamu ; Ueno, Akihiro ; Kosugi, Chika ; Yoshimura, Ko ; Kato, Toshiaki
概要:
金沢大学理工研究域サステナブルエネルギー研究センター<br />The present study is an attempt for assessing the relationship between iron deficiency a
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nd discoloration in Undaria pinnatifida sporophytes. First, thallus discoloration and the decrease in photosynthetic pigment contents were examined in Undaria pinnatifida by employing an indoor iron-deficiency experiment. When Undaria pinnatifida sporophytes were cultured under iron-deficient conditions, which the iron concentrations were between 2 and 5 μg/L, the growth decreased, the thalli became discolored, and the photosynthetic pigment contents decreased. Iron deficiency caused the sporophytes to become lighter (L*) and less red (a*). Therefore, it appears that iron deficiency induces the discoloration of Undaria pinnatifida sporophytes, similar to how nitrogen and phosphorus deficiencies perform. Next, we investigated how the mechanism involved in the addition of iron affects the discolored Undaria pinnatifida sporophytes due to iron deficiency by performing an indoor iron-addition experiment. Undaria pinnatifida sporophyte growth, thallus color, and photosynthetic pigment content were all restored by the addition of dissolved iron solution, which the concentrations were between 10 and 50 μg/L. Iron addition made the sporophytes recover their lightness (L*) and redness (a*). In addition, the color was restored more quickly as the amount of added iron was increased. The discoloration of iron-deficient Undaria pinnatifida sporophytes can thus be restored by iron addition.
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| 2.
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Okumura, Chikako ; Miki, Osamu ; Sakamoto, Yusuke ; Fukami, Takuya ; 奥村, 真子 ; 三木, 理
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金沢大学理工研究域サステナブルエネルギー研究センター<br />Marine macroalgae are important for maintaining ecosystems in coastal areas. However, to
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our knowledge, only a few studies of marine macroalgae have developed protocols for assessing the toxic effects of growth inhibitors typically found in industrial wastewaters. Sargassum horneri, a large brown macroalga commonly found in seaweed beds in coastal Japan, can be easily collected, and its fertilized eggs can be preserved for approximately 170 days. Therefore, the present study evaluated the possibility of developing a seaweed bioassay using the germling growth of S. horneri to obtain toxicological data for phenol. The addition of phenol to culture media clearly inhibited the germling growth of S. horneri. The 14-day EC50 value on the basis of the specific growth rate was 58 mg phenol L−1, while the 21-day EC50 value on the basis of the thallus area was 36 mg phenol L−1. Furthermore, the no-observed-effect concentration was estimated to be 20 mg phenol L−1. Renewal of culture medium did not significantly affect germling growth of S. horneri during our 21 days of culturing. S. horneri appeared to be as sensitive to phenol as other marine macroalgae reported in the previous studies. Therefore, we consider that S. horneri is one of the appropriate candidates of macroalgae for toxicity testing. © 2018 Springer Science+Business Media B.V., part of Springer Nature<br />Embargo Period 12 months
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| 3.
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Miki, Osamu ; Okumura, Chikako ; Marzuki, Mawardi ; Tujimura, Yusuke ; Fujii, Takahito ; Kosugi, Chika ; Kato, Toshiaki ; 三木, 理 ; 奥村, 真子
概要:
The brown seaweed Sargassum horneri (Sargassaceae) is important for marine environment conservation. It could be used fo
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r a food material, medical applications, and future biofuel production. We compared the growth of S. horneri cultures under single wavelength blue and red light during the germling and immature stages. The growth rate based on the thallus area of S. horneri during the germling stage was faster under blue LED light than under red LED light. Furthermore, based on the wet weight of S. horneri, during the immature stage, blue LED light resulted in a faster growth rate than red LED light. Moreover, during the immature stage, compared with red LED light, blue LED light tended to increase the content of photosynthetic pigments. We conclude that use of blue LED light in indoor tanks during the germling and immature stages will improve the efficiency of S. horneri culture. © 2016 Springer Science+Business Media Dordrecht<br />Embargo Period 12 months
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| 4.
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奥村, 真子 ; Okumura, Chikako
概要:
取得学位：博士(工学)，学位授与番号：博甲第881号，学位授与年月日：平成19年3月22日
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Hasegawa, Hiroshi ; Rahman, M. Azizur ; Saitou, K. ; Kobayashi, M. ; Okumura, Chikako
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In this study, the effects of chelating ligands on iron movement in growth medium, iron bioavailability, and growth of r
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adish sprouts (Raphanus sativus) were investigated. Iron is an important nutrient for plant growth, yet the insoluble state of iron hydroxides in alkaline conditions decreases its bioavailability. Iron chelates increase iron uptake and have been used in agriculture to correct iron chlorosis. While previous studies have reported the effects of chelating ligands on iron solubility and bioavailability, the present study elucidates the pattern of iron movement by chelating ligands in plant growth medium. The apparent mobility of iron in growth medium was calculated using a '4-box' model. Ethylenediaminedisuccinic acid (EDDS) and hydroxy-iminodisuccinic acid (HIDS) produced the highest apparent mobility of iron from the bottom layer of the medium (initially 10-4M Fe(III)) to the upper layer (no iron), followed by glutamatediacetic acid (GLDA), ethylenediaminetetraacetic acid (EDTA), methylglycinediacetic acid (MGDA), and iminodisuccinic acid (IDS). Iron movement in the growth medium was influenced by the chelating ligand species, pH, and ligand exposure time. The iron uptake and growth of radish sprouts were related to the iron mobility produced by the chelating ligands. These results suggest that, in alkaline media, chelating ligands dissolve the hardly soluble iron hydroxide species, thus increasing iron mobility, iron uptake, and plant growth. HIDS, which is biodegradable, was one of the most effective ligands studied; therefore, this compound would be a good alternative to other environmentally persistent chelating ligands. © 2011 Elsevier B.V.
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| 6.
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Okumura, Chikako ; Rahman, M. Azizur ; Takimoto, Akira ; Hasegawa, Hiroshi
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Liquid scintillation counting (LSC) method using a radioisotope tracer has several advantages such as simple procedure,
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high sensitivity and low detection limit, and has been used for the determination Fe concentrations in water samples. Several factors such as nitrate concentration, pH, chelating ligand affect the efficiency of this method in the determination of iron (Fe) in waters. In this study, the effect of nitrate in phytoplankton culture medium on the determination of Fe concentration by LSC method using 55Fe radioisotope tracer was evaluated. The measured Fe concentrations in the medium were lower than its added concentration (1.5 μM) when liquid samples contain nitrate. Fe concentrations decreased exponentially as nitrate concentrations increased up to 2.64 mM, reaching a constant value of 1.31 μM Fe at nitrate concentrations higher than 2.64 mM. A correction factor (f = 1.14) was calculated from the decrease rate of Fe concentrations at different nitrate concentrations in the phytoplankton culture medium. This correction factor can be used to correct the measurement values of Fe concentrations in phytoplankton culture medium obtained from LSC method. Our results showed that up to 94 % of the added Fe can be determined by LSC using 55Fe radioisotope tracer. The remaining 6 % was probably bound to the walls of the culturing vessel. This method is also applicable for the measurement of Fe size-fractionation in phytoplankton culture medium. © 2012 Akadémiai Kiadó, Budapest, Hungary.
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| 7.
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論文
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Nagai, Taichi ; Miki, Osamu ; Okumura, Chikako ; 長井, 太一 ; 三木, 理 ; 奥村, 真子
概要:
Sargassaceae species are important macroalgae for maintaining marine environments. Furthermore, biofuel based on Sargass
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aceae species has become studied recently. However, Sargassaceae species have declined rapidly in coastal areas around Japan, which are called "isoyake", a term meaning barren areas. The development of effective measures to restore these "isoyake" and the construction of Sargassaceae beds are strongly needed. A lack of iron in coastal areas limits the growth of macroalgae, and may cause "isoyake". However, the effects of the iron concentration on the growth of macroalgae, such as species of Sargassaceae, are poorly studied. In this research, the effects of chelated iron on the growth of Sargassaceae species during the germling and immature stages were examined. The addition of Fe-EDTA promoted the growth of four Sargassaceae species during the germling stages. During the germling stage of Sargassum ringgoldianum, the maximum specific growth rate and the saturation constant were estimated to be 0.17 day-1 and 4.3 μg/L, respectively. Additionally, the periodic addition of Fe-EDTA promoted the stable growth of Sargassum horneri during the immature stage.
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| 8.
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Miki, Osamu ; Okumura, Chikako ; Tuji, Kiyoaki ; Takami, Masahaya
概要:
The effects of high concentrations of nitrogen sources on the germling growth of Sargassum horneri were investigated for
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the restoration of coastal barren ground using fertilization materials containing high concentrations of nitrogen. Moreover, the safekeeping period of fertilized eggs of S. horneri was studied to elucidate performance stability as an appropriate method using fertilized eggs. The fertilized eggs of S. horneri that had been preserved in a refrigerator for approximately 170 days were able to grow and demonstrate the same growth curve as those that had been preserved for shorter periods. This demonstrates that our culture method can be applied to examine the effects of nitrogen sources on the germling growth of S. horneri. The addition of over 2 mg N L−1 of ammonium (NH4–N) or nitrite (NO2–N) clearly inhibited growth, and the addition of 50 mg N L−1 of NH4–N or NO2–N had lethal effects on the germling growth of S. horneri. The addition of 1 mg N L−1 of NH4–N or NO2–N did not clearly promote or inhibit growth. The addition of 50 mg N L−1of nitrate (NO3–N) did not inhibit growth. It is expected that the effects of NH4–N or NO2–N on seaweed growth depends on the concentration level, growth stage of the seaweed, and seaweed species. On the basis of our results, nitrogen fertilizers that contain high concentrations of some nitrogen sources should be carefully considered before they are applied to restore barren ground in nutrient-deficient coastal areas. © 2016 Springer Science+Business Media Dordrecht<br />Embargo Period 12 months
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| 9.
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Miki, Osamu ; Nagai, Taichi ; Marzuki, Mawardi ; Okumura, Chikako ; Kosugi, Chika ; Kato, Toshiaki
概要:
To aid in the restoration of coastal barren ground areas, it is important to clarify the effects of chelated iron on the
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growth of seaweed. In particular, for the further development of practical methods to promote seaweed growth, Fe-binding organic ligands, such as humic substances (HSs) composed of humus materials, rather than Fe-binding inorganic ligands, such as ethylenediaminetetraacetic acid (EDTA), should be investigated. In this study, the effects of an Fe fertilizer, made from HSs and steelmaking slag, on the growth of the brown alga Sargassum horneri at the germling and immature stages were examined. The addition of the Fe fertilizer eluate containing Fe organic ligand complexes clearly promoted the growth of S. horneri at the germling and immature stages. It was also clear that the effect of Fe concentration in the Fe fertilizer eluate on the growth rate was almost the same as that of Fe–EDTA. Moreover, the addition of the Fe fertilizer eluate had a great effect on the brown color of S. horneri thalli and promoted the increased content of photosynthetic pigments, such as chlorophyll a. Based on these experimental results, the application of the Fe fertilizer containing Fe organic ligand complexes is expected to become an effective method for the restoration of the barren ground phenomenon in Fe-deficient coastal areas. © 2015 Springer Science+Business Media Dordrecht<br />Embargo Period 12 months
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| 10.
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Miki, Osamu ; Okumura, Chikako ; Marzuki, Mawardi ; Tujimura, Yusuke ; Fujii, Takahito ; Kosugi, Chika ; Kato, Toshiaki
概要:
The original version of this article unfortunately contained a mistake. Figure 7 was incorrect. The correct Figure is given below: (Figure presented). © 2017, Springer Science+Business Media Dordrecht.<br />Embargo Period 12 months
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