著者

Kobayashi Manami Kumagai Yuya Yamamoto Yohei Yasui Hajime Kishimura Hideki

出版者

MDPI

雑誌

Marine drugs (ISSN:16603397)

巻号頁・発行日

vol.18, no.3, pp.174, 2020-03

被引用文献数

14

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Red alga dulse possesses a unique xylan, which is composed of a linear beta-(1 -> 3)/beta-(1 -> 4)-xylosyl linkage. We previously prepared characteristic xylooligosaccharide (DX3, (beta-(1 -> 3)-xylosyl-xylobiose)) from dulse. In this study, we evaluated the prebiotic effect of DX3 on enteric bacterium. Although DX3 was utilized by Bacteroides sp. and Bifidobacterium adolescentis, Bacteroides Ksp. grew slowly as compared with beta-(1 -> 4)-xylotriose (X3) but B. adolescentis grew similar to X3. Therefore, we aimed to find the key DX3 hydrolysis enzymes in B. adolescentis. From bioinformatics analysis, two enzymes from the glycoside hydrolase family 43 (BAD0423: subfamily 12 and BAD0428: subfamily 11) were selected and expressed in Escherichia coli. BAD0423 hydrolyzed beta-(1 -> 3)-xylosyl linkage in DX3 with the specific activity of 2988 mU/mg producing xylose (X1) and xylobiose (X2), and showed low activity on X2 and X3. BAD0428 showed high activity on X2 and X3 producing X1, and the activity of BAD0428 on DX3 was 1298 mU/mg producing X1. Cooperative hydrolysis of DX3 was found in the combination of BAD0423 and BAD0428 producing X1 as the main product. From enzymatic character, hydrolysis of X3 was completed by one enzyme BAD0428, whereas hydrolysis of DX3 needed more than two enzymes.

著者

Mizuta Hiroyuki Uji Toshiki Yasui Hajime

出版者

Elsevier

雑誌

Algal research (ISSN:22119264)

巻号頁・発行日

vol.58, pp.102369, 2021-10

被引用文献数

5

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The process of biogenic silicon (Si) deposition in sporophytes of kelp (Saccharina japonica) was investigated by culturing sporophyte disks in the medium with and without hydrogen peroxide (H2O2). Culture with H2O2 remarkably promoted silicate-Si uptake by the disks. Silicate-Si uptake was completely inhibited by the treatment with potassium bromide (KBr), a competitive inhibitor of iodoperoxidase (IPO), even in the medium with H2O2. In addition, disk culture with phenol red in the medium with H2O2 resulted in the formation of bromophenol blue, indicating the presence of extracellular IPO. However, KBr treatment inhibited the formation of bromophenol blue in the medium with H2O2. These results showed that silicate-Si uptake is activated by extracellular IPO in the presence of radical oxygen species (ROS), such as H2O2. Interestingly, 1 mM salicylic acid also promoted silicate-Si uptake, even in the medium without H2O2. Furthermore, the allocation of silicate-Si to the soluble and cell wall-bound phlorotannin fractions using rhodamine 123 (R123), a tracer of biogenic Si, was estimated. Tracer fluorescence was detected in not only the soluble but also the cell wall-bound phlorotannin fraction. R123 fluorescence was histologically detected in the apoplasts of the epidermal and outer cortical layers of the disk, overlapping the histochemical distribution of IPO activity. These results suggested that silicate-Si uptake is activated by an oxidative burst induced by various stresses, and Si deposition is catalyzed by extracellular IPO in the presence of both ROS and phlorotannin in the extracellular matrix of sporophytes. Based on these findings, the hypothetical mechanisms of the extracellular silicate-Si uptake for defense responses in kelp were discussed.

著者

Mizuta Hiroyuki Yasui Hajime

出版者

Walter de Gruyter

雑誌

Botanica Marina (ISSN:00068055)

巻号頁・発行日

vol.53, no.5, pp.409-416, 2010-10

被引用文献数

1 14

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We investigated production of radical oxygen species (ROS) in sorus development of sporophyte discs and during zoospore germination of Saccharina japonica (Phaeophyceae) using the fluorescent dye 2',7'-dichlorofluorescein diacetate (DCFH-DA). Quantitative analysis of ROS showed high intracellular production during the stages of zoosporangium formation when paraphyses elongated. In this stage, remarkable ROS release was observed. ROS production was also observed histologically (under a fluorescence microscope) in the elongating paraphyses and the sorus zoosporangia of the sorus. The sorus had significantly higher phenol content, anti-oxidant capacity and ROS scavenging enzyme activities (ascorbate peroxidase, catalase, glutathione reductase and superoxide dismutase) than adjacent non-sorus blade sectors. Thus, intracellular ROS scavenging mechanisms are active during ROS production in sorus formation. In contrast, iodine content was lower in the sorus than in the adjacent non-sorus tissues, suggesting the existence of an anti-oxidant defense mechanism based on iodine efflux. We demonstrated that ROS production is an important phenomenon in the reproduction of the sporophyte in S. japonica. Furthermore, ROS were also observed in the zoospore germination processes. We discuss the physiological and ecological roles of ROS production in sorus formation and zoospore germination.