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Published Papers 【 display / non-display 】

• Vegetation variety affected by local environments in a coral reef lagoon

  Kandai Tozaki, Gregory N. Nishihara, Azusa Kawate, Teruko Konishi, Yoichi Sato, Michihiro Ito, Hiroyuki Fujimura, Atsuko Tanaka

  Phycological Research ( Wiley )    2024.01 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  Abstract From shore to sea, coral reefs can generally be divided into a lagoon zone, a reef crest, and a fore reef. Environmental variables, such as nutrient fluxes, light availability, and water temperature, vary among the zones and influence the biodiversity of submerged macrophytes. Additionally, the biodiversity of vegetation within the lagoon appears to be affected by multiple and extremely localized conditions. We investigated the impact of small‐scale variations on vegetation diversity, and implemented an ecological survey within a well‐defined area inside of a lagoon at Bise Point, Okinawa, Japan. A total of 20 macroalgal species (four green algae, six brown algae, and ten red algae) and four seagrass species were identified from the surveyed quadrats over a period of 19 months, from October 2019 to March 2021. Patterns in species occurrence were spatially and temporally heterogeneous. Notably, water motion and sediment flux were highly variable among the monitoring sites. Redundancy analysis allowed us to evaluate the significance of environmental factors on the vegetation of each monitoring area. Six environmental factors were considered in this study, but their impacts on local vegetation were not equivalent. Redundancy analysis suggested that water depth, flow velocity, and the ratio of the small fraction of deposition particles were the three factors with the strongest influence on local vegetation. This study provides some crucial insights into the determinants of vegetation in a coral reef lagoon. Our findings suggest that the factors we examined exert more influence on the vegetation than seasonal effects.

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• Characterization of cell wall polysaccharide from <scp><i>Cladosiphon okamuranus</i></scp> cultivated in different locations

  Mahanama Geegana Gamage Awanthi, Natsuki Nakasone, Hirosuke Oku, Kanefumi Kitahara, Michihiro Ito, Atsuko Tanaka, Yoichi Sato, Yuichiro Numata, Teruko Konishi

  Phycological Research ( Wiley )    2023.08 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  SUMMARY Cladosiphon okamuranus is an excellent source of fucoidan among any brown algae spp. However, the structure of polysaccharide varies significantly depending on the species, harvesting season and geographical location. To understand how geographic location affects the structure of cell wall polysaccharide, C. okamuranus cultivated in eight places (Bise, Katsuren, Yonashiro, Shikiya, Karimata, Nishihara, Hisamatsu and Ishigaki) in Ryukyu archipelago were collected during the peak harvesting time and the cell wall polysaccharide was analyzed physiochemically. The cell wall was sequentially fractionated into five fractions and its 80% was consisted of hot water fraction (HW) (60–70%) and hemicellulose‐I fraction (HC‐I) (15–20%), which mainly contained fucoidan composed of fucose (Fuc), glucuronic acid (GlcA) and sulfate (SO₃⁻). Although the chemical composition and molecular weight of fucoidan in HW was slightly different at different places, the composition of Fuc, GlcA and SO₃⁻ was constant in the molar ratio of 1.0:0.5:0.7–1.0 respectively, suggesting that relatively similar structural fucoidan from C. okamuranus can be obtained from any geographical location in Okinawa Prefecture during peak time. However, considerable variation in the sugar composition in HC‐I was observed, despite the uniform molecular weight and SO₃⁻. Particularly, HC‐I from Bise, where is the northern part of Okinawa Island, is composed of significantly higher amounts of Glc, Gal, Man, Xyl and morphologically thicker lateral branches compared to algae from the other parts of the island.

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• Localization and characterization θ carbonic anhydrases in Thalassiosira pseudonana

  Hermanus Nawaly, Atsuko Tanaka, Yui Toyoshima, Yoshinori Tsuji, Yusuke Matsuda

  Photosynthesis Research ( Springer Science and Business Media LLC )    2023.03 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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• Pleiotropic Functions of Nitric Oxide Produced by Ascorbate for the Prevention and Mitigation of COVID-19: A Revaluation of Pauling's Vitamin C Therapy

  Hideo Yamasaki, Hideyuki Imai, Atsuko Tanaka, Joji M. Otaki

  Microorganisms ( MDPI AG )  11 ( 2 ) 397 - 397   2023.02 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  Linus Pauling, who was awarded the Nobel Prize in Chemistry, suggested that a high dose of vitamin C (l-ascorbic acid) might work as a prevention or treatment for the common cold. Vitamin C therapy was tested in clinical trials, but clear evidence was not found at that time. Although Pauling's proposal has been strongly criticized for a long time, vitamin C therapy has continued to be tested as a treatment for a variety of diseases, including coronavirus infectious disease 2019 (COVID-19). The pathogen of COVID-19, SARS-CoV-2, belongs to the β-coronavirus lineage, which includes human coronavirus, severe acute respiratory syndrome (SARS), and Middle East respiratory syndrome (MERS). This review intends to shed new light on vitamin C antiviral activity that may prevent SARS-CoV-2 infection through the chemical production of nitric oxide (NO). NO is a gaseous free radical that is largely produced by the enzyme NO synthase (NOS) in cells. NO produced by upper epidermal cells contributes to the inactivation of viruses and bacteria contained in air or aerosols. In addition to enzymatic production, NO can be generated by the chemical reduction of inorganic nitrite (NO2−), an alternative mechanism for NO production in living organisms. Dietary vitamin C, largely contained in fruits and vegetables, can reduce the nitrite in saliva to produce NO in the oral cavity when chewing foods. In the stomach, salivary nitrite can also be reduced to NO by vitamin C secreted from the epidermal cells of the stomach. The strong acidic pH of gastric juice facilitates the chemical reduction of salivary nitrite to produce NO. Vitamin C contributes in multiple ways to the host innate immune system as a first-line defense mechanism against pathogens. Highlighting chemical NO production by vitamin C, we suggest that controversies on the therapeutic effects of vitamin C in previous clinical trials may partly be due to less appreciation of the pleiotropic functions of vitamin C as a universal bioreductant.

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• Fractionation and characterization of cell wall polysaccharides from the brown alga Cladosiphon okamuranus

  Mahanama Geegana Gamage Awanthi, Manatsu Umosa, Yoshiaki Yuguchi, Hirosuke Oku, Kanefumi Kitahara, Michihiro Ito, Atsuko Tanaka, Teruko Konishi

  Carbohydrate Research ( Elsevier BV )  523   108722 - 108722   2023.01 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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Grant-in-Aid for Scientific Research 【 display / non-display 】

Grant-in-Aid for Scientific Research 【 display / non-display 】

• Grant-in-Aid for Scientific Research(B)

  Project Year: 2020.04  -  2023.03 

  Direct: 13,800,000 (YEN)  Overheads: 17,940,000 (YEN)  Total: 4,140,000 (YEN)

• Mitigating climate change through seaweed aquaculture

  Grant-in-Aid for Scientific Research(B)

  Project Year: 2020.04  -  2023.03 

  Direct: 13,700,000 (YEN)  Overheads: 17,810,000 (YEN)  Total: 4,110,000 (YEN)

• Grant-in-Aid for Scientific Research(C)

  Project Year: 2017.04  -  2020.03 

  Direct: 3,900,000 (YEN)  Overheads: 1,170,000 (YEN)  Total: 5,070,000 (YEN)

• Grant-in-Aid for Scientific Research(C)

  Project Year: 2017.04  -  2020.03 

  Direct: 3,900,000 (YEN)  Overheads: 5,070,000 (YEN)  Total: 1,170,000 (YEN)

• Regulation of plasmodesmata in brown algae

  Grant-in-Aid for Scientific Research(C)

  Project Year: 2014.04  -  2017.03 

  Investigator(s): NAGASATO Chikako, FUJITA Tomomichi 

  Direct: 3,900,000 (YEN)  Overheads: 5,070,000 (YEN)  Total: 1,170,000 (YEN)

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  Brown algae show multicellularity and possess cellular connections called plasmodesmata which enable exchange of molecules between the neighboring cells. Plasmadesmata take tubular structure with 10 - 20 nm in diameter, and vary appearance and distribution with the developmental stages. Some new findings concerning brown algal plasmodesmata were given in this study as follows; 1) plasmodesmata are divided into primary and secondary plasmodesmata as in land plants, 2) plasmodesmatal size exclusion limit are set between 20-40 kDa in multiseriate species, and 3) pit fields in which plasmodesmata concentrate one place on the cross wall pass molecules less than 10 kDa to the next cell.