A5023249276- Photosynthetic Processes and Mechanisms
- Isotope Analysis in Ecology
- Marine and coastal ecosystems
- Protist diversity and phylogeny
- Microbial Community Ecology and Physiology
- Paleontology and Stratigraphy of Fossils
- Geology and Paleoclimatology Research
- Photoreceptor and optogenetics research
- Algal biology and biofuel production
- Light effects on plants
- Genomics and Phylogenetic Studies
- Porphyrin and Phthalocyanine Chemistry
- Marine Biology and Ecology Research
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Marine Bivalve and Aquaculture Studies
- Evolution and Paleontology Studies
- Marine and environmental studies
- bioluminescence and chemiluminescence research
- Metal-Catalyzed Oxygenation Mechanisms
- Food Industry and Aquatic Biology
- Geochemistry and Geologic Mapping
- Aquatic Ecosystems and Phytoplankton Dynamics
- Antioxidant Activity and Oxidative Stress
- Fiber-reinforced polymer composites
Fukui University of Technology
2013-2024
Ritsumeikan University
2012-2024
University of Fukui
2022
Japan Agency for Marine-Earth Science and Technology
2006-2021
National Institute for Environmental Studies
2019
Graduate School USA
2018
Japan Science and Technology Agency
2013-2014
University of Tsukuba
2010-2012
The University of Tokyo
2004-2008
Planetary Science Institute
2005-2008
The nitrogen isotopic composition (δ 15 N) of amino acids is potentially useful as an alternative method for estimating the trophic levels organisms in food webs. However, because this “amino acid method” has been constructed from observations only a few case studies food‐consumer combinations previous studies, universality approach remains unclear. In study, we investigated δ N signatures 17 photoautotrophs and relationships during four controlled feeding experiments using green algae,...
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout JournalEditorsTheme Sections 342:85-90 (2007) - doi:10.3354/meps342085 Metabolic control of nitrogen isotope composition amino acids in macroalgae and gastropods: implications for aquatic food web studies Yoshito Chikaraishi1,*, Yuichiro Kashiyama1,2, Nanako O. Ogawa1, Hiroshi Kitazato1, Naohiko Ohkouchi1 1Institute Research on Earth...
Significance Members of the diatom family Rhopalodiaceae possess a cyanobacterial endosymbiont called “spheroid body.” The spheroid body evolved much more recently than did mitochondria or plastids and is predicted to fix nitrogen. Here we present what is, our knowledge, first completely sequenced genome from rhopalodiacean diatom. Comparative analyses revealed that metabolically reduced, confirming its status as an obligate endosymbiont. possesses genes for nitrogen fixation, and, surprise,...
We have established a procedure for removing interfering materials from extracts of geological and biological samples, in order to determine precise compound-specific nitrogen isotopic compositions amino acids. employed cation-exchange chromatography protein non-protein acids prior derivatization gas chromatographic separation. The average recovery standard acid solution was better than 94%, without isotope fractionation during the chromatography. applied various environmental samples...
Kleptoplasts (kP) are distinct among photosynthetic organelles in eukaryotes (i.e., plastids) because they routinely sequestered from prey algal cells and function only temporarily the new host cell. Therefore, hosts of kleptoplasts benefit photosynthesis without constitutive photoendosymbiosis. Here, we report that euglenozoan Rapaza viridis has derived a specific strain green alga, Tetraselmis sp., but no canonical plastids like those found its sister group, Euglenophyceae. R. showed...
Although analyses of chlorophyll d (Chl d)-dominated oxygenic photosystems have been conducted since their discovery 12 years ago, Chl distribution in the environment and quantitative importance for aquatic photosynthesis remain to be investigated. We analyzed pigment compositions surface sediments detected its derivatives from diverse environments. Our data show that viable habitat d-producing phototrophs extends across salinities 0 50 practical salinity units temperatures 1 degrees 40 C,...
Abstract. In Livello Bonarelli black shale deposited during Cretaceous Oceanic Anoxic Event 2 (OAE-2, ca. 94 Ma), nitrogen isotopic compositions of bulk sediments are mostly in a narrow range from –2.7 to –0.7‰. We also determined molecular distribution and geoporphyrins extracted the shale. The C32 Ni deoxophylloerythroetioporphyrin (DPEP) total porphyrins –3.5 –3.3‰, respectively, leading us estimation that mean composition photoautotrophic cells were around +1‰ formation This value is...
Chlorophylls are essential components of the photosynthetic apparati that sustain all life forms ultimately depend on solar energy. However, a drawback extraordinary photosensitizing efficiency certain chlorophyll species is their ability to generate harmful singlet oxygen. Recent studies have clarified catabolic processes involved in detoxification chlorophylls land plants, but little understood about these strategies aquatic ecosystem. Here, we report variety heterotrophic protists...
Secondary loss of photosynthesis is observed across almost all plastid-bearing branches the eukaryotic tree life. However, genome-based insights into transition from a phototroph secondary heterotroph have so far only been revealed for parasitic species. Free-living organisms can yield unique evolutionary consequence photosynthesis, as lifestyle requires specific adaptations to host environments. Here, we report on diploid genome free-living diatom Nitzschia putrida (35 Mbp),...
Abstract Loss of photosynthesis is a recurring theme in eukaryotic evolution. In organisms that have lost the ability to photosynthesize, nonphotosynthetic plastids are retained because they play essential roles processes other than photosynthesis. The unicellular algal genus Cryptomonas contains both photosynthetic and members, latter having photosynthesize on at least three separate occasions. To elucidate evolutionary underlying loss photosynthesis, we sequenced plastid genomes two...
Microbial rhodopsins, comprising a protein moiety (rhodopsin apoprotein) bound to the light-absorbing chromophore retinal, function as ion pumps, channels, or light sensors. However, recent genomic and metagenomic surveys showed that some rhodopsin-possessing prokaryotes lack known genes for retinal biosynthesis. Since rhodopsin apoproteins cannot absorb energy, rhodopsins produced by prokaryotic strains lacking biosynthesis are hypothesized be non-functional in cells. In present study, we...
An unusually low-diversity shallow marine benthic community in a siliciclastic setting was identified and described from the Lower Triassic (Smithian) Hiraiso Formation (Southern Kitakami Mountains, northeast Japan). The fauna includes bivalve species of widespread genera, such as Eumorphotis, Entolium, Bakevellia (Maizuria), Unionites, Neoschizodus, oldest record crinoid genus Holocrinus. Facies analysis enabled reconstruction an environmental gradient ranging through storm-dominated...
Joint carbon and nitrogen isotope measurements were made from chlorins (chlorophyll a , phaeophytin pyrophaeophytin ) extracted the last glacial‐interglacial transition sediments of Lake Suigetsu, central Japan. These data highlight both potential difficulty using chlorin‐specific isotopes to track aquatic change lake sediments. δ 13 C 15 N three show coherent patterns with time, supporting theory that are early diagenetic products chlorophyll despite this transition, their isotopic...
Abstract. Chloropigments and their derivative pheopigments preserved in sediments can directly be linked to photosynthesis. Their carbon nitrogen stable isotopic compositions have been shown a good recorder of recent past surface ocean environmental conditions tracing the sources dominant assimilation processes phytoplanktonic community. In this study we report results from combined compound-specific radiocarbon isotope analysis examine time-scales synthesis fate chlorophyll-a its...
Compound-specific isotope analyses of geoporphyrins, which are derivatives chloropigments possessed by phototrophs, provide essential records the biogeochemical cycle past aquatic environments. Here, we evaluated uncertainties in carbon and nitrogen isotopic compositions (δ13C δ15N) associated with high-performance liquid chromatography (HPLC) purification measurements geoporphyrins. Evaluation total blank for HPLC our sensitivity-improved elemental analyzer/isotope ratio mass spectrometer...
Both 13(2),17(3)-cyclopheophorbide a and b enols were produced along with ingestion of green microalgae containing chlorophylls by centrohelid protist (phycophagy). The results suggest that chlorophyll as well directly degraded to colored yet non-phototoxic catabolites in the protistan phycophagic process. Such simple process predators makes contrast much sophisticated degradation land plants some algae, where phototoxicity was cancelled through multiple enzymatic steps resulting colorless...
Abstract The phototoxic effects of chlorophylls on the cells organisms have been debated for decades. extreme phototoxicity uncontrolled and concomitant need rapid elimination in again attracted attention since robust processes higher plants their catabolism during senescence clarified (e.g., autumnal tints). Recently, another type chlorophyll has identified aquatic microbes that digest algae. Both these involve detoxification chlorophylls: former degrading them into colorless compounds...
Abstract. We determined both the nitrogen and carbon isotopic compositions of various vanadyl alkylporphyrins isolated from siliceous marine sediments Onnagawa Formation (middle Miocene, northeastern Japan) to investigate biogeochemistry ecology photoautotrophs living in paleo-ocean. The distinctive signals support interpretations previous works that origin 17-nor-deoxophylloerythroetioporphyrin (DPEP) is chlorophylls-c1-3, whereas 8-nor-DPEP may have originated chlorophylls-a2 or b2...
Abstract After the severest mass extinction event in Phanerozoic, biotic recovery from at Permian–Triassic boundary required approximately 5 my, which covers entire Early Triassic. It is important to obtain information on superocean Panthalassa, occupied most of world ocean, explore paleoenvironmental changes during Triassic global scale. In order establish continuous lithostratigraphy pelagic sediments Panthalassa Triassic, high‐resolution reconstruction Lower sequence Japan was conducted...
The order Trypanosomatida has been well studied due to its pathogenicity and the unique biology of mitochondrion. In Trypanosoma brucei, four DNA polymerases, namely PolIA, PolIB, PolIC, PolID, related bacterial polymerase I (PolI), were shown be localized in mitochondria experimentally. These mitochondrion-localized polymerases are phylogenetically distinct from other family A such as PolI, gamma (Polγ) human yeasts, "plant protist organellar (POP)" diverse eukaryotes. However, diversity...
Plastid electron transport systems are essential not only for photosynthesis but also dissipating excess reducing power and sinking electrons generated by various redox reactions. Although numerous organisms with plastids have lost their photoautotrophic lifestyles, there is a spectrum of known functions remnant in non-photosynthetic algal/plant lineages; some still retain diverse metabolic pathways involving reactions while others, such as apicoplasts apicomplexan parasites, possess highly...