Author
Nils Kröger
Other affiliations: University of Regensburg, Georgia Institute of Technology, Georgia Tech Research Institute
Bio: Nils Kröger is an academic researcher from Dresden University of Technology. The author has contributed to research in topics: Thalassiosira pseudonana & Diatom. The author has an hindex of 37, co-authored 65 publications receiving 10549 citations. Previous affiliations of Nils Kröger include University of Regensburg & Georgia Institute of Technology.
Topics: Thalassiosira pseudonana, Diatom, Cell wall, Biomineralization, Frustule
Papers published on a yearly basis
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University of Washington1, University of Wisconsin–Milwaukee2, École Normale Supérieure3, University of British Columbia4, University of Wisconsin-Madison5, Princeton University6, Martek Biosciences Corporation7, University of California, Santa Barbara8, University of Melbourne9, University of California, San Diego10, Sandia National Laboratories11, University of California, Santa Cruz12, University of Regensburg13, Oak Ridge National Laboratory14, University of Hull15, Joint Genome Institute16, Academy of Sciences of the Czech Republic17, University of Massachusetts Medical School18, Woods Hole Oceanographic Institution19, Alfred Wegener Institute for Polar and Marine Research20, San Francisco State University21, University of California, Berkeley22
TL;DR: The 34 million-base-pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand-base pair plastid and 44 thousand base-pair mitochondrial genomes were reported in this article.
Abstract: Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for approximately 20% of global carbon fixation. We report the 34 million-base pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand-base pair plastid and 44 thousand-base pair mitochondrial genomes. Sequence and optical restriction mapping revealed 24 diploid nuclear chromosomes. We identified novel genes for silicic acid transport and formation of silica-based cell walls, high-affinity iron uptake, biosynthetic enzymes for several types of polyunsaturated fatty acids, use of a range of nitrogenous compounds, and a complete urea cycle, all attributes that allow diatoms to prosper in aquatic environments.
1,945 citations
École Normale Supérieure1, J. Craig Venter Institute2, Joint Genome Institute3, Alfred Wegener Institute for Polar and Marine Research4, University of Konstanz5, University of Wisconsin–Milwaukee6, University of Melbourne7, University of Washington8, University of Nantes9, University of Wisconsin-Madison10, Ghent University11, University of Rhode Island12, Sewanee: The University of the South13, University of Arizona14, Hebrew University of Jerusalem15, Georgia Institute of Technology16, Leibniz Institute for Neurobiology17, Stazione Zoologica Anton Dohrn18, University of British Columbia19, Stanford University20, Scottish Association for Marine Science21, University of North Carolina at Wilmington22
TL;DR: Analysis of molecular divergence compared with yeasts and metazoans reveals rapid rates of gene diversification in diatoms, and documents the presence of hundreds of genes from bacteria, likely to provide novel possibilities for metabolite management and for perception of environmental signals.
Abstract: Diatoms are photosynthetic secondary endosymbionts found throughout marine and freshwater environments, and are believed to be responsible for around one- fifth of the primary productivity on Earth(1,2). The genome sequence of the marine centric diatom Thalassiosira pseudonana was recently reported, revealing a wealth of information about diatom biology(3-5). Here we report the complete genome sequence of the pennate diatom Phaeodactylum tricornutum and compare it with that of T. pseudonana to clarify evolutionary origins, functional significance and ubiquity of these features throughout diatoms. In spite of the fact that the pennate and centric lineages have only been diverging for 90 million years, their genome structures are dramatically different and a substantial fraction of genes (similar to 40%) are not shared by these representatives of the two lineages. Analysis of molecular divergence compared with yeasts and metazoans reveals rapid rates of gene diversification in diatoms. Contributing factors include selective gene family expansions, differential losses and gains of genes and introns, and differential mobilization of transposable elements. Most significantly, we document the presence of hundreds of genes from bacteria. More than 300 of these gene transfers are found in both diatoms, attesting to their ancient origins, and many are likely to provide novel possibilities for metabolite management and for perception of environmental signals. These findings go a long way towards explaining the incredible diversity and success of the diatoms in contemporary oceans.
1,500 citations
TL;DR: A set of polycationic peptides isolated from diatom cell walls were shown to generate networks of silica nanospheres within seconds when added to a solution of silicic acid.
Abstract: Diatom cell walls are regarded as a paradigm for controlled production of nanostructured silica, but the mechanisms allowing biosilicification to proceed at ambient temperature at high rates have remained enigmatic. A set of polycationic peptides (called silaffins) isolated from diatom cell walls were shown to generate networks of silica nanospheres within seconds when added to a solution of silicic acid. Silaffins contain covalently modified lysine-lysine elements. The first lysine bears a polyamine consisting of 6 to 11 repeats of the N-methyl-propylamine unit. The second lysine was identified as epsilon-N,N-dimethyl-lysine. These modifications drastically influence the silica-precipitating activity of silaffins.
1,306 citations
TL;DR: Time-resolved analysis of silica morphogenesis in vitro detected a plastic silaffin-silica phase, which may represent a building material for diatom biosilica.
Abstract: Silaffins are uniquely modified peptides that have been implicated in the biogenesis of diatom biosilica. A method that avoids the harsh anhydrous hydrogen fluoride treatment commonly used to dissolve biosilica allows the extraction of silaffins in their native state. The native silaffins carry further posttranslational modifications in addition to their polyamine moieties. Each serine residue was phosphorylated, and this high level of phosphorylation is essential for biological activity. The zwitterionic structure of native silaffins enables the formation of supramolecular assemblies. Time-resolved analysis of silica morphogenesis in vitro detected a plastic silaffin-silica phase, which may represent a building material for diatom biosilica.
734 citations
TL;DR: The chemical structure of long-chain polyamines (up to 20 repeated units), which represent the main organic constituent of diatom biosilica, are described, which are the longest polyamine chains found in nature and induce rapid silica precipitation from a silicic acid solution.
Abstract: Biomineralizing organisms use organic molecules to generate species-specific mineral patterns. Here, we describe the chemical structure of long-chain polyamines (up to 20 repeated units), which represent the main organic constituent of diatom biosilica. These substances are the longest polyamine chains found in nature and induce rapid silica precipitation from a silicic acid solution. Each diatom is equipped with a species-specific set of polyamines and silica-precipitating proteins, which are termed silaffins. Different morphologies of precipitating silica can be generated by polyamines of different chain lengths as well as by a synergistic action of long-chain polyamines and silaffins.
629 citations
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TL;DR: This review covers the literature published in 2014 for marine natural products, with 1116 citations referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms.
4,649 citations
TL;DR: The common design motifs of a range of natural structural materials are reviewed, and the difficulties associated with the design and fabrication of synthetic structures that mimic the structural and mechanical characteristics of their natural counterparts are discussed.
Abstract: Natural structural materials are built at ambient temperature from a fairly limited selection of components. They usually comprise hard and soft phases arranged in complex hierarchical architectures, with characteristic dimensions spanning from the nanoscale to the macroscale. The resulting materials are lightweight and often display unique combinations of strength and toughness, but have proven difficult to mimic synthetically. Here, we review the common design motifs of a range of natural structural materials, and discuss the difficulties associated with the design and fabrication of synthetic structures that mimic the structural and mechanical characteristics of their natural counterparts.
3,083 citations
University of California, Los Angeles1, United States Department of Energy2, University of Paris3, Duke University4, University of Massachusetts Medical School5, University of California, Berkeley6, Centre national de la recherche scientifique7, University of California, San Francisco8, Sun Yat-sen University9, University of Tennessee Health Science Center10, University of Minnesota11, Iowa State University12, Genetic Information Research Institute13, Salk Institute for Biological Studies14, Stanford University15, University of Liège16, University of Nebraska–Lincoln17, University of Cambridge18, Washington University in St. Louis19, University of Córdoba (Spain)20, Kyoto University21, Carnegie Institution for Science22, National Autonomous University of Mexico23, University of Münster24, École Normale Supérieure25, University of Melbourne26, University of Paris-Sud27, University of Mainz28, Scripps Research Institute29, Ohio State University30, University of Chicago31, University of Jena32, University of Arizona33, Louisiana State University34, University of New Brunswick35, University College London36, University of Potsdam37, Delaware Biotechnology Institute38, Boyce Thompson Institute for Plant Research39, Macquarie University40, Oklahoma State University Center for Health Sciences41, İzmir University of Economics42, Academy of Sciences of the Czech Republic43, Charles University in Prague44, St. Edward's University45, University of Puget Sound46, Hokkaido University47, Tsinghua University48, Washington State University49, Appalachian State University50, Marquette University51
TL;DR: Analyses of the Chlamydomonas genome advance the understanding of the ancestral eukaryotic cell, reveal previously unknown genes associated with photosynthetic and flagellar functions, and establish links between ciliopathy and the composition and function of flagella.
Abstract: Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years ago. It is a model system for studying chloroplast-based photosynthesis, as well as the structure, assembly, and function of eukaryotic flagella (cilia), which were inherited from the common ancestor of plants and animals, but lost in land plants. We sequenced the approximately 120-megabase nuclear genome of Chlamydomonas and performed comparative phylogenomic analyses, identifying genes encoding uncharacterized proteins that are likely associated with the function and biogenesis of chloroplasts or eukaryotic flagella. Analyses of the Chlamydomonas genome advance our understanding of the ancestral eukaryotic cell, reveal previously unknown genes associated with photosynthetic and flagellar functions, and establish links between ciliopathy and the composition and function of flagella.
2,554 citations
TL;DR: The rates of reduction of the metal ions by Neem leaf extract are much faster than those observed by us in earlier studies using microorganisms such as fungi, highlighting the possibility that nanoparticle biological synthesis methodologies will achieve rates of synthesis comparable to those of chemical methods.
2,339 citations
TL;DR: This review is focused on current approaches emerging at the intersection of materials research, nanosciences, and molecular biotechnology, which is closely associated with both the physical and chemical properties of organic and inorganic nanoparticles.
Abstract: Based on fundamental chemistry, biotechnology and materials science have developed over the past three decades into today's powerful disciplines which allow the engineering of advanced technical devices and the industrial production of active substances for pharmaceutical and biomedical applications. This review is focused on current approaches emerging at the intersection of materials research, nanosciences, and molecular biotechnology. This novel and highly interdisciplinary field of chemistry is closely associated with both the physical and chemical properties of organic and inorganic nanoparticles, as well as to the various aspects of molecular cloning, recombinant DNA and protein technology, and immunology. Evolutionary optimized biomolecules such as nucleic acids, proteins, and supramolecular complexes of these components, are utilized in the production of nanostructured and mesoscopic architectures from organic and inorganic materials. The highly developed instruments and techniques of today's materials research are used for basic and applied studies of fundamental biological processes.
2,268 citations