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Reconstituição da Anexina V em sistemas de lipossomos: associação com a fosfatase alcalina e correlação com estudos de biomineralização; Reconstitution of Annexin V in liposome systems: association with Alkaline Phosphatase and correlation with biomineralization studies

Bolean, Maytê
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/04/2014 PT
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37.3%
A biomineralização óssea é um processo complexo e multifatorial sendo um grande desafio para a ciência à compreensão dos seus mecanismos regulatórios. Este processo é mediado pela liberação de vesículas da matriz (MVs), as quais surgem das superfícies de osteoblastos e são secretadas no local específico do início da biomineralização. MVs têm a capacidade de acumular altas concentrações de íons Ca2+ e fosfato (Pi), proporcionando um microambiente adequado para a formação inicial e propagação dos cristais de hidroxiapatita. Especial atenção deve ser dada a duas proteínas: Anexina V (AnxA5) e Fosfatase Alcalina (TNAP). As anexinas são as proteínas mais abundantes detectadas nas MVs e responsáveis pela formação de canais de cálcio. TNAP apresenta atividade fosfomonohidrolítica, produzindo Pi a partir, principalmente, de pirofosfato (PPi) e ATP. O enfoque deste projeto foi produzir e caracterizar proteolipossomos com diferentes composições lipídicas de dipalmitoil fosfatidilcolina (DPPC) e dipalmitoil fosfatidilserina (DPPS) contendo TNAP e AnxA5, e manter a funcionalidade das proteínas após incorporação nos sistemas miméticos. Foi possível incorporar AnxA5 em DPPC-proteolipossomos (11,64 µg/mL)...

Biocompatibility and biomineralization assessment of a new root canal sealer and root-end filling material

Cintra, Luciano Tavares Angelo; Ribeiro, Thiago Alexandre Alves; Gomes-Filho, João Eduardo; Bernabé, Pedro Felício Estrada; Watanabe, Simone; Silva Facundo, Aguinaldo Cândido da; Samuel, Renata Oliveira; Dezan Junior, Eloi
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 145-150
ENG
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Objective: This study investigated the short-term subcutaneous tissue reaction and biomineralization ability of two epoxy-based root canal sealers containing calcium hydroxide (MBP and MBPc) and ProRoot MTA. Materials and methods: Polyethylene tubes containing the materials were implanted into the dorsal connective tissue of Wistar rats (n = 52) for 7 or 30 days; empty implanted tubes served as controls. Specimens were stained with hematoxylin-eosin and von Kossa stain or left unstained for observation under polarized light. Qualitative and quantitative evaluations of all tissue reactions were performed. One-way anova and the Kruskal-Wallis test were used for statistical analysis (P < 0.05). Results: No significant differences were observed among the groups. All three materials induced mild-to-moderate tissue reactions at 7 days, which decreased over time. Dystrophic mineralization and birefringent structures were observed only in the ProRoot MTA ® group. Conclusion: Both MBP and MBPc appear to be biocompatible but do not stimulate biomineralization. © 2012 John Wiley & Sons A/S.

Biomineralization in chitosan/Bioglass® composite membranes under different dynamic mechanical conditions

Caridade, S. G.; Merino, Esther G.; Alves, N. M.; Mano, J. F.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /06/2013 ENG
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Fundamental aspects of biomineralization may be important in order to understand and improve calcification onto the surface of biomaterials. The biomineralization process is mainly followed in vitro by assessing the evolution of the apatite layer that is formed upon immersion of the material in Simulated Body Fluid (SBF). In this work we propose an innovative methodology to monitor apatite deposition by looking at the evolution of the mechanical/viscoelastic properties of the sample while immersed in SBF, using non-conventional dynamic mechanical analysis (DMA) performed under distinct displacement amplitudes (d). The biomimetic biomineralization process in composite membranes of chitosan (CTS) with Bioglass® (BG) was followed by measuring the change of the storage modulus, E′, and the loss factor, tan δ, at 37 °C and in SBF, both online (d = 10 μm and d = 30 μm) and offline (d = 0 μm). The online experiments revealed that the E′ decreased continuously up in the first hours of immersion in SBF that should be related to the dissolution of BG particles. After that, an increase of the stiffness was verified due to the apatite deposition. SEM/EDS observations upon 24 h of immersion in SBF showed higher development of apatite deposition with increasing displacement amplitude.

Polysaccharide-based nanostructured multilayers with distinct sulfated and aminated composition to improve cells response and biomineralization

Oliveira, S. M.; Silva, Tiago H.; Reis, R. L.; Mano, J. F.
Fonte: Wiley Publicador: Wiley
Tipo: Conferência ou Objeto de Conferência
Publicado em /09/2013 ENG
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Publicado em "Journal of Tissue Engineering and Regenerative Medicine", vol. 7, supp. 1 (2013); In vitro cell expansion, differentiation for further cell transplantation and biomaterials-cell fundamental assays are still performed more often on inert 2D surfaces than on 3D culture. 3D systems do not allow an easy cell monitoring and may demand higher cell density, being more costly and time consuming. Inert surfaces (polystyrene, biodegradable thermoplastics or metals) neither resemble the extracellular matrix (ECM) milieu nor trigger intercellular signaling. Several studies are focused on surface modification and on the correlation of the surface properties such as roughness, wettability and chemistry with cell behavior with regard to the effects on cell adhesion, morphology, proliferation, survival and differentiation.1,2 Proteins, hormones, small peptides, cytokines, inorganic molecules, sulfated and non-polysaccharides (PS) compose the natural 3D ECM milieu. PS vary on the sulfur content, sulfonic group (Sg) position and on base units. Sulfonated and sulfated PS have intrinsic very high affinity towards growth factors and positively charged molecules through the functional groups turning the combination of themvery bioactive hybrids mats. Current surface modification models make the transposition to 3D systems complicate. Layer-by-Layer (LbL) assembling is a versatile technique to coat any 2D/3D structure with polyelectrolytes (PE) which coatings properties can be modelled and controlled. Herein...

An alternative interpretation of nanobacteria-induced biomineralization

Cisar, John O.; Xu, De-Qi; Thompson, John; Swaim, William; Hu, Lan; Kopecko, Dennis J.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 10/10/2000 EN
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The reported isolation of nanobacteria from human kidney stones raises the intriguing possibility that these microorganisms are etiological agents of pathological extraskeletal calcification [Kajander, E. O. & Çiftçioglu, N. (1998) Proc. Natl. Acad. Sci. USA 95, 8274–8279]. Nanobacteria were previously isolated from FBS after prolonged incubation in DMEM. These bacteria initiated biomineralization of the culture medium and were identified in calcified particles and biofilms by nucleic acid stains, 16S rDNA sequencing, electron microscopy, and the demonstration of a transferable biomineralization activity. We have now identified putative nanobacteria, not only from FBS, but also from human saliva and dental plaque after the incubation of 0.45-μm membrane-filtered samples in DMEM. Although biomineralization in our “cultures” was transferable to fresh DMEM, molecular examination of decalcified biofilms failed to detect nucleic acid or protein that would be expected from growth of a living entity. In addition, biomineralization was not inhibited by sodium azide. Furthermore, the 16S rDNA sequences previously ascribed to Nanobacterium sanguineum and Nanobacterium sp. were found to be indistinguishable from those of an environmental microorganism...

cDNA Microarrays as a Tool for Identification of Biomineralization Proteins in the Coccolithophorid Emiliania huxleyi (Haptophyta)

Quinn, Patrick; Bowers, Robert M.; Zhang, Xiaoyu; Wahlund, Thomas M.; Fanelli, Michael A.; Olszova, Daniela; Read, Betsy A.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /08/2006 EN
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Marine unicellular coccolithophore algae produce species-specific calcite scales otherwise known as coccoliths. While the coccoliths and their elaborate architecture have attracted the attention of investigators from various scientific disciplines, our knowledge of the underpinnings of the process of biomineralization in this alga is still in its infancy. The processes of calcification and coccolithogenesis are highly regulated and likely to be complex, requiring coordinated expression of many genes and pathways. In this study, we have employed cDNA microarrays to investigate changes in gene expression associated with biomineralization in the most abundant coccolithophorid, Emiliania huxleyi. Expression profiling of cultures grown under calcifying and noncalcifying conditions has been carried out using cDNA microarrays corresponding to approximately 2,300 expressed sequence tags. A total of 127 significantly up- or down-regulated transcripts were identified using a P value of 0.01 and a change of >2.0-fold. Real-time reverse transcriptase PCR was used to test the overall validity of the microarray data, as well as the relevance of many of the proteins predicted to be associated with biomineralization, including a novel gamma-class carbonic anhydrase (A. R. Soto...

The role of seawater endocytosis in the biomineralization process in calcareous foraminifera

Bentov, Shmuel; Brownlee, Colin; Erez, Jonathan
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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Foraminifera are unicellular organisms that inhabit the oceans in various ecosystems. The majority of the foraminifera precipitate calcitic shells and are among the major CaCO3 producers in the oceans. They comprise an important component of the global carbon cycle and also provide valuable paleoceanographic information based on the relative abundance of stable isotopes and trace elements (proxies) in their shells. Understanding the biomineralization processes in foraminifera is important for predicting their calcification response to ocean acidification and for reliable interpretation of the paleoceanographic proxies. Most models of biomineralization invoke the involvement of membrane ion transporters (channels and pumps) in the delivery of Ca2+ and other ions to the calcification site. Here we show, in contrast, that in the benthic foraminiferan Amphistegina lobifera, (a shallow water species), transport of seawater via fluid phase endocytosis may account for most of the ions supplied to the calcification site. During their intracellular passage the seawater vacuoles undergo alkalization that elevates the CO32− concentration and further enhances their calcifying potential. This mechanism of biomineralization may explain why many calcareous foraminifera can be good recorders of paleoceanographic conditions. It may also explain the sensitivity to ocean acidification that was observed in several planktonic and benthic species.

MMS6 Protein Regulates Crystal Morphology during Nano-sized Magnetite Biomineralization in Vivo*

Tanaka, Masayoshi; Mazuyama, Eri; Arakaki, Atsushi; Matsunaga, Tadashi
Fonte: American Society for Biochemistry and Molecular Biology Publicador: American Society for Biochemistry and Molecular Biology
Tipo: Artigo de Revista Científica
EN
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Biomineralization, the process by which minerals are deposited by organisms, has attracted considerable attention because this mechanism has shown great potential to inspire bottom-up material syntheses. To understand the mechanism for morphological regulation that occurs during biomineralization, many regulatory proteins have been isolated from various biominerals. However, the molecular mechanisms that regulate the morphology of biominerals remain unclear because there is a lack of in vivo evidence. Magnetotactic bacteria synthesize intracellular magnetosomes that comprise membrane-enveloped single crystalline magnetite (Fe3O4). These nano-sized magnetite crystals (<100 nm) are bacterial species dependent in shape and size. Mms6 is a protein that is tightly associated with magnetite crystals. Based on in vitro experiments, this protein was first implicated in morphological regulation during nano-sized magnetite biomineralization. In this study, we analyzed the mms6 gene deletion mutant (Δmms6) of Magnetospirillum magneticum (M. magneticum) AMB-1. Surprisingly, the Δmms6 strain was found to synthesize the smaller magnetite crystals with uncommon crystal faces, while the wild-type and complementation strains synthesized highly ordered cubo-octahedral crystals. Furthermore...

Identification and Localization of Proteins Associated with Biomineralization in the Iron Deposition Vesicles of Honeybees (Apis mellifera)

Hsu, Chin-Yuan; Chan, Yu-Pei
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 26/04/2011 EN
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Honeybees (Apis mellifera) form superparamagnetic magnetite to act as a magnetoreceptor for magnetoreception. Biomineralization of superparamagnetic magnetite occurs in the iron deposition vesicles of trophocytes. Even though magnetite has been demonstrated, the mechanism of magnetite biomineralization is unknown. In this study, proteins in the iron granules and iron deposition vesicles of trophocytes were purified and identified by mass spectrometry. Antibodies against such proteins were produced. The major proteins include actin, myosin, ferritin 2, and ATP synthase. Immunolabeling and co-immunoprecipitation studies suggest that iron is stored in ferritin 2 for the purpose of forming 7.5-nm diameter iron particles and that actin-myosin-ferritin 2 may serve as a transporter system. This system, along with calcium and ATP, conveys the iron particles (ferritin) to the center of iron deposition vesicles for iron granules formation. These proteins and reactants are included in iron deposition vesicles during the formation of iron deposition vesicles from the fusion of smooth endoplasmic reticulum. A hypothetical model for magnetite biomineralization in iron deposition vesicles is proposed for honeybees.

The HtrA/DegP family protease MamE is a bifunctional protein with roles in magnetosome protein localization and magnetite biomineralization

Quinlan, Anna; Murat, Dorothée; Vali, Hojatollah; Komeili, Arash
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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Magnetotactic bacteria contain nanometer-sized, membrane-bound organelles, called magnetosomes, which are tasked with the biomineralization of small crystals of the iron oxide magnetite allowing the organism to use geomagnetic field lines for navigation. A key player in this process is the HtrA/DegP family protease MamE. In its absence, Magnetospirillum magneticum str AMB-1 is able to form magnetosome membranes but not magnetite crystals, a defect previously linked to the mislocalization of magnetosome proteins. In this work we use a directed genetic approach to find that MamE, and another predicted magnetosome-associated protease, MamO, likely function as proteases in vivo. However, as opposed to the complete loss of mamE where no biomineralization is observed, the protease-deficient variant of this protein still supports the initiation and formation of small, 20 nm-sized crystals of magnetite, too small to hold a permanent magnetic dipole moment. This analysis also reveals that MamE is a bifunctional protein with a protease-independent role in magnetosome protein localization and a protease-dependent role in maturation of small magnetite crystals. Together these results imply the existence of a previously unrecognized “checkpoint” in biomineralization where MamE moderates the completion of magnetite formation and thus committal to magneto-aerotaxis as the organism’s dominant mode of navigating the environment.

Common ancestry of iron oxide- and iron-sulfide-based biomineralization in magnetotactic bacteria

Abreu, Fernanda; Cantão, Mauricio E; Nicolás, Marisa F; Barcellos, Fernando G; Morillo, Viviana; Almeida, Luiz GP; do Nascimento, Fabrícia F; Lefèvre, Christopher T; Bazylinski, Dennis A; R de Vasconcelos, Ana Tereza; Lins, Ulysses
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
EN
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Magnetosomes are prokaryotic organelles produced by magnetotactic bacteria that consist of nanometer-sized magnetite (Fe3O4) or/and greigite (Fe3S4) magnetic crystals enveloped by a lipid bilayer membrane. In magnetite-producing magnetotactic bacteria, proteins present in the magnetosome membrane modulate biomineralization of the magnetite crystal. In these microorganisms, genes that encode for magnetosome membrane proteins as well as genes involved in the construction of the magnetite magnetosome chain, the mam and mms genes, are organized within a genomic island. However, partially because there are presently no greigite-producing magnetotactic bacteria in pure culture, little is known regarding the greigite biomineralization process in these organisms including whether similar genes are involved in the process. Here using culture-independent techniques, we now show that mam genes involved in the production of magnetite magnetosomes are also present in greigite-producing magnetotactic bacteria. This finding suggest that the biomineralization of magnetite and greigite did not have evolve independently (that is, magnetotaxis is polyphyletic) as once suggested. Instead, results presented here are consistent with a model in which the ability to biomineralize magnetosomes and the possession of the mam genes was acquired by bacteria from a common ancestor...

Shedding Light on Fish Otolith Biomineralization Using a Bioenergetic Approach

Fablet, Ronan; Pecquerie, Laure; de Pontual, Hélène; Høie, Hans; Millner, Richard; Mosegaard, Henrik; Kooijman, Sebastiaan A. L. M.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 14/11/2011 EN
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Otoliths are biocalcified bodies connected to the sensory system in the inner ears of fish. Their layered, biorhythm-following formation provides individual records of the age, the individual history and the natural environment of extinct and living fish species. Such data are critical for ecosystem and fisheries monitoring. They however often lack validation and the poor understanding of biomineralization mechanisms has led to striking examples of misinterpretations and subsequent erroneous conclusions in fish ecology and fisheries management. Here we develop and validate a numerical model of otolith biomineralization. Based on a general bioenergetic theory, it disentangles the complex interplay between metabolic and temperature effects on biomineralization. This model resolves controversial issues and explains poorly understood observations of otolith formation. It represents a unique simulation tool to improve otolith interpretation and applications, and, beyond, to address the effects of both climate change and ocean acidification on other biomineralizing organisms such as corals and bivalves.

The Periplasmic Nitrate Reductase Nap Is Required for Anaerobic Growth and Involved in Redox Control of Magnetite Biomineralization in Magnetospirillum gryphiswaldense

Li, Yingjie; Katzmann, Emanuel; Borg, Sarah; Schüler, Dirk
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /09/2012 EN
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The magnetosomes of many magnetotactic bacteria consist of membrane-enveloped magnetite crystals, whose synthesis is favored by a low redox potential. However, the cellular redox processes governing the biomineralization of the mixed-valence iron oxide have remained unknown. Here, we show that in the alphaproteobacterium Magnetospirillum gryphiswaldense, magnetite biomineralization is linked to dissimilatory nitrate reduction. A complete denitrification pathway, including gene functions for nitrate (nap), nitrite (nir), nitric oxide (nor), and nitrous oxide reduction (nos), was identified. Transcriptional gusA fusions as reporters revealed that except for nap, the highest expression of the denitrification genes coincided with conditions permitting maximum magnetite synthesis. Whereas microaerobic denitrification overlapped with oxygen respiration, nitrate was the only electron acceptor supporting growth in the entire absence of oxygen, and only the deletion of nap genes, encoding a periplasmic nitrate reductase, and not deletion of nor or nos genes, abolished anaerobic growth and also delayed aerobic growth in both nitrate and ammonium media. While loss of nosZ or norCB had no or relatively weak effects on magnetosome synthesis, deletion of nap severely impaired magnetite biomineralization and resulted in fewer...

Molecular Mechanisms of Compartmentalization and Biomineralization in Magnetotactic Bacteria

Komeili, Arash
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/2012 EN
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Magnetotactic bacteria are remarkable organisms with the ability to exploit the earth’s magnetic field for navigational purposes. To do this, they build specialized compartments called magnetosomes that consist of a lipid membrane and a crystalline magnetic mineral. These organisms have the potential to serve as models for the study of compartmentalization as well as biomineralization in bacteria. Additionally, they offer the opportunity to design applications that take advantage of the particular properties of magnetosomes. In recent years, a sustained effort to identify the molecular basis of this process has resulted in a clearer understanding of the magnetosome formation and biomineralization. Here, I present an overview of magnetotactic bacteria and explore the possible molecular mechanisms of membrane remodeling, protein sorting, cytoskeletal organization, iron transport and biomineralization that lead to the formation of a functional magnetosome organelle.

The magnetosome membrane protein, MmsF, is a major regulator of magnetite biomineralization in Magnetospirillum magneticum AMB-1

Murat, Dorothée; Falahati, Veesta; Bertinetti, Luca; Csencsits, Roseann; Körnig, André; Downing, Kenneth; Faivre, Damien; Komeili, Arash
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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27.41%
Magnetotactic bacteria (MTB) use magnetosomes, membrane bound crystals of magnetite or greigite, for navigation along geomagnetic fields. In Magnetospirillum magneticum sp. AMB-1, and other MTB, a magnetosome gene island (MAI) is essential for every step of magnetosome formation. An 8-gene region of the MAI encodes several factors implicated in control of crystal size and morphology in previous genetic and proteomic studies. We show that these factors play a minor role in magnetite biomineralization in vivo. In contrast, MmsF, a previously uncharacterized magnetosome membrane protein encoded within the same region plays a dominant role in defining crystal size and morphology and is sufficient for restoring magnetite synthesis in the absence of the other major biomineralization candidates. In addition, we show that the 18 genes of the mamAB gene cluster of the MAI are sufficient for the formation of an immature magnetosome organelle. Addition of MmsF to these 18 genes leads to a significant enhancement of magnetite biomineralization and an increase in the cellular magnetic response. These results define a new biomineralization protein and lay down the foundation for the design of autonomous gene cassettes for the transfer of the magnetic phenotype in other bacteria.

The magnetosome model: insights into the mechanisms of bacterial biomineralization

Rahn-Lee, Lilah; Komeili, Arash
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 26/11/2013 EN
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Though the most ready example of biomineralization is the calcium phosphate of vertebrate bones and teeth, many bacteria are capable of creating biominerals inside their cells. Because of the diversity of these organisms and the minerals they produce, their study may reveal aspects of the fundamental mechanisms of biomineralization in more complex organisms. The best-studied case of intracellular biomineralization in bacteria is the magnetosome, an organelle produced by a diverse group of aquatic bacteria that contains single-domain crystals of the iron oxide magnetite (Fe3O4) or the iron sulfide greigite (Fe3S4). Here, recent advances in our understanding of the mechanisms of bacterial magnetite biomineralization are discussed and used as a framework for understanding less-well studied examples, including the bacterial intracellular biomineralization of cadmium, selenium, silver, nickel, uranium, and calcium carbonate. Understanding the molecular mechanisms underlying the biological formation of these minerals will have important implications for technologies such as the fabrication of nanomaterials and the bioremediation of toxic compounds.

The Terminal Oxidase cbb3 Functions in Redox Control of Magnetite Biomineralization in Magnetospirillum gryphiswaldense

Li, Yingjie; Raschdorf, Oliver; Silva, Karen T.; Schüler, Dirk
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /07/2014 EN
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The biomineralization of magnetosomes in Magnetospirillum gryphiswaldense and other magnetotactic bacteria occurs only under suboxic conditions. However, the mechanism of oxygen regulation and redox control of biosynthesis of the mixed-valence iron oxide magnetite [FeII(FeIII)2O4] is still unclear. Here, we set out to investigate the role of aerobic respiration in both energy metabolism and magnetite biomineralization of M. gryphiswaldense. Although three operons encoding putative terminal cbb3-type, aa3-type, and bd-type oxidases were identified in the genome assembly of M. gryphiswaldense, genetic and biochemical analyses revealed that only cbb3 and bd are required for oxygen respiration, whereas aa3 had no physiological significance under the tested conditions. While the loss of bd had no effects on growth and magnetosome synthesis, inactivation of cbb3 caused pleiotropic effects under microaerobic conditions in the presence of nitrate. In addition to their incapability of simultaneous nitrate and oxygen reduction, cbb3-deficient cells had complex magnetosome phenotypes and aberrant morphologies, probably by disturbing the redox balance required for proper growth and magnetite biomineralization. Altogether, besides being the primary terminal oxidase for aerobic respiration...

Characterization of the Mantle Transcriptome of Yesso Scallop (Patinopecten yessoensis): Identification of Genes Potentially Involved in Biomineralization and Pigmentation

Sun, Xiujun; Yang, Aiguo; Wu, Biao; Zhou, Liqing; Liu, Zhihong
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 09/04/2015 EN
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The Yesso scallop Patinopecten yessoensis is an economically important marine bivalve species in aquaculture and fishery in Asian countries. However, limited genomic resources are available for this scallop, which hampers investigations into molecular mechanisms underlying their unique biological characteristics, such as shell formation and pigmentation. Mantle is the special tissue of P. yessoensis that secretes biomineralization proteins inducing shell deposition as well as pigmentation on the shells. However, a current deficiency of transcriptome information limits insight into mechanisms of shell formation and pigmentation in this species. In this study, the transcriptome of the mantle of P. yessoensis was deeply sequenced and characterized using Illumina RNA-seq technology. A total of 86,521 unique transcripts are assembled from 55,884,122 reads that passed quality filters, and annotated, using Gene Ontology classification. A total of 259 pathways are identified in the mantle transcriptome, including the calcium signaling and melanogenesis pathways. A total of 237 unigenes that are homologous to 102 reported biomineralization genes are identified, and 121 unigenes that are homologous to 93 known proteins related to melanin biosynthesis are found. Twenty-three annotated unigenes...

Four hundred million years of silica biomineralization in land plants

Trembath-Reichert, Elizabeth; Wilson, Jonathan Paul; McGlynn, Shawn E.; Fischer, Woodward W.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Article; PeerReviewed Formato: application/pdf; text/plain; text/plain; text/plain; text/plain
Publicado em 28/04/2015
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Biomineralization plays a fundamental role in the global silicon cycle. Grasses are known to mobilize significant quantities of Si in the form of silica biominerals and dominate the terrestrial realm today, but they have relatively recent origins and only rose to taxonomic and ecological prominence within the Cenozoic Era. This raises questions regarding when and how the biological silica cycle evolved. To address these questions, we examined silica abundances of extant members of early-diverging land plant clades, which show that silica biomineralization is widespread across terrestrial plant linages. Particularly high silica abundances are observed in lycophytes and early-diverging ferns. However, silica biomineralization is rare within later-evolving gymnosperms, implying a complex evolutionary history within the seed plants. Electron microscopy and X-ray spectroscopy show that the most common silica-mineralized tissues include the vascular system, epidermal cells, and stomata, which is consistent with the hypothesis that biomineralization in plants is frequently coupled to transpiration. Furthermore, sequence, phylogenetic, and structural analysis of nodulin 26-like intrinsic proteins from diverse plant genomes points to a plastic and ancient capacity for silica accumulation within terrestrial plants. The integration of these two comparative biology approaches demonstrates that silica biomineralization has been an important process for land plants over the course of their >400 My evolutionary history.

Biomineralization by neutrophilic, lithotrophic iron-oxidizing bacteria

Krepski, Sean
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
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Chan, Clara S.; Biogenic Fe oxides influence the cycling of nutrients and contaminants in the environment, and may hold clues to understanding environments on ancient Earth. In many freshwater and marine habitats, these minerals are produced by lithotrophic bacteria that inhabit low-oxygen zones of redox gradients and comprise a significant part of the microbial community. Extracellular Fe-organic bacteriogenic filaments, such as the widely-observed Gallionella-like stalks often dominate the structures of Fe mats. Scientific interest in neutrophilic, lithotrophic FeOB is due to their influence on modern biogeochemical cycles, as well as their possible activities throughout Earth history (for instance, deposition of the Precambrian banded iron formations). In spite of this interest, much remains unknown about the diversity and physiology of these organisms, and their formation of filamentous Fe mats. Fe-depositing microbes were first recognized in the first half of the 19th Century, however our understanding of microbial Fe oxidation and biomineralization is limited, in part, because few FeOB isolates exist. Furthermore, there are no available freshwater isolates that form filamentous mats. Therefore, the first objective of the research presented here was to isolate a novel Fe stalk-forming FeOB from a freshwater environment. We successfully isolated strain R-1 from an Fe seep in Newark...