scholarly journals Ferromagnetic Resonance Spectroscopy and Rock Magnetic Characterization of Fossil Coral Skeletons in Ishigaki Islands, Japan

Geosciences ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 400
Author(s):  
Yuho Kumagai ◽  
Norihiro Nakamura ◽  
Tetsuro Sato ◽  
Toshitaka Oka ◽  
Hirokuni Oda
Keyword(s):  
Ferromagnetic Resonance ◽  
Single Domain ◽  
Coral Skeleton ◽  
Resonance Spectroscopy ◽  
Continuous Growth ◽  
Coral Skeletons ◽  
Ishigaki Island ◽  
Biogenic Magnetite ◽  
A Chain ◽  
Fossil Coral

Skeletons of hermatypic corals (e.g., Porites) might have enormous potential as a high-resolution paleomagnetic recorder owing to their rapid and continuous growth over hundreds of years at a rate of up to 2 cm/year, although typical corals show an extremely weak intensity of remanence and low stability. We found that coral tsunami boulders with negligible amounts of calcite on Ishigaki Island show a measurable intensity of remanence; thus, we attempted to characterize the magnetic assemblages in this coral skeleton to determine whether it is of biogenic or detrital magnetite using first-order reversal curve (FORC) measurements, ferromagnetic resonance (FMR) spectroscopy, and petrological observations through field-emission type scanning electron microscope (FE-SEM) with an acid treatment. The FMR derivative spectra of coral skeleton samples represent multiple derivative maxima and extended low-field absorption, indicating the presence of intact biogenic magnetite chains. FORC diagrams represent a “central ridge” signature with a vertical spread. These FMR and FORC features indicate the magnetization of these coral skeletons that are mainly created using intact biogenic magnetites and mixtures of grains from collapsed biogenic magnetites, pseudo-single domain grains, and multi-domain grains such as detrital magnetite. FE-SEM observations confirm the presence of a chain-like structure of iron oxides corresponding to the features of biogenic magnetite. Therefore, the magnetic mineral assemblage in coralline boulders from Ishigaki Island consists of dominant biogenic-origin single-domain magnetite and a trace amount of detrital component, indicating that fossil coral skeletons in Ishigaki Island have potential for utilization in paleomagnetic studies.

scholarly journals A genomic view of coral-associated Prosthecochloris and a companion sulfate-reducing bacterium

2019 ◽  
Author(s):  
Yu-Hsiang Chen ◽  
Shan-Hua Yang ◽  
Kshitij Tandon ◽  
Chih-Ying Lu ◽  
Hsing-Ju Chen ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Sulfur Metabolism ◽  
Genomic Analysis ◽  
Coral Skeleton ◽  
Pigment Synthesis ◽  
Sulfate Reducing ◽  
Coral Skeletons ◽  
Functional Genomic Analysis ◽  
Ecological Roles ◽  
Isopora Palifera

AbstractEndolithic microbial symbionts in the coral skeleton may play a pivotal role in maintaining coral health. However, compared to aerobic microorganisms, research on the roles of endolithic anaerobic microorganisms and microbe-microbe interactions in the coral skeleton are still in their infancy. In our previous study, we showed that a group of coral-associated Prosthecochloris (CAP), a genus of anaerobic green sulfur bacteria, was dominant in the skeleton of the coral Isopora palifera. Though CAP is diverse, the 16S rRNA phylogeny presents it as a distinct clade separate from other free-living Prosthecochloris. In this study, we build on previous research and further characterize the genomic and metabolic traits of CAP by recovering two new near-complete CAP genomes—Candidatus Prosthecochloris isoporaea and Candidatus Prosthecochloris sp. N1—from coral Isopora palifera endolithic cultures. Genomic analysis revealed that these two CAP genomes have high genomic similarities compared with other Prosthecochloris and harbor several CAP-unique genes. Interestingly, different CAP species harbor various pigment synthesis and sulfur metabolism genes, indicating that individual CAPs can adapt to a diversity of coral microenvironments. A novel near-complete SRB genome—Candidatus Halodesulfovibrio lyudaonia—was also recovered from the same culture. The fact that CAP and various sulfate-reducing bacteria (SRB) co-exist in coral endolithic cultures and coral skeleton highlights the importance of SRB in the coral endolithic community. Based on functional genomic analysis of Ca. P. sp. N1 and Ca. H. lyudaonia, we also propose a syntrophic relationship between the SRB and CAP in the coral skeleton.ImportanceLittle is known about the ecological roles of endolithic microbes in the coral skeleton; one potential role is as a nutrient source for their coral hosts. Here, we identified a close ecological relationship between CAP and SRB. Recovering novel near-complete CAP and SRB genomes from endolithic cultures in this study enabled us to understand the genomic and metabolic features of anaerobic endolithic bacteria in coral skeletons. These results demonstrate that CAP members with similar functions in carbon, sulfur, and nitrogen metabolisms harbor different light-harvesting components, suggesting that CAP in the skeleton adapts to niches with different light intensities. Our study highlights the potential ecological roles of CAP and SRB in coral skeletons and paves the way for future investigations into how coral endolithic communities will respond to environmental changes.

Broadband ferromagnetic resonance spectroscopy of permalloy triangular nanorings

2012 ◽  
Vol 100 (6) ◽  
pp. 062401 ◽  
Author(s):  
J. Ding ◽  
M. Kostylev ◽  
A. O. Adeyeye
Keyword(s):  
Ferromagnetic Resonance ◽  
Resonance Spectroscopy

scholarly journals Reviews and syntheses: Revisiting the boron systematics of aragonite and their application to coral calcification

2018 ◽  
Vol 15 (9) ◽  
pp. 2819-2834 ◽  
Author(s):  
Thomas M. DeCarlo ◽  
Michael Holcomb ◽  
Malcolm T. McCulloch
Keyword(s):  
Partition Coefficient ◽  
Isotopic Fractionation ◽  
Computer Code ◽  
Comprehensive Analysis ◽  
Coral Skeleton ◽  
Carbonate Chemistry ◽  
Carbonate System ◽  
Coral Skeletons ◽  
User Friendly ◽  
Propagation Of Uncertainties

Abstract. The isotopic and elemental systematics of boron in aragonitic coral skeletons have recently been developed as a proxy for the carbonate chemistry of the coral extracellular calcifying fluid. With knowledge of the boron isotopic fractionation in seawater and the B∕Ca partition coefficient (KD) between aragonite and seawater, measurements of coral skeleton δ11B and B∕Ca can potentially constrain the full carbonate system. Two sets of abiogenic aragonite precipitation experiments designed to quantify KD have recently made possible the application of this proxy system. However, while different KD formulations have been proposed, there has not yet been a comprehensive analysis that considers both experimental datasets and explores the implications for interpreting coral skeletons. Here, we evaluate four potential KD formulations: three previously presented in the literature and one newly developed. We assess how well each formulation reconstructs the known fluid carbonate chemistry from the abiogenic experiments, and we evaluate the implications for deriving the carbonate chemistry of coral calcifying fluid. Three of the KD formulations performed similarly when applied to abiogenic aragonites precipitated from seawater and to coral skeletons. Critically, we find that some uncertainty remains in understanding the mechanism of boron elemental partitioning between aragonite and seawater, and addressing this question should be a target of additional abiogenic precipitation experiments. Despite this, boron systematics can already be applied to quantify the coral calcifying fluid carbonate system, although uncertainties associated with the proxy system should be carefully considered for each application. Finally, we present a user-friendly computer code that calculates coral calcifying fluid carbonate chemistry, including propagation of uncertainties, given inputs of boron systematics measured in coral skeleton.

scholarly journals S-band ferromagnetic resonance spectroscopy and the detection of magnetofossils

2013 ◽  
Vol 10 (80) ◽  
pp. 20120790 ◽  
Author(s):  
Andreas U. Gehring ◽  
Jessica Kind ◽  
Michalis Charilaou ◽  
Inés García-Rubio
Keyword(s):  
Ferromagnetic Resonance ◽  
Uniaxial Anisotropy ◽  
Magnetotactic Bacteria ◽  
Time Frame ◽  
Resonance Spectroscopy ◽  
Verwey Transition ◽  
Geological Time ◽  
Change Of Direction ◽  
X Band ◽  
Magnetite Particles

We report the use of S-band ferromagnetic resonance (FMR) spectroscopy to compare the anisotropic properties of magnetite particles in chains of cultured intact magnetotactic bacteria (MTB) between 300 and 15 K with those of sediment samples of Holocene age in order to infer the presence of magnetofossils and their preservation in a geological time frame. The spectrum of intact MTB at 300 K exhibits distinct uniaxial anisotropy because of the chain alignment of the cellular magnetite particles and their easy axes. This anisotropy becomes less pronounced upon cooling and below the Verwey transition ( T V ) it is nearly vanished mainly owing to the change of direction of the easy axes. In a natural sample, magnetofossils were detected by uniaxial anisotropy traits similar to those obtained from cultured MTB above T V . Our comparative study emphasizes that indispensable information can be obtained from S-band FMR spectra, which offers even a better resolution than X-band FMR for discovering magnetofossils, and this in turn can contribute towards strengthening our relatively sparse database for deciphering the microbial ecology during the Earth's history.

Publisher's Note: Ferromagnetic resonance spectroscopy of parametric magnons excited by a four-wave process [Phys. Rev. B75, 140405(R) (2007)]

2007 ◽  
Vol 75 (18) ◽  
Author(s):  
V. V. Naletov ◽  
G. de Loubens ◽  
V. Charbois ◽  
O. Klein ◽  
V. S. Tiberkevich ◽  
...  
Keyword(s):  
Ferromagnetic Resonance ◽  
Wave Process ◽  
Resonance Spectroscopy

scholarly journals Identification of Unusual E6 and E7 Proteins within Avian Papillomaviruses: Cellular Localization, Biophysical Characterization, and Phylogenetic Analysis

2009 ◽  
Vol 83 (17) ◽  
pp. 8759-8770 ◽  
Author(s):  
Koenraad Van Doorslaer ◽  
Abdellahi Ould M'hamed Ould Sidi ◽  
Katia Zanier ◽  
Vladimir Rybin ◽  
François Deryckère ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cellular Localization ◽  
Binding Domain ◽  
Single Domain ◽  
Zinc Binding ◽  
Resonance Spectroscopy ◽  
E6 And E7 ◽  
E7 Proteins ◽  
Zinc Binding Domain ◽  
Terminal Domains

ABSTRACT Papillomaviruses (PVs) are a large family of small DNA viruses infecting mammals, reptiles, and birds. PV infection induces cell proliferation that may lead to the formation of orogenital or skin tumors. PV-induced cell proliferation has been related mainly to the expression of two small oncoproteins, E6 and E7. In mammalian PVs, E6 contains two 70-residue zinc-binding repeats, whereas E7 consists of a natively unfolded N-terminal region followed by a zinc-binding domain which folds as an obligate homodimer. Here, we show that both the novel francolin bird PV Francolinus leucoscepus PV type 1 (FlPV-1) and the chaffinch bird PV Fringilla coelebs PV contain unusual E6 and E7 proteins. The avian E7 proteins contain an extended unfolded N terminus and a zinc-binding domain of reduced size, whereas the avian E6 proteins consist of a single zinc-binding domain. A comparable single-domain E6 protein may have existed in a common ancestor of mammalian and avian PVs. Mammalian E6 C-terminal domains are phylogenetically related to those of single-domain avian E6, whereas mammalian E6 N-terminal domains seem to have emerged by duplication and subsequently diverged from the original ancestral domain. In avian and mammalian cells, both FlPV-1 E6 and FlPV-1 E7 were evenly expressed in the cytoplasm and the nucleus. Finally, samples of full-length FlPV-1 E6 and the FlPV-1 E7 C-terminal zinc-binding domain were prepared for biophysical analysis. Both constructs were highly soluble and well folded, according to nuclear magnetic resonance spectroscopy measurements.

Noncollinear states in a chain of single-domain magnetic particles

JETP Letters ◽  
2011 ◽  
Vol 93 (12) ◽  
pp. 716-719 ◽  
Author(s):  
K. P. Mukhamatchin ◽  
A. A. Fraerman
Keyword(s):  
Magnetic Particles ◽  
Single Domain ◽  
A Chain
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