Different skeletal protein toolkits achieve similar structure and performance in the tropical coral Stylophora pistillata and the temperate Oculina patagonica

Stony corals (order: Scleractinia) differ in growth form and structure. While stony corals have gained the ability to form their aragonite skeleton once in their evolution, the suite of proteins involved in skeletogenesis is different for different coral species. This led to the conclusion that the organic portion of their skeleton can undergo rapid evolutionary changes by independently evolving new biomineralization-related proteins. Here, we used liquid chromatography-tandem mass spectrometry to sequence skeletogenic proteins extracted from the encrusting temperate coral Oculina patagonica. We compare it to the previously published skeletal proteome of the branching subtropical corals Stylophora pistillata as both are regarded as highly resilient to environmental changes. We further characterized the skeletal organic matrix (OM) composition of both taxa and tested their effects on the mineral formation using a series of overgrowth experiments on calcite seeds. We found that each species utilizes a different set of proteins containing different amino acid compositions and achieve a different morphology modification capacity on calcite overgrowth. Our results further support the hypothesis that the different coral taxa utilize a species-specific protein set comprised of independent gene co-option to construct their own unique organic matrix framework. While the protein set differs between species, the specific predicted roles of the whole set appear to underline similar functional roles. They include assisting in forming the extracellular matrix, nucleation of the mineral and cell signaling. Nevertheless, the different composition might be the reason for the varying organization of the mineral growth in the presence of a particular skeletal OM, ultimately forming their distinct morphologies

YS-TaS2 and YxLa1–xS-TaS2 (0 ≤ x ≤ 1) nanotubes: A family of misfit layeredcompounds

We present the analysis of a family of nanotubes (NTs) based on the quaternary misfit layered compound (MLC) YxLa1–xS-TaS2. The NTs were successfully synthesized within the whole range of possible compositions via the chemical vapor transport technique. In-depth analysis of the NTs using electron microscopy and spectroscopy proves the in-phase (partial) substitution of La by Y in the (La,Y)S subsystem and reveals structural changes compared to the previously reported LaS-TaS2 MLC-NTs. The observed structure can be linked to the slightly different lattice parameters of LaS and YS. Raman spectroscopy and infrared transmission measurements reveal the tunability of the plasmonic and vibrational properties. Density-functional theory calculations showed that the YxLa1–xS-TaS2 MLCs are stable in all compositions. Moreover, the calculations indicated that substitution of La by Sc atoms is electronically not favorable, which explains our failed attempt to synthesize these MLC and NTs thereof.A.E. acknowledges the support by Act 211 Government of the Russian Federation, Contract No. 02.A03.21.0006. The support of the Israel Science Foundation (Grant No. 7130970101), Irving and Cherna Moskowitz Center for Nano and Bio-Nano Imaging, and the Perlman Family Foundation and the Kimmel Center for Nanoscale Science (Grant No. 43535000350000) is greatly acknowledged. R.A. gratefully acknowledges the support from the Spanish Ministry of Economy and Competitiveness (MINECO) through Project Grant MAT2016-79776-P (AEI/FEDER, UE) and from the European Union H2020 program “ESTEEM3” (823717). S.H. acknowledges funding by the German Research Foundation (HE 7675/1-1). I.P. is the incumbent of the Sharon Zuckerman Research Fellow Chair.Peer reviewe

Chiral Motifs in Highly Interpenetrated Metal-Organic Frameworks Formed from Achiral Tetrahedral Ligands

Formation of highly interpenetrated frameworks is demonstrated. An interesting observation is the presence of very large adamantane-shaped cages in a single network, making these crystals new entries in the collection of diamondoid-type metal-organic frameworks (MOFs). The frameworks were constructed by assembling tetrahedral pyridine ligands and copper dichloride. Currently, the networks' degree of interpenetration is among the highest reported and increases when the size of the ligand is increased. Highly interpenetrated frameworks typically have low surface contact areas. In contrast, in our systems, the voids take up to 63 % of the unit cell volume. The MOFs have chiral features but are formed from achiral components. The chirality is manifested by the coordination chemistry around the metal center, the structure of the helicoidal channels, and the motifs of the individual networks. Channels of both handednesses are present within the unit cells. This phenomenon shapes the walls of the channels, which are composed of 10, 16, or 32 chains correlated with the degree of interpenetration 10-, 16-, and 32-fold, respectively. By changing the distance between the center of the ligand and the coordination moieties, we succeeded in tuning the diameter of the channels. Relatively large channels were formed, having diameters up to 31.0 angstrom x14.8 angstrom

Mineral formation in the primary polyps of pocilloporoid corals

In reef-building corals, larval settlement and its rapid calcification provides a unique opportunity to study the bio-calcium carbonate formation mechanism involving skeleton morphological changes. Here we investigate the mineral formation of primary polyps, just after settlement, in two species of the pocilloporoid corals: Stylophora pistillata (Esper, 1797) and Pocillopora acuta (Lamarck, 1816). We show that the initial mineral phase is nascent Mg-Calcite, with rod-like morphology in P. acuta, and dumbbell morphology in S. pistillata. These structures constitute the first layer of the basal plate which is comparable to Rapid Accretion Deposits (Centers of Calcification, CoC) in adult coral skeleton. We found also that the rod-like/dumbbell Mg-Calcite structures in subsequent growth step will merge into larger aggregates by deposition of aragonite needles. Our results suggest that a biologically controlled mineralization of initial skeletal deposits occurs in three steps: first, vesicles filled with divalent ions are formed intracellularly. These vesicles are then transferred to the calcification site, forming nascent Mg-Calcite rod/pristine dumbbell structures. During the third step, aragonite crystals develop between these structures forming spherulite-like aggregates

Detection of Light Images by Simple Tissues as Visualized by Photosensitized Magnetic Resonance Imaging

In this study, we show how light can be absorbed by the body of a living rat due to an injected pigment circulating in the blood stream. This process is then physiologically translated in the tissue into a chemical signature that can be perceived as an image by magnetic resonance imaging (MRI). We previously reported that illumination of an injected photosynthetic bacteriochlorophyll-derived pigment leads to a generation of reactive oxygen species, upon oxygen consumption in the blood stream. Consequently, paramagnetic deoxyhemoglobin accumulating in the illuminated area induces changes in image contrast, detectable by a Blood Oxygen Level Dependent (BOLD)-MRI protocol, termed photosensitized (ps)MRI. Here, we show that laser beam pulses synchronously trigger BOLD-contrast transients in the tissue, allowing representation of the luminous spatiotemporal profile, as a contrast map, on the MR monitor. Regions with enhanced BOLD-contrast (7-61 fold) were deduced as illuminated, and were found to overlap with the anatomical location of the incident light. Thus, we conclude that luminous information can be captured and translated by typical oxygen exchange processes in the blood of ordinary tissues, and made visible by psMRI (Fig. 1). This process represents a new channel for communicating environmental light into the body in certain analogy to light absorption by visual pigments in the retina where image perception takes place in the central nervous system. Potential applications of this finding may include: non-invasive intra-operative light guidance and follow-up of photodynamic interventions, determination of light diffusion in opaque tissues for optical imaging and possible assistance to the blind

WS2 fullerene/plate nanofibers: the tunable crossroad between dimensionalities

Our work describes the nanofibrous materials of tungsten disulfide, which can be tuned by the precursor\u27s crystallinity degree. The carefully formulated nanofibers create the morphological crossroad between fullerenes (0D), nanotubes (1D), plates (2D), and a nonwoven web of nanofibers (3D), containing all the advantageous properties of the presented material categories. Our synthetic methodology (electrospinning, reductive sulfidation) allows scale-up to industrial production. In addition, we studied the optical properties of the WS2 nanofibers using extinction and absolute absorption measurement. The results of the optical analysis further indicate the higher crystallinity of the closed stacked fullerene-based structure. By comparison of the extinction with the absorbance, we find that all the examined nanostructures display typical polaritonic spectra. However, the open plate structure exhibits a stronger scattering and thus better pronounced polaritonic features. Moreover, the ability to control the morphology allows for variating polaritonic features of the final nanofibrous material, which can directly impact the potential optoelectronic and photocatalytic applications

Determining alloy composition in MoxW(1-x)S2 from low wavenumber Raman spectroscopy

Mixed alloy MoxW(1-x)S2 (0x1) bulk samples are characterized by low wavenumber Raman spectroscopy. The results provide a convenient and reliable means for systematically determining the sample Mo/W composition. The absence of disorder effects in its interlayer motion (unlike for the intralayer motion) and the lack of Mo/W composition dependence of the shear mode force constants enable the facile employment of a reduced monoatomic linear chain model by treating the bulk alloy as a series of single balls' of mass (xm(Mo)+(1-x)m(W)+2m(S))attached by interlayer springs with a composition-independent interlayer force constant of 2.52Nm. Shear mode Raman scattering analysis may consequently be complementary to the electronic spectroscopy tools (X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS)), commonly used for mixed alloy bulk composition characterization. Copyright (c) 2017 John Wiley & Sons, Ltd

Calcium Sulfate Hemihydrate (Bassanite) Crystals in the Wood of the Tamarix Tree

The most abundant mineral produced in the wood and leaves of trees is calcium oxalate monohydrate (whewellite), and after burning the wood the ash obtained is calcite. In the case of the Tamarix sp. tree, the freshly prepared ash is calcium sulfate (anhydrite). The aim of this study is to determine the calcium sulfate mineral phase in the fresh wood of Tamarix aphylla prior to burning. SEM images of the crystals show that they express smooth faces, are about 5–15 microns in their longest dimensions and are located in the ray cells. Fourier transform infrared spectroscopy (FTIR) and Raman microspectroscopy of the crystals in the wood and after extraction, both showed that the crystals are composed of calcium sulfate hemihydrate (bassanite). As elemental analyses of the crystals showed that in addition to calcium and sulfur, around 20 atom percent of the cations are sodium and potassium, we also obtained an X-ray powder diffraction pattern. This pattern excluded the possibility that the crystals are composed of another related mineral, and confirmed that, indeed, the crystals in the T. aphylla wood are composed of calcium sulfate hemihydrate (bassanite)

Crystallinity assessment of anthropogenic calcites using Raman micro-spectroscopy

Abstract Anthropogenic calcite is a form of calcium carbonate produced through pyrotechnological activities, and it is the main component of materials such as lime binders and wood ash. This type of calcite is characterized by a significantly lower degree of crystallinity compared with its geogenic counterparts, as a result of different formation processes. The crystallinity of calcite can be determined using infrared spectroscopy in transmission mode, which allows decoupling particle size effect from atomic order and thus effectively distinguish anthropogenic and geogenic calcites. On the contrary, Raman micro-spectroscopy is still in the process of developing a reference framework for the assessment of crystallinity in calcite. Band broadening has been identified as one of the proxies for crystallinity in the Raman spectra of geogenic and anthropogenic calcites. Here we analyze the full width at half maximum of calcite bands in various geogenic and anthropogenic materials, backed against an independent crystallinity reference based on infrared spectroscopy. Results are then used to assess the crystallinity of anthropogenic calcite in archaeological lime binders characterized by different states of preservation, including samples affected by the formation of secondary calcite, and tested on micromorphology thin sections in which lime binders are embedded in sediments