Two-dimensional X-ray diffraction as a tool for the rapid, non-destructive detection of low calcite quantities in aragonitic corals

Paleoclimate reconstructions based on reef corals require precise detection of diagenetic alteration. Secondary calcite can significantly affect paleotemperature reconstructions at very low amounts of ~1%. X-ray powder diffraction is routinely used to detect diagenetic calcite in aragonitic corals. This procedure has its limitations as single powder samples might not represent the entire coral heterogeneity. A conventional and a 2-D X-ray diffractometer were calibrated with gravimetric powder standards of high and low magnesium calcite (0.3% to 25% calcite). Calcite contents <1% can be recognized with both diffractometer setups based on the peak area of the calcite [104] reflection. An advantage of 2-D-XRD over convenient 1-D-XRD methods is the nondestructive and rapid detection of calcite with relatively high spatial resolution directly on coral slabs. The calcite detection performance of the 2-D-XRD setup was tested on thin sections from fossil Porites sp. samples that, based on powder XRD measurements, showed <1% calcite. Quantification of calcite contents for these thin sections based on 2-D-XRD and digital image analysis showed very similar results. This enables spot measurements with diameters of ∼4 mm, as well as systematic line scans along potential tracks previous to geochemical proxy sampling. In this way, areas affected by diagenetic calcite can be avoided and alternative sampling tracks can be defined. Alternatively, individual sampling positions that show dubious proxy results can later be checked for the presence of calcite. The presented calibration and quantification method can be transferred to any 2-D X-ray diffractometer

Chloroplast HCF101 is a scaffold protein for [4Fe-4S] cluster assembly

Oxygen-evolving chloroplasts possess their own iron-sulfur cluster assembly proteins including members of the SUF (sulfur mobilization) and the NFU family. Recently, the chloroplast protein HCF101 (high chlorophyll fluorescence 101) has been shown to be essential for the accumulation of the membrane complex Photosystem I and the soluble ferredoxin-thioredoxin reductases, both containing [4Fe-4S] clusters. The protein belongs to the FSC-NTPase ([4Fe-4S]-cluster-containing P-loop NTPase) superfamily, several members of which play a crucial role in Fe/S cluster biosynthesis. Although the C-terminal ISC-binding site, conserved in other members of the FSC-NTPase family, is not present in chloroplast HCF101 homologues using Mössbauer and EPR spectroscopy, we provide evidence that HCF101 binds a [4Fe-4S] cluster. 55Fe incorporation studies of mitochondrially targeted HCF101 in Saccharomyces cerevisiae confirmed the assembly of an Fe/S cluster in HCF101 in an Nfs1-dependent manner. Site-directed mutagenesis identified three HCF101-specific cysteine residues required for assembly and/or stability of the cluster. We further demonstrate that the reconstituted cluster is transiently bound and can be transferred from HCF101 to a [4Fe-4S] apoprotein. Together, our findings suggest that HCF101 may serve as a chloroplast scaffold protein that specifically assembles [4Fe-4S] clusters and transfers them to the chloroplast membrane and soluble target proteins

Sensitivity of tetrodotoxin and saxitoxin to changing ocean conditions

This dataset, consisting of 3 separate files, provides the basis for our manuscript entitled "Saxitoxin and tetrodotoxin bioavailability increases in future oceans". Each file contains the data for one figure. For detailed calculation methods please refer to the method and supplementary information sections of the associated manuscript. Fig1_STX_and_TTX_pH-availability contains abundance data of saxitoxin (STX) and tetrodotoxin (TTX) protonation states across the pH range from 6 to 10 at 3 different temperatures. It is calculated based on published pKa data using the Henderson-Hasselbalch equation. Temperature is taken into account employing a pKa-influencing factor of -0.2/+10C. Fig2_Dinos_HAEDAT_STX_concatenated contains all the information required for plotting the pH and temperature dependent global toxicity map. It combines georeferenced records for localities with STX-related HABs (extracted from the Harmful Algal Information System metadatabase - HAEDAT) and the distribution of two dinoflagellate genera, which are known to produce STX, Gymnodinium and Alexandrium (extracted from the NOAA COPEPOD database). For each location we also extracted current and future pH and sea surface temperature from the Global marine environment dataset (GMED)/ IPCC (WCRP CMIP3) multi-model database. We calculated the abundance of the toxic STX form based on the pH and temperature for each of the respective locations in current and future conditions. Fig3_STXinClamTissue contains the compiled total STX content in clam tissue data from the PSP Program website of the Quagan Tayagungin Tribe for the time frame between June 2012 and July 2018 for each month at Spit Beach, Sand Point (Alaska). Based on this data we further calculated the current and future toxic proportion of this total STX content for the location's specific current and future temperature and pH data

NOD-like receptor signaling in cholesteatoma

$\textit {Background.}$ Cholesteatoma is a destructive process of the middle ear resulting in erosion of the surrounding bony structures with consequent hearing loss, vestibular dysfunction, facial paralysis, or intracranial complications. The etiopathogenesis of cholesteatoma is controversial but is associated with recurrent ear infections. The role of intracellular innate immune receptors, the NOD-like receptors, and their associated signaling networks was investigated in cholesteatoma, since mutations in NOD-like receptor-related genes have been implicated in other chronic inflammatory disorders. $\textit {Results.}$ The expression of NOD2 mRNA and protein was significantly induced in cholesteatoma compared to the external auditory canal skin, mainly located in the epithelial layer of cholesteatoma. Microarray analysis showed significant upregulation for NOD2, not for NOD1, TLR2, or TLR4 in cholesteatoma. Moreover, regulation of genes in an interaction network of the NOD-adaptor molecule RIPK2 was detected.In addition to NOD2, NLRC4, and PYCARD, the downstream molecules IRAK1 and antiapoptotic regulator CFLAR showed significant upregulation, whereas SMAD3, a proapoptotic inducer, was significantly downregulated. Finally, altered regulation of inflammatory target genes of NOD signaling was detected. $\textit {Conclusions.}$ These results indicate that the interaction of innate immune signaling mediated by NLRs and their downstream target molecules is involved in the etiopathogenesis and growth of cholesteatoma