Exploring the Sea Urchin Neuropeptide Landscape by Mass Spectrometry

Neuropeptides are essential cell-to-cell signaling messengers and serve important regulatory roles in animals. Although remarkable progress has been made in peptide identification across the Metazoa, for some phyla such as Echinodermata, limited neuropeptides are known and even fewer have been verified on the protein level. We employed peptidomic approaches using bioinformatics and mass spectrometry (MS) to experimentally confirm 23 prohormones and to characterize a new prohormone in nervous system tissue from Strongylocentrotus purpuratus, the purple sea urchin. Ninety-three distinct peptides from known and novel prohormones were detected with MS from extracts of the radial nerves, many of which are reported or experimentally confirmed here for the first time, representing a large-scale study of neuropeptides from the phylum Echinodermata. Many of the identified peptides and their precursor proteins have low homology to known prohormones from other species/phyla and are unique to the sea urchin. By pairing bioinformatics with MS, the capacity to characterize novel peptides and annotate prohormone genes is enhanced.

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Fine structure in the α decay of202Rn

The α decay of mass-separated²⁰²Rn is studied at the ISOLDE separator. Time sequential α-singles spectra together with α-X-t and α-e-t coincidence events are collected. Fine structure in the α decay is observed and feeding of a low-lying 0 ₂ ⁺ state at 816 keV in¹⁹⁸Po is evidenced. This 0⁺ state can be interpreted as the bandhead of an intruder-state based deformed band, coexisting with the spherical groundstate band. Mixing between normal and intruder states is discussed. A preliminary α-decay study of²⁰⁰Rn did not yet reveal any fine structure.     

A comparison between secondary-ion mass-spectrometry and spark-source mass-spectrometry for the quantitative analysis of steel wire

A comparison has been made between the results of the matrix-ion species ratio (MISR) method for quantification of secondary-ion mass-spectrometry data and spark-source mass-spectrometry analysis using photoplate detection for analysis of the steel basis of AlZn coated wire products. For SIMS quantification a suitable set of sensitivity factors, corrected for the actual surface sampling condition, was used. The results of both methods compare well. The SIMS results were, for most elements, within 25% of the concentration determined by SSMS. This could indicate that reasonably accurate results can be obtained by using the matrix-ion species ratio method for SIMS.     

Synthesis,biological activity,and conformational analysis of CD-ring modified trans-decalin 1 alpha,25-dihydroxyvitamin D analogs

A novel series of analogs of 1,25-dihydroxyvitamin D3, the hormonally active metabolite of vitamin D3, characterised by the presence of a trans-fused decalin CD-ring system, possesses surprising biological activities in combination with specific structural modifications in the flexible parts of the molecule, when compared with the natural hydrindane derivatives. (1) A large difference in biological activity is observed between the 20-epimeric trans-decalin analogs that follows a pattern opposite to what is usually observed for the natural ring size. (2) Several trans-decalin analogs that are modified in the seco-B-ring region, including previtamin derivatives, possess a pronounced vitamin D-like activity, whereas the corresponding hydrindane derivatives are inactive. The molecular origin of this behavior is still under study.     

In vitro and in vivo metabolism studies of dimethazine

The use of anabolic steroids is prohibited in sports. Effective control is done by monitoring their metabolites in urine samples collected from athletes. Ethical objections however restrict the use of designer steroids in human administration studies. To overcome these problems alternative in vitro and in vivo models were developed to identify metabolites and to assure a fast response by anti‐doping laboratories to evolutions on the steroid market. In this study human liver microsomes and an uPA^+/+‐SCID chimeric mouse model were used to elucidate the metabolism of a steroid product called ‘Xtreme DMZ’. This product contains the designer steroid dimethazine (DMZ), which consists of two methasterone molecules linked by an azine group. In the performed stability study, degradation from dimethazine to methasterone was observed. By a combination of LC‐High Resolution Mass Spectrometry (HRMS) and GC‐MS(/MS) analysis methasterone and six other dimethazine metabolites (M1–M6), which are all methasterone metabolites, could be detected besides the parent compound in both models. The phase II metabolism of dimethazine was also investigated in the mouse urine samples. Only metabolites M1 and M2 were exclusively detected in the glucuro‐conjugated fraction; all other compounds were also found in the free fraction. For effective control of DMZ misuse in doping control samples, screening for methasterone and methasterone metabolites should be sufficient. Copyright © 2016 John Wiley & Sons, Ltd.     

Modeling of the sputtering process of cubic silver halide microcrystals and its relevance in depth profiling by secondary-ion mass spectrometry (SIMS)

Secondary-ion mass spectrometry is frequently used for concentration–depth profiling of macroscopic samples, but it is certainly not a common analytical technique for the analysis of sub-micrometer-size particles. This is because of the additional ion-bombardment-induced artifacts which can occur when a three-dimensional microvolume is sputtered, instead of a flat surface. This paper presents a model of how small cubic photographic Ag(Cl,Br) crystals are eroded under primary-ion bombardment, and the extent to which secondary ions generated at different faces are extracted. The latter is studied by means of the program SIMION, which simulates ion trajectories in complex electrical field systems. It is shown that up to 90% of the secondary ions originating from the side face of a cubic crystal are unable to reach the detector, in contrast with most secondary ions originating from the top face. The angular dependence of the sputtering yield and the elemental ratio of Br/Cl sputtered particles have been calculated by using the well-known computer code TRIM (transport of ions in matter) under some limiting assumptions (possible preferential sputtering is disregarded and a steady-state sputtering process is assumed). The validity of the theoretical model and the calculated results were checked with experimental data. On the basis of the depth profiles presented it is explained why it is still possible to measure an interface inside a cubic volume, even though a group of several hundred crystals is sputtered simultaneously, and even though the orientations of the distinct faces of the cubes relative to the angle of incidence of the primary-ion beam are different.     

Tetranuclear d-f Metallostars: Synthesis, Relaxometric, and Luminescent Properties

A novel ditopic ligand DTPA-ph-phen, based on 1,10-phenanthroline and diethylenetriaminepentaacetic acid (DTPA) units, has been designed and fully characterized by (1)H, (13)C, and 2D-COSY NMR spectroscopy, IR and electrospray ionization mass spectrometry (ESI-MS) techniques. The DTPA core of the ligand specifically binds Ln(III) ions (Ln = Eu, Gd) resulting in formation of the [Ln{DTPA-ph-phen}(H(2)O)](-) complex. The photophysical properties of the Eu(III) compound have been investigated, and the complex shows characteristic red luminescence with an overall quantum yield of 2.2%. Reaction of [Gd{DTPA-ph-phen}(H(2)O)](-) with Ru(II) leads to further self-assembly into a heterobimetallic metallostar complex containing Gd(III) and Ru(II) in a 3:1 ratio. This tetranuclear [(Gd{DTPA-ph-phen})(3)(H(2)O)(3)Ru](-) complex (Gd(3)Ru), formed by the coordination of Ru(II) to the 1,10-phenanthroline unit, has been characterized by a range of experimental techniques and evaluated toward its feasibility as a potential bimodal optical/MRI agent. The Gd(3)Ru metallostar shows intense metal-to-ligand charge transfer (MLCT) transition resulting in intense light absorption in the visible spectral region. Upon irradiation into this MLCT band at 450 nm, the Gd(3)Ru complex exhibits red broad-band luminescence in the range of 550-800 nm centered at 610 nm with a quantum yield of 4.8%. Proton nuclear magnetic relaxation dispersion (NMRD) measurements indicate that the Gd(3)Ru complex exhibits an enhanced relaxivity value r(1) of 36.0 s(-1) mM(-1) per metallostar molecule at 20 MHz and 310 K. The ability of the complex to noncovalently bind to human serum albumin (HSA) was investigated, but no significant interaction was detected.