Enantioselective Crystallization of Sodium Chlorate in the Presence of Racemic Hydrophobic Amino Acids and Static Magnetic Fields

We study the bias induced by a weak (200 mT) external magnetic field on the preferred handedness of sodium chlorate crystals obtained by slow evaporation at ambient conditions of its saturated saline solution with 20 ppm of added racemic (dl) hydrophobic amino acids. By applying the Fisher test to pairs of experiments with opposing magnetic field orientation we conclude, with a confidence level of 99.7%, that at the water-air interface of this saline solution there is an enantioselective magnetic interaction that acts upon racemic mixtures of hydrophobic chiral amino acids. This interaction has been observed with the three tested racemic hydrophobic amino acids: dl-Phe, dl-Try and dl-Trp, at ambient conditions and in spite of the ubiquitous chiral organic contamination. This enantioselective magnetic dependence is not observed when there is only one handedness of added chiral amino-acid, if the added amino acid is not chiral or if there is no additive. This effect has been confirmed with a double blind test. This novel experimental observation may have implications for our view of plausible initial prebiotic scenarios and of the roles of the geomagnetic field in homochirality in the biosphere.This research was supported by the Instituto Nacional de Técnica Aerospacial (INTA) and by the grant AYA2006-15648-C02-02 of the Ministerio de Educación y Ciencia (Spain) and by the project grants AYA2011-25720 and AYA2012-38707 of MINECO (Spain).We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).Peer reviewe

Chronic Venous Disease in Pregnant Women Causes an Increase in ILK in the Placental Villi Associated with a Decrease in E-Cadherin

Chronic venous disease (CVD) is a multifactorial vascular disorder frequently manifested in lower limbs in the form of varicose veins (VVs). Women are a vulnerable population for suffering from CVD, especially during pregnancy, when a plethora of changes occur in their cardiovascular system. Previous studies have indicated a worrisome association between CVD in pregnancy with the placental structure and function. Findings include an altered cellular behavior and extracellular matrix (ECM) composition. Integrin-linked kinase (ILK) is a critical molecule involved in multiple physiological and pathological conditions, and together with cadherins, is essential to mediate cell to ECM and cell to cell interplay, respectively. Thus, the aim of this study was to evaluate the implication of ILK and a set of cadherins (e-cadherin, cadherin-6 and cadherin-17) in placentas of women with CVD in order to unravel the possible pathophysiological role of these components. Gene expression (RT-qPCR) and protein expression (immunohistochemistry) studies were performed. Our results show a significant increase in the gene and protein expression of ILK, cadherin-6 and cadherin-17 and a decrease of e-cadherin in the placenta of women with CVD. Overall, this work shows that an abnormal expression of ILK, e-cadherin, cadherin-6 and cadherin-17 may be implicated in the pathological changes occurring in the placental tissue. Further studies should be conducted to determine the possible associations of these changes with maternal and fetal well-being

Prussian Blue as Prebiotic Reagent

Poster presented at: Bioastronomy 2007: Molecules, Microbes and Extraterrestrial Life (July 16-20, 2007, San Juan de Puerto Rico).Ferrocyanide has been proposed as a potential prebiotic reagent by Arrhenius. The complex salt named Prussian Blue, Fe4[Fe(CN)6]3, [ferric hexacyaneferrate (II)], might be an important reservoir of hydrogen cyanide, HCN, in the early Earth. HCN is a major product of spark discharge experiments on various gas mixtures; it is considered the main precursor of amino acids and purine bases under prebiotic conditions. The presence of banded iron formations shows that dissolved iron (ferrous iron) was present in high quantities in the ocean water during Archean epoch. Recently, we observed the formation of Prussian Blue in spark discharge experiments using saline solutions of ferrous chloride, FeCl3. Using Prussian Blue as starting material in ammonium solutions at different values of pH, and carrying out the reactions under middle conditions of temperature and concentration, some organic compounds were formed. We detected urea, imidazole, substituted imidazoles, methyl hydantoines and other heterocycles containing nitrogen and some amino acids by GC-MS of their trimethylsilyl derivatives. These results seem to indicate that Prussian Blue could be a sink of HCN in the early Earth. Subsequent reactions, triggered by pH fluctuations, might lead to organic life precursors.Peer reviewe

Prebiotic chemistry in eutectic solutions at the water-ice matrix

A crystalline ice matrix at subzero temperatures can maintain a liquid phase where organic solutes and salts concentrate to form eutectic solutions. This concentration effect converts the confined reactant solutions in the ice matrix, sometimes making condensation and polymerisation reactions occur more favourably. These reactions occur at significantly high rates from a prebiotic chemistry standpoint, and the labile products can be protected from degradation. The experimental study of the synthesis of nitrogen heterocycles at the ice–water system showed the efficiency of this scenario and could explain the origin of nucleobases in the inner Solar System bodies, including meteorites and extra-terrestrial ices, and on the early Earth. The same conditions can also favour the condensation of monomers to form ribonucleic acid and peptides. Together with the synthesis of these monomers, the ice world (i.e., the chemical evolution in the range between the freezing point of water and the limit of stability of liquid brines, 273 to 210 K) is an under-explored experimental model in prebiotic chemistry.Peer reviewe

First find of kristiansenite in spain: comparison with the type specimen by non-destructive techniques

We report herein a new ¿ nd of kristiansenite from a pocket in an intra-granite pegmatite from Cadalso de los Vidrios, near Madrid, Spain. This specimen of a late hydrothermal scandium silicate has been studied by Environmental Scanning Electron Microscopy with Energy Dispersive Spectrometry probe (ESEM-EDS), Micro-Raman Spectrometry and ESEM-Cathodoluminescence (ESEM-CL), all of them non-destructive techniques. The sample is a single perfect pyramidal monocrystal found in a small cavity less than one mm across. The experimental chemical, molecular and spectral luminescent information was later compared with the type specimen from Norway and the second ¿nd, at Baveno, Italy. Our Raman spectrum matches the spectrum of the Norwegian specimen, with minor variation in the intensity of the peaks; the chemical composition recorded by EDS also shows minor variations. In addition, the CL spectrum displays several narrow peaks, probably associated with REE in Ca positions. The geochemical framework of this new locality, with pegmatite pockets in A-type granites rich in Sc-bearing minerals and other REE, have many similarities with those of Norway and Italy.Peer Reviewe

Mechanisms for gas-phase molecular formation of neutral formaldehyde (H

Context. Formaldehyde is a potential biogenic precursor involved in prebiotic chemical evolution. The cold conditions of the interstellar medium (ISM) allow H2CO to be reactive, playing a significant role as a chemical intermediate in formation pathways leading to interstellar complex organic molecules. However, gas-phase molecular formation mechanisms in cold regions of the ISM are poorly understood. Aims. We computationally determine the most favored gas-phase molecular formation mechanisms at local thermodynamic equilibrium conditions that can produce the detected amounts of H2CO in diffuse molecular clouds (DMCs), in dark, cold, and dense molecular clouds (DCDMCs), and in three regions of circumstellar envelopes of low-mass protostars (CELMPs). Methods. The potential energy surfaces, thermodynamic functions, and single-point energies for transition states were calculated at the CCSD(T)-F12/cc-pVTZ-F12 and MP2/aug-cc-pVDZ levels of theory and basis sets. Molecular thermodynamics and related partition functions were obtained by applying the Maxwell-Boltzmann quantum statistics theory from energies computed at CCSD(T)-F12/cc-pVTZ-F12 with corrections for zero-point energy. A literature review on detected abundances of reactants helped us to propose the most favorable formation routes. Results. The most probable reactions that produce H2CO in cold astrophysical regions are: 1CH2 + ⋅3O2 →1H2CO + O⋅(3P) in DMCs, ⋅3CH2 + ⋅3O2 →1H2CO + ⋅O(3P) in DCDMCs, and ⋅CH3 + ⋅O(3P) →1H2CO + ⋅H in region III, ⋅CH3 +⋅O(1D) →1H2CO + ⋅H in region II, and 1CH2 + ⋅3O2 →1H2CO + ⋅O(3P) in region I belonging to CELMPs. Conclusions. Quantum chemical calculations suggest that the principal carbonaceous precursors of H2CO in cold regions for the gas-phase are CH2(a1A1), and ⋅CH2(X3B1) combined with ⋅O2(3Σg) and ⋅CH3(2A”) + ⋅O(3P) / O(1D). Reactions based on more complex reagents yield less effective thermodynamics in the gas-phase H2CO molecular formation