Gas-phase study on uridine: Conformation and X-ray photofragmentation

Fragmentation of RNA nucleoside uridine, induced by carbon 1s core ionization, has been studied. The measurements by combined electron and ion spectroscopy have been performed in gas phase utilizing synchrotron radiation. As uridine is a combination of d-ribose and uracil, which have been studied earlier with the same method, this study also considers the effect of chemical environment and the relevant functional groups. Furthermore, since in core ionization the initial core hole is always highly localized, charge migration prior to fragmentation has been studied here. This study also demonstrates the destructive nature of core ionization as in most cases the C 1s ionization of uridine leads to concerted explosions producing only small fragments with masses ≤43 amu. In addition to fragmentation patterns, we found out that upon evaporation the sugar part of the uridine molecule attains hexagonal formFinancial support from the Academy of Finland, the European COST Action XLIC CM1204 and the EU Transnational Access to Research Infrastructures programme. Computational resources from the FGI project (Finland) are acknowledged. D.T.H. acknowledges the Finnish Cultural Foundation for funding and the MINECO Project No. FIS2013-42002- R. E.R. acknowledges funding from the Swedish Research Council (VR

Geochemistry of cave pools in the Guadalupe Mountains, NM : implications for geomicrobiology

The study of the chemistry of waters in cave pools in the Guadalupe Mountains, NM was conducted to determine the variation in cave pool water geochemistry, explain hydrogeologic variations in a geologic context, identify the processes that control cave pool hydrologic variations and determine geochemical controls on modern and paleo-bacterial communities. Structural studies indicate cave pools align along NE and NW structures in the karst system. The intersection of Permian structures and Cenozoic related structures provide pathways for infiltrating water. Water samples were collected from 19 new cave pools; the results were integrated with published geochemistry from 192 cave pools, aquifer samples, and surface sites. The waters were analyzed for major and minor ions, modeled to explain flow paths, connected with structural data, examined for thermodynamic potential to support metabolic reactions, and to elucidate the relationship between current geochemistry and presence of biothems (biogenically mediated speleothems, including pool fingers). Infiltrating waters dominant the character of the cave pool waters. Variations in geochemistry of the cave pools can be explained by several geochemical processes: 1) infiltrating water-rock interactions 2) outgassing of CO2 3) precipitation of minerals and 4) evaporation. The thermodynamic data of available energy for use by microbial communities predicted the potential for nitrate, nitrite, oxygen, and sulfate to be used as terminal electron acceptors. The geochemical trends of pools containing biothems showed no connection between pool geochemistry and the presence of biothems. The small number of processes governing the variation in geochemistry give rise to a complex, unique geochemical signature and history for each cave pool thus unique microbial communities