A new purge and trap headspace technique to analyze low volatile compounds from fluid inclusions of rocks and minerals

A new method for the analysis of trace gases from fluid inclusions of minerals has been developed. The purge and trap GC-MS system is based on the system described by Nolting et al. (1988) and was optimized for the analyses of halogenated volatile organic compounds (VOCs) having boiling points as low as -128. °C (carbon tetrafluoride).The sample preconcentration cold trap consists of a U-shaped glass lined steel tube (GLT™), that is immersed into a small liquid nitrogen Dewar vessel for cooling. A rapid desorption step heats up the preconcentration tube in <30s from -196°C to 200°C. The process is carried out by using a pressurized air stream to dissipate the liquid nitrogen followed by resistive heating of the trap. The design of the cold trap and the direct transfer of desorbed analytes onto the GC column via a deactivated capillary column retention gap made sample refocusing within the GC oven unnecessary. Furthermore, a special air-tight grinding device was developed in which samples ranging from soft halite (hardness 2, Mohs scale) to hard quartz (hardness 7) are effectively ground to average diameters of 1000nm or below, thereby releasing gases from fluid inclusions of minerals. The gases are then purged from the grinding chamber with a He carrier gas flow. The detection and quantitative determination of gases, such as SF6 and CF4 released from fluorites and CH3Cl from halite samples is demonstrated.DFG/FOR/76

A non-enzymatic function of 17 beta-hydroxysteroid dehydrogenase type 10 is required for mitochondrial integrity and cell survival

Deficiency of the mitochondrial enzyme 2-methyl-3-hydroxybutyryl-CoA dehydrogenase involved in isoleucine metabolism causes an organic aciduria with atypical neurodegenerative course. The disease-causing gene is HSD17B10 and encodes 17beta-hydroxysteroid dehydrogenase type 10 (HSD10), a protein also implicated in the pathogenesis of Alzheimer's disease. Here we show that clinical symptoms in patients are not correlated with residual enzymatic activity of mutated HSD10. Loss-of-function and rescue experiments in Xenopus embryos and cells derived from conditional Hsd17b10(-/-) mice demonstrate that a property of HSD10 independent of its enzymatic activity is essential for structural and functional integrity of mitochondria. Impairment of this function in neural cells causes apoptotic cell death whilst the enzymatic activity of HSD10 is not required for cell survival. This finding indicates that the symptoms in patients with mutations in the HSD17B10 gene are unrelated to accumulation of toxic metabolites in the isoleucine pathway and, rather, related to defects in general mitochondrial function. Therefore alternative therapeutic approaches to an isoleucine-restricted diet are required

Organic compounds in fluid inclusions of Archean quartz—Analogues of prebiotic chemistry on early Earth

<div><p>The origin of life is still an unsolved mystery in science. Hypothetically, prebiotic chemistry and the formation of protocells may have evolved in the hydrothermal environment of tectonic fault zones in the upper continental crust, an environment where sensitive molecules are protected against degradation induced e.g. by UV radiation. The composition of fluid inclusions in minerals such as quartz crystals which have grown in this environment during the Archean period might provide important information about the first organic molecules formed by hydrothermal synthesis. Here we present evidence for organic compounds which were preserved in fluid inclusions of Archean quartz minerals from Western Australia. We found a variety of organic compounds such as alkanes, halocarbons, alcohols and aldehydes which unambiguously show that simple and even more complex prebiotic organic molecules have been formed by hydrothermal processes. Stable-isotope analysis confirms that the methane found in the inclusions has most likely been formed from abiotic sources by hydrothermal chemistry. Obviously, the liquid phase in the continental Archean crust provided an interesting choice of functional organic molecules. We conclude that organic substances such as these could have made an important contribution to prebiotic chemistry which might eventually have led to the formation of living cells.</p></div

Remnant of a typical hydrothermal quartz dyke in the northern Jack Hills region / Western Australia which crystallized presumably in Archaean time in deeper parts of a shear-dominated crust (photograph by Thomas Kirnbauer, with permission).

<p>Remnant of a typical hydrothermal quartz dyke in the northern Jack Hills region / Western Australia which crystallized presumably in Archaean time in deeper parts of a shear-dominated crust (photograph by Thomas Kirnbauer, with permission).</p

Organic compounds identified in hydrothermally grown quartz crystals near Jack Hills in Western Australia.

<p>The index letter “a” refers to the technical approach used for the analysis: a = 1 for one-dimensional gas chromatography with flame ionization detector⁸, a = 2 for comprehensive two-dimensional gas chromatography coupled to a quadrupole MS and a = 3 for liquid chromatography with a high-resolution TOF-MS.</p

Stable carbon (δ¹³C) and hydrogen isotope (δ²H) composition of CH₄ in the fluid inclusions of Australian quartz samples.

<p>For comparison, the plot shows data regions typical for biogenic sources (green), thermogenic sources (red) and abiotic sources (black) (modified after Etiope and Sherwood Lollar [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0177570#pone.0177570.ref023" target="_blank">23</a>]). The codes assigned to the data points (black open squares) refer to the sample locations and are explained in Text A in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0177570#pone.0177570.s001" target="_blank">S1 File</a>.</p