Bio-organic materials in the atmosphere and snow: measurement and characterization.

Bio-organic chemicals are ubiquitous in the Earth's atmosphere and at air-snow interfaces, as well as in aerosols and in clouds. It has been known for centuries that airborne biological matter plays various roles in the transmission of disease in humans and in ecosystems. The implication of chemical compounds of biological origins in cloud condensation and in ice nucleation processes has also been studied during the last few decades, and implications have been suggested in the reduction of visibility, in the influence on oxidative potential of the atmosphere and transformation of compounds in the atmosphere, in the formation of haze, change of snow-ice albedo, in agricultural processes, and bio-hazards and bio-terrorism. In this review we critically examine existing observation data on bio-organic compounds in the atmosphere and in snow. We also review both conventional and cutting-edge analytical techniques and methods for measurement and characterisation of bio-organic compounds and specifically for microbial communities, in the atmosphere and snow. We also explore the link between biological compounds and nucleation processes. Due to increased interest in decreasing emissions of carbon-containing compounds, we also briefly review (in an Appendix) methods and techniques that are currently deployed for bio-organic remediation.

Thin-layer chromatography-pyrolysis-gas chromatography-mass spectrometry: a multidimensional approach to marine lipid class and molecular species analysis.

A new multidimensional chromatographic method is described in which material separated into lipid-class bands on silica-coated quartz thin-layer chromatography (TLC) rods (Chromarods) is desorbed using a pyrolysis unit interface and introduced directly into a gas chromatograph-mass spectrometer for molecular species analysis. Steryl esters, wax esters, hydrocarbons, ketones, and fatty-acid methyl esters (FAMEs) are thermally desorbed without pretreatment. In order to desorb free sterols, monoacylglycerols (MAGs), aliphatic alcohols, and free fatty acids, the esters are converted to trimethylsilyl derivatives on the rod. Triacylglycerols and phospholipids are converted to FAMEs by thermochemolysis with tetramethylammonium hydroxide. The method's utility is demonstrated with lipids from seawater particulate matter by first confirming the identity of lipid bands with the appropriate standards. The wax ester-steryl ester TLC band contained no more than 8% steryl esters. Wax esters of up to C42 are detected. In six individual acyl lipid classes, C14-C22 fatty acids are detected with C16 acids predominant in all but wax esters. C16-C22 MAGs are identified in the complex acetone-mobile polar lipid band. The method successfully extends the scope of latroscan TLC-flame-ionization detection on Chromarods, which is a widely used technique for lipid-class analysis. Modification of the pyrolysis probe to handle intact TLC rods is a future objective.

Energy substrates and the completion of spontaneous meiotic maturation.

This study was carried out to examine how different combinations of pyruvate and glucose affect spontaneous meiotic maturation of cumulus-cell-enclosed mouse oocytes (CEO) to metaphase II (MII). Most experiments used an open system in which oocytes were cultured in 1 ml medium in plastic tubes. Initial experiments examined the dose response effects of pyruvate or glucose alone in the presence or absence of 2 mM glutamine. When medium lacked both pyruvate and glucose, more than 91% of the oocytes died in glutamine-free medium during 15 h of culture; viability was restored with the addition of glutamine, but only 11% of the CEO reached MII. In the absence of glutamine, 62-68% of oocytes completed maturation in 0.23-2.3 mM pyruvate, while 44-60% MII was observed in 0.55-27.8 mM glucose. The addition of glutamine to these cultures had a general suppressive effect on the completion of maturation. When glucose was added to pyruvate-containing cultures, the combination of 1 mM pyruvate/5.5 mM glucose was most effective in supporting maturation (about 90% MII), with little effect of glutamine. No further increase in maturation was observed when glucose was increased five-fold (to 27.8 mM). The positive effect of glucose was in part attributed to stimulation of glycolysis and increased production of pyruvate, since a reduced culture volume (8 microl), which allows the accumulation of secreted pyruvate, improved maturation in glucose-containing, but not pyruvate-containing, medium, and FSH, which stimulates glycolysis, increased progression to MII in glucose-containing, but not pyruvate-containing, medium. Yet these results also suggest that glucose has a beneficial effect on maturation apart from simple provision of pyruvate. The pyruvate effect was directly on the oocyte, because denuded oocytes responded more effectively than CEO to this energy substrate. The highest percentage of MII oocytes (96-97%) occurred in microdrop cultures containing glucose but lacking glutamine. These results indicate that glutamine supports oocyte viability but is not an adequate energy source for the completion of spontaneous meiotic maturation and may be detrimental. In addition, while pyruvate and glucose alone can each support meiotic progression of CEO to MII, optimal maturation requires the provision of both substrates to the culture medium when a large volume (1 ml) is used. It is concluded that careful attention to specific energy substrate supplementation and culture volume is important to optimise spontaneous meiotic maturation in vitro.