Mirror image hydrocarbons from Tropical and Boreal forests

Monoterpenes, emitted in large quantities by trees to attract pollinators and repel herbivores, can exist in mirror image forms called enantiomers. In this study such enantiomeric pairs have been measured in ambient air over extensive forest ecosystems in South America and northern Europe. For the dominant monoterpene, α-pinene, the (−)-form was measured in large excess over the (+)-form over the Tropical rainforest, whereas the reverse was observed over the Boreal forest. Interestingly, over the Tropical forest (−)-α-pinene did not correlate with its own enantiomer, but correlated well with isoprene. The results indicate a remarkable ecosystem scale enantiomeric fingerprint and a nexus between the biosphere and atmosphere

In-situ measurement of reactive hydrocarbons at Hohenpeissenberg with comprehensive two-dimensional gas chromatography (GC×GC-FID): use in estimating HO and NO₃

International audienceDuring a field campaign at the Meteorological Observatory Hohenpeissenberg (MOHp) in July 2004, volatile organic compounds (VOCs) were measured using comprehensive two-dimensional gas chromatography (GC×GC). Comparison to routinely made gas chromatography mass spectrometry (GC-MS) measurements showed good agreement for a variety of anthropogenic and biogenic ambient VOCs ranging in concentration from below the detection limit (0.1 pmol mol?1) to 180 pmol mol?1. Pronounced diurnal cycles were found for both the biogenic and anthropogenic compounds, driven for the most part by the daily rise and fall of the boundary layer over the station. For the reactive compounds (lifetimes 6molecules cm?3), which compares well to that measured at the site, 3.2±2.3×106molecules cm?3. The analysis was extended to the night time data to estimate concentrations for NO3 (1.47±0.2×108molecules cm?3), which is not measured at the site. The feasibility of this approach for environments dominated by emissions of short-lived VOCs to estimate ambient levels of radical species is discussed

Shoot chloride exclusion and salt tolerance in grapevine is associated with differential ion transporter expression in roots

BACKGROUND: Salt tolerance in grapevine is associated with chloride (Cl-) exclusion from shoots; the rate-limiting step being the passage of Cl- between the root symplast and xylem apoplast. Despite an understanding of the physiological mechanism of Cl- exclusion in grapevine, the molecular identity of membrane proteins that control this process have remained elusive. To elucidate candidate genes likely to control Cl- exclusion, we compared the root transcriptomes of three Vitis spp. with contrasting shoot Cl- exclusion capacities using a custom microarray. RESULTS: When challenged with 50 mM Cl-, transcriptional changes of genotypes 140 Ruggeri (shoot Cl- excluding rootstock), K51-40 (shoot Cl- including rootstock) and Cabernet Sauvignon (intermediate shoot Cl- excluder) differed. The magnitude of salt-induced transcriptional changes in roots correlated with the amount of Cl- accumulated in shoots. Abiotic-stress responsive transcripts (e.g. heat shock proteins) were induced in 140 Ruggeri, respiratory transcripts were repressed in Cabernet Sauvignon, and the expression of hypersensitive response and ROS scavenging transcripts was altered in K51-40. Despite these differences, no obvious Cl- transporters were identified. However, under control conditions where differences in shoot Cl- exclusion between rootstocks were still significant, genes encoding putative ion channels SLAH3, ALMT1 and putative kinases SnRK2.6 and CPKs were differentially expressed between rootstocks, as were members of the NRT1 (NAXT1 and NRT1.4), and CLC families. CONCLUSIONS: These results suggest that transcriptional events contributing to the Cl- exclusion mechanism in grapevine are not stress-inducible, but constitutively different between contrasting varieties. We have identified individual genes from large families known to have members with roles in anion transport in other plants, as likely candidates for controlling anion homeostasis and Cl- exclusion in Vitis species. We propose these genes as priority candidates for functional characterisation to determine their role in chloride transport in grapevine and other plants.Sam W Henderson, Ute Baumann, Deidre H Blackmore, Amanda R Walker, Rob R Walker and Matthew Gilliha

Ion homeostasis in the Chloroplast

peer reviewedThe chloroplast is an organelle of high demand for macro- and micro-nutrient ions, which are required for the maintenance of the photosynthetic process. To avoid deficiency while preventing excess, homeostasis mechanisms must be tightly regulated. Here, we describe the needs for nutrient ions in the chloroplast and briefly highlight their functions in the chloroplastidial metabolism. We further discuss the impact of nutrient deficiency on chloroplasts and the acclimation mechanisms that evolved to preserve the photosynthetic apparatus. We finally present what is known about import and export mechanisms for these ions. Whenever possible, a comparison between cyanobacteria, algae and plants is provided to add an evolutionary perspective to the description of ion homeostasis mechanisms in photosynthesis

In-situ measurement of reactive hydrocarbons at Hohenpeissenberg with comprehensive gas chromatography (GCxGC-FID): use in estimating HO and NO₃

International audienceDuring a field campaign at the Meteorological Observatory Hohenpeissenberg (MOHp) in July 2004, VOCs were measured using GCxGC-FID. Comparison to routinely made GC-MS measurements showed good agreement for a variety of anthropogenic and biogenic ambient VOCs ranging in concentration from below the detection limit (0.1 pmol mol?1) to 180 pmol mol?1. Pronounced diurnal cycles were found for both the biogenic and anthropogenic compounds, driven for the most part by the daily rise and fall of the boundary layer over the station. For the reactive compounds (lifetimes 6 molecules cm?3), which compares well to that measured at the site, 3.2±2.3×106 molecules cm?3. The analysis was extended to the night time data to estimate concentrations for NO3 (1.47±0.2×108 molecules cm?3), which is not measured at the site. The feasibility of this approach for environments dominated by emissions of short-lived VOCs to estimate ambient levels of radical species is discussed

Determination of Lewisites and their hydrolysis products in aqueous and multiphase samples by in-sorbent tube butyl thiolation followed by thermal desorption-gas chromatography-full scan mass spectrometry

A rapid, sensitive and robust method for determining the chemical warfare agents Lewisites and their hydrolysis products in aqueous and multiphase sample matrices has been developed as an extension of the previous work (Terzic, 2010 [32]). In the new method, the acidification of the sample and use of 1-butanethiol derivatisation instead of trimethylsilylation significantly improved both, qualitative and quantitative aspects of targeted analysis of Lewisite species. The limit of detection was ≤100 ng/ml in full scan MS, with sample volume of 10 μl only. The whole sample preparation procedure took 9 min, while the gas chromatography (GC)-mass spectrometry (MS) analysis cycle was under 22 min. The method deals efficiently with the multiphase sample matrices offering a fast and simple alternative to the conventional approach of liquid-liquid extraction combined with derivatisation. Multiphase sample matrices can be encountered or formed when preparing environmental, industrial, waste or decontamination waste samples for a GC-MS analysis. The applicability and robustness of the method were demonstrated by the successful analysis of 11 years old OPCW Official Proficiency Test sample and a triphase liquid sample. The same equipment set-up, tubes and derivatising agent have been used for collection, preparation and analysis of Lewisites in air samples (Terzic et al., 2012 [35]). The minimal logistic requirements, ease of operation, versatility and other features aforementioned, make this method an excellent choice for an environmental or forensic field laboratory

under a Creative Commons License. Atmospheric Chemistry and Physics Mirror image hydrocarbons from Tropical and Boreal forests

Abstract. Monoterpenes, emitted in large quantities by trees to attract pollinators and repel herbivores, can exist in mirror image forms called enantiomers. In this study such enantiomeric pairs have been measured in ambient air over extensive forest ecosystems in South America and northern Europe. For the dominant monoterpene, α-pinene, the (−)form was measured in large excess over the (+)-form over the Tropical rainforest, whereas the reverse was observed over the Boreal forest. Interestingly, over the Tropical forest (−)-α-pinene did not correlate with its own enantiomer, but correlated well with isoprene. The results indicate a remarkable ecosystem scale enantiomeric fingerprint and a nexus between the biosphere and atmosphere.