The 'photosynthetic C pathway' links carbon assimilation and growth in California poplar.

Although primarily studied in relation to photorespiration, serine metabolism in chloroplasts may play a key role in plant CO fertilization responses by linking CO assimilation with growth. Here, we show that the phosphorylated serine pathway is part of a 'photosynthetic C pathway' and demonstrate its high activity in foliage of a C tree where it rapidly integrates photosynthesis and C metabolism contributing to new biomass via methyl transfer reactions, imparting a large natural C-depleted signature. Using CO-labelling, we show that leaf serine, the S-methyl group of leaf methionine, pectin methyl esters, and the associated methanol released during cell wall expansion during growth, are directly produced from photosynthetically-linked C metabolism, within minutes of light exposure.

Isotopic analysis (δC and δH) of lignin methoxy groups in forest soils to identify and quantify lignin sources.

The relative apportion of above and below ground carbon sources is known to be an important factor in soil organic matter formation. Although lignin is the most abundant aromatic plant material in the terrestrial biosphere, our understanding of lignin source contributions to soil organic matter (SOM) is limited due to the complex molecular structure and analysis of lignin. In this study, we novelly apply the dual isotopic analysis (δC and δH values) of lignin methoxy groups (LMeO) with the Bayesian mixing model, MixSIAR, to apportion lignin sources in two contrasting soil types, a podzol and a stagnosol.

Comparison of Carbon Isotope Ratio Measurement of the Vanillin Methoxy Group by GC-IRMS and C-qNMR.

Site-specific carbon isotope ratio measurements by quantitative C NMR (C-qNMR), Orbitrap-MS, and GC-IRMS offer a new dimension to conventional bulk carbon isotope ratio measurements used in food provenance, forensics, and a number of other applications. While the site-specific measurements of carbon isotope ratios in vanillin by C-qNMR or Orbitrap-MS are powerful new tools in food analysis, there are a limited number of studies regarding the validity of these measurement results. Here we present carbon site-specific measurements of vanillin by GC-IRMS and C-qNMR for methoxy carbon.

Natural Abiotic Iron-Oxido-Mediated Formation of C and C Compounds from Environmentally Important Methyl-Substituted Substrates.

Organic and inorganic volatile compounds containing one carbon atom (C), such as carbon dioxide, methane, methanol, formaldehyde, carbon monoxide, and chloromethane, are ubiquitous in the environment, are key components in global carbon cycling, play an important role in atmospheric physics and chemistry, e.g., as greenhouse gases, destroy stratospheric and tropospheric ozone, and control the atmospheric oxidation capacity.

Methane accumulation and its potential precursor compounds in the oxic surface water layer of two contrasting stratified lakes.

Methane (CH) supersaturation in oxygenated waters is a widespread phenomenon despite the traditional perception of strict anoxic methanogenesis. This notion has recently been challenged by successive findings of processes and mechanisms that produce CH in oxic environments. While some of the processes contributing to the vertical accumulation of CH in the oxygenated upper water layers of freshwater lakes have been identified, temporal variations as well as drivers are still poorly understood.

Methane formation driven by light and heat prior to the origin of life and beyond.

Methane is a potent greenhouse gas, which likely enabled the evolution of life by keeping the early Earth warm. Here, we demonstrate routes towards abiotic methane and ethane formation under early-earth conditions from methylated sulfur and nitrogen compounds with prebiotic origin. These compounds are demethylated in Fenton reactions governed by ferrous iron and reactive oxygen species (ROS) produced by light and heat in aqueous environments.

Radical-Driven Methane Formation in Humans Evidenced by Exogenous Isotope-Labeled DMSO and Methionine.

Methane (CH), which is produced endogenously in animals and plants, was recently suggested to play a role in cellular physiology, potentially influencing the signaling pathways and regulatory mechanisms involved in nitrosative and oxidative stress responses. In addition, it was proposed that the supplementation of CH to organisms may be beneficial for the treatment of several diseases, including ischemia, reperfusion injury, and inflammation. However, it is still unclear whether and how CH is produced in mammalian cells without the help of microorganisms, and how CH might be involved in physiological processes in humans.

Effect of immune responses on breath methane dynamics.

Methane (CH) which can be detected in human breath has long been exclusively associated with anaerobic microbial activity (methanogenesis) in the gastrointestinal tract. However, recent studies challenge this understanding by revealing that CHmight also be produced endogenously in cells through oxidative-reductive stress reactions. Consequently, variations in breath CHlevels compared to an individual's baseline level might indicate enhanced oxidative stress levels, and, therefore, monitoring breath CHlevels might offer great potential for '' diagnostics such as disease diagnosis, monitoring the efficacy of treatments, or during the application of personalized medicine.

ROS-driven cellular methane formation: Potential implications for health sciences.

Recently it has been proposed that methane might be produced by all living organisms via a mechanism driven by reactive oxygen species that arise through the metabolic activity of cells. Here, we summarise details of this novel reaction pathway and discuss its potential significance for clinical and health sciences. In particular, we highlight the role of oxidative stress in cellular methane formation.

Making plant methane formation visible-Insights from application of C-labeled dimethyl sulfoxide.

Methane (CH) formation by vegetation has been studied intensively over the last 15 years. However, reported CH emissions vary by several orders of magnitude, thus making global estimates difficult. Moreover, the mechanism(s) for CH formation by plants is (are) largely unknown.

Methane formation driven by reactive oxygen species across all living organisms.

Methane (CH), the most abundant hydrocarbon in the atmosphere, originates largely from biogenic sources linked to an increasing number of organisms occurring in oxic and anoxic environments. Traditionally, biogenic CH has been regarded as the final product of anoxic decomposition of organic matter by methanogenic archaea. However, plants, fungi, algae and cyanobacteria can produce CH in the presence of oxygen.

A surprise from the deep.

Isotope patterns of methoxyl groups reveal the origin an d production potential of methane from coal.

C-chloromethane incubations provide evidence for novel bacterial chloromethane degraders in a living tree fern.

Chloromethane (CH Cl) is the most abundant halogenated volatile organic compound in the atmosphere and contributes to stratospheric ozone depletion. CH Cl has mainly natural sources such as emissions from vegetation. In particular, ferns have been recognized as strong emitters.

Temperature signal recorded in δH and δC values of wood lignin methoxyl groups from a permafrost forest in northeastern China.

Stable isotopes in wood lignin methoxyl groups (δH and δC values) have been suggested as valuable complementary paleoclimate proxies. In permafrost forests, tree growth is influenced by multiple factors, however temperature appears to have the strongest impact on tree growth and, therefore, on carbon cycling. To test whether δH and δC values of trees from permafrost regions might record climate parameters, two dominant tree species (Larix gmelinii, larch, and Pinus sylvestris var.

Sources and sinks of chloromethane in a salt marsh ecosystem: constraints from concentration and stable isotope measurements of laboratory incubation experiments.

Chloromethane (CHCl) is the most abundant long-lived chlorinated organic compound in the atmosphere and contributes significantly to natural stratospheric ozone depletion. Salt marsh ecosystems including halophyte plants are a known source of atmospheric CHCl but estimates of their total global source strength are highly uncertain and knowledge of the major production and consumption processes in the atmosphere-halophyte-soil system is yet incomplete. In this study we investigated the halophyte plant, Salicornia europaea, and soil samples from a coastal salt marsh site in Sardinia/Italy for their potential to emit and consume CHCl and using flux measurements, stable isotope techniques and Arrhenius plots differentiated between biotic and abiotic processes.

High Spatiotemporal Dynamics of Methane Production and Emission in Oxic Surface Water.

The discovery of methane (CH) accumulation in oxic marine and limnic waters has redefined the role of aquatic environments in the regional CH cycle. Although CH accumulation in oxic surface waters became apparent in recent years, the sources are still subject to controversial discussions. We present high-resolution in situ measurements of CH concentration and its stable isotope composition in a stratified mesotrophic lake.

Chlorine Isotope Fractionation of the Major Chloromethane Degradation Processes in the Environment.

Chloromethane (CHCl) is an important source of chlorine in the stratosphere, but detailed knowledge of the magnitude of its sources and sinks is missing. Here, we measured the stable chlorine isotope fractionation (ε) associated with the major abiotic and biotic CHCl sinks in the environment, namely, CHCl degradation by hydroxyl (OH) and chlorine (Cl) radicals in the troposphere and by reference bacteria CM4 and MB2 from terrestrial and marine environments, respectively. No chlorine isotope fractionation was detected for reaction of CHCl with OH and Cl radicals, whereas a large chlorine isotope fractionation (ε) of -10.

Methane Production and Bioactivity-A Link to Oxido-Reductive Stress.

Biological methane formation is associated with anoxic environments and the activity of anaerobic prokaryotes (Archaea). However, recent studies have confirmed methane release from eukaryotes, including plants, fungi, and animals, even in the absence of microbes and in the presence of oxygen. Furthermore, it was found that aerobic methane emission in plants is stimulated by a variety of environmental stress factors, leading to reactive oxygen species (ROS) generation.

Methylotrophs and Methylotroph Populations for Chloromethane Degradation.

Chloromethane is a halogenated volatile organic compound, produced in large quantities by terrestrial vegetation. After its release to the troposphere and transport to the stratosphere, its photolysis contributes to the degradation of stratospheric ozone. A better knowledge of chloromethane sources (production) and sinks (degradation) is a prerequisite to estimate its atmospheric budget in the context of global warming.

Methyl sulfates as methoxy isotopic reference materials for δ C and δ H measurements.

Rationale: Stable hydrogen and carbon isotope ratios of methoxy groups (OCH ) of plant organic matter have many potential applications in biogeochemical, atmospheric and food research. So far, most of the analyses of plant methoxy groups by isotope ratio mass spectrometry have employed liquid iodomethane (CH I) as the reference material to normalise stable isotope measurements of these moieties to isotope-δ scales. However, comparisons of measurements of stable hydrogen and carbon isotopes of plant methoxy groups are still hindered by the lack of suitable reference materials.

Nitrous oxide effluxes from plants as a potentially important source to the atmosphere.

The global budget for nitrous oxide (N O), an important greenhouse gas and probably dominant ozone-depleting substance emitted in the 21 century, is far from being fully understood. Cycling of N O in terrestrial ecosystems has traditionally exclusively focused on gas exchange between the soil surface (nitrification-denitrification processes) and the atmosphere. Terrestrial vegetation has not been considered in the global budget so far, even though plants are known to release N O.

Chloromethane formation and degradation in the fern phyllosphere.

Chloromethane (CHCl) is the most abundant halogenated trace gas in the atmosphere. It plays an important role in natural stratospheric ozone destruction. Current estimates of the global CHCl budget are approximate.

Chloromethane Degradation in Soils: A Combined Microbial and Two-Dimensional Stable Isotope Approach.

Chloromethane (CHCl, methyl chloride) is the most abundant volatile halocarbon in the atmosphere and involved in stratospheric ozone depletion. The global CHCl budget, and especially the CHCl sink from microbial degradation in soil, still involves large uncertainties. These may potentially be resolved by a combination of stable isotope analysis and bacterial diversity studies.